On this day in 1944, Allied forces landed on the beaches of Normandy, marking the beginning of the end of Hitler’s genocidal Nazi regime.

It’s hard to imagine now, 75 years later, how we would meet that challenge if it occurred today. Would it look like our response to global climate change – this generation’s greatest threat to lives and liberty?

Would modern-day Roosevelts and Churchills have to argue with “Fascist-denialists” who claim that totalitarian regimes are part of the natural political cycle, or that Germany and Japan did not really exist? Would the American president say, “We are not landing our troops until China and India land theirs”?

Would we expect individual U.S. states to make their own European invasion plans? Or individual citizens?

Because, as absurd as it sounds, that is the approach we are taking to fight manmade climate change, a phenomenon that presents a threat to civilization as great or greater than anything that Hitler could have imagined.

Climate change is not just a problem for polar bears or people with beachfront property. Through drought, wildfires and extreme weather, the warming planet is already driving people from their homes. When you factor in the social unrest and civil wars that are fueled by famine and governments’ inability to take care of their citizens, we can expect to see as many as 1 billion migrants by 2050, according to the United Nations.

Since over the last decade it took “only” 1 million refugees from Syria to destabilize the post-Cold War order in Europe, it’s hard to imagine the impact of a humanitarian crisis that’s a thousand times greater. A peer-reviewed study published in the journal Nature found that if not dramatically reduced, carbon emissions will be responsible for 150 million premature deaths by 2040, twice the combined civilian and military death toll of all sides in World War II.

But the global climate crisis is easier to ignore than the Nazi blitzkrieg. It involves an invisible gas that’s produced by some of the most popular features of modern life in rich industrial countries, like gas-powered cars, air conditioners and cheap food. Its effects are gradual, cumulative.

And fighting it is not as simple as a military campaign. There is no D-Day landing to beat climate change. That takes a decades-long commitment to maintaining a global strategy that would outlast the career of any president or sitting member of Congress.

It is a diabolical problem for a political system that puts so much emphasis on short-term results, but it’s one we should be able to handle. After all, the kinds of sacrifices we are being asked to make are nothing compared to the ones the men of D-Day made in 1944. We don’t have to die for this cause – we just have to change the way we produce and use energy.

On this anniversary of D-Day, as we honor the men who gave their lives for a free world, we should take a moment to wonder how the future might remember us.

Seventy-five years from now, will people be grateful for our foresight and steadfastness? Or will they wonder why, when it was our turn, we didn’t even show up?