The consequences are hard to predict and include potentially serious outcomes

The societal consequences of climate change in the decades ahead are hard to predict because exactly how climate will change and how capable human society will be at absorbing climate impacts are issues characterized by deep uncertainty. This deep uncertainty will almost certainly remain for the foreseeable future.

For example, different experts who assess climate change risks often reach very different conclusions. Some experts think the consequences of climate change over the next several decades are most likely to be small—perhaps a few percent of GDP. They tend to foresee some combination of stabilizing climate feedbacks, lower sensitivity of physical systems, biological resources, and social institutions to climate changes, and greater capacity for human society to deal with climate impacts. This latter capacity could result, in part, from humanity’s considerable scientific and technological capabilities.

Other experts see climate change as a much more serious risk to society. The reasons for this include that the changes in climate expected over the next several decades are faster than anything the world has experienced since the start of human civilization (i.e., over the past 10,000 years) and will take us to climate conditions that are entirely unprecedented for human society. Furthermore, the physical characteristics of the planet, the biological resources on which society depends, and the social systems that we have developed are all heavily adapted to existing conditions because those conditions have been relatively stable for thousands of years. This increases the potential for changes in climate to be disruptive. Finally, relatively small changes in climate have, at times, had large consequences on societies locally or regionally, illustrating the potential for serious consequences of climate change.

Even in the absence of deep uncertainty over climate change’s consequences—illustrated by the divergence in views among subject matter experts—climate change represents a difficult risk management challenge. Policy responses necessarily integrate both objective information about the climate system and our relationship with it and subjective value judgments, most notably whether we are more averse to the risks of changes in climate or the policy responses; the ways we assess issues of fairness among nations and peoples; and the consideration we give to cultural heritage or nonhuman species. This creates a complex and often contentious risk management challenge.

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Why not assess the risks of climate change for yourself based on what you know and what you believe?

Further reading: Higgins, 2014; Tol 2009; Barnosky et al. 2012; Hansen et al. 2012; Rockström et al. 2009; Diamond 2005