I wrote my last blog in the middle of a heat wave that covered the city where I live along with great swaths of the East Coast and other parts of the world. The heat wave lasted almost a week; by Thursday, July 5th, peak temperature here in NYC was still above 90oF. Last time, I promised to examine the impacts of climate change on the global wine industry but I have decided to postpone the topic by another week. When I was writing my last post, I experienced a feeling that many might find familiar – guilt about the way I live.

Last week I included some of the ways I was handling the heat, namely: air conditioning and visiting family who live in the suburbs and have a pool.

I emphasized that these options are available to me but not to billions of people all around the world – including many other New Yorkers and Americans. However, I didn’t mention the ways in which these luxuries that make my life more comfortable actually contribute to the warming of the climate. These aspects include my drive out to the suburbs and the massive amount of power required for my nonstop use of air conditioning at home. There are ways in which I could have done everything I wanted without contributing to climate change, but I didn’t bother to try. I use my classes and my blog to teach and (mostly inadvertently) preach about the dangers of climate change but often forget to listen to my own message. Unfortunately, I am not alone in this dilemma.

On October 4, 2016 I wrote a blog about similar practices by Al Gore – probably the US’s greatest advocate for mitigating our emissions that cause climate change:

Al Gore is now a rich and famous man. A short internet search brings up images of his mansion in California, which puts the Nashville one to shame, but the sheer size of these buildings requires a lot of energy. If the energy use approximately matches the average energy mix in the US, it generates large amount of greenhouse gases. I didn’t follow up on his efforts to cut down on energy usage and replace his energy sources with a more sustainable mix. However, the message from his personal life certainly undermined his message to society and, if nothing else, served as a combustible weapon in the hands of climate deniers who refuse to heed his plea.

I am guilty of the same hypocrisy on a smaller scale.

I showed the following graph in previous blogs (December 10, 2012 and September 26, 2017) to illustrate climate sensitivity (increase in global temperature as a function of the increased atmospheric concentration of carbon dioxide):

IPCC equilibrium global mean temperature increaseFigure 1

The graph shows the expected rise in temperature as a function of possible rise in atmospheric concentrations of carbon dioxide, in the form of a broad band bisected by a dark line. I have already discussed the origin of the band and how it represents the uncertainty in estimating the exact value of the temperature rise. This is because two thirds of the driving forces behind the temperature rise do not come from direct exposure to greenhouse gases such as carbon dioxide but rather feedback to the direct heating. The feedback comes from physical heat-dependent driving forces such as changes in the atmospheric water vapor, clouds, snow melt, permafrost melt, changes in solubility of carbon dioxide in the ocean, etc. The J. Hansen et. al. manuscript, “Climate Sensitivity: Analysis of Feedback Mechanisms” (1984), is an excellent early paper on many of these feedback mechanisms.

The extent of these feedback mechanisms cannot yet be predicted quantitatively.

To my knowledge, human feedback – as in the repercussions of the actions we take to make our lives a bit more bearable when the impacts strike – has never quantified in comparison to the above-mentioned natural feedback to direct heating. There is no question in my mind that its importance will increase along with the direct impact, thus accelerating the damage.

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Heat Wave

My school’s academic year is over and the summer break has started in full swing. Usually I take this time for a vacation and some new research initiatives. It is not surprising that I have far more flexibility now than during the academic year. This enables me to keep in contact with family and friends. Last week was no different. Wine drinking is not uncommon on such occasions. But during such happy times, questions often arise regarding the future of wine making as climate change takes its toll. This issue is particularly important in the context of French wine because it is based on the notion of “terroir,” which links the style of wine to a specific location. If we drink Bordeaux wine it means that the grapes and the winery are from the Southwest region of France around the city of Bordeaux; Champagne comes from the Champagne wine region in Northern France, etc. Since climate change shifts the climatic regions, such an affiliation will start to be problematic, so it is a valid question how much of this shift is already happening. Well, this sounded like a great topic for a blog. I started to collect the material and was ready to start writing on Friday (June 29th). I got up early, picked up my phone, and the first thing that I saw was an urgent warning from a weather application powered by NOAA (National Oceanic and Atmospheric Administration):

Heat Advisory in effect from Saturday, 12:00 PM EDT until Saturday, 9:00 PM EDT. Source: U.S. National Weather Service

It had some specific notes for the place where I live:



The National Weather Service in Upton has issued a Heat Advisory, which is in effect from noon to 9 PM EDT Saturday.

* HEAT INDEX VALUES …In the upper 90s. Heat index values will be at least a few degrees higher on Sunday.

* TIMING …Highest heat indices in the mid to late afternoon.

* IMPACTS …Extreme heat can cause illness and death among at- risk population who cannot stay cool. The heat and humidity
may cause heat stress during outdoor exertion or extended

I immediately went to a site that gave me more specifics in terms of combining heat and humidity to provide me with the “heat index” mentioned above. Figure 1 shows this conversion, followed by definitions that translate the warnings into more specific terms.

Figure 1


Heat Wave:  At least 3 consecutive days with high temperatures of at least 90 degrees.

Highest Temperatures:  Mid July through mid August across interior locations.

Heat Index:  An estimate of how hot it feels when air temperature and humidity are combined.

Heat Advisory:  Issued when the heat index is forecast to reach 95 to 99F for at least 2 consecutive days or 100 to 104F for any length of time.

Excessive Heat:  Issued when heat index values are forecast to reach or exceed 105°F for at least 2 consecutive hours.
Watch is issued 24 to 48 hours of the event.
Warning is issued within 24 hours of the event.

The warning focused on Friday and Saturday and hinted that Sunday would be worse. Further searching made it clear that this weather was not confined to NYC. Figure 2 shows the weather projections over the Eastern parts of US and Canada and the map is almost solid red.

Figure 2

Shortly after this on Friday morning, I had my breakfast and read my local morning paper and found the following piece:

Climate change could sharply diminish living conditions for up to 800 million people in South Asia, a region that is already home to some of the world’s poorest and hungriest people, if nothing is done to reduce global greenhouse gas emissions, the World Bank warned Thursday in an ominous new study.

The study noted that some of the hottest parts of the region are getting hotter, faster. From 1950 to 2010, for example, western Afghanistan and southwestern Pakistan have already seen average temperatures rise in the range of 1 degree Celsius to 3 degrees per year.

By contrast, some of the cooler countries of the region, like Nepal, will not be sharply affected by rising temperatures. But that will not necessarily make up for the risks those countries face from extreme weather events, the study concluded.

The intensity of outcomes vary depending on future measures to reduce greenhouse gas emissions. For instance, across South Asia annual average temperatures are projected to rise by 2.2 degrees Celsius (3.9 degrees Fahrenheit) by 2050 under a high emissions scenario, and by 1.6 degrees Celsius if steps are taken to reduce global emissions.

Half a planet away the situation is similar, with hundreds of millions of people subjected to equal miseries but they lack the resources to protect themselves with air conditioning and other comforts that many of us here have at our disposal.

