As the movement of refugees strains countries worldwide and becomes fuel for political clashes in the United States, the Trump administration has eliminated guidelines that the government once gave to American diplomats about how to plan for the impact of climate change on migration and global security.

In a report released Thursday, the Government Accountability Office recommended the State Department restore the guidelines so U.S. diplomats are prepared for major population shifts that could destabilize a country or region.

"Without clear guidance, State may miss opportunities to identify and address issues related to climate change as a potential driver of migration," the report said.

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In the report, the GAO, an auditing and analysis arm of Congress, sought to assess the U.S. government's shifting response to human migration driven by climate change. It highlighted the impact of President Donald Trump's decision in March 2017 to revoke an Obama-era executive order and presidential memorandum that called on federal agencies to weigh the effects of climate change on international development decisions.

The GAO found that as a result of Trump's changes, the State Department no longer provides its diplomatic missions "with guidance on whether and how to include climate change risks" as they develop country strategies. The guidance is effectively a toolkit diplomats use to establish the priorities that the U.S. has in a given country and plans to best address them.

State Department's Response Raises Eyebrows

The State Department offered a contradictory response to the GAO's recommendation. It said it would "update" the guidelines, but did not go into detail as to how. At the same time, the State Department wrote that it will consider recommending that climate change be further scrubbed from its priorities, which would mean asking Trump to rescind yet another executive order.

The report's co-author, David Gootnick, said that such a response was unusual. "After the GAO put the spotlight on the fact that they've dropped two executive orders, their response is to say, 'Okay, we might drop the third,'" Gootnick said. "To drop this executive order would be a potentially controversial thing to do."

The GAO plans to monitor the State Department's work over the next four years to see if it complies with the report's recommendation.

State Department spokesman James Dewey said he could not "offer an official response at the moment due to the partial shutdown." At the root of the government shutdown is a dispute over a wall to keep migrants out.

Migration Has Risen Around the World

Estimates vary considerably of how many people are migrating because of climate change-fueled events or might be displaced in the future, because of the lack consistent data. Still, the decisions by the State Department to stop providing climate guidance have occurred as migration has risen worldwide. Globally, about 244 million people are international migrants, and an additional 740 million people are migrants within their home countries, according to the International Organization for Migration's 2018 World Report.

Further, the IOM found that since 2008, an average of 25.3 million people have been newly displaced annually, the vast majority due to disasters rather than violence. In 2016, 97 percent of the people who fled their homes did so because of "disasters triggered by climate and weather-related hazards," the IOM said.

In the U.S., the national security apparatus has described climate change for years as a "threat multiplier"—the extra pressure that could destabilize countries where resources such as water and arable land are limited and governance is weak. In a 2015 report to Congress, the Pentagon pointed to the Syrian civil war as an example of how climate change can aggravate the fragility of a nation already beset by tensions and unpopular leaders.

Researchers are now looking into how drought and higher temperatures fueled by climate change might be driving the migration of thousands of people from Honduras, Guatemala and Nicaragua northward to Mexico and the United States. The migration has become a political flashpoint in the U.S., as President Trump's insistence on funding for a controversial border wall to deter migrants has led to the longest government shutdown in American history.

A Global Challenge & National Security Threat

The GAO has written in past reports that climate change exposes the U.S. to profound fiscal risks. In February 2017, it recommended a "cohesive strategic approach" to planning for climate risks across the federal government.

In its new report on climate change and migration, it focused on the work of the State Department, the U.S. Agency for International Development (USAID) and the Defense Department because of their roles in promoting national interests, development and stability overseas. The report was written at the request of five Democratic senators, including Edward Markey of Massachusetts, who voiced concern this week about the findings.

"Our diplomats lack the clear guidance they need to deal with climate change," Markey said, in a written statement. "Because climate change is a global challenge and a national security threat, the United States needs to prepare and take preemptive measures for an uncertain future instead of just waiting to address unforeseen consequences."

The report said that the Obama administration did not focus on climate change as a driver of migration. But it did take steps to ensure federal agencies factored climate change into strategic planning by issuing executive orders on international development, requiring federal agencies to gather and disseminate information on climate preparedness, and issuing a 2016 Presidential Memo on "Climate Change and National Security."

In March 2017, Trump signed his own executive order nullifying all but the international development order. The White House described them at the time as an undue "burden" on the development of fossil fuels.

Besides getting rid of guidance for diplomats to better plan for country-level threats from climate change, the administration has also cut foreign aid to developing nations and international organizations that would help address climate risks.

The joint strategic plan between the State Department and USAID in 2015 described climate change as "an urgent and growing threat to U.S. national security, contributing to increased natural disasters, refugee flows and conflicts over basic resources like food and water." The 2017 joint plan does not take climate change into account, the report said.

The U.S. has also pulled back from multinational collaboration on climate risks, beyond its withdrawal from the 2015 Paris climate accord. The report noted that there is a UN Global Compact for Migration that would work in part to mitigate the impact that climate change could have on migration and a Platform on Disaster Displacement to address the needs of people displaced by climate-driven disasters. The U.S. has declined to participate in both initiatives.