WASHINGTON -- Climate change is accelerating, and it will place unparalleled strains on American military and intelligence agencies in coming years by causing ever more disruptive events around the globe, the nation's top scientific research group said in a report issued Friday.
The group, the National Research Council, says in a study commissioned by the C.I.A. and other intelligence agencies that clusters of apparently unrelated events exacerbated by a warming climate will create more frequent but unpredictable crises in water supplies, food markets, energy supply chains and public health systems.
Hurricane Sandy provided a foretaste of what can be expected more often in the near future, the report's lead author, John D. Steinbruner, said in an interview.
"This is the sort of thing we were talking about," said Mr. Steinbruner, a longtime authority on national security. "You can debate the specific contribution of global warming to that storm. But we're saying climate extremes are going to be more frequent, and this was an example of what they could mean. We're also saying it could get a whole lot worse than that."
Mr. Steinbruner, the director of the Center for International and Security Studies at the University of Maryland, said that humans are pouring carbon dioxide and other climate-altering gases into the atmosphere at a rate never before seen. "We know there will have to be major climatic adjustments -- there's no uncertainty about that -- but we just don't know the details," he said. "We do know they will be big."
The study was released 10 days late: its authors had been scheduled to brief intelligence officials on their findings the day Hurricane Sandy hit the East Coast, but the federal government was shut down because of the storm.
Climate-driven crises could lead to internal instability or international conflict and might force the United States to provide humanitarian assistance or, in some cases, military force to protect vital energy, economic or other interests, the study said.
The Defense Department has already taken major steps to plan for and adapt to climate change and has spent billions of dollars to make ships, aircraft and vehicles more fuel-efficient. Nonetheless, the 206-page study warns in sometimes bureaucratic language, the United States is ill prepared to assess and prepare for the catastrophes that a heated planet will produce.
"It is prudent to expect that over the course of a decade some climate events -- including single events, conjunctions of events occurring simultaneously or in sequence in particular locations, and events affecting globally integrated systems that provide for human well-being -- will produce consequences that exceed the capacity of the affected societies or global system to manage and that have global security implications serious enough to compel international response," the report states.
In other words, states will fail, large populations subjected to famine, flood or disease will migrate across international borders, and national and international agencies will not have the resources to cope.
The report cites the simultaneous heat wave in Russia and floods in Pakistan in the summer of 2010 as disparate but linked climate-related events that taxed those societies.
It also cites the Nile River watershed as a place where climate-related conflict over water and farmland could arise as the combined populations of Egypt, Sudan and Ethiopia approach 300 million. South Korea and Saudi Arabia have purchased fertile land in the Nile watershed to produce crops to feed their people, but local forces could decide to seize the crops for their own use, potentially leading to international conflict, the report says.
The 18-month study is not the first such report from government agencies or research organizations to draw a direct link between climate change and national security concerns.
The National Intelligence Council produced a classified national intelligence estimate on climate change in 2008 and has issued a number of unclassified reports since then. The Pentagon and the White House have also highlighted the role of climate change in humanitarian crises and security threats.
The National Research Council recommends in the new report that all government agencies improve their ability to monitor the global climate and assess the risks to populations and critical resources around the world.
Yet Mr. Steinbruner said that as the need for more and better analysis is growing, government resources devoted to them are shrinking. Republicans in Congress objected to the C.I.A.'s creation of a climate change center and tried to deny money for it. The American weather satellite program is losing capability because of years of underfinancing and mismanagement, imperiling the ability to predict and monitor major storms.
This article originally appeared in The New York Times.