Heat waves in the North China Plain — China's breadbasket — are predicted to become so severe, they would "limit habitability in the most populous region of the most populous country on Earth," a new study finds.
The big picture: Such heat waves could both threaten lives and dampen economic output in the region, where 400 million people live. Earlier studies along with a separate new analysis released Thursday found the potential emergence of extreme heat waves — from China to West Africa to South Asia — that are far worse than those currently experienced.
Key findings: Like the previous two studies by this MIT team, which focused on the Persian Gulf region and South Asia, the researchers found that given the current pace of greenhouse gas emissions, extreme heat waves are likely to emerge in the agricultural region of the North China Plain between 2070 and 2100. (In the Gulf, the most severe heat is projected to occur over the Gulf waters, rather than land.)
- The North China Plain is one of the most-threatened areas of the globe due to heat extremes, the study found.
- The soil there, near the Yellow, Huai and Hai rivers, is ideal for agriculture. Irrigation tends to lower air temperatures, but increase evaporation — with the net effect of making heat waves more intense and intolerable for the human body.
How they did it: Elfatih Eltahir and co-author Suchil Kang of the Singapore-MIT Alliance for Research and Technology focused on wet bulb temperatures — measures of the amount of water vapor in the air that are taken by wrapping a wet cloth around the bulb (or sensor) of a thermometer, to let evaporation of water cool the bulb.
- At 100% humidity, with no evaporation possible, the wet bulb temperature equals the actual temperature.
- The study combines wet bulb temperatures with air temperatures to arrive at a thermal index that corresponds to how the human body responds to heat.
- The researchers ran a group of regional climate models to simulate changes to this thermal index across the North China Plain region. They looked at the climate during the past 30 years, and used the models that produced the closest matches to reality in order to project future climate in this area.
What it means: As global temperatures increase, the researchers predict heat waves will become far less tolerable as the combination of air temperatures and humidity levels causes the maximum wet bulb temperature to reach or even exceed 35°C, or 95°F.
"Climate change could bring a significant risk of deadly heat waves, heat waves that are very severe, heat waves that touch on livability for humans."— Elfatih Eltahir, MIT
Go deeper: Read the full story in the Axios stream.