Now it is clear that Trump's decision could be reduced to a single sentence.
So ... let's unravel that phrase. Because that phrase - and, consequently, the participation of the United States in the Paris Agreement - could help determine the future of the planet.
Here it is, Article 4.11 of the 2015 Paris Agreement (warning: it's boring, but stick with me):"The Parties may adjust their current nationally determined contribution at any time with a view to increasing their level of ambition, in accordance with the guidance provided by the Conference of the Parties serving as the meeting of the Parties to this Agreement".
And here is my harsh human language translation: Any country that signs the Paris Agreement has to commit to reducing pollution, which was defined as a "nationally determined contribution." The United States, for example, has pledged to reduce heat-trapping emissions 26-28% below 2005 levels by 2025.
Those commitments are fundamental building blocks of this agreement. The overall goal is to eliminate fossil fuel pollution this century, prevent low-lying islands from sinking and cities like New Orleans from continuing to flood, and create a way out of the warming that scientists say could result in mass extinction. Hopefully these pollution reduction commitments will become MORE AMBITIOUS over time. But we are not explicitly saying that they MUST be more ambitious.
The last part - the one on ambition - seems to be the sticking point for Trump.
Does this phrase REQUIRE that the United States maintain its current commitment, which was acquired by the Barack Obama administration? Or can you reconsider your commitment and be LESS AMBITIOUS?
The first possibility may push Trump out of the deal. The second could be more easily digestible for the government.
It must be clearly stated that none of these options is good for the planet.
The best thing for the health of the Earth and its inhabitants would be for Trump to remain in the Paris Agreement and to maintain his current commitment. Policymakers have identified a rise of 2 ° C (3.6 Fahrenheit) as the red line of warming.
We have already overcome that warming and we live in a world in which the climate is completely changing (man's footprints are in many of the extreme weather events that we are experiencing, especially in heat waves and in temperature records).
Existing commitments in the Paris Agreement have put the world around 3.4 ° C warming, which is unacceptable. For this reason, negotiators encourage countries to enhance their commitments over time.
Climate experts often speak of this ambition issue as a "ratchet mechanism." It is an apt metaphor. Think of your toolbox. A ratchet - or socket wrench - is a tool that allows you to tighten screws in only one direction. You can't turn the key the other way without having trouble.
It is the same that happens with the objective of the Paris Agreement: that countries recognize that their current commitments are not enough and that they move forward to pollute less, until one day the world depends on clean energies, such as wind energy, solar energy, hydraulics, etc.
Todd Stern, Obama's special envoy on climate change, explained to me this week that while that is the goal of the Paris Agreement, countries are not legally bound to increase their ambitions. In fact, he told me, the negotiators discussed that issue and then excluded from the wording of all the important sentences that countries were required not to moderate their commitments.
"Obviously we don't want parts to back down, but we also think it would be counterproductive to have a legal bar that says you can't do it," Stern told me.
Stern would prefer that the Trump administration remain in the Paris Agreement while developing any kind of policies against global warming, rather than simply and formally withdraw from the agreement.
Both are horrible options, he acknowledges. But the first would be less catastrophic.
Think of the Paris Agreement as one big global party, Stern tells me. He prefers to see Trump's America "sitting in a corner, pissed off," and not leaving the party. Because if that happens, he says, "suddenly" the other countries will start to think "that this really isn't such an interesting party."
And then they may cancel the party entirely.
Will the United States stay at the party or not? The decision can be shortened one sentence.