Within the course of only a few months, freshman Congresswoman Alexandria Ocasio-Cortez has gone from proclaiming the end of the world in a mere 12 years – to claiming she was merely being sarcastic, and that Republicans would have to have the “social intelligence of a sea sponge” to think she was being literal.
And then 16 days after the latter comment, she once again warned about climate catastrophe a mere 12 years out, with no obvious sarcasm (or hint or irony) to be detected.
Hypocrisy aside, Congresswoman Chicken Little’s 12-year time-time is based on an estimate from the United Nation’s Intergovernmental Panel on Climate Change, which stated that we only have 12 years to contain global warming to a maximum of a 1.5 degree Celsius rise in global temperature. A 1.5C rise was the target of most the world’s governments in the Paris Climate Agreement. According to the UN, meeting their goals would require ending the use of fossil fuels by the year 2030, which the authors estimate would cost the global economy $54 trillion, but say that’s cheaper than the consequences of climate chance. With that price tag, color me skeptical.
At the UN’s Rio Climate Summit in 1992 top scientists said we only had 10 years to get climate change under control, so clearly the goalpost has been moved throughout history (and there are dozens of similar examples). Three years prior, in 1989, a senior UN environmental official predicted doomsday by the year 2000, by which “entire nations could be wiped off the face of the Earth by rising sea levels.”
Clearly, pinpointing a future “point of no return” is problematic.
As Michael Marshall explains:
A study published in August in Earth System Dynamics takes a close look at the idea of a point of no return, and it is revealing. The researchers examined what it would take to limit global warming to either 1.5°C or 2°C. They first ask how certain we want to be: we could either have a 67% probability of meeting our target, or a 95% probability.
Next they ask how rapidly we can increase renewable energy’s share of the market: 2% per year, or a more ambitious 5% per year. And finally they ask whether we will use lots of “negative emissions technologies” later this century, to remove carbon dioxide from the air on an industrial scale and thus limit the temperature rise.
Depending on which combination of factors the researchers plugged in, they got a different point of no return. In the most exacting case, where we try to limit warming to 1.5°C with a 95% probability of success, without relying on carbon dioxide removal later in the century, they found that we might well be too late. On the other hand, if we’re prepared to accept 2°C, with a larger probability of going over and a heavy reliance on carbon dioxide removal, the point of no return looks to be way off in the 2040s.
The point is that the climate is not so simple as to give us a neat cutoff date for action.
As for the UN’s “12 years” estimate, the UN’s climate models overestimate warning massively. The UN’s estimates assume that the Earth’s equilibrium climate sensitivity (ECS) is somewhere between 1.5C-4.5C. The ECS is an estimate of how much the Earth’s temperature would increase if the amount of carbon in the atmosphere doubled above pre-industrial levels.
In contradiction to those figures, a study in the Journal of Climate found the planet’s ECS to be at least 30-45% lower than the UN estimates. The UN’s average estimate was 3.1C, while the JOC’s was only 1.66C. Similarly, a study published in Nature Climate Change in 2017 estimated an ECS of 1.5C.
If the sky is indeed falling, we have more time to adapt than AOC and her ilk pretend to believe. Indeed, it’s unlikely that even they truly believe doomsday is right around the corner, but do believe that fear is the only way to convince the American public to mindlessly spend tens of trillions of dollars on whatever they please.
