Oxford Dictionaries define complementarity in the following way:
A relationship or situation in which two or more different things improve or emphasize each other’s qualities.
‘a culture based on the complementarity of men and women’
Complementarity may refer to:
Physical sciences and mathematics 
- Complementarity (molecular biology), a property of nucleic acid molecules in molecular biology
- Complementarity (physics), the principle that objects have complementary properties which cannot all be observed or measured simultaneously
- Complementarity theory, a type of mathematical optimization problem
- Quark–lepton complementarity, a possible fundamental symmetry between quarks and leptons
Society and law 
- Complementarianism, a theological view that men and women have different but complementary roles
- Complementary good, a good for which demand is increased when the price of another good is decreased
- An element of interpersonal compatibility in social psychology
- The principle that the International Criminal Court is a court of last resort
See also 
- Complementarity-determining region, part of the variable chains in immunoglobulins
- Complementary angles, in geometry
- Self-complementary graph, in graph theory
- Yin and yang, complementary relation between apparent opposites in Chinese philosophy
- Complimentary (disambiguation)
- Complement (disambiguation)
Since the physical sciences are close to my heart, I will use the Encyclopedia Britannica to expand upon both the meaning of the complementarity principle in physics and its origin, which lies with Niels Bohr (one of the most important architects of modern physics):
- Complementarity principle, in physics, tenet that a complete knowledge of phenomena on atomic dimensions requires a description of both wave and particle properties. The principle was announced in 1928 by the Danish physicist Niels Bohr. Depending on the experimental arrangement, the behaviour of such phenomena as light and electrons is sometimes wavelike and sometimes particle-like; i.e., such things have a wave-particle duality (q.v.). It is impossible to observe both the wave and particle aspects simultaneously. Together, however, they present a fuller description than either of the two taken alone.
- In effect, the complementarity principle implies that phenomena on the atomic and subatomic scale are not strictly like large-scale particles or waves (e.g., billiard balls and water waves). Such particle and wave characteristics in the same large-scale phenomenon are incompatible rather than complementary. Knowledge of a small-scale phenomenon, however, is essentially incomplete until both aspects are known.
The Oxford Dictionaries entry and Bohr’s complementary principal both require a unifying element of beneficial overlap with which to bridge two (or more) distinct populations. In the OD, that unifying property is culture; in Bohr’s principle it’s the complete knowledge of phenomena on atomic dimensions.The two populations in the dictionary definition are men and women, while those under Bohr’s principle are wave and particle properties (assigned to the same objects).
Now let’s shift to the present time and analyze the recent behavior of the US government:
My recent blogs (December 4, 11; October 16, 23 2018) have enumerated an avalanche of detailed reports about current realities and near future projections of the impacts of climate change on the US – and on the planet (NCA, WMO, IPCC SR1.5). The US government issued these reports under the present administration (NCA, EPA); the international organizations (IPCC, WMO), in which the US remains a member, participate in writing and approving the reports. At the same time, the official response from the highest US administrators is a complete denial of climate change and they have been actively reversing measures that were previously put in place to mitigate its damage and adapt to its impacts wherever possible.
There is probably no clearer marker for the US government’s complementarity on the climate change issue than the actions of its representatives in the mid-December international negotiations that took place in Katowice, Poland (COP24). Vox describes the meeting’s conclusions below:
UPDATE, December 15: International climate change negotiators announced late Saturday that they have reached an agreement at COP24 in Poland. The text charts a path forward for countries to set tougher targets for cutting greenhouse gases under the Paris climate agreement, as well as stronger transparency rules for countries in disclosing their emissions. However, questions on how to use markets to limit carbon dioxide remain, and discussions will continue next year. Read on for the context around these negotiations and why environmental groups, governments, and private companies were so concerned about the outcome of this conference.
KATOWICE, Poland — President Trump’s top White House adviser on energy and climate stood before the crowd of some 200 people on Monday and tried to burnish the image of coal, the fossil fuel that powered the industrial revolution — and is now a major culprit behind the climate crisis world leaders are meeting here to address.
“We strongly believe that no country should have to sacrifice economic prosperity or energy security in pursuit of environmental sustainability,” said Wells Griffith, Trump’s adviser.
Mocking laughter echoed through the conference room. A woman yelled, “These false solutions are a joke!” And dozens of people erupted into chants of protest.
“There are two layers of U.S. action in Poland,” said Paul Bledsoe, an energy fellow at the Progressive Policy Institute and former Clinton White House climate adviser.
One is the public support of fossil fuels, which Bledsoe said is “primarily aimed at the president’s domestic political base, doubling down on his strategy of energizing them by thumbing his nose at international norms.”
The quieter half is the work of career State Department officials who continue to offer constructive contributions to the Paris climate agreement that President Trump loves to loathe.
Which facet of the American presence proves more influential in Poland could have a big impact on whether this year’s climate summit, now in its second week, ends in success or failure?
Wells Griffith proposes a complementarity between economic prosperity and environmental sustainability. His conclusion is that we don’t have to choose. Andrew Light, in a USA Today piece, tries to explain how it works:
Andrew Light, a professor of public policy and atmospheric sciences at George Mason University, was one of the Obama administration’s climate negotiators in Paris. He said the deal cut Saturday, which requires developed and developing nations to follow similar guidelines, was a crucial outcome that could encourage the United States to return to the accord.
Light said it is important that rules on transparency and record keeping be “flexible” for small, poor countries that might struggle to comply. But the rules must be fundamentally the same, he said.
“We wanted an agreement that would make it easy for the U.S. to get back in,” Light told USA TODAY. “This is a deal that we would want to be part of, a deal where China, India, other big, developing countries don’t have different rules from the U.S. It does make all the countries play by the same rules.”
Michael Mann, a professor of atmospheric sciences at Penn State, said the transparency requirements coming out of Poland are important in light of indications that China’s carbon emissions increased over the past year in a manner that is inconsistent with its Paris commitments.
He said the United States and China reaching agreements with the other nations should “help to create an atmosphere of good faith” and encourage increased emission cutback commitments required in 2020.
Next week I will look into the complementarity of economic prosperity and environmental sustainability on a more fundamental level.