Climate Letter #2105

What is the likelihood that the global average temperature increase—relative to pre-industrial—will remain less than1.5C? This is arguably the most important of all questions relevant to the future direction of climate change. There are a number of different ways to answer it, as well as a number of different approaches to each of the different ways, which leads to confusion if you choose to go that route. Most public discussion makes an effort to keep things more simple by sticking to the most literal definition of global average temperatures without reference to regional differences that keep getting wider and wider. (See CL#2098, Dec. 30.) Every temperature reading, regardless of location, is treated equally. This seems quite logical as an approach, except that in reality climate change does not work that way. Under the same set of changing conditions, some places warm up rapidly, some more slowly, and some not at, or even go in reverse. That is the reality we have to deal with, and it is generally being avoided in the public discourse. The global number is still interesting and useful for many purposes.

There is another problem with the basic question, at the literal level. We are now at +1.1C, and we want to keep this number below 1.5C, knowing that some amount of increase is unavoidable. The laws of nature need to be taken into account and human behavior must also be taken into account. Both of these have a great deal of potential influence and both are subject to debate, considering numerous questions about each that are difficult if not impossible to resolve. Who can we look to for the best answers? People who are trained in the physical sciences are in the best position concerning the laws of nature. They don’t all agree, but a clear majority of climate scientists who are the most outspoken on the subject keep telling us it is possible, although less than 100% certain, that we can remain under 1.5 if the public follows certain recommended practices and procedures. These optimists are often emboldened by specialists who offer additional hopefulness based on promises of forthcoming technological advancement.

And then there is the public. Which individuals have the best vantage point for predicting what the “public” will do, globally speaking, given its various proclivities and states of awareness, along with its dependence on political operatives of all different stripes who usually agendas of their own to pursue? Astute public-interest observers can be found in all walks of life, many of whom are well-trained in a wide variety of sciences. Their deliberations are worth listening to with an open mind, but we always seem to be left weighing in balance a lot of different opinions with no closure, leaving nothing but our own personal judgment.

One group of individuals is uniquely positioned and qualified with respect to gaining a deep understanding of both climate science and political reality.  These are the people who write up the contents of IPCC reports.  The reports are purposely designed with a primary intent of steering the various political operatives into courses of action that would do the maximum possible amount of good, and might actually be pursued under the rules of political reality.  These authors all become familiar with the kind of responses expected from various policymakers and the limits to which they can be pushed.  Nature magazine, a preeminent publisher of scientific studies, ran a survey of 234 currently active authors and received 92 responses.  The eye-opening results and extra commentary were reported in November in a Scientific American article that is available at this link:  https://www.scientificamerican.com/article/top-climate-scientists-are-skeptical-that-nations-will-rein-in-global-warming/.  Only 4% of the respondents believe the 1.5 target will prove to be successful up to the year 2100, while 60% expect warming to reach three degrees or more by that time.  “Their answers suggest strong scepticism that governments will markedly slow the pace of global warming, despite political promises made by international leaders as part of the 2015 Paris climate agreement…..Most of the survey’s respondents—88%—said they think global warming constitutes a ‘crisis’, and nearly as many said they expect to see catastrophic impacts of climate change in their lifetimes.”

These expert authors are all called upon to assume that the laws of nature will allow the 1.5 target can hold, if emissions are fully controlled, and would never offer an opinion to the contrary. They have been informed about innovative technologies that are in the pipeline. Their concern is squarely based on their knowledge of the ruling class, and their conclusions are highly unfavorable.

Carl