A few weekends ago, a local group I volunteer with had a “Science Pub Night” with Dr. Deborah Lawrence, a UVA professor of environmental science, about climate change. Dr. Lawrence studies the effects of deforestation on climate and has also worked extensively in the policy aspects of forest and climate science, and her talk was (mostly) about the importance of forests and land use to climate change. If you want to see more, I livetweeted it.
One thing I especially liked was a way she mentions she tries to better frame climate change to make it more relatable to people. It is (rightly) acknowledged that the Earth has seen larger temperature variations, but it is equally right to point out that those generally happen on longer time scales than we see now, or at least they do if they’re not also accompanied by mass extinction events. So Dr. Lawrence had a very human timescale to relate this change to. One of the most optimistic climate goals is to keep global warming to an average global temperature rise (compared to “preindustrial” temperatures, often early 1900s before extensive fossil fuel burning) of only 1 degree Celsius by 2100. 200 years for one degree might not sound bad to our scale, but Dr. Lawrence points out prior to the 20th century, ALL OF CIVILIZATION (e.g. let’s go with recorded history, so about 5000 years) had only seen the average global temperature only vary within a window of half a degree C*. So even our most hopeful plan essentially means adapting to a doubling of whatever variance any human society with large infrastructure has seen, and doing that in a time frame shorter than the building of some temples and cathedrals during the Middle Ages.
Another way she framed it was to more directly relate climate to weather, since most people don’t think in terms of average temperatures. (To prove this, Dr. Lawrence asked if anyone in the bar could say the average temperature for Charlottesville or wherever they were from off the top of their head, and no one could.) So instead, she has looked at models to see how a warming climate changes how often certain temperature thresholds are reached in different places. Dr. Lawrence has studied forests in Kenya, and one concern there is days of “debilitating heat”. This is when the temperature goes above 39 degrees C (102 degrees F!), and for people who generally live without air conditioning, the point where your body can basically only regulate your temperature if you don’t do much physical activity. Currently, Kenya has about 20 days of debilitating heat in a year, but in a world of 1 deg C warming, that goes to over 100 days per year! That would drastically change their lives. Even if you assume air conditioning becomes common, having AC and the electrical grid deal with over 100 degree temperatures for almost a third of the year becomes a great drain on infrastructure and communities will need to plan for that if they want to make sure their systems don’t overload.
*Edit to add: I may have misunderstood Dr. Lawrence or she may have mispoke in giving her value of “average temperature variance” across history, but I do want to point out that some temperature reconstructions of the Little Ice Age suggest that temperature went down more than 0.5 C from the pre-industrial norm, maybe up to 0.7-0.9 C. (The graph there compares temperatures to the 1950-1980s average.) Dr. Lawrence may also think those reconstructions are less reliable, but that was way outside the focus of her talk, so I don’t know why and didn’t get a chance to ask her. Those very deep decreases also quickly oscillate back to less extreme values, so the average may still work out to 0.5 C if you exclude short-term climate cycles.