The National Academy of Sciences and its British counterpart, the Royal Society, have published Climate Change: Evidence and Causes, a very easy to understand primer on the science of greenhouse-driven global warming. Although there is not a lot new in this report as a matter of science, it makes the strong scientific consensus on human-induced climate change that has existed for some time clearer and more accessible for non-scientists particularly on the major issues that need to be understood by policy-makers and interested citizens. The report is written in simple language and filled with pictures and graphs which illustrate why almost all mainstream scientists actually engaged in climate change science are virtually certain that human activity is causing very dangerous climate change.
This report is ethically significant because:
a. It is a report of two of the most prestigious scientific institutions in the world, namely US National Academy of Sciences and the British Royal Society. Because of the prestige of both of the institutions writing this report, those opposing actual climate change have an ethical duty to acknowledge that the scientific basis supporting action on climate change is entitled to respect. They cannot reasonably claim that there is no strong scientific basis for policy action on climate change or even worse that climate change science is a “hoax.” Which institutions have made claims that humans are engaged in dangerous behavior has ethical significance. If, for instance, someone is told by an expert in toxicology that chemicals he or she is discharging into a water supply will kill people, he or she has more of an ethical duty to stop discharging the chemicals until the issue of toxicology issues are resolved than they would if the claim about poisoning came from a religious leader or a tax accountant. When claims about danger are made by world-class scientific experts, as a matter of ethics, the burden of proof shifts to those potentially harming others to show that their behavior is not dangerous.
Skepticism in climate science should still be encouraged, but skeptics must play by the rules of science including: (a) subjecting all claims contradicting the mainstream scientific view on climate change to peer-review, (b) subjecting claims that humans are not causing dangerous climate impacts to review by scientific institutions that have sufficient broad interdisciplinary expertise among its members to review such claims against all the contrary evidence from all relevant scientific disciplines, and (c) acknowledging all the contradictory evidence. Given the enormity of harms to citizens around the world and future generations predicted by mainstream scientists, those who seek to undermine proposed climate change policies on scientific certainty grounds should be understood to have the burden of proof to show by high levels of proof that human-induced climate change is not dangerous.
b. The report includes clear explanations of the scientific evidence in regard to specific justifications for not taking action on climate change very frequently made by those who oppose climate change policies. These justifications and responses to them include, for instance:
Scientists don’t know that recent climate change is largely caused by human activities?
Scientists know that recent climate change is largely caused by human activities from an understanding of basic physics, comparing observations with models, and fingerprinting the detailed patterns of climate change caused by different human and natural influences.
Direct measurements of CO₂ in the atmosphere and in air trapped in ice show that atmospheric CO₂ increased by about 40 percent from 1800 to 2012. Measurements of different forms of carbon reveal that this increase is because of human activities.
The recent slowdown of warming means that climate change is no longer happening?
No, recent weather is not evidence that warming is not happening. Since the very warm year 1998 that followed the strong 1997-1998 El Niño, the increase in average surface temperature has slowed relative to the previous decade of rapid temperature increases. Despite the slower rate of warming, the 2000s were warmer than the 1990s. A short-term slowdown in the warming of Earth’s surface does not invalidate our understanding of long-term changes in global temperature.
CO₂ is already in the atmosphere naturally, and so human emissions are not significant.
Human activities have significantly disturbed the natural carbon cycle by extracting long-buried fossil fuels and burning them for energy, thus releasing CO₂ into the atmosphere.
Variations in output from the sun have caused the changes in the Earth’s climate in recent decades.
The sun provides the primary source of energy driving Earth’s climate system, but its variations have played very little role in the climate-changes observed in recent decades. Direct satellite measurements since the late 1970s show no net increase in the sun’s output while, at the same time, global surface temperatures have increased.
If the world is actually warming, some recent winters and summers would not have been so cold?
Global warming is a long-term trend, but that does not mean that every year will be warmer than the previous one. Day-to-day and year-to-year changes in weather patterns will continue to produce some unusually cold days and nights, and winters and summers, even as the climate warms.
A few degrees of warming is not cause for concern.
Even though an increase of a few degrees in global average temperature does not sound like much, global average temperature during the last ice age was only about 4°C to 5°C (7 °F to 9 °F) colder than now. Global warming of just a few degrees will be associated with widespread changes in regional and local temperature and precipitation, as well as with increases in some types of extreme weather events.
These are only a few of the justifications that have been made by those denying responsibility to reduce the threat of climate change that are directly and clearly refuted in the report.
c. The report also has ethical significance because its so clear that policy makers cannot reasonably claim that there is no scientific evidence about the major issues of concern to the climate change scientific community. As we have explained on this website, policy-makers may not, as a matter of ethics, rely on their own uninformed opinion about climate change science once they are informed by respectable scientific organizations that people and organizations within their jurisdiction are likely harming others around the world. This responsibility to not rely upon their own uninformed opinions increases when there are easy to understand explanations from respected scientific institutions of the scientific basis for concluding that people within their jurisdiction are harming others. The new report from the US Academy of Sciences and the Royal Society is such a clear explanation. And so government officials have a strong duty to go beyond their own uninformed opinion about whether humans are causing dangerous climate change. They must justify their refusal to act on strong, peer-reviewed scientific evidence that is accepted by mainstream scientific institutions that have the breadth of expertise to consider the interdisciplinary scientific issues that make up climate change science.
d. Because politicians have an affirmative duty to rely upon mainstream scientific views in regard to human activities that could cause great harm until peer-reviewed science establishes that the mainstream view is erroneous, the press has a journalistic duty to help citizens understand the limitations of any politician’s views that opposes action on climate change on scientific grounds particularly when there are easy to understand explanations of climate change science such as that in the new US National Academy and Royal Academy report. The new report will enable the press to fulfill its journalistic responsibilities by asking more precise and clearer questions of those who deny the mainstream scientific view.
For these reasons, the new report is ethically significant.
Donald A. Brown
Scholar in Residence and Professor
Sustainability Ethics and Law, Widener University School of Law,