Smog hangs over a construction site in Weifang city, Shandong province, Oct 16. 2015. Air quality went down in many parts of China since Oct 15 and most cities are shrounded by haze. [Photo/IC]

Guest essay by Eric Worrall

According to scientists China’s irrigation system is increasing humidity, raising the risk of deadly heat combined with humanity exceeding the “wet bulb” limit.

Climate change in China could force 400M to flee killer heatwaves

By Jamie Seidel, News.com.au August 2, 2018 | 4:14pm

Now we know why Beijing is so interested in the South China Sea: Killer heatwaves are set to sweep across northern China within just 50 years. If they don’t leave, 400 million citizens could face a day where they’re left with only hours to live.

And that day will be a pressure cooker.

A report published on July 31 in the science journal Nature Communications details the effect of climate change on China’s great North Plain, which contains the megacities Beijing and Tianjin. The area’s once-fertile open fields have become among the most densely inhabited places on Earth.

But things are warming up. Fast.

“This spot is going to be the hottest spot for deadly heatwaves in the future, especially under climate change,” warned lead author MIT professor Elfatih Eltahir.

…

Read more: https://nypost.com/2018/08/02/climate-change-in-china-could-force-400m-to-flee-killer-heatwaves/

The abstract of the study;

North China Plain threatened by deadly heatwaves due to climate change and irrigation

Suchul Kang & Elfatih A. B. Eltahir
Nature Communications volume 9, Article number: 2894 (2018)

North China Plain is the heartland of modern China. This fertile plain has experienced vast expansion of irrigated agriculture which cools surface temperature and moistens surface air, but boosts integrated measures of temperature and humidity, and hence enhances intensity of heatwaves. Here, we project based on an ensemble of high-resolution regional climate model simulations that climate change would add significantly to the anthropogenic effects of irrigation, increasing the risk from heatwaves in this region. Under the business-as-usual scenario of greenhouse gas emissions, North China Plain is likely to experience deadly heatwaves with wet-bulb temperature exceeding the threshold defining what Chinese farmers may tolerate while working outdoors. China is currently the largest contributor to the emissions of greenhouse gases, with potentially serious implications to its own population: continuation of the current pattern of global emissions may limit habitability in the most populous region, of the most populous country on Earth.

Read more: https://www.nature.com/articles/s41467-018-05252-y

My question – if this nightmare ever actually occurs (unlikely – they used RCP8.5 for their projection), why can’t people affected by the heatwave just turn on their air conditioners?

I live on the edge of the tropics. When conditions are hot and humid, the solution is to go inside and switch on the air conditioner. Or jump into the pool.

The interior of the poorly ventilated chemical factory I once worked in frequently hit 130F in Summer. I’m not sure what the humidity inside was, but given the temperature and conditions it must have been pretty spectacular.

I have mown large lawns with a push mower in 115F and 80% humidity. Sometimes the lawn can’t wait, in my part of the world you have to mow once a week in Summer, sometimes more frequently. Occasionally you have to mow the lawn in the middle of a heatwave to discourage snakes from invading your house.

My friends who used to work in an underground mine in Marble Bar, Western Australia laughed at me when I told them about my lawn mowing and factory work experiences. During their old mining job, scorching hot air from the surface of one of the hottest places on Earth used to be pumped into the stifling hot and humid underground mine, to help provide cool relief from even more extreme conditions underground.

Providing you are used to the conditions, you have somewhere cool to rest, and plenty of water to drink (as in gallons per day), working in extremely hot and humid conditions is not the problem the study authors make it out to be.