Prevent deadly heat waves in China due to climate change
By The nuevodia.com Science, August 1, 2018.
The new findings show that the plain of northern China faces the greatest risks to human life, this area will be the warmest place for deadly heat waves in the future, especially under climate change. The three regions studied by the researchers were chosen because past records indicate that the combined levels of temperature and humidity reached higher extremes there than in any other landmass. The new study indicates that under normal scenarios of greenhouse gas emissions, that threshold will be reached several times in the region of the North China Plain between 2070 and 2100.
The risk of deadly heat waves increases significantly due to intensive irrigation in this relatively dry but highly fertile region. (EFE)
Research by the Massachusetts Institute of Technology (MIT) has shown that beyond a certain threshold of temperature and humidity, a person cannot survive without outdoor protection for prolonged periods, as, for example, farmers should.
The study shows that unless drastic measures are taken to limit the emissions that cause climate change, the most populated and agricultural region of China could face such deadly conditions repeatedly, suffering the most damaging heat effects, at least as far as regarding human life, from anywhere on the planet.
The publication shows that the risk of deadly heat waves increases significantly due to intensive irrigation in this relatively dry but highly fertile region, known as the North China Plain (NCP), a region whose role in that country is comparable to that the West medium of the United States
This greater vulnerability to heat arises because irrigation exposes more water to evaporation, which causes greater humidity in the air than would otherwise be present and exacerbated the physiological stresses of temperature.
The new findings of Elfatih Eltahir at MIT and Suchul Kang at the Singapore-MIT Alliance Research and Technology are reported in the journal Nature Communications. The study is the third in a set; the two previous projected increases of deadly heat waves in the Persian Gulf area and in South Asia. While previous studies found serious imminent risks, the new findings show that the plain of northern China faces the greatest risks to human life from rising temperatures, from any location on Earth. “The response is significantly greater than the corresponding response in the other two regions,” says Eltahir, professor of hydrology and climate at Breene M. Kerr and professor of civil and environmental engineering.
The three regions studied by the researchers were chosen because past records indicate that the combined levels of temperature and humidity reached higher extremes there than in any other landmass. Although some risk factors are clear: low valleys and proximity to seas or warm oceans, “we do not have a general quantitative theory through which we could have predicted” the location of these global access points, he explains. Looking empirically at the climate data of the past, “Asia is what stands out,” he says.
Although the study of the Persian Gulf found some even higher extreme temperatures, those were limited to the area above the water of the Gulf itself, not on the land. In the case of northern China, “This is where the people live,” says Eltahir.
El índice clave para determinar la capacidad de supervivencia en climas cálidos, explica Eltahir, involucra la combinación de calor y humedad, según lo determinado por una medición llamada temperatura de bulbo húmedo. Se mide al envolver literalmente la tela húmeda alrededor del bulbo (o sensor) de un termómetro, de modo que la evaporación del agua pueda enfriar el bulbo. Con 100 por ciento de humedad, sin evaporación posible, la temperatura del bulbo húmedo es igual a la temperatura real.
The key index for determining survival capacity in hot climates, Eltahir explains, involves the combination of heat and humidity, as determined by a measurement called wet bulb temperature. It is measured by literally wrapping the wet fabric around the bulb (or sensor) of a thermometer, so that the evaporation of the water can cool the bulb. With 100 percent humidity, without possible evaporation, the temperature of the wet bulb is equal to the actual temperature.
This measure reflects the effect of extreme temperatures on an outdoors person, which depends on the body’s ability to shed heat through the evaporation of sweat from the skin. At a wet bulb temperature of 35 degrees Celsius (95 ° F), a healthy person may not be able to survive outdoors for more than six hours, research shows. The new study indicates that under normal scenarios of greenhouse gas emissions, that threshold will be reached several times in the region of the North China Plain between 2070 and 2100.
“This place is going to be the warmest place for deadly heat waves in the future, especially under climate change,” says Eltahir. And the signs of that future have already begun: there has been a substantial increase in extreme heat waves in the NCP already in the last 50 years, the study shows. The warming in this region during that period has been almost double the world average.
In 2013, extreme heat waves in the region persisted for up to 50 days, and maximum temperatures exceeded 38 ° C (100 ° F) in some places. The main heat waves occurred in 2006 and 2013, breaking records. Shanghai, the largest city in eastern China, broke a temperature record of 141 years in 2013, and dozens of people died.