For the first time, the U.S. Department of Defense has detailed what it views as its greatest challenges related to climate change.

In a report to Congress, the Defense Department said that global warming poses a "present security threat, not strictly a long-term risk."

The report, delivered to the Senate Appropriations Committee on Tuesday and publicly released Wednesday, further stated the Defense Department is "already observing the impacts of climate change in shocks and stressors to vulnerable nations and communities," including in the United States, the Arctic, Middle East, Africa, Asia and South America.

As the Pentagon and intelligence community have done in previous national security-related analyses on global warming, the report mainly presents global warming as a threat-multiplier, rather than something that will by itself threaten U.S. national security.

"Although climate-related stress will disproportionately affect fragile and conflict-affected states, even resilient, well-developed countries are subject to the effects of climate change in significant and consequential ways," the report states.

The report, which was undertaken at senators' request, said each of the Pentagon's seven combatant commands are incorporating climate change-related risks into their planning, but that risks vary by region.

"Global climate change will have wide-ranging implications for U.S. national security interests over the foreseeable future because it will aggravate existing problems — such as poverty, social tensions, environmental degradation, ineffectual leadership, and weak political institutions — that threaten domestic stability in a number of countries," the report states.

The combatant commands, particularly U.S. Africa Command, which oversees the entire African continent from its headquarters in Germany, views climate change as a security risk because of its effects on human security and the government's ability to meet populations' needs.

The same can be said for Central Command, which has responsibility for the Middle East, where a devastating drought in Syria precipitated a significant internal migration and refugee crisis prior to the outbreak of the ongoing, deadly civil war that has pulled in the U.S. military.

The report cites the drought, which began in 2007, as a factor that helped overwhelm the government's capacity to provide for its people, and may have contributed to the subsequent civil war. A peer-reviewed study published in March linked the drought to global warming-related shifts in air circulation across the Mediterranean.

According to the Pentagon, climate-related stress can also create new vulnerabilities, such as water scarcity, that can lead to instability and conflict.

Studies published in June found that humanity is rapidly depleting a third of the world's largest groundwater aquifers, with the top three most stressed groundwater basins in the political hotspots of the Middle East, the border region between India and Pakistan, and the Murzuk-Djado Basin in northern Africa.

People wade through a flooded road caused by heavy rains in Lahore, Pakistan, Tuesday, July 21, 2015. Image: K.M. Chaudary/Associated Press

Making matters worse, researchers found that we don't know how much water is left in these massive aquifers — which water resources scientists often refer to as Earth's water savings accounts. The fact that the majority of the world's groundwater accounts “are past sustainability tipping points” was not known before, according to James Famiglietti, an author of both studies and a professor of Earth system science at the University of California, Irvine and senior water scientist at NASA's Jet Propulsion Laboratory.

Not surprisingly, U.S. Africa Command, or AFRICOM, ranks humanitarian crises as the most likely climate change-related risk under its purview, given the tendency for drought to trigger famine in Sub-Saharan Africa. The report states that climate change could interact with fragile governance and other challenges to "tip states toward systemic breakdowns."

In contrast, Northern Command sees the opening of the Arctic Ocean to resource exploitation, shipping and military traffic as a potential complicating factor from global warming. And for Pacific Command, sea level rise, which endangers the existence of several small island states in the Pacific basin, ranks highest on the list of threats.

In addition, the Defense Department views climate change, particularly sea level rise and increased heat waves, as a risk to its domestic and overseas bases and training facilities.

The report comes at a time when congressional appropriators have been cutting funding for climate research, particularly NASA's earth science programs, which helps agencies like the Defense Department project and anticipate global warming-related impacts.

Pentagon climate assessments such as this one may themselves be in danger.

House Republicans have voted to cut funds from the Pentagon and Central Intelligence Agency budgets that are directed at researching the national security implications of global warming.

Some Republican senators have criticized the Obama administration for viewing climate change as a major national security threat.