Fourth National Climate Assessment

• 1. Introduction

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  The Fourth National Climate Assessment landed on Black Friday, the 23rd of November, 2018, one of the least-read news days of the American year. The report ran to 1,500 pages. It arrived a full month before its anticipated publication date. Steven Milloy, a climate-change denier who served on Trump's EPA transition team, acknowledged the calculation. He told reporters the administration chose that day "on a day when nobody cares, and hope it gets swept away by the next day's news."

  Milloy also noted the administration had not altered a single finding in the report. White House officials dismissed the document as "inaccurate" while releasing it unchanged.

  The report described a warming climate already reshaping every region of the United States. It projected harm for communities and economies from coast to coast. How was a report of that scale built inside a government skeptical of its conclusions? What did the scientists behind it actually find? And what happened to the institutions meant to carry those findings into law?

• 2. The 1990 Foundation

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  On the 16th of November, 1990, President George H.W. Bush signed the Global Change Research Act into law. The act established the United States Global Change Research Program. It also created a legal requirement: a comprehensive climate assessment delivered to Congress every four years.

  Only four reports have been produced since the act was enacted. NCA1 appeared in 2000, NCA2 in 2009, NCA3 in 2014, and NCA4 spanned 2017 and 2018. The gaps between each report stretched well beyond what the law had envisioned.

  The act charged the program with understanding the cumulative effects of human activities and natural processes on the environment. It also directed the program to promote international protocols in global change research. That mandate applied regardless of which party occupied the White House. Its full weight became visible when the fourth report landed in the hands of an administration at odds with its findings.

  Like previous assessments, NCA4 was designed as a stand-alone examination of the state of climate science and its physical impacts.

• 3. Thirteen Agencies, One Report

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  The National Oceanic and Atmospheric Administration served as the administrative lead agency for NCA4. It was one of thirteen federal agencies that contributed to the effort. The other twelve included the departments of Agriculture, Commerce, Defense, Energy, and Health and Human Services. The departments of Interior, State, and Transportation were also involved, as were the EPA, NASA, NSF, the Smithsonian Institution, and USAID.

  Roughly 1,000 people contributed to the production of NCA4. About 300 of them were leading scientists, and approximately half of those came from outside the government. The Federal Science Steering Committee for Volume 1 included representatives from NOAA, NASA, DOE, and the USGCRP, along with three Coordinating Lead Authors.

  The Obama administration opened a public review draft of Volume 1 for comment on the 15th of December, 2016. That review period ran through the 3rd of February, 2017, a window that crossed the presidential transition. By the time the new administration had fully taken shape, the first volume had already been subjected to public scrutiny and peer review.

  Two volumes emerged from this two-year process. Volume 1, the "Climate Science Special Report," appeared in October 2017. Volume 2, "Impacts, Risks, and Adaptation in the United States," followed in November 2018. What those scientists had gathered to determine was not whether climate was changing, but how confidently the evidence allowed them to establish the cause.

• 4. What "Extremely Likely" Means

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  "Extremely likely" was the phrase Volume 1's authors chose to characterize their conclusion on causation. The Climate Science Special Report stated that human activities, "especially emissions of greenhouse gases," were the dominant cause of observed warming since the mid-20th century. The authors added there was "no convincing alternative explanation supported by the extent of the observational evidence."

  A 2018 Congressional Research Service analysis summarized the evidence behind that finding. Detection and attribution studies, climate models, direct observations, ancient climate records, and physical understanding all pointed to the same conclusion. Researchers reported high confidence that more than half of the global mean warming since 1951 was caused by humans. Internal climate variability played only a minor role, and possibly even a negative one.

  That body of evidence aligned with the IPCC Fifth Assessment Report. Volume 1 was explicit that the Climate Science Special Report was designed as "an authoritative assessment of the science of climate change" in the United States. It contained no policy recommendations. The science and its implications for governance were treated as entirely separate questions. What Volume 2 would tackle was what that warming would cost an economy and a country that chose not to act.

• 5. A Price Tag for the Century

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  Volume 2, "Impacts, Risks, and Adaptation in the United States," organized its warnings around geography. Its fifteen chapters moved through the country region by region. Chapter 11 tracked Arctic changes and their effects on Alaska and the rest of the United States. Chapter 15 addressed what the authors called "Potential Surprises: Compound Extremes and Tipping Elements."

  Without substantial mitigation, losses in some sectors were projected to reach hundreds of billions of dollars by the end of the century. A 2017 study in the journal Science, which the report cited, had estimated those damages against rising global mean surface temperatures. The report also warned that climate change would impede the rate of economic growth over the century as a whole.

  Chapter 1 identified "poor and marginalized communities" as those most likely to face the sharpest exposure to intensifying storms and changing weather. Risks were "often highest for those that are already vulnerable, including low-income communities, some communities of color, children, and the elderly." The report explicitly linked climate change to the deepening of existing social and economic inequalities.

  By July 2019, The New York Times cited NCA4 to document the threat sea level rise posed to the trillion-dollar coastal real estate market.

• 6. Dismissed and Praised

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  In a scrum with reporters in Washington, DC, on the 26th of November, 2018, President Trump said he had read some of the report. He said he didn't believe it. White House spokesperson Lindsay Walters called the report "largely based on the most extreme scenario" and pressed for "a more transparent and data-driven process" in future assessments.

  Katharine Hayhoe, an atmospheric scientist at Texas Tech University, called Walters's claim "demonstrably false." Hayhoe stated that the assessment covered every scenario. The range ran, she confirmed, "from those where we go carbon negative before end of century to those where carbon emissions continue to rise." Steven Milloy, for his part, called the report a product of the "deep state" and described its findings as "made-up hysteria."

  The Atlantic described the document as "massive," "a grave climate warning," and "a huge achievement for American science." The Washington Post and Vox both called it "major." The Hill described it as "damning." The Verge labeled it "a bleak Black Friday report."

  Collin O'Mara, President of the National Wildlife Federation, issued a statement calling the Black Friday timing "an absolute disgrace." He noted the report had been buried during a year that "saw hundreds of Americans die during devastating climate-fueled megafires, hurricanes, floods, and algal blooms." The New York Times reported that White House officials had calculated that Trump's core supporters would not care. The report's findings were too far at odds with the president's own statements and policies.

• 7. The Advisory Gap

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  On the 20th of August, 2017, the Trump administration announced it was dissolving the fifteen-person Federal Advisory Committee for the Sustained National Climate Assessment. A Washington Post article from that same date described the committee's role. Its task was to assist policymakers and private-sector officials in incorporating the government's climate analysis into long-term planning. The panel was specifically tasked with translating dozens of studies and scientific revelations into policy actions that states could use to reduce greenhouse gas emissions.

  In January 2018, New York Governor Andrew Cuomo reconvened a modified version of the advisory panel as part of a coalition of states. Richard Moss of Columbia University's Earth Institute chaired it. The states acknowledged their panel could not "replace federal support for science, including maintaining satellites and building better climate models." Nor would it have any "sway over federal climate policy."

  In May 2019, The New York Times reported the Trump administration's plans to change the climate modeling approach for the next assessment, due in 2022. Rather than projecting impacts through the end of the century, as all previous reports had done, the new methodology would stop at 2040. The administration also planned a review panel to question that future report's conclusions. The Times reported that William Happer, described as someone who "would be a fringe figure even for climate skeptics," would head it.

  A Los Angeles Times article observed that the report addressed a common misconception: many Americans still believed climate change did not affect them personally. The report was built to show that impacts were already being felt "whether we live in Texas or Minnesota or Hawai'i or Florida."