The letter comes after the Washington Democrat's committee held a hearing this week on how climate change and associated extreme weather events hit the federal budget and the White House Council on Economic Advisers released a report detailing the financial costs of delaying action to curb greenhouse gas emissions.
"[T]his is not just an environmental issue. Climate change will also have serious ramifications for our economy and the federal budget, and failure to confront it will make it harder to meet our nation's long-term fiscal challenges," Murray said in the memo, which was first obtained by the Washington Post.
Democrats and the Obama administration have sought to define the White House's climate push along health and financial lines, with an increasing focus on the latter. Conservatives and industry groups, however, have said the president's policies — including a proposed Environmental Protection Agency rule to restrict carbon emissions from power plants — would raise costs in the short term, burdening businesses and low-income residents.
"Using just these four examples together, climate change, if left unaddressed, will add tens and potentially hundreds of billions of dollars in fiscal costs over the next decade alone, with much larger costs in later decades," Murray said.
Though, according to the Congressional Budget Office, publicly held debt is now expected to hit 108 percent of gross domestic product in 2040 — compared with earlier projections of 233 percent — Murray said climate change is not accurately accounted for in such estimates.
"The federal budget is exposed to the risks of climate change impacts in a variety of ways, and most of them are not adequately accounted for in current long-term budget projections," Murray said. "Current long-term budget projections rest on various assumptions about economic growth and federal spending that are mainly rooted in recent history."
The White House report earlier this week, which drew from 16 studies, said waiting to act on climate would increase costs of playing catch-up by 40 percent a decade as more carbon gets baked into the atmosphere and the effects of global warming become more entrenched.
An increase of 3 degrees Celsius above preindustrial temperatures, rather than 2 degrees, by 2100 would result in a 0.9 percent loss of global economic output, the report said. For comparison, 0.9 percent of U.S. GDP amounted to about $150 billion in 2014 dollars.
Murray cited events like Hurricane Sandy, which hit the East Coast in October 2012 and resulted in a congressionally passed $60 billion relief package, as reasons climate change will make budgeting more unpredictable. Other effects, such as shifting agricultural yields, also would hamper U.S. economic productivity, she said.
Included in the memo is a "numbers to know" section that details projected climate change-related losses, including an added $97 billion worth due to extreme weather events between 2015 and 2024, an additional $23 billion for maintaining infrastructure and more than $100 billion annually in food assistance programs to buttress rising prices.
"In the absence of a budget baseline that adequately accounts for the impacts of climate change or policies that explicitly limit climate change impacts, the effects of climate change will appear as additional costs to the federal budget," Murray said.