The White House, in coordination with 14 federal agencies, today released the Fifth National Climate Assessment (NCA), a comprehensive report on the impacts of climate on the United States and what future warming may hold for ecosystems, the economy, and communities across the country.
The report establishes that the effects of rising temperatures are already “worsening across every region of the United States” sending ecosystems into death spirals, reshaping crops and forests, and fueling deadly heat waves. And without deeper cuts in global greenhouse gas emissions and accelerated adaptation to changes already underway, the report authors warn that “severe climate risks to the United States will continue to grow.”
Since 1990, Congress has required federal agencies to figure out how climate change will affect the country, with a report due at least every four years. Each assessment tallies up the latest damages, summarizes the newest science, and presents a sharper picture of the future. Unlike other major climate change reports, like those from the Intergovernmental Panel on Climate Change, the National Climate Assessment is meant to explicitly inform policy and action, from interstate emissions trading rules to how many cooling shelters a city will need during a heat wave.
The new assessment highlights how scientists have improved their ability to attribute signals of human-caused warming in extreme weather events like storm surges and heat waves. In addition, it tracks efforts to adapt to climate change, particularly incorporating traditional Indigenous knowledge. It also dedicates more space to racial and economic disparities in climate impacts.
In a conference call with reporters, White House officials highlighted the new findings and used the report’s release to boast about their efforts to curb heat-trapping gasses, deploy clean energy, and adapt to warming through programs like the Inflation Reduction Act and the Bipartisan Infrastructure Law. The presentation and release of the latest assessment stand in stark contrast to the last iteration of the report in 2018, when the Trump administration quietly posted it over a holiday weekend.
The question, as always, is how much the report will change the country’s trajectory on climate change. Though US emissions are declining, they aren’t falling fast enough to stay in line with the country’s climate change commitments. As international delegates gather later this month for negotiations at the COP28 climate conference to further map out how they’ll address warming, the US will be one of many countries coming to the table with alarmingly little progress on a problem that the research continues to show is getting worse.
The National Climate Assessment is a scientific report with strong political implications
The National Climate Assessment has the dual remits of summarizing the latest in climate science and making it understandable for the public. Since the report is required by law, the whims of whoever is in the White House can’t quash it. But politics do change what’s emphasized and what’s downplayed.
The last report cycle came under President Donald Trump, and scientists worried that the climate change denier would attempt to block its release. Though the report did publish, the administration dropped it on Black Friday, the day after Thanksgiving, in 2018. None of the federal agencies involved in assembling it helped publicize the release, and Trump afterward told reporters he “didn’t believe it.”
Now, the Biden administration is leading with a splashier release: The fifth assessment has new bells and whistles, including an accompanying podcast, art series, and even a poetry anthology compiled by two poet laureates and a climate scientist. There is a new atlas that allows users to explore their local climate impacts, and the full text is available in Spanish for the first time. We’re doing “whatever we can do to get this in the hands of people making decisions across the country every day,” Nature Conservancy chief scientist Katharine Hayhoe, a lead author of the NCA, said on a White House press call.
More granularly relevant to the US than the scientific analysis of the Intergovernmental Panel on Climate Change, the NCA will play an important role in the policies shaped by federal, state, and local agencies. Regulators can use it to guide future building standards, insurance policies, coastal development, and more. Even the buried assessment released by a reluctant Trump administration was cited thousands of times across the country. This time, the report will factor in the reforms spurred by new federal climate spending from the infrastructure law and the Inflation Reduction Act.
The goal of public communication infuses the entire report because it is first and foremost intended as a decision-making tool.
To that end, one shift since the 2018 report is a greater emphasis on Indigenous people and racial justice, including dedicated chapters focused on the impacts of climate change on these groups. In the past five years, there’s been a surge in literature looking at climate change’s unequal burden from the lens of discrimination and historical practices like redlining, where lenders withheld services in communities of color. “There’s been a huge advance in our understanding of how impacts of climate change are felt disproportionately among our neighbors in cities in areas all over the country,” said Jeremy Hoffman, who led the Southeast chapter. “We’ve learned so much about how extreme heat disproportionately affects individuals with preexisting conditions or in outdoor work.”
