If another country were invading the United States, there would be no doubt that we would use our $733 billion defense budget to fight them.

The Climate Crisis is invading our country. If it continues unopposed, sea level rise will destroy infrastructure in dozens of our coastal cities, including Honolulu. Across the country, hundreds of thousands of people will need to abandon their homes. Ever greater wildfires, hurricanes and tornados will take hundreds of lives. Droughts and floods in equatorial countries will cause even larger mass migrations of refugees to our borders.

These are not wild-eyed fears. They are solid predictions and near certainties based on thousands of scientific studies, many by U.S. government agencies. Back in October 2014, the Pentagon itself issued a statement saying that climate change poses “immediate risks” to our national security. The most recent “Doomsday” report from the United Nations says we have only 12 years to take immediate, significant action. Climate disasters like this summer’s heat wave are already multiplying. Soon they will be inevitable.

Faced with this real and immediate threat to our homeland, it is madness to spend billions of defense dollars on things like futuristic weapons systems and more than 400 overseas military bases. Instead of new stealth bombers and killer satellites, how about a way to turn carbon dioxide (CO2) into airplane fuel? How about innovative ways to harden our cities against flooding and our forests against fires? The Pentagon is very good at solving the kinds of technological problems posed by the climate crisis.

The Pentagon also has the simple manpower required to plant millions of trees. That low-tech method is currently the surest way we know to remove CO2 from the atmosphere. Large-scale deployment of existing technology can cut greenhouse emissions substantially, and the Pentagon is equipped to do it.

Virtually every candidate running in the Democratic presidential primary has signed on to some form of the Green New Deal, but their worthy ambitions tend to founder when presented with the logical question, “How are you going to pay for it?” The National Defense Appropriations Act is a very good way to do this. The House just passed its 2020 draft of the NDAA, and it is now moving to the Senate. The current figure is $733 billion, roughly as much money as the next eight largest military spenders — Russia, China, the European Union, etc. — spend on defense combined.

Hawaii is exceptionally vulnerable to the climate crisis — but fortunately, Hawaii’s senators and congresspersons serve on the appropriations, armed services, defense and science committees. Sen. Brian Schatz, for instance, chairs the Senate Special Committee on the Climate Crisis. Our representatives are well placed to put forward climate crisis amendments to the NDAA.

But we shouldn’t stop there. The climate crisis is a global issue, and every country with a defense budget should contribute to a global effort. It doesn’t mean the U.S. would abandon traditional military spending. Just 10% of what we now spend on the military would generate $73 billion a year. Worldwide, humanity spends $1.8 trillion a year on defense. What if every country agreed to spend 10% of its defense budget to fight the climate crisis, signing on to an international agreement similar to the Paris Climate Accord? Hawaii’s representatives should advance this idea in Congress, and it should be a subject for debate in the upcoming presidential elections.

Nothing unites people like a common enemy. We have one. The world must unite to fight the climate crisis, not each other.

Richard Tillotson is a writer based in Honolulu.