Friday evening I had plans in the city. I took the subway, which was air-conditioned and comfortable, as was the theater that I visited. On Sunday I had a family engagement in the suburbs. My family has a small swimming pool that we were invited to share. That was great while you were in the pool itself but getting in and out, walking on the concrete floor was impossible. Driving to and from the suburbs in an air-conditioned car was a pleasure. The car’s external thermometer recorded an outside temperature around 102oF (39oC) both ways. Back home, my apartment has a thermometer that records outside temperature. During the last 4 days it floated between the upper 90s (F) and lower 100s. I had no way to directly measure the outside humidity aside from knowing it was high but Figure 1 tells me that the heat index was around 110o.

I grew up in Israel so I am used to high temperatures and humidity. This was not a big deal for me because I am well equipped to handle it, unlike many people in NYC or even more around the world. Such people can become desperate, sick, or even die. Leaving climate change on its current trajectory will make life for all of us much more uncomfortable and dangerous.

The impact on wine will wait for next week.

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Vulnerabilities: Coral Reefs

In one of my earliest blogs (July 31, 2012), I talked a little bit about the start of my interest in man-made contributions to global climate change. Up until that time my main academic interest was focused on energy use. I grew up in Israel, where energy played an important role in political development: almost all the energy that people used was powered by fossil fuels, a significant amount of which came out of Arab countries that were in a state of war with Israel. Many Israeli scientists worked hard to develop alternative energy sources, reducing the world’s dependence on fossil fuels and their suppliers. Sustainability didn’t play much of a role in these considerations because the resources seemed almost limitless.

Suddenly, in 1992 the world became aware of the impact of carbon dioxide on the climate. The Earth Summit (see the November 3, 2015 blog) and the famous Keeling-Whorf curve (December 1, 2015 blog) of the accelerating accumulation of carbon dioxide in the atmosphere showed CO2 levels to have major impacts on changing the chemical composition of the atmosphere, driving changes in the planetary energy balance with the sun. I spent the next five years after the Energy Summit trying to figure out how I could contribute to the study of this occurrence. In 1996–97 the world press was full of stories that a significant increase in sea-surface temperature affects almost all coral species, leading to global coral bleaching and mortality. Some of the bleached corals were more than 1,000 years old. 1997 was also the National Oceanic and Atmospheric Administration’s (NOAA) Year of the Coral Reef. At that time I had already decided that since the main imbalance in the carbon dioxide concentration comes from our use of fossil fuels, the only way that we can impact these emissions is by shifting our energy sources away from fossil fuels. I was also sure that these changes must be global and include as many people as possible in the decision making process. I started to work on a book to try to explain climate change to the general public, making sure to include descriptions of the bleached corals.

At that time I was already an advanced-middle-aged guy. My wife was younger but not by much. In the summer of 1997 she happened to have a conference in the Yucatan Peninsula in Mexico. I went along. We manage to find the time to take a diving course that gave us a diving certificate. The next year we went to Northern Queensland in Australia to spend a week diving around the Great Barrier Reef.

Figure 1 shows a photograph that my wife took of a bleached coral. The photograph ended up in my book (Climate Change: The Fork at the End of Now – Momentum Press) in the chapter dedicated to early signs.

   Figure 1 – A bleached coral

Since that time, some of the corals were able to recuperate but then more heat waves came, adding to the carnage.

Two recent pieces from The Economist summarize most of the impact:

The impact of climate change on the Great Barrier Reef

Under prolonged stress corals can expel algae, causing them to starve and die. About a fifth of the reef’s corals died from the 2016 bleaching. In the northern region, where bleaching was most intense, the coral mortality figure was alarming: about two-thirds. Depending on different coral species’ capacity to resist stress, and the distribution of heat patterns through waters, reefs can revive over several years. The difference this time, say experts, is that back-to-back bleaching from two successive seasons of extreme heat have given the reef no time to recover, and have lowered its corals’ stress tolerance. It is too early to measure coral deaths from the 2017 bleaching, but the Climate Council predicts “high mortality rates”.

The second piece examines the long-term history of the impact. It’s based on new research by scientists from the University of Sidney, published in Nature Geoscience:

Australia’s coral barrier reef keeps dying and coming back

Figure 2

Figure 3

The reality of the Great Barrier Reef’s existence is that it is a movable feast. Reef-forming corals prefer shallow water so, as the world’s sea levels have yo-yoed during the Ice Ages, the barrier reef has come and gone. The details of this have just been revealed in a paper published in Nature Geoscience by Jody Webster of the University of Sydney and her colleagues. The authors examined cores drilled through the reef in different places. They discovered, as the chart shows that it has died and then been reborn five times during the past 30,000 years. Two early reefs were destroyed by exposure as sea levels fell. Three more recent ones were overwhelmed by water too deep for them to live in, and also smothered by sediment from the mainland. The current reef is therefore the sixth of the period.

Figures 2 and 3 show that the history goes back around 30,000 years, and cover the last ice age’s drastic impacts on sea level changes. Following these changes, the corals died when their habitat went dry and revived when the sea levels rose again to create a new habitat. These changes took thousands of years but they show that over a long period of time corals can adapt to major environmental changes. However, none of these previous changes mimic those that we are inflicting upon the oceans now.

Nor are the impacts restricted to the Great Barrier Reef; they are global. Figure 4 shows the global distribution of the thermal stress.

Figure 4

Here is how the World Resources Institute explains this figure:

Mapping of past thermal stress on coral reefs (1998–2007) suggests that almost 40 percent of reefs may have been affected by thermal stress, meaning they are located in areas where water temperatures have been warm enough to cause severe bleaching on at least one occasion since 1998. This figure shows the estimated percentage of reefs per region that experienced thermal stress based on the satellite-detected thermal stress and coral bleaching observations shown in Map 3.2: Thermal Stress on Coral Reefs, 1998-2007.

The stress is not limited to the thermal impact. Acidity changes due to absorption of carbon dioxide in the water inflict stresses of their own that I will cover in a separate blog. None of us will live to see the reversibility of the coral’s decline.

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Uncertainties Can Bring The Best Possible Outcomes, The Worst Possible Outcomes, and Everything In Between: Ocean Currents

I have addressed uncertainty on a number of previous occasions (December 10, 2012; May 16, 2017; January 9, 2018; and other blogs) but some important work came to light recently that put this idea to a test. Most of the uncertainty in predicting impacts of climate change originates from positive feedbacks to direct heating of the planet (such feedback takes various forms, such as increased humidity, melting ice, melting frozen tundra, changes in the ability of oceans to store carbon dioxide, etc.). The impacts of these feedbacks and their extensions vary. Deniers use the ambiguity as an excuse to do nothing, saying that they will take actions to save the world once they are sure of what’s happening. Attempts to show that by the time we can be “certain” it will be too late have met with limited success.

I, along with the IPCC, and most other scientists, am working hard to try to convince people of the above point. Wikipedia defines risk management in the following way:

Risk management is the identification, evaluation, and prioritization of risks (defined in ISO 31000 as the effect of uncertainty on objectives) followed by coordinator and economical application of resources to minimize, monitor, and control the probability or impact of unfortunate events[1] or to maximize the realization of opportunities. Risk management’s objective is to assure uncertainty does not deflect the endeavor from the business goals.[2]

Almost every respectable business above a particular size employs people to estimate risks and advise management on strategies for addressing them. When unexpected disaster strikes, all eyes go to these people: what were their expectations? Did they give management warnings? How did management react to these warnings?

Who is in charge of risk management in the US government?!

