Every once in a while, something truly bizarre gets published in the climate business. The latest iteration would be “Higher CO2 Concentrations Increase Extreme Event Risk in a 1.5°C World”, published online on June 12th in the prestigious Nature Climate Change by Baker et al.
The extreme events under consideration include
1) days hotter (less cold) in the summer (winter) than the 90th percentile of current temperatures at a given location,
2) a measure of atmospheric stickiness called the “wet bulb globe temperature”, expressed as its 95th percentile for the amount of moisture in near-surface air at a given location, and
3) the 95th percentile rainfall on days when it rains.
The paper claims that carbon dioxide itself will “have a significant direct impact on Northern Hemisphere summer temperatures, heat stress, and tropical precipitation extremes”. That’s what it claims, but it is really not what it shows.