Climate impacts grow, and US must act, says new report

The 4th National Climate Assessment takes the temperature of climate change across the United States. The message? Adapt.

On November 23, the US government agencies released a heavily anticipated new report about how climate change is impacting the United States. The 4th National Climate Assessment (NCA4) lays out a detailed picture of how communities across the country are already feeling the effects of climate change—from intensified risk of wildfires in California, to droughts slowing agricultural production in Iowa and much more.

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Firefighters battle the Woolsey Fire as it burns through Malibu, California.
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The report is the second half of a vast effort by scientists, land managers, public health officials, and others to assess the state of the climate across the US. The report's first volume, published in 2017, summarised the state-of-the-art knowledge about how climate is affecting temperatures, water resources, sea-level rise, and other natural systems around the country. The second half, published recently, focuses on how climate change is already tugging at the economic and social fabric of the United States.

In clear, unwavering terms, the new report states that without "substantial and sustained reductions" in greenhouse gas emissions, climate change will hurt people, economies, and resources across the US. But the report also highlights how its worst impacts can be avoided, by adapting to our warmer world and by working to lessen future changes in Earth's climate.

“It joins the mounting evidence about the scope and magnitude of climate-change impacts,” says Jupiter Intelligence director Julie Pullen, an ocean scientist at Jupiter Intelligence who reviewed an earlier version of the report. And because the report drills down into the local-scale impacts, Pullen adds, it gives Americans a realistic view of exactly how climate change influences their day-to-day experiences.

News from the future

As the report makes clear, different parts of the country face different risks posed by climate change. In vulnerable Southeastern states, coastal flooding is projected to increase dramatically; Charleston, South Carolina, could experience 180 tidal floods in a year by 2045, compared to 11 per year in 2014. In the Southern Great Plains, extreme heat could cause thousands of premature deaths and billions in lost work-hours by the end of the century. Echoing the 2017 scientific report, the new volume reinforces that human activity—primarily the release of greenhouse gases—is the culprit.

 

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Notably, the new report also examines how climate change is affecting different sectors of the economy—like agriculture, forests, or fisheries—and highlights how they are vulnerable to future change. If climate change continues unabated, the report says, the agricultural sector's annual losses could reach billions of dollars by the middle of the century.

These risks aren’t just in the future, the report emphasises; they have arrived. The U.S. is already grappling with climate change's heavy costs, like when a powerful ocean heatwave struck the Northeast and devastated the region's lobster fishery. In addition, climate change's blows probably will worsen social and economic inequality across the country. Already, the poor, very young or very old, and communities of colour disproportionately face the dangers of our climate-weirded present—and will bear an even greater burden in the decades to come.

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It took years for this condemned home and a string of others like it in Nags Head to be demolished. Dare County is the only county in North Carolina to have an equal number of people and houses. Forty-four percent of those houses are seasonal homes, according to a 2010 US census.
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Despite these costs, the report says that US cities, states, and federal officials rarely incorporate future climate risk into their decisions. However, thoughtful planning around climate change could yield major benefits for communities across the country.

“The message is it's us, humans, changing the climate,” says Heidi Roop, a research scientist with the Climate Impacts Group at the University of Washington, which helped author a chapter of the new report. It's already affecting "many things we take advantage of every day—our wastewater management, our natural environment, our power generation, our roadways, our food. But the report highlights the other part of that: that people are doing something, and there's hope.”

This emphasis on action marks a major difference between this report and its last edition, published in 2014. In the last four years, Americans have gained more experience in trying to mitigate climate change and adapt to the new challenges it poses. The report pointedly calls out successful adaptation efforts underway, much to Pullen's approval: “I think that's actually one of the strengths of the report, is calling out the examples.”

Will Americans hear the message?

The new document follows on the heels of another widely publicised report by the UN's Intergovernmental Panel on Climate Change, which spoke bluntly about the challenges the planet faces in limiting the damages of climate change. Without aggressive action to control carbon emissions, that report warns, climate change could wreak havoc on the world's economy, social structures, and natural resources by 2030.

Taken together, the reports spell out a message of urgency. “What we're seeing is extreme impacts from climate change already,” even when the overall warming is relatively small compared to what will happen in the future, says Cecilia Bitz, an atmospheric scientist at the University of Washington, who reviewed an earlier draft of the report. “And the relentlessness of it, the shifting of both the means and the extremes—we're seeing tremendous impacts of it.”

The report is being released on the Friday after Thanksgiving, a day when many Americans are out of the office and news attention is low. Concerned that the messages from the report might be lost, some scientists are planning a Twitter campaign, with the hashtag #ClimateFriday in lieu of “Black Friday,” aiming to bring attention to the report.

“I had a gut level response,” said Tessa Hill, a marine scientist at the University of California’s Bodega Marine Laboratory, who organised the #ClimateFriday campaign. “If the current administration wants to bury the 4th Climate Assessment behind Black Friday, then we should just flip that whole notion on its head and spend the day talking about the outcomes of the Assessment.”

"[The report] is really about impacts, about how we adapt, and the choices we have to make. It's an incredibly important dialogue to be having, and to miss out on that would be a loss," says Hill.

The stage was set long ago

This new report is an instalment in an ongoing series. It was produced by the U.S. Global Change Research program, a consortium made up of representatives from thirteen different federal agencies that was established in 1990, after George H.W. Bush signed the Global Change Research Act into law.

The 1990 act—which passed with not a single dissent in the Senate—required a report every four years to pull together the best available research on how climate change affects the US. The reports were supposed to look into the future, predicting how climate would influence Americans 25 to 100 years ahead.

Energy to address the growing spectre of climate change was high in the late 1980s. Climate change had been a topic of conversation in the halls of government for over a decade: in 1978, Congress had passed a proto-version of the act that called for “assessments of the effect of climate” on society. And throughout the 1980s, discussion about climate change fomented within agencies and across scattered committees.

Simultaneously, the science about how increasing carbon dioxide concentrations in the atmosphere would affect global temperatures progressed quickly, so that by 1988, NASA scientist James Hansen could sit in front of a Senate Committee, peering over a bouquet of microphones, and say that he was “99% certain'' that global warming was underway.

Decades later, the science about climate change has become even clearer. But “we have fewer discussions about what that means for communities, for cities, for families, and also about what choices we have in front of us, and how we adapt going forward,” says Hill. “And that’s what this is about. I think we really need to grab those opportunities to have those discussions.”

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