The important work that I am addressing here refers directly to predictions of key impacts of climate change, as expressed in the IPCC’s 4th Report (AR4). I addressed some of these in my April 24, 2018 blog, including, “ecosystem changes due to weakening of the Meridional Overturning Circulation (MOC).” The IPCC predicts the most serious effects to be triggered as global temperature rises by 4.5oC. Business as usual scenarios calculate that this temperature rise will not take effect until the end of the century. Here are some of the impacts of such changes, according to AR4: Possible changes in the North Atlantic meridional overturning circulation (MOC)

Potential impacts associated with MOC changes include reduced warming or (in the case of abrupt change) absolute cooling of northern high-latitude areas near Greenland and north-western Europe, an increased warming of Southern Hemisphere high latitudes, tropical drying (Vellinga and Wood, 2002, 2006; Wood et al., 2003, 2006), as well as changes in marine ecosystem productivity (Schmittner, 2005), terrestrial vegetation (Higgins and Vellinga, 2004), oceanic CO2 uptake (Sarmiento and Le Quéré, 1996), oceanic oxygen concentrations (Matear and Hirst, 2003) and shifts in fisheries (Keller et al., 2000; Link and Tol, 2004). Adaptation to MOC-related impacts is very likely to be difficult if the impacts occur abruptly (e.g., on a decadal time-scale). Overall, there is high confidence in predictions of a MOC slowdown during the 21st century, but low confidence in the scale of climate change that would cause an abrupt transition or the associated impacts (Meehl et al., 2007 Section 10.3.4). However, there is high confidence that the likelihood of large-scale and persistent MOC responses increases with the extent and rate of anthropogenic forcing (e.g., Stocker and Schmittner, 1997; Stouffer and Manabe, 2003).

The editorial in the April 2018 volume of Nature (Nature, vol. 556, page 149 (2018)), written by Sammer K. Praetorius, examined two papers published in the same issue. AMOC refers to the Atlantic meridional overturning circulation:

North Atlantic circulation slows down: Evidence suggests that the circulation system of the North Atlantic Ocean is in a weakened state that is unprecedented in the past 1,600 years, but questions remain as to when exactly the decline commenced. See Article p.191 & Letter p.227

Given the importance of the AMOC to heat exchange between the ocean and the atmosphere, the varying strength of this system is thought to have major impacts on the global cli­mate, and has been implicated widely in some of the most remarkable and abrupt climate changes of the past2. Direct measurements of the mod­ern AMOC flow rates show a decline in its strength in the past decade3. Reconstructions of the natural vari­ability and long-term trends of the AMOC are needed, however, to put these recent changes in context. In this issue, Caesar et al.4 (page 191) and Thornalley et al.5 (page 227) report on past AMOC variability using dif­ferent approaches. Both conclude that the modern AMOC is in an unusually subdued state, but they diverge in the details of how and when the AMOC’s decline commenced.

The researchers found that the strength of the AMOC was relatively stable from about ad 400 to 1850, but then weakened around the start of the industrial era. This transition coincides with the end of the Lit­tle Ice Age — a multi-centennial cold spell that affected many regions of the globe10. Thornalley and colleagues infer that the weakening of the AMOC at that time was probably a result of the input of fresh water from the melting of Little Ice Age glaciers and sea ice. They estimate that the AMOC declined in strength by about 15% during the industrial era, relative to its flow in the preceding 1,500 years. This is remarkably similar to Caesar and co-workers’ estimate, despite the different time periods on which they base their estimates.

However, the roughly 100-year dif­ference in the proposed timing of the start of the AMOC decline in these two studies has big implications for the inferred trigger of the slowdown. Caesar et al. clearly put the onus on anthropogenic forcing, whereas Thornalley et al. suggest that an earlier decline in response to natural climate variability was perhaps sustained or enhanced through further ice melting associated with anthropogenic global warming. Nevertheless, the main culprit in both scenarios is surface-water freshening.

The two studies are classic examples of ‘top-down’ and ‘bottom-up’ approaches, and so it is unsurpris­ing that there is some misalignment between them. Caesar et al. take the top-down approach: their inferences of changes in the AMOC strength are made from reconstructions of regional and global SSTs that are derived from direct measurements of temperature. It is possible that regions other than the North Atlantic in which there has been decadal-scale variability in SSTs could influence the mean global SST from which the AMOC strength is calculated — although the authors do attempt to quell such doubts by showing that the subpolar-gyre SST anomaly is robust relative to the global mean SST for a subset of time periods (see Extended Data Fig. 2 in ref. 4).

Figure 1 shows a good representation of global ocean currents, otherwise known as the Global Conveyor Belt, with key focus on the North Atlantic current.

The figure also provides a short description of the roles that these currents play in the storage of carbon dioxide. Once these currents stop, the carbon dioxide that cannot be stored locally will end up in the atmosphere, adding to the feedback and amplifying the impact.

Figure 1

Using two different research approaches, the two papers show that the impacts are not relegated to some distant future (in a human time scale) but are already well underway. There is a difference in their findings (not surprising given the dissimilar methodologies) as to the start of the weakening of these currents, meaning they also present different views of the role that anthropogenic climate change plays in the process. There is no dispute, however, that climate change, with its associated melting of polar ice and homogenization of ocean temperature, has a large role in amplifying this impact. With uncertainty, the worst probable outcome can, and often does, come to pass.

Slowing of ocean currents is not the only climate change impact that is “worse than predicted.” The last few weeks brought a global response to new research published in Nature that the polar ice in Antarctica is melting at a much faster pace than previously predicted and is causing major changes in the resulting predictions for global sea level rise.

Stay tuned!

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The Economic Impacts of Ocean Decline

Last week’s blog about the Ocean Health Index stressed the importance of including the sustainability of human impacts in any discussions about ocean health (this accounted for about 50% of the indexing). This blog will focus on the economic impacts of our declining oceans. For quite some time, I was thinking it would have been convenient if the World Bank had compiled a study of the “blue economy” as a separate indicator that would allow us to do a comparative economic and environmental analysis. We have done similar comparisons with “employment in agriculture” and “agricultural value added” in a previous blog (March 27, 2018). In principle, we can use the Ocean Health Index for this purpose but as yet, it suffers some problematic deficiencies – namely that it focuses on territorial waters and its understanding of “sustainability” is driven by human needs rather than human deeds.

The World Bank recognized this earlier omission and published a report on April 6, 2018, focused on some of these issues: “Oceans, Fisheries and Coastal Economies.” It includes some detailed examples of what the World Bank is doing to address some of the specific issues listed below. The data in this section of the report were taken from FAO (Food and Agricultural Organization of the United Nation), which incorporates the UN data on fisheries and other oceanic activities.


Billions of people worldwide —especially the world’s poorest— rely on healthy oceans to provide jobs and food, underscoring the urgent need to sustainably use and protect this natural resource.

According to the OECD, oceans contribute $1.5 trillion annually in value-added to the overall economy. The FAO estimates that fisheries and aquaculture assure the livelihoods of 10-12 percent of the world’s population with more than 90 percent of those employed by capture fisheries working in small-scale operations in developing countries. In 2014, fisheries produced roughly 167 million tons of fish and generated over US$148 billion in exports, while securing access to nutrition for billions of people and accounting for 17 percent of total global animal protein — even more in poor countries.

