Marking Climate Week and the United Nations General Assembly, both happening in New York this week, there’s an opinion piece in The New York Times today titled The Climate May Have Some Surprises in Store co-authored by opinion writer David Wallace-Wells and climate scientist Zeke Hausfather. The piece summarizes the current state of climate change forecasts. The picture is … cloudy.

3 Takeaways

1. We have made some progress against climate change. We’re gradually transitioning to clean energy especially in the electricity generation sector. That’s having some impact. Earlier this year the U.N.’s Intergovernmental Panel on Climate Change (IPCC) retired it’s most dire climate change scenario known as RCP8.5 under which average global temperatures could rise by 4.4 degrees Celsius by 2100. That now seems implausible.
   
   
2. But we’re still on track for bad outcomes. The U.N. acknowledged recently that we’re going to miss the Paris Agreement goal of limiting global warming to 1.5°C. Forecasts show we have a 50/50 chance of hitting 2°C by 2050 and we’re virtually certain to hit that mark by 2100. In fact, the most likely scenario is 2.9°C of warming by 2100.
   
   
3. There are big risks that we could warm the planet even more. Climate forecasts are based on mathematical models which are in turn based on our understanding of the climate and planetary systems like the carbon cycle. We do not full understand these things. So scientists couch their forecasts in terms of ranges and probabilities to reflect the uncertainty in their models. And as they say in this piece, when it comes to climate change, uncertainty is not our friend.

3 Details

1. Hausfather has an accompanying post on his substack called The Climate Brink that provides more details and some helpful charts about recent climate forecasts. For example, this graph shows how likely it is that we’ll pass 2°C, 3°C, 4°C or even 5°C between now and 2150. It’s good to see forecasts starting to extend past 2100. Warming won’t suddenly stop at the end of the century.
   
   
2. The oceans and the land are warming at different rates as this graph shows. On land, warming has already passed 2°C. It’s a good thing the oceans absorb about half the carbon dioxide we’re dumping into the atmosphere, but scientists don’t know how long this will continue. That’s one of the great uncertainties in climate modeling.
   
   
3. The authors note that “… by moving too slowly we’ve lost the opportunity to avoid disruptive climate change.” We’re already experiencing that disruption in form of wildfires, heatwaves, rapidly melting glaciers, and a “Godzilla” El Niño that’s about to hit North America.

Politicians and governments around the world have backed away from climate change in the last couple of years. The U.S. government has completely reversed course. But the risks are very real and we still need sustained action to avoid them.