WASHINGTON — The old lament that everybody talks about the weather but nobody ever does anything about it was never more appropriate than now.

The summer heat that is currently torching Europe and and North America has come to President Biden’s doorstep in a way that demands much more than words of sympathy over the uncommon pubic discomfort.

Yet the first word from the White House on the subject was that Biden was not ready to declare a full-scale national emergency to cope with it, but that all options were on the table. Such hesitancy in itself could only invite public laments that Biden was not up to the challenge or even lacks the mental capacity to lead in the domestic crisis due to his age of 79.

But later on Wednesday, speaking at a decommissioned coal plant in Massachusetts, Biden said climate change “is literally, not figuratively, a clear and present danger. The health of our citizens and our communities is literally at stake.”

He added: “Let me be clear: Climate change is an emergency. In the coming weeks, I’m going to use my power to turn these words into formal, official government actions. … When it comes to fighting climate change, I will not take no for an answer.”

In contrast, former president Donald Trump continues to snap at Biden’s heels, reiterating his threat to seek a return to the Oval Office in the 2024 election. The president’s only response has been to say that, while he is not “predicting” another Trump vs. Biden race, he “would not be disappointed” at the prospect.

In an interview with Israeli television last week, Biden observed: “The one thing I know about politics, and American politics in particular, is there’s no way to predict what’s going to happen. I’m not even halfway through my term yet, and so there’s a lot of room to figure out what’s going to happen.”

In any event, Biden has made clear his determination to do whatever it takes to prevent a Trump return to the Oval Office. Former Democratic Gov. Ed Rendell of Pennsylvania, an old Biden friend and colleague, says of him: “Joe Biden believes in himself. He’s not going to give this thing up,” and particularly not to Trump.

Another former Biden campaign manager, Greg Schultz, said Biden never entertained the thought of settling for one term after besting Trump in 2020. And now, he has said, “the threat of Trump (again) is enough” to assure Biden will seek a second term.

Biden also has said he regrets not having run against Trump in 2016, when he believes he could have prevented Trump from gaining the presidency in the first place. “I regret it every day,” he has said.

The next time around, however, Trump could have a serious challenge from within the Republican Party, from Florida Gov. Ron DeSantis, who has reported having out-fundraised Trump in campaign money as November’s congressional midterm elections approach.

If DeSantis were to become the GOP presidential nominee, Biden no longer could play the I’m-not-Trump card that clearly enabled him to win as the only alternative choice for voters in 2020.

So the sitting president is now obliged instead to respond to public demands for declaring severe climate change a national emergency. He has already said his actions “will create jobs, improve our energy security, bolster domestic manufacturing and supply chains, protect us from oil and gas price hikes in the future and address climate change.”

In other words, simply being the alternative to Donald Trump will no longer be enough to get Joe Biden re-elected in 2024. It’s a preferable outcome for him and for the country as well.

Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.