Healthy oceans, coasts and freshwater ecosystems are crucial for economic growth and food production, but they are also fundamental to global efforts to mitigate climate change. “Blue carbon” sinks such as mangroves and other vegetated ocean habitats sequester 25 percent of the extra CO2 from fossil fuels and protect coastal communities from floods and storms. In turn, warming oceans and atmospheric carbon are causing ocean acidification that threatens the balance and productivity of the oceans.

While ocean resources have the potential to boost growth and wealth, human activity has taken a toll on ocean health. Fish stocks have deteriorated due to overfishing — the share of fish stocks outside biologically sustainable levels rose from 10 percent in 1974 to 32 percent in 2013, while in the same year approximately 57 percent of fish stocks were fully exploited. Fish stocks are affected by illicit fishing, which may account for up to 26 million tons of fish catches a year or more than 15 percent of total catches. In fact, poor fisheries management squanders roughly US$80 billion annually in lost economic potential and 11 percent in catch potential. Fish habitats are also under pressure from pollution, coastal development, and destructive fishing practices that undermine fish population rehabilitation efforts.

Oceans are also threatened by marine plastic pollution and each year, an estimated 8 million tons of plastic enter the oceans, with microplastics becoming part of the food chain. Scientists estimate that without urgent action, there could be more plastic than fish in the ocean by 2050.  While complex, the issue of ocean plastic waste is a solvable challenge. Five countries are responsible for more than 50 percent of total plastic waste in the oceans (China, Indonesia, Vietnam, Philippines, and Thailand). We also know that an estimated 80 percent of ocean plastic pollution originates from inadequate land-based solid waste management.

Proper management of fisheries, investment in sustainable aquaculture and protection of key habitats can restore the productivity of the ocean and return benefits to billions in developing countries while ensuring future growth, food security and jobs for coastal communities.

The report highlights the global picture, estimating that the oceans contribute $1.5 trillion annual added value to the global economy (out of $76 trillion in current US dollars); fisheries and aquaculture assure the livelihoods of 10-12% of the world population, with more than 90% of those employed by capture fisheries working in small-scale operations in developing countries. The report also emphasizes that the captured fish secure access to nutrition for billions of people, accounting for 17% of total globally consumed animal protein – a percentage even higher in poorer countries.

Going back to the original 2016 FAO report, Figure 1 shows some of the data for the distribution of production of aquaculture.

Figure 1

Here is what this report says about employment in this sector:

Many millions of people around the world find a source of income and livelihood in the fisheries and aquaculture sector. The most recent estimates (Table 10) indicate that 56.6 million people were engaged in the primary sector of capture fisheries and aquaculture in 2014. Of this total, 36 percent were engaged full time, 23 percent part time, and the remainder were either occasional fishers or of unspecified status.

Table 10 in the report indicates 47.7 million people (out of the global 56.6 million) employed in aquaculture activities are in Asia, 5.7 million in Africa, 2.4 million in Latin America and the Caribbean’s and the rest from Europe, Oceania and North America. Converting these numbers to percentage yields: 84% in Asia, 10% in Africa, 4% in Latin America and 2% from the rest of the world.

Table 11 in this report indicates that China (30% of Asian fisheries) and Indonesia (13%) are the two largest practitioners.

Figure 2 illustrates the changes in global aquaculture production in the context of the increase in global (human) population.

Figure 2

Comparison of global activities of aquaculture production with those of individual countries is difficult. One reason for this difficulty is the multitude of definitions of what constitutes ocean economy. The 2014 paper, “Rebuilding the Classification System of the Ocean Economy” (Journal of Ocean and Coastal Economics: Vol. 2014: Iss. 1, Article 4.), attempted to compare some of these definitions:

Definition of the Ocean Economy by Country

Nevertheless, I find it instructive to compare the extent of the US ocean economy with the global one as depicted by the World Bank and the United Nations. The data describing the US ocean economy are taken from the Surfrider Foundation and are summarized in Figures 3 and 4

Source: State of the U.S. Ocean and Coastal Economies, National Ocean Economics Program, 2009

Figure 3

Source: State of the U.S. Ocean and Coastal Economies, National Ocean Economics Program, 2009

Figure 4

As can be seen in these two figures, the tourism and recreation industries dominate the ocean economy – both in terms of GDP contribution and especially with regards to employment. More data focused on the US ocean economy can be found within a NOAA-financed report.

I started this series of blogs focusing on the human impact on the oceans, citing a recent study that attributes the 4th mass extinction to the suffocation of ocean life due to lack of oxygen. The biggest question is what will happen if history repeats itself. If we create similar conditions by raising the temperature, increasing the acidity, exhausting the oxygen content, or combination these inputs within the oceans we will cause such drastic changes in conditions we might eradicate all life within them. Will life on land follow?

People all around the world are starting to think about these issues. Perhaps unsurprisingly, most are less focused on decreasing the damage and more interested in how best to harvest resources in the deeper parts of the oceans that have so far been spared most of the destruction.

Stay tuned.

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Ocean Health Issues – How Do We Measure Health?

Last week’s blog was an introduction to the vulnerabilities that we face with the deterioration of our oceans. It paid particular attention to the recently published study of evidence associating the 4th mass extinction with ocean deoxygenation – which effectively suffocated all existing oceanic life.

Today starts a series in which we try to follow the present state of our oceans’ health and how they are impacted by anthropogenic climate change. Here are two competing approaches:

The first method lists the rapid (on a geological time scale) physical changes that oceans are experiencing; left unabated such transformations will eventually extinguish all life within these bodies of water. I am citing information from the Climate Science Special Report: Fourth National Climate Assessment (CSSR NCA4), Volume I (see August 15, 2017 and January 30, 2018 blogs), an authoritative evaluation of the science of climate change, with a focus on the United States, as mandated by the Global Change Research Act of 1990.

The second approach relies on recently compiled data in the Ocean Health Index. This new methodology was initiated by a group of scientists who held the opinion that the current attitude of describing the health of oceans is based too heavily on negative indicators. Instead, they proposed an index anchored on a popular definition of sustainability and mostly measured in the territorial waters of individual countries.

I will start with the general introduction to Chapter 13 of the CSSR report:

13.0: A Changing Ocean

Anthropogenic perturbations to the global Earth system have included important alterations in the chemical composition, temperature, and circulation of the oceans. Some of these changes will be distinguishable from the background natural variability in nearly half of the global open ocean within a decade, with important consequences for marine ecosystems and their services. However, the timeframe for detection will vary depending on the parameter featured.

Here I will show some data on the recent accumulation of ocean heat content and ocean heat feedback as they have major impacts on sea level rise. Future blogs will focus on the other indicators that are only mentioned briefly here. Chapter 12 of the CSSR report is fully devoted to sea level rise, which I have repeatedly discussed.

