As a pandemic hijacked the nation's attention, we pushed aside other, even bigger problems. But now that COVID-19 is being cornered, the crisis of climate change is returning to page one.

The threat of a rapidly warming planet is actually harder to deal with. It can't be fixed with a vaccine. Slower-moving, it's easier to put off addressing the impending disaster. And worldwide in scope, it's politically hard for America to step forward. After all, the United States produces 13 percent of the world's greenhouse emissions, but China is responsible for 26 percent.

Left unchecked, however, climate change will visit catastrophe on places where millions of Americans live. It will unleash global mass migrations that are dangerous and difficult to control. And it will pile on any number of medical crises.

Some health emergencies are already upon us. The wildfires in the western U.S. set off an epidemic of respiratory ailments. The surge of heat waves, floods, and storms — said to be churned by higher temperatures — has produced growing numbers of injuries and deaths.

Hotter and wetter conditions are spawning huge populations of mosquitoes and ticks. These insects spread such infectious diseases as malaria, Lyme disease, and West Nile virus.

Extreme weather events are breaking water, sanitation, food distribution, and electric systems. Hospitals caught in these disruptions can hardly manage their usual patient loads, much less take on the newly distressed.

Then there is drought. The 2018 Camp Fire in Northern California took 85 lives and incinerated 11,000 homes, plus schools and businesses. Some residents are building back, but many are moving elsewhere. All are suffering from PTSD.

Warming waters are increasing the number and intensity of storms and feeding the emotional turmoil that follows. Even as the focus in 2020 was on the virus, the Atlantic hurricane season broke the record for the most named storms. Twelve of them made landfall in the continental U.S. Louisiana was hit by a parade of five — Tropical Storms Cristobal and Marco, and Hurricanes Laura, Delta and Zeta. Each one caused dislocation, personal stress and economic loss.

The nonprofit research firm First Street Foundation estimates that the flooding caused by climate change will be worse than government estimates. Its models suggest that by 2050, up to 84 percent of the buildings in Cape Coral, Florida, and nearly all buildings in New Orleans will be at substantial risk of flood damage.

The Department of Defense has labeled climate change "a threat multiplier." This means that security threats already out there will become more ominous. They include poverty, environmental degradation, political instability and social tensions — any of which can enable terrorism and spawn other forms of violence.

Climate change is endangering U.S. military installations themselves. Rising seas now imperil the giant Navy station in Norfolk, Virginia. As retired Rear Adm. David Titley, a naval oceanographer, put it, "These guys are in a whole heap ton of trouble."

More and more places are becoming uninhabitable. As one example, a doctor at a public hospital in New York writes of two patients whose villages in northeast Africa, plagued by drought and scorching temperatures, can no longer support human life.

Climate change is expected to turn millions of Americans into migrants as well. Matt Hauer, a sociologist at Florida State University, projects that the homes of 13 million Americans living on the coasts will sink under the waves. The residents will obviously have to go somewhere else.

Those who think President Biden's aggressive climate change agenda is radical should think about how very radically their world will change if the trend continues unhindered. Meeting the challenge will be the ultimate moon shot — making the defeat of COVID seem easy by comparison.

Follow Froma Harrop on Twitter @FromaHarrop. She can be reached at fharrop@gmail.com. To find out more about Froma Harrop and read features by other Creators writers and cartoonists, visit the Creators webpage at www.creators.com