During the flash floods that swept through the Washington region last month, Fox 5 news reporter Melanie Alnwick tweeted about a rescue:

“Scary situation at 5500 Columbia Pike @ArlingtonVA — a woman was trapped in her car with her 6yo daughter in the back car seat. Says thank you to the unknown man who walked through the flood to pull the girl out of the window to safety. @fox5dc #flood.”

We often hear about ordinary citizens acting courageously during weather-related crises. In the aftermath of tornadoes and hurricanes, during floods and wildfires, we see demonstrations of empathy and cooperation that might otherwise have seemed impossible in a nation so polarized by fear and bias.

What appears to be in short supply, however, are leaders who can bring us together before disaster strikes, people with the intellectual and diplomatic skills to mobilize a national response to climate change. We don’t have much time.

According to a U.N. report on climate change released last week, to prevent catastrophic, irreversible damage to the planet and the people who live here, the world needs to cut greenhouse gas emissions in half by 2030, and then down to zero by 2050.

Half of global human-caused emissions of the greenhouse gas methane comes from agriculture — growing livestock and rice, mostly. And 75 percent of nitrous oxide emission — another potent greenhouse gas — comes from nitrogen fertilizer.

The report recommends, for starters, eating less red meat and more plant-based foods such as coarse grains, legumes, fruits and vegetables, nuts and seeds.

That’s a tall order.

“Addressing climate change . . . requires people to take action now to redress consequences that will not occur until far into the future,” Richard J. Lazarus, an environmental lawyer, wrote in the Cornell Law Review in 2009. “Unfortunately, this is precisely the kind of thinking and decision-making in which people do not naturally engage.”

But the future is here. The effects of climate change are happening much faster than many of us expected. A Washington Post analysis of more than a century of temperature data across the Lower 48 states found that in some major areas climate change is already here.

Snow melts more quickly, lakes that once froze don’t do so as often, and weeds and insects that ordinarily would die in the cold don’t, according to The Post report.

We need to get moving. Instead, the nation seems more divided and in conflict than it has been in decades.

In 2014, the National Capital Planning Commission released a report outlining the challenges posed by climate change. Cooperation is the key.

“The neighborhoods of the Washington, DC region are at risk of losing their strength and vitality due to changes in climate that may cause serious disruptions to public transportation, flood homes and parks, and reduce the economic vigor of the area,” the report said.

To meet the challenges, we’ll need strong social networks. Transportation infrastructure needs strengthening. Metrorail has got to be more reliable. We need more trees. Better ways to collect rainwater, like rooftop gardens. We need solar power instead of being so reliant on outdated electrical grids. We need ways to prevent basement flooding and mitigate the health hazards of mold and mildew.

We still don’t have a reliable way to evacuate the nation’s capital in an emergency.

There is much work to be done.

“We need to gain consensus on our collective risks and what we consider to be acceptable risks,” the report said. “The problem is not just about technology; it is a people and systems problem.”

Is it even realistic to think that the leadership skills needed to help solve such problems exists?

In 2015, President Barack Obama’s national security team issued a report, saying, “Climate change is an urgent and growing threat to our national security, contributing to increased natural disasters, refugee flows, and conflicts over basic resources like food and water.”

Many people did respond with a certain kind of urgency. Gun sales skyrocketed at the mention of the threat to security. Warnings that climate change could cause food and water shortages drove others to stockpile those basics in addition to the guns and ammunition.

In February, Daniel Coats, then director of national intelligence under President Trump, echoed the Obama administration warnings during testimony before a Senate subcommittee.

“Climate hazards such as extreme weather, higher temperatures, droughts, floods, wildfires, storms, sea level rise, soil degradation, and acidifying oceans are intensifying, threatening infrastructure, health, and water and food security,” Coats said.

The president’s response? His administration has sought to strip mentions of climate change from policy statements. On a cold day in January, Trump tweeted, “Wouldn’t be bad to have a little of that good old fashioned Global Warming right now.”

That’s exactly what we’re getting. Higher temperatures, rising oceans, ever more dangerous storms.

We shouldn’t have to wait for a hurricane or flood or some other catastrophic event before we take action. But if we keep procrastinating, catastrophe is what awaits.

And there might not be enough everyday heroes left to save us.