13.1: Ocean Warming

13.1.1 General Background

Approximately 93% of excess heat energy trapped since the 1970s has been absorbed into the oceans, lessening atmospheric warming and leading to a variety of changes in ocean conditions, including sea level rise and ocean circulation (see Ch. 2: Physical Drivers of Climate Change, Ch. 6: Temperature Change, and Ch. 12: Sea Level Rise in this report). , This is the result of the high heat capacity of seawater relative to the atmosphere, the relative area of the ocean compared to the land, and the ocean circulation that enables the transport of heat into deep waters. This large heat absorption by the oceans moderates the effects of increased anthropogenic greenhouse emissions on terrestrial climates while altering the fundamental physical properties of the ocean and indirectly impacting chemical properties such as the biological pump through increased stratification. , Although upper ocean temperature varies over short- and medium timescales (for example, seasonal and regional patterns), there are clear long-term increases in surface temperature and ocean heat content over the past 65 years. , ,

13.1.2 Ocean Heat Content

Fig. 1
Global Ocean heat content change time series. Ocean heat content from 0 to 700 m (blue), 700 to 2,000 m (red), and 0 to 2,000 m (dark gray) from 1955 to 2015 with an uncertainty interval of ±2 standard deviations shown in shading. All time series of the analysis performed by Cheng et al. are smoothed by a 12-month running mean filter, relative to the 1997–2005 base period. (Figure source: Cheng et al. 2017).

13.1.3 Sea Surface Temperature and U.S. Regional Warming

13.1.4 Ocean Heat Feedback

The residual heat not taken up by the oceans increases land surface temperatures (approximately 3%) and atmospheric temperatures (approximately 1%), and melts both land and sea ice (approximately 3%), leading to sea level rise (see Ch. 12: Sea Level Rise). , , The meltwater from land and sea ice amplifies further subsurface ocean warming and ice shelf melting, primarily due to increased thermal stratification, which reduces the ocean’s efficiency in transporting heat to deep waters. Surface ocean stratification has increased by about 4% during the period 1971–2010 due to thermal heating and freshening from increased freshwater inputs (precipitation and evaporation changes and land and sea ice melting). The increase of ocean stratification will contribute to further feedback of ocean warming and, indirectly, mean sea level. In addition, increases in stratification are associated with suppression of tropical cyclone intensification, retreat of the polar ice sheets, and reductions of the convective mixing at higher latitudes that transports heat to the deep ocean through the Atlantic Meridional Overturning Circulation. Ocean heat uptake therefore represents an important feedback that will have a significant influence on future shifts in climate (see Ch. 2: Physical Drivers of Climate Change).

Below are the topics covered in Chapter 13. I will explore these in separate blogs with complementary information from other sources:

13.2: Ocean Circulation

13.3: Ocean Acidification

13.4: Ocean Deoxygenation

13.5: Other Coastal Changes

13.5.1 Sea Level Rise

13.5.2 Wet and Dry Deposition

13.5.3 Primary Productivity

13.5.4 Estuaries

The Ocean Health Index (OHI) approach relies heavily on individual states’ attempts to keep the condition of the oceans sustainable. See my January 5, 2016 post for more about what constitutes sustainability:

The 1987 United Nations’ Brundtland Report (World Commission on Environment and Development) was the first platform to articulate the idea of “sustainable development” to a wide audience. The Report framed it as “…development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” It posited that the only truly sustainable form of progress is that which simultaneously addresses the interlinked aspects of economy, environment and social well-being.

A short paper in Nature by Halpern, Longo, and Zeller covers the process of calculating this index:

An index to assess the health and benefits of the global ocean

Benjamin S. Halpern, Catherine Longo and Dirk Zeller


The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.

Figure 2 illustrates the methodology:

Figure 2Conceptual framework for calculating the index

The authors provide some explanations of their goals:

For six of the ten goals, production (or delivery) of the goal involves activities by people that can negatively feedback on the potential of the goal to be realized (for example, overfishing ultimately reduces the total catch that is available). The six goals include ‘food provision’, ‘artisanal fishing opportunity’, ‘natural products’, ‘tourism and recreation’, ‘coastal livelihoods and economies’, and ‘sense of place’ (for example, visiting cultural sites can have a negative impact on them). This type of sustainability is built into the status assessment for the goals for which it can be assessed and assumed to be neutral in other goals (for example, ‘sense of place’) for which we currently do not have research or data to inform how this feedback works.

By the authors’ own admission, the goals are highly anthropocentric (using the Merriam-Webster definition, “interpreting or regarding the world in terms of human values and experiences”):

Results for individual goals may seem counterintuitive because we assessed ocean health through the lens of coupled human–natural systems. For example, extractive goals such as ‘natural products’ score best when harvest levels are high but sustainable, with inherent impacts on nature captured as pressures on other goals.

The index represents the health of coupled human–natural systems.

You can find a detailed description of the Ocean Health Index here. The website provides the OHI for all the countries with details of the methodology used; they are compiled annually and indicate changes within the last year.

The next blog will focus on aspects and areas of the oceans that relate to livelihood and the vulnerabilities of individual countries.

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Vulnerabilities: Oceans

Let’s get back to vulnerabilities, focusing specifically on the oceans this time. Since they cover 70% of the planet, the health of our oceans is paramount. The connections between anthropogenic climate change and said health are complex and multifaceted, so I’ll spread the topic out over the next few weeks.

Climate change coffee mug, without coffee

Climate change coffee mug with my morning coffee

The coffee mug above was given to me by a graduating student who presented her thesis, “A Heated Atmosphere: Driving Forces in American Attitude Toward Anthropogenic Climate Change,” at Brooklyn College’s Science Day (May 4, 2018).

As you can see, the hot coffee inside the mug changes the map, enlarging deserts, shrinking forests, and illustrating other major transformations to the planet’s geography. It shows the effects of sea level rise, including the disappearance of Florida, Cuba, and much of Central America. Of course the mug is a gimmick but it is a thought provoking one that starts interesting and productive conversations with our guests.

I have repeatedly invoked doomsday scenarios (see an extended series from August 29October 10, 2017) and assessed extinctions in the Anthropocene (February 3, 2015). I tried to analyze the methods used to predict some of these scenarios and the role that climate change plays in these predictions. The February 3, 2015 blog, partially based on a publication in Science magazine that discussed marine defaunation, included some of the most striking projections.

Figure 1 shows the predicted timeline of changes, both on land and in the oceans, and the following paragraph from the same blog post offers some explanation:

Figure 1 – Timeline of marine and terrestrial defauntation

I mentioned that article, “Marine Defaunation: Animal Loss in the Global Ocean,” (Science, 347, 247 (2015)) last week, together with the book The Sixth Extinction by Elizabeth Kolbert. Both publications deal with species extinctions of the past, present, and future. The picture shows an artist’s representation of how the world once looked and how it might look in the future, both on land and in the ocean. As always, there is no way of knowing what the future will actually bring; the best we can do is to base our suppositions on models that we hope can inform us about what the future will entail. In this case, the picture’s scope extends from 50,000 years ago – the approximate time that early modern humans started to spread from Africa to Asia and Europe – to toward the end of this century.

