The real surprise, from the standpoint of those closely following climate science over recent years, was that there was no real surprise: The findings of the latest major U.S. government report largely reaffirm much of what was already understood.Report cover

“The same, only worse,” began a November 4 New York Times news article on the study. That about said it all, though one could argue the reporters might have added “and sooner.”

The U.S. Global Change Research Program’s “Climate Science Special Report,” issued just days before international climate talks were to open November 6 in Bonn, Germany, is the product of work by career scientists and civil servants representing 13 federal departments and agencies. It’s volume one of a planned two-part fourth National Climate Assessment report scheduled to be released over the next year.

Federal agencies' report rebuts Trump administration positions on underlying #climatechange science. Click To Tweet

Required by law under the Global Change Research Act of 1990, the CSSR report consists of findings, language, and cautions that might just as well have come from organizations such as the National Academy of Sciences and, at the global level, from the Intergovernmental Panel on Climate Change. That the report instead came from a Trump administration vocally dismissive of much of its scientific findings seemed for many its most significant element.

Some examples:

  • The period from 1901 through 2016, with an increase of about 1.8 degrees F (1 degree C), “is now the warmest in the history of modern civilization.”
  • “It is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. From the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.” (So much for EPA Administrator Scott Pruitt’s arguments to the contrary.)
  • “The magnitude of climate change beyond the next few decades will depend primarily on the amount of greenhouse gases (especially carbon dioxide) emitted globally.” Lacking “major reductions in emissions,” annual average global temperatures relative to preindustrial times “could reach 9 degrees F (5 degrees C) by 2100 … and atmospheric concentrations “not experienced in tens to hundreds of millions of years.”

While only adding incrementally to prevailing scientific understanding of climate change, the agencies in their new government report say its findings are buttressed by “new observations and new research” since publication of the third national assessment in May 2014. “Stronger evidence has emerged for continuing, rapid, human-caused warming of the global atmosphere and ocean,” it says.

The report points to “record-breaking, climate-related weather extremes, the warmest years on record for the globe, and continued decline in Arctic sea ice.” Those trends “are expected to continue in the future over climate (multidecadal) timescales.” The report adds that “significant advances have been made in the attribution of the human influence for individual climate and weather extreme events” since the 2014 assessment.

In announcing release of the report, representatives of the National Oceanic and Atmospheric Administration, NOAA, and of the U.S. Geological Survey said the report had undergone extensive reviews by 13 USGCRP federal agencies and by the National Academies of Sciences, Engineering, and Medicine. They said multiple comments and suggestions from those interests had been considered prior to the White House’s Office of Science and Technology Policy approving public release of the report. While NOAA was the “administrative lead agency” in preparing the report, it did so over the past nine months in a period when it still did not have a Trump-nominated agency administrator.

Along with an executive summary, the full report consists of 15 individual chapters addressing issues such as warming of oceans, sea-level rise, and ocean acidification; the “significant possibility for unanticipated changes”; climate change mitigation; extreme storms; precipitation and temperature changes in the U.S.; and “Potential Changes: Compound Extremes and Tipping Elements.”

The full report and chapter-by-chapter sections can be downloaded, along with high-resolution artwork with captions and source and credit details, at Science2017.GlobalChange.gov.

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