WASHINGTON, Sept. 28 (UPI) -- Global climate change presents a serious national security threat to the United States, heightening tensions and instabilities worldwide, lawmakers were told.

The Investigations and Oversight Subcommittee of the House Committee on Science and Technology heard testimony Thursday from several experts, principally retired Gen. Gordon Sullivan, the former chief of staff of the U.S. Army and now chairman of a blue-ribbon commission of a dozen retired U.S. admirals and generals.

The commission, set up by the CNA Corp., recently reported on “National Security and the Threat of Climate Change” over the next 30-40 years -- the timeframe for developing new military capabilities.

The effects of global warming, Sullivan said “include reduced access to fresh water; impaired food production, health catastrophes -- especially from vector- and food-borne diseases; and land loss, flooding and the displacement of major populations.”

These “destabilizing effects” will “increase the potential for failed states and the growth of terrorism; mass migrations will lead to greater regional and global tensions; and conflicts over resources are almost certain to escalate,” he concluded.