A few days ago, a team published its results from using geological and physics-based tools in a different context. The researchers weren’t aiming to predict the future but rather trying to figure out the reasons for one of the most devastating global extinctions in history: the Ordovician-Silurian extinction, which took place about 450 million years ago. Here’s Wikipedia’s blurb on what we know about it:

The Ordovician–Silurian extinction events, when combined, are the second-largest of the five major extinction events in Earth’s history in terms of percentage of genera that became extinct. This event greatly affected marine communities, which caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, and graptolites.[1] The Ordovician–Silurian extinction occurred during the Hirnantian stage of the Ordovician Period and the subsequent Rhuddanian stage of the Silurian Period.[2] The last event is dated in the interval of 455–430 Ma ago, i.e., lasting from the Middle Ordovician to Early Silurian, thus including the extinction period.[3] This event was the first of the big five Phanerozoic events and was the first to significantly affect animal-based communities.[4]

The new analysis was published in the Proceedings of the National Academy of Science (PNAS), one of our country’s most prestigious and selective scientific publications. Below is the authors’ synopsis:

Abrupt global-ocean anoxia during the Late Ordovician–early Silurian detected using uranium isotopes of marine carbonates

Rick Bartlett, Maya Elrick, James R. Wheeley, Victor Polyak, André Desrochers, and Yemane Asmerom


The Late Ordovician mass extinction (LOME) terminated one of the greatest biodiversity radiations in Earth history eliminating ∼85% of marine animals, and it is coincident with the first major glaciation of the Phanerozoic. To evaluate LOME origins, we use uranium isotopes from marine limestones as a proxy for global-ocean redox conditions. Our results provide evidence of an abrupt global-ocean anoxic event coincident with the LOME onset and its continuation after the biologic recovery, through peak glaciation, and the following early Silurian deglaciation. These results also provide evidence for widespread ocean anoxia initiating and continuing during icehouse conditions.

The essence of this finding is that the massive global extinction took place because of major oxygen deprivation in the ocean, which basically suffocated every living organism that needed the element for respiration. This included photosynthetic organisms that require oxygen for respiration when the sun is not shining. One of the technical terms for such oxygen deprivation is anoxia:

Oceanic anoxic events or anoxic events (anoxia conditions) refer to intervals in the Earth’s past where portions of oceans become depleted in oxygen (O2) at depths over a large geographic area. During some of these events, euxinia, waters that contained H2S hydrogen sulfide, developed.[2] Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them.[3] These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating.[4] Many geologists believe oceanic anoxic events are strongly linked to slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (the release of CO2) as the “central external trigger for euxinia”.[5]

The trigger for the anoxia 450 million years ago was most likely major volcanic eruptions in and around what we now call Siberia. Humans were obviously not a factor then but we are an important one now. Decline in the oxygen content of the oceans is already being recorded but there are other ocean impacts that can lead to the same results (i.e. mass extinctions). The next few blogs will explore some of the specifics, including what we can do to try to mitigate the situation and slow down or limit the already occurring sixth mass extinction.

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Referencing vs. Plagiarism

The semester is about over (only some finals and the graduation ceremony remain). In a few days I’ll be celebrating my birthday – time for a selfie reflecting the integrity of my writing. I addressed some aspects of the ethics of my writing earlier (January 6, 2015) but a lot has happened since then and things do change.

I have been writing this blog for more than six years using basically the same methodology: trying to connect current events to some basic science, focusing on anthropogenic (human-influenced) climate change in a way that people with different backgrounds can relate to. My targeted audience is the general public, including my students. I also have the benefit of editors who, while not trained in the sciences, are much better qualified in writing than I am. This has proved to be an excellent synthesis, the need for which is visible throughout the blog.

Why a return to the ethics question now? It was a Google alert that brought up this story:

Republican lawmaker: Rocks tumbling into ocean causing sea level rise

By Scott Waldman, E&E News May. 17, 2018, 9:10 AM

Originally published by E&E News

The Earth is not warming. The White Cliffs of Dover are tumbling into the sea and causing sea levels to rise. Global warming is helping grow the Antarctic ice sheet.

Those are some of the skeptical assertions echoed by Republicans on the U.S. House of Representatives Science, Space and Technology Committee yesterday. The lawmakers at times embraced research that questions mainstream climate science during a hearing on how technology can be used to address global warming.

The article describes in some detail the confrontation between many committee members and the scientist that testified in front of them. The title comes from a comment by representative Mo Brooks:

Every time you have that soil or rock or whatever it is that is deposited into the seas, that forces the sea levels to rise, because now you have less space in those oceans, because the bottom is moving up.

                                                           Representative Mo Brooks (R–AL)

Even though Representative Brooks’ response is, scientifically speaking, absolutely absurd, I found what happened to the piece itself very interesting. The original (cited above) comes from E&E News. On two consecutive days, Google alerts notified me that a variety of different publications had reprinted the same piece. Direct Googling of the title produced even more. Some of them would not grant me access to the full publication without a subscription. As usual, if I didn’t have one, I skipped it (as I’m sure you do). I pay for subscriptions to many publications and have access to many more through my school’s library, but some of these were not available to me. I have no idea how many publications that repeated the original E&E piece charge for subscription. Are they plagiarizing? is it theft? Did Science magazine, one of the most respected interdisciplinary science magazine that we have, pay to republish the E&E piece? – I have no idea. In general, publications that are directly republishing a piece from another publication do cite the original. And even if they are not directly republishing something, the original is often at least referenced, and a link is placed in the new story.

On the internet, there are rules that govern reprinting or republishing articles. Often, however, those rules are overlooked since most online publications feel that the more their story gets around the internet, the more people will visit their publication’s site, hopefully leading to more readership.

But I was trained in writing scientific papers, in which data and methodology are key so readers can evaluate my arguments based on the data. That way, if they so wish, readers can try to reproduce my data if they disagree with some aspect of my methods. Academic papers also generally include introductions with references to other people’s work and conclusions broader than their own data justify. In cases of more theoretical work, some scientists might not present any data of their own – just new interpretations of data that were already published by other researchers. Almost all scientific papers include extensive lists of references that can be checked and scrutinized.

Given that my blogs and my teaching target the general public, it is a good bet that the majority of my readers will not actually visit the originals. In reality, scientists rarely do so either but the practice is cherished for other reasons (such as the prestige for original authors in being added to the citation index). The general practice is instead to cite a relevant paragraph or figure that substantiates the argument being made. I do the same, always including a full reference to the original (and a link, where possible); anybody that wishes to check whether I am using the excerpt out of context is more than welcome to refer back to the original papers.

So, am I plagiarizing? The best argument that I can make is that which I already made in a paper that I wrote together with Geraldine DeLuca, a productive writer and professor of English at my school. Below is a short abstract of the paper as well as a longer segment that describes my thought process after I wrote my book on climate change:

Personalizing the Anti‐Plagiarism Campaign

Geraldine DeLuca and Micha Tomkiewicz

Abstract: In response to a pamphlet on ways to avoid plagiarism published by their university, a science professor and an English professor reflect on their own writing practices. They also explore such topics as electronic plagiarism detectors, the history of “imitation” in literature, the Popperian formulation of the scientific method, the postmodern notion that “everything is already written,” the problem of “unconscious plagiarism,” Foucault’s “author function,” and the different assumptions about truth made in the “objective” work of science and the “subjective” work of the humanities.   They reflect on some reasons why teachers’ guidelines may foster plagiarism among students, and they suggest ways to frame assignments that help students to do their own work.

The Limits of Acknowledgement: An Extended Example in the Sciences

Toward the end of my first reading of CUNY’s anti-plagiarism pamphlet, I find myself feeling horrified. Have I been plagiarizing? I have just finished writing a book on energy use and the consequential climate changes. The book sits now on a publisher’s desk and goes through the usual vetting process. I wrote the book with the premise that the issue of global energy use has reached the existential point where it is directly related to the future existence of the human race. Some characterize the situation in terms of a feeding transition that will take place as organisms suddenly need to change their food source. The present estimate is that this transition will occur over the next two or three generations, that it will require collective action in response, and that, at least in democratic societies, this action should be initiated by the election of legislators who will respond to it. But in order for voters to respond intelligently to this crisis, they need to understand what’s happening. Thus, my book, which is heavily based on centralized data sources that, in the majority of cases, are freely available through the Web. And since climate change affects and will continue to affect global income distribution, competition for natural resources and economic security, it is no surprise that one can find opinions, references and new research throughout the media.

