A pedestrian uses an umbrella to shield from the rain while walking along 13th Street NW in Washington DC on June 18. Photo / Matt McClain, the Washington Post
America’s Commerce Department has indefinitely suspended work on a tool to help communities predict how rising global temperatures will alter the frequency of extreme rainfall, according to three current and former federal officials.
It is a move that experts said will make the United States more vulnerable to storms supercharged by climate change.
The tool is part of the National Oceanic and Atmospheric Administration’s Atlas 15 project - a massive dataset that will show how often storms of a given duration and intensity could be expected to occur at locations across the US.
The project was intended to be published in two volumes: one that would assess communities’ current risks and a second that would project how those risks will change under future climate scenarios.
Atlas 15’s release had been long awaited by civil engineers, regional planners and other groups that use Noaa’s precipitation frequency estimates to develop regulations and design infrastructure.
Many parts of the country rely on decades-old data to determine their rainfall risks, and there is no authoritative national dataset of how rainfall and flood threats will rise in a warmer world.
But work on Atlas 15’s climate projections has been on hold for months after Commerce Secretary Howard Lutnick ordered a review of volume two in the northern spring, according to current and former Noaa officials with knowledge of the project.
National Weather Service spokeswoman Erica Grow Cei confirmed the move to delay the forward-looking component of Atlas 15, saying Lutnick’s review is aimed at “making sure research dollars and technology investments are being put to the very best use for the American people”. She declined to say how long the hold is expected to last.
Ed Clark, who had worked extensively on Atlas 15 as director of the agency’s National Water Centre, said that research for volume two was almost complete before he retired in late April and that the remaining work did not have “a large price tag”.
Meanwhile, the toll of intensifying storms is becoming increasingly apparent.
In the first 15 days of July, the National Weather Service has reported twice the usual number of flash floods - including the deluge that killed at least 130 people in central Texas and heavy rains in the northeast that drowned two people in New Jersey and left New York subway stations submerged.
The review of Atlas 15 is among a number of efforts by the Trump Administration to curb climate science.
The Administration dismissed the scientists responsible for writing the National Climate Assessment - a congressionally mandated study typically published every four to five years - and dismantled the programme that oversees the reports.
In a budget document submitted to Congress last month, President Donald Trump proposed zeroing out funding for Noaa’s climate research and eliminating many of the agency’s laboratories and institutes.
Clark worries that delaying the release of Atlas 15 climate projections - or cancelling the volume altogether - could leave communities unprepared for shifting flood risks and make it harder for engineers to ensure that buildings, bridges and other projects can cope with future rainfall extremes.
“Designing our infrastructure for resilience is fundamentally a cost-saving measure,” he said.
Preliminary data for volume one, which is based on historical observations, is still on track to be made public by the end of the year, according to Fernando Salas, director of the geo-intelligence division at the National Water Centre.
For every location in the contiguous US, the dataset will show the likelihood of a given amount of precipitation falling in a certain period - helping communities determine the level of rainfall they should expect to occur every year, as well as the sort of storm that would be expected to happen once every century.
“It’s going to ensure we’ve got that baseline established for the entire country,” Salas said.
But the speed with which rising global temperatures are altering precipitation patterns means that the volume one estimates “will be out of date very quickly”, said Jeremy Porter, head of climate implications research at the non-profit First Street Foundation.
It is a fact of physics that rising global temperatures allow the atmosphere to hold more moisture, providing additional fuel for extreme storms.
In a peer-reviewed analysis published in 2023, First Street scientists found that 20% of the US has already seen a fourfold increase in the likelihood of 100-year rainfall (an event with a 1% chance of happening in any given year).
Once-rare events are expected to become even more common as the world continues to warm.
A pilot version of Atlas 15 that includes current and future precipitation frequency estimates for Montana was released last year.
Though the state is not expected to be among those hit hardest by extreme rainfall in a warming climate, the volume two estimates showed that rainfall rates for one-in-100-year events could increase by more than a tenth of an inch per hour if the world stays on its current warming path.
The Northeast, Appalachia and other flood-prone regions are expected to experience even bigger increases in the intensity and frequency of extreme events, Porter said. But if Noaa doesn’t restart work on volume two, those states won’t know exactly what those changes will be.
Though private groups like First Street may produce their own climate projections, Noaa’s precipitation frequency estimates provide an authoritative national standard, said Chad Berginnis, executive director of the Association of State Floodplain Managers.
City and state regulations have incorporated the federal data into building codes and development plans.
Civil engineers are required to consult Noaa when designing features such as road culverts and stormwater drainage systems, which may be intended to last 50 years or more.
“Knowing the future condition helps make that investment more resilient,” Berginnis said.
He noted that most federal spending on disasters goes towards helping communities rebuild infrastructure that frequently wasn’t designed to withstand the kinds of weather that climate change can bring.
“Think about it as a taxpayer,” he said. “If we have this future information, we won’t have to continue to be in the cycle of damage, repair, replace, damage again.”