“The last few years have also seen record-breaking, climate-related, weather extremes, as well as 30 of the warmest years on record for the globe,” a Climate Change Report notes.
The New York Times is reporting on a draft report written by scientists from 13 federal agencies – a report that has not been made public just yet, as it awaits approval by the Trump administration.
The Times reports that “(it) concludes that Americans are feeling the effects of climate change right now. It directly contradicts claims by President Trump and members of his cabinet who say that the human contribution to climate change is uncertain, and that the ability to predict the effects is limited.”
“Evidence for a changing climate abounds, from the top of the atmosphere to the depths of the oceans,” the draft of the report states.
The Times reports, “The average temperature in the United States has risen rapidly and drastically since 1980, and recent decades have been the warmest of the past 1,500 years.
“Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate change,” they wrote.
Katharine Hayhoe, a professor of political science at Texas Tech University, called the conclusions among “the most comprehensive climate science reports” to be published.
Another told the Times there are concerns that the report “would be suppressed.”
The report concludes “even if humans immediately stopped emitting greenhouse gases into the atmosphere, the world would still feel at least an additional 0.50 degrees Fahrenheit (0.30 degrees Celsius) of warming over this century compared with today. The projected actual rise, scientists say, will be as much as 2 degrees Celsius.”
They put that projection into context, and the consensus is that the world has warmed by about 1.6 (degrees F) and 0.9 (degrees C) from 1865 to 2015.
The Times writes, “A small difference in global temperatures can make a big difference in the climate: The difference between a rise in global temperatures of 1.5 degrees Celsius and one of 2 degrees Celsius, for example, could mean longer heat waves, more intense rainstorms and the faster disintegration of coral reefs.”
“The increases in extreme weather that accompany global climate change are having significant, direct effects on the United States and the global economy and society,” the report continues. “The frequency and intensity of heavy precipitation and extreme heat events are increasing in most regions of the world and will very likely continue to rise in the future. Trends for some other types of extreme events, such as floods, droughts, and severe storms, vary by region.”
The impact is likely to be felt here in the west: “Reductions in western US winter and spring snowpack are projected as the climate warms. Under higher-emissions scenarios, and assuming no change to current water-resources management, chronic, long-lasting, hydrological drought is possible by end of century.”
Meanwhile, with the report being leaked to the New York Times, it figures to put pressure on the Trump administration.
The Times reports, “The E.P.A. is one of 13 agencies that must approve the report by Aug. 18. The agency’s administrator, Scott Pruitt, has said he does not believe that carbon dioxide is a primary contributor to global warming.”
“It’s a fraught situation,” said Michael Oppenheimer, a professor of geoscience and international affairs at Princeton University who was not involved in the study. “This is the first case in which an analysis of climate change of this scope has come up in the Trump administration, and scientists will be watching very carefully to see how they handle it.”
The Times reports, “Scientists say they fear that the Trump administration could change or suppress the report. But those who challenge scientific data on human-caused climate change say they are equally worried that the draft report, as well as the larger National Climate Assessment, will be publicly released.”
The key debate point is the extent to which climate change is driven by human influence. Here the report notes “significant advances” in the ability to link human influence to individual extreme weather events. However, critical uncertainties remain.
“It is extremely likely that most of the global mean temperature increase since 1951 was caused by human influence on climate,” the report states. “The influences of human activities on the climate system are now so pervasive that the current and future behavior of these previous ‘natural’ climate features can no longer be assumed to be independent of those human influences.”
Meanwhile, in the U.S., the report finds with “very high” confidence that the number and severity of cool nights have decreased since the 1960s, while the frequency and severity of warm days have increased.
The report finds that extreme cold waves are less common since the 1980s, while extreme heat waves are more common.
“It is very likely that the accelerated rate of Arctic warming will have a significant consequence for the United States due to accelerating land and sea ice melting that is driving changes in the ocean including sea level rise threatening our coastal communities,” the report says.
Human activity, the report states, is a primary culprit.
The report does not make policy recommendations but it does conclude that stabilizing the global mean temperature increase to two degrees Celsius would require significant reductions in global levels of carbon dioxide.
—David Greenwald reporting