So I had good reason to worry. Was I using all of this research appropriately? My wife and I were recently married by Judge Richard Owen, an opera composer of some notoriety, who is famous in certain circles for coining the phrase “subconscious plagiarism.” He used this phrase in a trial in which former Beatle George Harrison was accused of plagiarizing the melody for “My Sweet Lord” from the Chiffons’ 1963 hit “He’s so Fine.” The two operating criteria for plagiarism, he said, were opportunity (Harrison had heard the song) and sufficient similarity. Intent to copy was not necessary.

Controversial topics like energy use and climate change are prime suspects for “subconscious plagiarism.” So I asked my wife, who is a psychologist, what to do about my own work.

You have three options, she said:

1. eliminate the cause of your anxieties by dropping the project;

2. live with your anxieties; or

3. confront the cause by checking for plagiarism. Use the same tools that an unfriendly reader or your publisher might use.

The full paper is available online and includes what I did with my wife’s advice.

Am I self-plagiarizing here? How many of you actually went to the original blog that I linked to in the beginning to check what I wrote there and compare? Those of you who did so found that while I am repeating the abstract here, the long section that directly relates to my own writing appears here for the first time.

Am I stealing anything from anybody else? In the book that I wrote (which I referenced in the plagiarism paper), most of the figures were taken from readily available literature. In all required cases I asked for permission before posting. The book was published by a commercial publisher so they guided me through the process. The permission process took time that is not feasible in a blog setting (I publish weekly and write each post a few days before posting). That said, I have never gotten any complains about permissions for citing works within my blog.

In this age of social media, data comes in many forms and gets passed around blithely; one might refer to tweets or Q&As from an interview. In a political environment where the president is known for his heavy reliance on tweets, what we need to remember is to check the original sources and verify the data whenever possible.

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Vulnerabilities: Desertification

The ecological counterpart to water stress (May 1, 2018) is desertification. The table summarizing the IPCC’s assessments of five categories directly or indirectly connected to water use (April 24, 2018) refers to: “Decreasing water availability and increasing drought in mid-latitudes and semi-arid low latitudes.” The IPCC devotes long sections of its Fourth Assessment Report (AR4) to this issue (sections 3ES, 3.4.1 and 3.4.2). The IPCC predicts that the comprehensive impacts will start to be shown as we approach a 4.5oC change relative to the 1980-1999 standard. That said, desertification is already in full force and having a major global impact.

The definition of what constitutes or contributes to desertification is controversial. Wikipedia mentions the disagreement between its sources:

Desertification is a type of land degradation in which a relatively dry area of land becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife.[2] It is caused by a variety of factors, such as through climate change (particularly the current global warming) and through the overexploitation of soil through human activity.[3] When deserts appear automatically over the natural course of a planet’s life cycle, then it can be called a natural phenomenon; however, when deserts emerge due to the rampant and unchecked depletion of nutrients in soil that are essential for it to remain arable, then a virtual “soil death” can be spoken of,[4] which traces its cause back to human overexploitation. Desertification is a significant global ecological and environmental problem.[5]

Figure 1, also taken from Wikipedia, illustrates the global distribution of vulnerability to desertification.Figure 1

Desertification is a term that many scientists shy away from – both because it lacks specificity and because it comes with a bevvy of associated emotions. Figure 2 was taken by my French relative Rafik Mezouane on his recent holiday in Algiers. It’s a stereotypical picture of the implied consequences of the term.

Figure 2 (taken by Mr. Rafik Mezouane) – Saharan desert landscape in Algeria

Figure 3 shows a map of the extent of the Sahara desert.

Figure 3Map of the span of the Sahara Desert across the African continent

There is also active discussion regarding the degree of reversibility of degraded (desertified) lands. In this case, reversibility of desertification is usually defined in terms of one generation (25 years). Of course, such a feat would be impossible with the Sahara. Nor did the enormous desert come into its status recently. The general belief is that in the past what is now known as the Sahara desert was a fertile land. Science Magazine published an interesting article a while back about the desert’s origins:

New Clue to Sahara’s Origins by Mark Sincell Jul. 9, 1999

Studies of fossilized pollen have shown grasses and shrubbery covered what is now the Sahara desert until some unknown environmental catastrophe dried up all the water, leaving nothing but sand. The exact timing is uncertain, but one interpretation of the pollen data suggests that a relatively mild arid episode between 6000 and 7000 years ago was followed by a severe 400-year drought starting 4000 years ago. Such a disaster might have driven entire civilizations out of the desert, leading them to found new societies on the banks of the Nile, the Tigris, and the Euphrates rivers. But the cause of the postulated droughts remained a mystery.

Now, climatologist Martin Claussen and co-workers at the Potsdam Institute for Climate Impact Research in Germany are proposing that the changing tilt of the Earth triggered the rapid drying of the Sahara. Like a spinning top slowly wobbling on its tip, the Earth’s tilt has decreased from 24.14 degrees to 23.45 degrees in the last 9000 years, resulting in cooler summers in the Northern Hemisphere. When Claussen introduced cooler Northern summers into a computer simulation of the Earth’s atmosphere, ocean, and vegetation, the monsoon storms that provide water to the Sahara grew weaker, killing off some of the native plants. The initial reduction in vegetation further reduced rainfall, says Claussen, starting a vicious cycle of desertification that began to accelerate about 4000 years ago. Less than 400 years later, Claussen’s team found, the drought caused by the vegetation-feedback mechanism could have wiped out almost all plant life in the desert.

One of the places most vulnerable to desertification is Africa’s Sahel region, located directly south of the Sahara and shown in deep red in Figure 1.

According to Wikipedia, the Sahel part of Africa includes:

(from west to east) parts of northern Senegal, southern Mauritania, central Mali, northern Burkina Faso, the extreme south of Algeria, Niger, the extreme north of Nigeria, central Chad, central and southern Sudan, the extreme north of South Sudan, Eritrea, Cameroon, Central African Republic and extreme north of Ethiopia.[4]

As of the 1970s, the Sahel also became a political body, albeit with a somewhat different makeup than that described above:

In 1973 the Permanent Interstates Committee for Drought Control in the Sahel (CILSS) was formed by Burkina Faso, Cape Verde, Chad, Gambia, Guinea Bissau, Mali, Mauritania, Niger and Senegal to group countries that were then becoming interdependent.

CILSS countries alone are home to around 58 million people, the majority of them subsistence farmers, sharing similar cultures and livelihoods even while their religions, languages and customs vary widely.

CILSS estimates that more than half the working-age population in the Sahel is engaged in or dependent on agriculture and is responsible for more than 40 percent of the region’s collective gross domestic product (GDP). Dryland crops such as millet, sorghum and cowpea, and cash crops such as groundnut and cotton are the predominant agricultural produce.

