The Government Accountability Office delivered that warning in its update of the greatest threats the government faces in carrying out federal programs. Generally the GAO identifies things like flaws in the defense contracting process and fraud in health care programs.
This year's update of the High-Risk Series report included the increasingly obvious and growing external threat of climate change -- in spite of the continued insistence from many members of Congress that fears over global warming are overblown.
"Limiting the federal government's fiscal exposure to climate change is one of the new areas we have on the list," Comptroller General Gene Dodaro, the head of the GAO, told reporters at a Capitol Hill press conference. "The federal government is terribly exposed to this change," he added, noting that the government owns hundreds of thousands of buildings, operates defense installations, picks up the tab to help local governments with disasters, and runs crop and flood insurance programs.
"The government doesn't budget for disaster," Dodaro said, "and the record number of disasters hit above 90 in 2012."
Dodaro was aware that some in Congress might not like his agency's embrace of climate change, but he argued that the facts justified it.
"We believe that the information coming from the National Academy of Sciences and from the federal government's own global change research program ... has been very clear on the science underpinning this area," Dodaro said.
"We are not focusing on what's causing these changes. We know that there are efforts under way to deal with emission issues, so that's a policy matter for the Congress," he said. "We think there's enough scientific evidence to show, regardless of whether anything else changes, there's enough problems identified."
Still, while President Barack Obama has proposed making a stronger push to deal with climate change, and leaders in the Senate have praised him for it, the idea has received a chilly reception from leaders in the House.
Rep. Darrell Issa (R-Calif.), the chairman of the House Government Reform and Oversight Committee, joined Dodaro at the press conference to emphasize that it doesn't matter whether lawmakers agree on climate change, the effects are nonetheless occurring, and Congress should plan.
"We're recognizing that we have under-appropriated and under-prepared for a wide variety of disasters," Issa said. "If they're occurring more, not less, if we're seeing an absence of indexing for inflation, those are all areas that legitimately put it at high risk," Issa added, even while indicating he has some skepticism on the climate front.
"I hope all members of Congress on both sides of the issue recognize that it's really not about where you are on climate change, how much CO2 is being emitted -- which, by the way, has gone down, not up -- it's really about recognizing that Congress has not adjusted for the amount of money we are paying out," Issa said.
The cost issue was one of the prime factors Dodaro cited in deciding to take the potential political risk of officially elevating the threat.
"We also believe the timing is right because of the federal government's fiscal position," Dodaro said.
"We can no longer afford to take on these huge costs that occur as a result of disasters, and we need to prepare properly. We think we have a sound case."
Rep. Elijah Cummings (Md.), the top Democrat on the Oversight Committee, had the starkest warning for his colleagues.
"This landmark action by the nonpartisan experts at GAO ... is a wake-up call for Congress to finally start addressing this issue," Cummings said Thursday. "GAO warns that climate change is real, its impacts are already being felt, and its consequences will be devastating if we continue to ignore it."
Michael McAuliff covers Congress and politics for The Huffington Post. Talk to him on Facebook.