It is the first time that the issue of climate change has appeared on the GAO's high-risk review, which is conducted every two years to coincide with the start of a new Congress.
The report typically lists government operations considered at high risk for fraud, waste, abuse or mismanagement.
"Climate change creates significant financial risks for the federal government, which owns extensive infrastructure, such as defense installations; insures property through the National Flood Insurance Program; and provides emergency aid in response to natural disasters," the report, released Thursday, states.
While the Obama administration has made "some progress" toward improved organizing across agencies, within agencies and among different levels of government, "more comprehensive and systematic" planning is needed, GAO says.
"The federal government is not well positioned to address the fiscal exposure presented by climate change and needs a government wide strategic approach with strong leadership to manage related risks," the report says.
Measures that GAO says are needed include more information to manage federal insurance programs' long-term financial exposure to climate change; addressing gaps in satellite data; a government-wide approach to providing data and technical assistance to state and local governments.
U.S. Rep. Henry Waxman, D-Calif., the ranking member on the Energy and Commerce Committee, said the addition of climate change to the High Risk List "is a huge development."
"Congress can't ignore an issue that its own auditors say is a top risk to taxpayers," Waxman said in a statement, noting that both Republicans and Democrats rely on the GAO report.
"When GAO concludes that climate change is high risk, it becomes a fiscal imperative for the federal agencies and Congress to respond," he said. "The costs of inaction on climate change will be much higher than the costs of responsible action."
The National Oceanic and Atmospheric Administration says that over the past two years, the nation has experienced 25 weather disasters, causing the death of 1,100 people. In 2011, there were a record 14 extreme weather and climate events in the United States costing more than $60 billion.
NOAA hasn't released an aggregate cost estimate from the disasters of 2012, as it is revising the ways it adjusts disaster losses for inflation to ensure the data are sound, The Guardian reports. Those figures are expected to be released in the middle of this year but some cost estimates for Hurricane Sandy alone have approached $100 billion.
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