As atmospheric carbon dioxide hit a new record high of 415 parts per million recently, the immigration crisis on the U.S-Mexico border continued to grab headlines. Thousands of families from Guatemala, for instance, are pulling up stakes and setting off with small children in tow on a dangerous journey north to America. No matter what you think of immigration, one has to admire the sheer stamina of these young families migrating by foot for over a thousand miles.

So, what is the effect of climate change on immigration, equatorial agriculture, and national security in general?

In the Western Hemisphere, the equator goes through the northern part of South America, meaning that all of Central America lies north of the equator but well within the equatorial zone for agriculture. According to the administration of President Donald Trump, if polluting with carbon persists, we can expect a 3.4 degree Celsius rise in global temperatures by the end of the century. Climate and agricultural experts calculate that equatorial agriculture will collapse at 3 degrees of warming.

For a country like Guatemala this will be crushing — and for other equatorial regions, too. A remarkably consistent 23 percent reduction in food production in Central America, Africa, Middle East/North Africa, and Asia is predicted. Many of these areas have the world’s highest population growth, as well.

Indeed, climate change is already having an effect on Central America with large increases in climate-related events such as torrential rain, flooding, landslides, and drought since the 1970s. For the 37 percent of Guatemalans who are farmers, this spells a stark choice: migration or death. Migration is unlikely to the south toward an even warmer equator but to the north.

Mind you, this is under the best circumstances, where people just peacefully move to a more-hospitable climate. However, resource scarcity is a prime cause of conflict both within and between countries. The Syrian conflict, for instance, was sparked by years of climate change-induced drought overlain by long-simmering sectarian tensions.

Another example is the strain the presence of millions of Syrian refugees placed on European countries. This is why the U.S. military considers climate change a “threat multiplier” destined to place ever-increasing pressures on the U.S. military — assuming the military can get there.

For instance, Norfolk, Va., is a major Navy base and is already experiencing “blue sky” flooding on a regular basis from the combination of tides and sea-level rise. At 415 parts per million, the last time we had this much carbon dioxide in the atmosphere the oceans were 50-65 feet higher. Good bye, Norfolk.

Certainly, if an invading force was poised to contract the land mass of the United States by force of arms, we would rise up as one and make enormous sacrifices to defend the country; yet we have sat on our hands while the oceans are swelling.

Fortunately, the tide of climate inaction seems to ebbing a bit. Important “leadership cues” from prominent Republicans are easing the party toward the acceptance of climate science and the consideration of climate action. Importantly, at a recent Ways and Means Committee meeting of the U.S. House, not one Republican challenged climate science. They were more in favor of energy innovation through tax credits than carbon pricing or direct federal action. But, at this point, who cares? Overall, the tenor was constructive, and that was an enormous step forward.

Here’s to hoping our leaders work together to forge effective climate-action legislation before millions of Central Americans and other climate refugees are compelled to take the long march north.

Eric Enberg practices family medicine in West Duluth and is group leader for the Duluth Citizens' Climate Lobby (citizensclimatelobby.org/chapters/MN_Duluth). He also is a member of the Duluth Climate and Environment Network.