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Global Climate Change: Scientific Consensus, Political Challenge

Image: Keeling Curve showing change in atmospheric carbon dioxide concentrations over time.. Please refer to article for link to curve showing latest measurements. This image by Narayanese, Semhur, and NOAA, retrieved from Wikimedia, licensed through CC BY-SA 3.0.


While climate change is an urgent problem with global repercussions, efforts to address this challenge have been complicated, in part, by its complexity and uncertainty. Climate change complexity arises from the interconnectedness of earth systems and the anthropogenic stressors that contribute to and aggravate the phenomenon. Climate change uncertainty, in turn, arises from the difficulty in predicting the outcomes of the non-linear dynamics that characterize feedback mechanisms in the world’s different ecosystems.

Despite the complexity and uncertainty of climate change, modern understanding of the phenomenon has dramatically improved. As a group of researchers from the World Resources Institute, Yale University, the University of Toronto, and Carleton University explains in a 2012 article, “Climate change science is well-developed, relatively coherent in terms of theory and method and capable of measuring, analyzing, and assessing what we do and do not know about the environmental consequences of climate change.” Through recent expansions in observational datasets and improvements in analyses of large volumes of data, geographical coverage, quality of measurements, and a better understanding of uncertainties, climate change scientists have discerned with increasing certainty the anthropogenic nature of the problem. Indeed, reports by the Intergovernmental Panel on Climate Change, the scientific intergovernmental body for the United Nations Framework Convention on Climate Change, state that “it is extremely likely [with 95 percent confidence] that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”

The current impasse in climate change policy is in fact due less to the complexity and uncertainty of the science than to its politics. For the climate change issue, the distribution of interests, highlighted by the principle of Common But Differentiated Responsibilities (CBDR), elucidates why no single comprehensive institutional solution has yet emerged. The concept of CBDR was embodied by Principle 7 of the Rio Declaration at the 1992 United Nations Earth Summit in Rio de Janeiro. It asserts that all states are responsible for addressing global climate change, but not equally responsible. This difference in responsibility reflects a recognition of the historical contribution of greenhouse gas emission by now-developed countries as well as the wide disparity in the abilities and capacities of developed and developing countries to address associated problems. Unfortunately, the application of CBDR in global climate change governance, as formulated in the 1997 Kyoto Protocol, created a “firewall” between developed and developing country blocs.

Moreover, many governments have become wary of making costly commitments to reduce carbon emissions while they are unsure other countries will honor promises to do the same. Power-weighted interests and political uncertainty have led to problems in the coordination of emissions regulations and compensation for countries unable to adopt emissions controls. Governments are still struggling to find productive linkages across most of the cooperation problems in climate change. Climate change is a classic example of a wicked problem with many distinct component problems, each with its own attributes, administrative challenges, and distinctive associated interest groups. According to political scientists Robert O. Keohane and David G. Victor, the diversity of climate change problems results in “parallel diverse political patterns of interests, power, information and beliefs,” thus complicating the search for productive linkages.

One of the most cited consequences of climate change is global warming. Recent reports by NASA and the NOAA suggest that 2015 was the warmest year on record. Evidence suggests that global mean surface temperature has been trending upward for more than a century. While skeptics may claim that this is a natural phenomenon—after all, the greenhouse effect itself is responsible for making the Earth warm enough to be habitable and the Earth has experienced increases and decreases in surface temperature throughout its existence—what is alarming observers is analysis showing that the rate of change in global mean surface temperature has been markedly increasing. The past 25 years had a faster rate of increase in temperature per decade than the past 50 years, the past 100 years, and the past 150 years.

These trends correspond suspiciously with recent human activities that have unleashed unprecedented amounts of carbon into the Earth’s atmosphere. Environmental security expert Simon Dalby, in explaining the "Anthropocene", suggests that human drivers to the earth’s natural processes—and in turn the geopolitics surrounding those processes—can be divided into three periods: the Industrial Revolution, the Great Acceleration, and the future, as yet unknown. The Industrial Revolution, and the innovation in steam power and the rapid expansion of the use of coal as an energy source, is referred to as the start of the Anthropocene. The Great Acceleration most strongly corresponds with the alarmingly increasing rates of temperature change and the inability of modern economies to transition away from fossil fuels. Petroleum-powered industry and transportation expanded rapidly in the 1940s, and the world economy was placed on an inextricable track that put the carbon cycle off-balance and trapped more heat in the Earth. Indeed, the Keeling Curve provides some confirmation of this trend and shows a perfectly positive increase in CO2 parts per million, with the Earth’s atmosphere having recently breached 400 ppm.

Other correlations provide suggestions of a warming world. Near surface air temperatures, surface humidity, ocean heat content, sea-surface temperatures, temperatures over oceans, temperatures over land, and the sea level have all undoubtedly increased within the same period. Likewise, snow cover, glaciers, and sea ice have all decreased. In fact, within the past two decades from 1992 to 2012, the spatial extent of the Arctic sea ice cover has decreased by nearly 50 percent, or 3 million square kilometers. The full melting of Greenland’s ice sheet is predicted to increase sea levels by about 6 meters.

Rising sea levels are likely to represent one of the primary dangers of climate change for human populations. The next installment in this series will discuss the impact of rising sea levels and other possible consequences of climate change on vulnerable human populations, and how these are likely to contribute to humanitarian crises that will require the attention of all states in the global community.


Peter C.Y. Kim is a recent Master of Arts graduate in International Relations and International Economics at the Johns Hopkins University School of Advanced International Studies (SAIS), where he concentrated on international political economy and energy and environmental policy. He is a former research assistant at the FPI.

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