At the presidential debate Tuesday, moderator Chris Wallace remarkably brought up climate change — the first time the subject has been discussed in that setting since 2008. It was some long-overdue attention to the biggest problem by far that faces America and all humanity over the medium and long term.

Naturally, given his Fox News background, Wallace's questions were profoundly misleading. He set up a false dichotomy, accepting the premise from President Trump that there is a tradeoff between fighting climate change and keeping a strong economy. However, Joe Biden correctly disputed the idea, pointing out that climate policy can actually boost the economy, and conversely that unchecked climate change is going to be terrifically expensive. It wasn't much noticed thanks to all of Trump's chaos, but Biden's reasoning suggests he understands the need for super-aggressive climate policy.

Wallace suggested that Biden's $2 trillion climate plan would "tank the economy and cost millions of dollars." Biden debate performance was pretty flat, but he correctly parried both mistaken parts of the question. On the economy, he noted that spending a great deal of money would in fact create jobs while achieving lots of important goals, like reducing pollution, weatherizing homes, and so on. On the danger of climate change, he also pointed out that even today America is suffering constant severe disasters that are very expensive, and will only get worse. "We spend billions of dollars now … on floods, hurricanes, rising seas. We're in real trouble," he said. "Look what's happening just in the Midwest with these storms that come through and wipe out entire sections and counties of Iowa. That didn't happen before, [and it's] because of global warming."

This is exactly right. Faux-serious centrist politicians, and even some prominent climate economists, have downplayed the serious risk climate change poses to the biosphere, human society, and the economy. It will be stupendously expensive to let Miami be drowned, or to build seawalls around our coastal cities that might be saved, or to see California burned to the ground every couple years, or to see extreme weather of all kinds pummeling the country from one side to the other.

Now, Biden's climate plan leaves a lot to be desired. It is not nearly as big as Bernie Sanders' plan, which was the only one of any Democratic presidential candidate this cycle that was actually up to the scale of the problem. It is also yet to be seen how serious Biden is about this, and it was unfortunate to hear him give in to pressure to disclaim the Green New Deal as some kind of left-wing nuttery.

But on the other hand, Biden's climate policy approach actually does follow the basic logic of the Green New Deal — namely, spending a huge pile of money to replace all our greenhouse gas-emitting infrastructure, and in the process creating millions of jobs and getting economic output back up to capacity. As economist J.W. Mason detailed in a recent paper, this is exactly what happened during the Second World War, the closest analogue to a crash decarbonization program we have. The American economy is indeed in the toilet, and will need a very large rescue package to get it back to strength once there is a COVID-19 vaccine.

At bottom, once we have agreed that climate spending can provide a very badly-needed economic boost, and that climate change poses a dire threat to the biosphere and the economy, the only debate is about magnitudes. And that's where advocates of the Green New Deal might actually help Biden out in Congress. If he wins, a big climate-based economic rescue will probably be towards the top of the legislative agenda. As I have argued at length, what is needed is to get emissions down as fast as possible. A climate policy package should therefore be big enough to address the problem, not restricted to some arbitrary size because political "moderates" wet themselves when they see a really big number.

Green New Deal supporters will be able to argue convincingly to increase the size of any climate plan (whatever it happens to be called), on the grounds of doing America's part to crush emissions, and also ensuring the coronavirus economic crisis is fixed so Democrats don't get wiped out in the 2022 and 2024 elections.

It's called being serious about the threats facing the American people, and it's long since time moderate Democrats learned how to do it.