What is causing the refugee crisis in Central America? One major fuel is the war on drugs, as I have previously written. But another under-discussed factor is climate change, which has devastated many farms in Central America. These climate refugees are just the first glimmerings of a problem that is going to plague the world for the foreseeable future.

The PBS News Hour recently ran an excellent report on how climate problems are driving many farmers out of business in Honduras. One issue is drought — over the last decade or so, warming temperatures have created chronic rain shortfalls over much of the country, destroying whole crops and rendering traditional planting techniques impossible. Poorer farmers are even finding subsistence agriculture out of the question:

Don Alfredo says, 10 years ago, he could harvest around 4,000 pounds of corn each season. Now he says he's lucky if he gets around 500. He says he's lost over 90 percent of his crop, and what was left wasn't even enough to live on. [News Hour]

Elsewhere in the coffee business (Honduras is the fifth-largest coffee exporter in the world), high temperatures are fueling epidemics of rust fungus, or roya. If the temperature gets below 77 degrees Fahrenheit, then the fungus slows down sharply. But if it stays that hot continually, it quickly wipes out whole plantations.

Incidentally, a similar process has fueled an epidemic of bark beetle infestation in the American West. It used to be that winters would regularly get cold enough to kill off most of the beetles and their eggs. But without that limiting process, beetle populations have grown exponentially. From 2000-2017 beetles destroyed some 85,000 square miles of American forest.

At any rate, this also demonstrates the brutal logic driving refugee movements. The Hondurans interviewed by PBS know all about Trump, his deportation squads, and his camps. Indeed, Don Alfredo has already attempted to cross the border once and been caught and deported. But they simply have no other choice. It's take the risk, or starve.

One can imagine the Republican response to this: Just keep them out. However, Americans are fooling themselves if they think clamping down the southern border is going to save them from climate refugees. For one thing, the border is very long and hard to secure. It would take a full-blown police state to stop a real refugee flood, should one get going.

But more importantly, millions of climate refugees are unquestionably going to come from inside the United States as well. The Miami metro area, for instance, has a population of over six million and an average elevation of about 6 feet — and much of Miami is even lower. Sea levels have already increased by about 9 inches since the 1880s, and are increasing by about 3.3 millimeters per year. Miami Beach already experiences chronic flooding from mere high tides. Projections for 2100 predict an additional rise of anywhere from another foot to over 8 feet, depending on how things shake out — and that's leaving out worst-case scenarios like the rapid collapse of one of the major ice sheets. After 2100, of course, seas will only continue to rise for thousands of years.

What's more, it's nearly impossible to build seawalls around Miami, because it is built on permeable limestone. Real estate developers may be in a state of abject denial about this, but great chunks of Florida will almost certainly be abandoned over the coming decades, and millions of people will have to find somewhere else to live.

And that's just one city and one vector of climate change — other coastal communities around the country are vulnerable to sea level rise in varying degrees, and others further inland are vulnerable to drought, flooding, wildfires, economic dislocation, and so on.

The smart and humane thing to do would be to extend some humanitarian and economic aid to Central America and U.S. communities alike, as part of a general climate policy package to increase resilience and slash carbon emissions. Letting Honduras collapse into ruin is not just immoral, it will create vast problems for the U.S. as well.

Of course, our petulant president wants to slash aid to Central America. But Republican governance on climate change is an epic disaster for the United States as well. Donald Trump and the GOP will let American cities drown or burn to cinders out of pure culture war grievance, the narrow interests of fossil fuel barons, and their own intellectual degeneration.