In another example, the assessment observed that, by 2050, census tracts with a Black population greater than 20 percent were poised to experience almost twice the rate of losses due to floods as tracts where Black people made up less than 1 percent of the population.
What the report makes clear is how the entire country now has to grapple with worsening heat, flooding, drought, and smoky days. This increasingly personal experience of climate change affects how the administration considers its communication. Young people today “have not just intellectually started to appreciate the concept of this crisis, it is their lived experience to see the sky turn orange or to breathe in the smoke from wildfires, hundreds of miles [away],” Biden’s national climate adviser Ali Zaidi said on a press call.
Authors hope the report will help alleviate the harms of climate change
Since 2018, scientists have learned a lot more about the consequences of rising greenhouse gasses and peered through a window into the future: The planet experienced four out of the five hottest years humans have ever measured, including 2023, which is on track to be the hottest year on record.
Some of the biggest advances highlighted in the Fifth National Climate Assessment are in understanding the material ways that climate change has already started to affect us and how more warming will shape our future.
For instance, the new report talks about advances in understanding individual extreme weather events, called climate change attribution. By measuring specific features like sea level rise or shifts in the probabilities of certain events, researchers can tease out how humanity’s appetite for fossil fuels has altered severe weather.
Scientists can even perform these calculations during or shortly after a massive deluge, epic heat wave, or raging storm. For example, the report notes that 2017’s Hurricane Harvey, which broke a national rainfall record for a single storm as it drenched Houston, was about 15 to 20 percent worse due to climate change. Attribution helps scientists communicate the role of climate change in severe weather to the public. It also lays out how further warming will influence extreme events in the years to come.
Scientists have also learned more about how rising average temperatures affect the ecosystems that we depend on for our health and our economy. Climate change is reshaping how vegetation clears the air, how soils filter water, and how forests drive regional rainfall cycles.
Recent findings show that some ecosystems are close to tipping points, where the interplay between local plants, animals, microorganisms, and weather patterns will undergo unstoppable changes. Massive wildfires, for instance, can lead certain animal populations to permanently relocate. Others may go extinct.
“In some cases, we as humans can adapt to those changes, but what’s really worrisome, for a lot of these changes, some of them are going to be irreversible,” said Pamela McElwee, who led the ecosystems chapter of the climate assessment. “We can’t ever go back, even if we were to stop all of our greenhouse gas emissions right now.”
That’s alarming because these ecosystems provide benefits that scientists are only beginning to learn about and quantify. Coral reefs, for example, are not just popular tourist destinations but important shock absorbers for coastal storms. They help the US economy avoid about $1.8 billion in damages each year, explained McElwee, a professor of human ecology at Rutgers University. But coral reef ecosystems are facing enormous threats, from fertilizer runoff, from overfishing, from the changing chemistry of the ocean, and from warming water.
The report then connects the dots between research on warming and how that in turn affects people. “Social science is predictive of climate change outcomes in a very serious way,” said Elizabeth Marino, an associate professor of anthropology at Oregon State University Cascades, who led the chapter on social justice. “It’s one thing to say there will be sea level rise and it’s another thing to say these are the processes that lead to who will move and who will not.”
Scientists have begun to piece together how factors like race, income, construction techniques, and insurance rates can compound the effects of a disaster already worsened by climate change, creating social disruption and widening inequities.
The hope is that flagging these interconnections can reduce the suffering that people experience as the planet heats up. “One of the famous sayings within hazards and disaster literature is ‘there’s no such thing as a natural disaster,” said Fayola Jacobs, an assistant professor of urban planning at the University of Minnesota and a co-author of the NCA’s social science chapter. While rising temperatures can fuel hotter heat waves and more damaging storms, the harms that people experience —injuries, illnesses, homelessness, stress, financial loss — are a function of decisions they make as individuals and as communities.
The challenge is not only coming up with the decisions that maximize the benefits of addressing climate change and minimize its harms, but building public support for more aggressive actions on climate change. “While there is urgency to this, we can’t do it so quickly and carelessly,” Jacobs said. “We can only move at the speed of trust.”