General · 16th April 2014
Scientists — those specialists who explain to us how the world works — are becoming increasingly alarmed about our slow and inadequate response to the threat of global climate change. Their scientific evidence has confirmed an unfolding crisis that is serious enough for them to address their concerns directly to the public. One such example of this highly unusual appeal is a report to the citizens of the United States from the Climate Science Panel of the American Association for the Advancement of Science (AAAS). It joins similar appeals from the Royal Society, the Royal Institution, the US National Academy of Sciences, the US Geological Survey, the Intergovernmental Panel on Climate Change (IPCC) and national science bodies from about 30 other countries.
The AAAS report, What We Know: The Reality, Risks and Response to Climate Change, is not so much a scientific document as a restrained plea containing a mixture of indisputable evidence, considered advice and reasoned warnings. The impact of this report comes from its tone of sincerity, exasperation and constrained alarm.
The report begins by making clear that no essential doubt exists in the scientific community about the reality or severity of global climate change. It rejects the argument that “climate change is still a topic of significant scientific disagreement” by declaring that “about 97% of climate scientists have concluded that human-caused climate change is happening.” Then the tone darkens. “Thus,” it asserts, “it is important and increasingly urgent” for the public to be “aware that climate change is increasing the likelihood of certain local disasters”. Then the tone gets even darker. “Many people do not yet understand that there is a small, but real chance of abrupt, unpredictable and potentially irreversible changes with highly damaging impacts on people in the United States and around the world.”
Two powerful phrases explode from the early portions of this report. One of them is “important and increasingly urgent”. The other is a “real chance of abrupt, unpredictable and potentially irreversible changes”. These are much more than casual expressions of concern. To emphasize the seriousness of the situation, “abrupt, unpredictable and potentially irreversible” is repeated throughout the report. Humanity's failure to curb greenhouse gas emissions — now 36 billion tonnes per year and continuing to increase — is moving climate change toward critical and uncontrollable instability. And worse, the AAAS scientists admit that they don't know where the dangerous tipping point is located.
But scientists do know many things. “Average global temperature has increased by about 1.4°F [0.66°C] over the last 100 years,” they note. “Sea level is rising, and some types of extreme events — such as heat waves and heavy precipitation events — are happening more frequently. Recent scientific findings indicate that climate change is likely responsible for the increase in the intensity of many of these events in recent years.” The report goes on to add that “Earth’s climate is on a path to warm beyond the range of what has been experienced over the past millions of years” and that “the CO2 we produce accumulates in Earth’s atmosphere for decades, centuries, and longer.” From a human perspective, therefore, climate change is essentially permanent.
This unprecedented situation is in stark contrast with public opinion. “In 2013,” according to the AAAS, “only 42% of American adults understood that 'most scientists think global warming is happening' and 33% said, 'there is a lot of disagreement among scientists about whether or not global warming is happening.' Twenty percent said they 'don’t know enough to say'.” From the perspective of the AAAS scientists who are measuring an unfolding climate crisis, a majority of Americans are either misreading the science or are the victims of invented doubt.
In an effort to communicated directly to the ordinary American, the report employs language and metaphors they are likely understand. “The science linking human activities to climate change is analogous to the science linking smoking to lung and cardiovascular diseases,” it states. And “greenhouse gases have supercharged the climate just as steroids supercharged hitting in Major League Baseball.” The AAAS goes on to remind Americans about their tradition of insuring their homes and lives against loss, and then explains that cutting greenhouse gas emissions is really a similar risk-reduction action. It returns again and again to the possibility of “abrupt, unpredictable and potentially irreversible [climate change].”
In describing the other possible theories accounting for climate change, the report carefully explains that no other factors except the recent rise in atmospheric carbon dioxide from 280 parts per million to 400 ppm accounts for the planet's warming. It notes that “in the U.S., new record high temperatures now regularly outnumber new record lows by a ratio of 2:1,” adding that “since 1950, heat waves worldwide have become longer and more frequent” and that “the global area hit by extremely hot summertime temperatures has increased 50-fold” with the “fingerprint of global warming... firmly identified in these trends.” It warns that “climate change has amplified the threat of wildfires in many places”, including “some regions where they have been absent in recent history”, and anticipates an increased “threat of 'mega-fires' — large fires that burn proportionately greater areas.” It reminds Americans that rising sea levels are threatening many coastal towns, cities and regions — particularly Florida. It advises of the northward movement of serious tropical diseases and refers to the concern of “senior officers and officials in the U.S. Department of Defence” about the increased military threats arising from climate-induced social instability. It endorses the IPCC's position that present emission rates “could cause another 4 to 8° F [1.6 to 3.8°C] warming before the year 2100.”
This is a document that carefully and calmly informs. In doing so, however, it also manages to convey a desperate, pleading and chilling tone. It's written by American scientists who are so alarmed about an unfolding climate crisis that their only recourse is to write an honest and frank report to their fellow citizens. But it also make sober reading for everyone else.