An international group of folks put together an interim report analyzing “Deep Decarbonization Pathways”. Decarbonization refers to the process of using less carbon within an economy. The intent of the report was to show ways forward to keep global mean temperatures below 2C. Readers of this blog know that I no longer think such a goal is achievable given the scope and scale of decarbonization. We have not moved from a “business-as-usual” approach and have run out of time to reduce GHG emissions prior to relevant limits to meet this goal. I argue the exact opposite of what the authors describe in their summary:
We do not subscribe to the view held by some that the 2°C limit is impossible to achieve and that it should be weakened or dropped altogether.
Thus the main problem with this report. They’re using a threshold that was determined without robustly analyzing necessary actions to achieve it. In other words, they a priori constrain themselves by adopting the 2C threshold. Specifically, a more useful result would be to ascertain what real-world requirements exist to support different warming values in terms real people can intuitively understand. The report is not newsworthy in that it reaches the same results that other reports reached by making similar assumptions. Those assumptions are necessary and sufficient in order to meet the 2C threshold. But examination unveils something few people want to recognize: they are unrealistic. I will say that this report goes into more detail than any report I’ve read to date about the assumptions. The detail is only slightly deeper than the assumptions themselves, but are illuminating nonetheless.
An important point here: the authors make widespread use of “catastrophe” in the report. Good job there – it continues the bad habit of forcing the public to tune out anything the report has to say. Why do people insist on using physical science, but not social science to advance policy?
On a related note, the report’s graphics are terrible. They’re cool-color only, which makes copy/paste results look junky and interpretation harder than it should be. So they put up multiple barriers to the report’s results. I’m not sure why if the intent is to persuade policy makers toward action, but …