The population is growing very quickly in the Sahel. According to CILSS, there will be 100 million people in the region by 2020 and 200 million by 2050 – almost four times the current population. More than half of them, 141 million, will live in the three countries Egeland is visiting: Burkina Faso, Mali and Niger.

As Figure 1 shows, the region is prone to drought and desertification, meaning that it is unable to support the increasing population that subsists off of agriculture, be it herding or growing crops. So the people move elsewhere for subsistence – either they flock to cities within their own countries or they become environmental refugees in other countries. The Climate and Migration Coalition has written about this:

The Sahel region is highly dependent on agriculture for livelihoods and the wider economy. Agriculture is almost entirely rain fed, dependent upon a 3-4 month rainy season that refills lakes and the rivers which, in turn, irrigate crops. Annual rainfall is highly variable, some studies argue that the concept of ‘normal’ annual rainfall is almost meaningless in the Sahel. As well as erratic rainfall a number of other factors play an important part in creating the vulnerabilities of the people who live in the Sahel. Over the past half century a combination of land degradation, population growth and misplaced environmental and development policies have contributed to vulnerability. This vulnerability has in turn shaped patterns of migration and displacement. However, the changing climate is only one among a number of factors.

The article also includes a quote from one of the refugees:

“Migration has now become an inevitable method of adaptation for us … As a means of survival for us and our animals, we are forced to continuously migrate despite all the risks involved. This is our form of adaptation. We have always mastered it, but if nothing is done to ensure the safety of our space and activities, we risk, one day, being forced to abandon our way of life and join the swelling ranks of the unemployed in the city.”

– Hindu Oumarou Ibrahim, Peul Mbororo of Chad

In the Sahel the initiative to move is still mostly on the individual level. But we have already encountered (September 8, 2015) a different approach to a similar situation in Inner Mongolia (an autonomous region of China), where the government is forcing the Mongolian shepherds to stop herding and instead move to cities to minimize grazing and stop desertification.

Desertification, along with its causes and consequences, is a vast and complex issue. Any attempts to directly associate the phenomenon with climate change are controversial. Those of you with a desire to dig a bit deeper in this important issue might try two articles:

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Laboratory Observations of Collective Suicide

Rafik, a young, dear, French relative of mine, was born in Algeria. He still has family there that he visits often, occasionally going with some of them to tour the Sahara desert. We discussed his trips and the history of the Sahara desert; his stories fit nicely with the topic of desertification, one of the biggest vulnerabilities of climate change (April 24, 2018 blog). I was just starting to write about the topic, planning to include some of Rafik’s photographs, when my wife showed up with a short piece from the science section of The New York Times: “Fellow Travelers in Eco-Suicide.” It caught my imagination. When I visited the online version of the NYT, I found the article with a different title: “A Population That Pollutes Itself into Extinction (and It’s Not Us).” This change was sufficiently intriguing to motivate me to search for the original paper it described: “Ecological Suicide in Microbes.” The public response was widespread and immediate (as judged by Google’s response to the article’s title). People seemed to recognize the connection between this bacterial suicidal activity and the end result of humans ignoring the long-term consequences of climate change. I have long labeled climate change as self-inflicted genocide (see the November 15, 2016 blog). There is, however, a major difference between bacteria and us. Merriam Webster dictionary defines genocide as, “the deliberate and systematic destruction of a racial, political or cultural group.” The key word here is deliberate. One cannot be deliberate without a brain, and bacteria don’t have them. The same problem applies to the term suicidal in the other two titles.

Before proceeding, let’s get some details of the story from the abstract of the original paper that was published in Nature Ecology & Evolution (2018 May; 2(5): 867-872) by Christoph Ratzke, Jonas Denk and Jeff Gore. It is worth mentioning that all three authors are in physics departments: Ratzke and Gore at MIT in the US and Denk in Germany.

The growth and survival of organisms often depend on interactions between them. In many cases, these interactions are positive and caused by a cooperative modification of the environment. Examples are the cooperative breakdown of complex nutrients in microbes or the construction of elaborate architectures in social insects, in which the individual profits from the collective actions of her peers. However, organisms can similarly display negative interactions by changing the environment in ways that are detrimental for them, for example by resource depletion or the production of toxic byproducts. Here we find an extreme type of negative interactions, in which Paenibacillus sp. bacteria modify the environmental pH to such a degree that it leads to a rapid extinction of the whole population, a phenomenon that we call ecological suicide. Modification of the pH is more pronounced at higher population densities, and thus ecological suicide is more likely to occur with increasing bacterial density. Correspondingly, promoting bacterial growth can drive populations extinct whereas inhibiting bacterial growth by the addition of harmful substances—such as antibiotics—can rescue them. Moreover, ecological suicide can cause oscillatory dynamics, even in single-species populations. We found ecological suicide in a wide variety of microbes, suggesting that it could have an important role in microbial ecology and evolution.

The essence of the bacterial suicidal behavior (of which said bacteria is probably unaware) is a lack of ability to dispose of their waste within a relatively small enclosure. To take the human analogy further, Figure 1 shows the global extent of basic sanitation facility usage.

Figure 1Percent of global population that uses at least basic sanitation facilities

The World Bank defines the indicator as follows:

The percentage of people using at least basic sanitation services, that is, improved sanitation facilities that are not shared with other households. This indicator encompasses both people using basic sanitation services as well as those using safely managed sanitation services. Improved sanitation facilities include flush/pour flush to piped sewer systems, septic tanks or pit latrines; ventilated improved pit latrines, compositing toilets or pit latrines with slabs.

Not too long ago, humans didn’t use any sanitation facilities. But at that point, human density was low enough that we could move across the land and let nature apply the old dictum, “dilution is a solution.” The bacteria in the MIT-German study didn’t have that option. The bacteria’s waste consisted of various organic acids (developed from the metabolization of the glucose supplied as the source of nutrition). The organic acids produced changed the pH of the medium to values that inhibited digestion and eventually led to collective bacterial death. When the experimenters included a buffer into the medium that was able to keep the pH approximately constant, the bacteria did fine.

We can drive the analogy even further: about 25% of the carbon dioxide that is produced by our consumption of fossil fuels ends up dissolved into our oceans, thus changing the oceans’ pH to more acidic values which in turn inhibit almost all life forms. Since the oceans are so large, complete collective death will take some time.

The untreated waste that humans excrete becomes a poison, just as we saw with the bacteria. We need to improve digestion/processing mechanisms (in the same way that the experimenters added the buffer) to neutralize the problem and increase our chances of survival. (See “Tragedy of the Commons” July 2, 2012 blog).

While the paper itself is only five pages long (including a full page of references), there is a separately published online supplement that spans 25 pages. The supplement includes a suggested outline for a mathematical approach to facing ecological suicide that might be applicable to many other situations. The approach is based on logistic growth (February 4, 2014), which leads to saturation in concentration (carrying capacity). In this case, the saturation level changes with the waste concentration that manifests itself in terms of change in the pH of the medium. This is probably one of the first quantitative analyses of the collective suicide of a living system.

Both titles – that of the important Ratzke paper just published in Nature and the one heading this blog – falsely invoke commonality between humans and life forms that lack, functioning, thinking brains. The tragedy is that even with the advantage of our thinking power, we are in a similar situation to Paenibacillus sp. bacteria.

Stay tuned for next week’s examination of desertification.

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