Editor's Note: (Vice Admiral Dennis McGinn, US Navy (Ret) is a Member of the Center for Climate and Security Advisory Board, and former Assistant Secretary of the Navy for Energy, Installations and Environment. The opinions in this article belong to the author. )
(CNN) US Defense Secretary James Mattis is one of this country's greatest military leaders. A former four-star Marine General, he's well read, thoughtful, pragmatic and highly intelligent. As our foremost national security strategist, in 2017, he described climate change as a threat facing the US.
"The effects of a changing climate -- such as increased maritime access to the Arctic, rising sea levels, desertification, among others -- impact our security situation," he wrote.
Since then, 15 other senior US defense leaders have reaffirmed that view.
Our world is warming every year. It's a fact that's evident in consistently rising temperature gauges around the world -- and to anyone in the US who stuck their head outside recently.
This year has seen heat records broken from California to Shanghai. Europe is melting in a heatwave. Who remembers when temperatures broke 50C in Iran last year?
As President Trump, US Commander-in-Chief, travels to Europe to meet our closest military allies, this growing security threat should be a top priority on his agenda.
We know from reports in the past week that the President is likely to arrive at NATO headquarters with a demand for member states to ramp up military spending. We know threats of US troop withdrawal have been hinted at. And we know Europe should and could do more.
But this exclusive obsession with all NATO member states hitting their 2% of GDP defense funding target risks missing the bigger picture.
New ships, planes, tanks and cyber technology are all vital for the continued resilience of NATO amid threats from Russia, the Middle East and Asia.
But a strategy that fails to look beyond the next move is one that will fail. A leader who ignores longer-term trends and growing future threats risks lives. That leader risks losing.
The President's narrow focus on the near term billions that NATO needs misses a key point: climate change is an oncoming reality that could cost us trillions.
Lloyds of London's 2017 annual report said the "cost of major claims to the Lloyd's market in 2017 is the third highest since 2003." The largest hits in the US were Hurricane Irma, Hurricane Harvey and wildfires across California. Direct costs were more than $140 billion.
"Global risks are changing and the potential consequences are severe," Lloyds said. "Increased frequency and severity of major weather events mean that climate change has increased the risks and costs of insurance."
Further, the banking giant Schroders warns that global supply chains worth billions of dollars are at material risk from extreme weather.
"Without public policy looking to change private sector behavior, economies run the risk of continuing to pollute to a point where it is too late and the economic costs are catastrophic."
The Pentagon also has done extensive analysis and produced multiple reports explicitly spelling out the dangers the US faces from a warming climate, including under the Trump administration.
"DoD looks at climate through the lens of its mission. From that perspective, changes in climate affect national security in several ways. Changes in climate can potentially shape the environment in which we operate and the missions we are required to do," the Pentagon said in a report released just this past January.
In 2015, the Pentagon also noted -- and this is important: "Department of Defense sees climate change as a present security threat, not strictly a long-term risk."
Seawalls may help stop some storm surges and coastal erosion, but building walls is not always the answer, especially when our economic security rests on the foundation of reliable allies for trade.
In Brussels, the President is not likely to change course and honestly admit that, as a strategic leader, he's concerned about climate change. But he should. And leaders in the US and NATO must continue to press their case.
Take migration -- already a controversial and complex issue for both the US and Europe. With climate change things are not going to get better. The British government's Foresight report on environmental threats makes plain what a warming world will deliver.
"There will be different migration patterns in the future because of environmental change," it reads. And why should that surprise us? In the wake of Hurricane Katrina 250,000 people shifted from New Orleans to Texas as a result of the floods.
If I were at the NATO meeting, a key point that I would make to President Trump and allied leaders is that if we're serious about dealing with migration, about containing threats in the Middle East, about maintaining economic growth and trade, then climate change must be a priority.
For too long we've ignored a threat that is staring us in the face -- that is statistically more likely to happen than war with North Korea because it's already happening.
To quote Mattis, "The most important six inches on the battlefield is between your ears." Let's start using it.