President Trump announced the United States will withdraw from the Paris climate agreement, a landmark accord in which nearly 200 countries agreed to confront globe warming by reducing their greenhouse gases.

Here are five things you need to know about what this would mean and what comes next.

1.Paris is popular. Fully unraveling ourselves from this treaty will take up to four years but once that’s done, we’ll join Nicaragua and Syria as the only countries unwilling to participate. And there’s no reason to expect a broader exodus. China and Europe are openly reaffirming their commitments. Among the major polluters, only Russia and Turkey have dithered, but even their departure probably wouldn’t suffice to unravel the pact.

2.This isn’t really about climate policy. This might ring strange, given the green-themed celebrations that accompanied the successful negotiation of the Paris pact, but it’s perfectly possible to sign up and still pollute. In fact, Trump could pursue his carbon-hungry, coal-first energy policy while staying nominally committed to the agreement — because there are no provisions for punishing countries that fail to reduce emissions. Leaving, however, would give Trump a big symbolic victory, burnishing his credentials as America’s true defender against the out-of-touch concerns of the global elite.

3.Even in the United States, support for global action on climate change is high. Yes, the United States has its share of climate skeptics, not to mention one of the only major political parties in the world to embrace climate change denial. Yet public support for the Paris agreement is actually quite high, around 70 percent in one post-election poll. That matches the number of Americans who support limits on greenhouse gases, meaning that Americans’ support for climate action is slightly lower than what you find in Europe but not far off the global average.

4.Paris might become another presidential hot potato. There’s a growing list of partisan acts presidents take the moment they arrive in the White House. Newly minted Republican presidents quickly reinstate the global gag rule, blocking federal funding for international health groups that provide abortion counseling. Democratic presidents rush to revoke it. It might be the same with Paris. Every time the presidency flips parties, our commitment to Paris might flip, too — especially as presidents can make this switch without input from Congress.

5.Global warming marches on. Temperature will continue to go up, leading arctic ice to melt, floodwaters to rise, hurricanes to grow more powerful, droughts to get longer, and more species to die off. A decision to leave the Paris agreement doesn’t fundamentally change any of this; Trump wasn’t planning to aggressively tackle global warming before, and he still won’t.

The fundamental task is currently on hold; there is no US commitment to making the technological and lifestyle changes necessary to ensure that humanity can flourish in the long term.

Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the United States. He can be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz.