Like the wedding reception of a runaway bride, the Paris Agreement on global warming is free to go on, just minus a pretty important player. The 2015 accord among almost 200 countries -- the U.S. joins only Syria and Nicaragua on the outside looking in -- brought together the developed and developing worlds to pledge limits on the fossil-fuel pollution that causes climate change. The goal of the accord -- holding temperature rises well below 2 degrees Celsius from pre-industrial levels, to avoid the rising seas and superstorms that climate models predict -- was going to be a challenge even with U.S. involvement. Now the agreement is without the biggest carbon producer in history.
The U.S. withdrawal doesn’t necessarily kill it, since participation is voluntary. But without American involvement, the global effort to cut greenhouse-gas emissions stands even less chance of achieving targets that scientists say would avert catastrophic climate change. Making matters worse, the U.S. was being counted on to contribute financially to help poorer nations invest in renewable energy. Then there’s the concern that the American withdrawal could have a domino effect, prompting other nations to reconsider the effort and expense of cutting their emissions.