Wet bulb temperature and heatwave deaths

In view of the seering temperatures in India it is worth rereading this article from 2013

China Falls Under Suspicion of Covering Up Deaths as Ocean Heat Dome Expands to Blanket Korea and Japan

US Weather Fatalities by Type,,(Image source: NOAA)

Robertscribbler,

13 August, 2013

According to recent reports from NOAA and the CDC, heat is the most lethal form of weather in the United States. Death and injury rates have been on the rise as human-forced temperature increases have expanded, surging northward into major metro areas such as New York City. The CDC report showed a growing number of heat deaths and injuries for this northern region, with the New York Metro area seeing an average of 13 deaths and over 440 heat injuries each year during the period from 2000 to 2011. Nationwide, the average number of heat fatalities surged to 117 during a period from 2003 to 2011.

Heatwaves have hit the NYC region time and time again over the past decade, driving the death and injury rate inexorably higher. However, the heat impacting that area is paltry when compared to the extreme and deadly temperatures that have broiled southeastern China since late July. For more than three weeks, the Shanghai region of China has experienced almost daily temperatures in excess of 100 degrees Fahrenheit and sweltered under very high humidity for such hot conditions. This combination has pushed wet bulb temperatures (a measure that simulates the temperature of human skin) into a range of 29 to 32 degrees Celsius, very close to the lethal human limit of 35 degrees C.

On Sunday, an extreme heat pulse sent thermometers soaring to 109 degrees Fahrenheit in the city of Shengxian — its hottest temperature ever recorded and a scorching 32.3 degree wet bulb temperature. Meanwhile, on the same day, Hangzhou had hit a new all time record high temperature of 105.8 degrees Fahrenheit, the twelfth time since July 24th that Hangzhou has tied or broken its old all time temperature record which, in some cases, was set just the day before.

High heat and humidity of this kind is deadly to humans because as temperatures approach 35 degree C wet bulb readings, it is nearly impossible for the human body to carry away the excess heat it generates through evaporation. Never has a wet bulb temperature of 35 degrees C been recorded by humans. However, climate scientists such as James Hansen have asserted that it’s just a matter of time under the current regime of human-caused warming before we hit that ominous mark.

So have thousands did?

Road Sign Burns Under Record Heat in Shanghai Region (Image source: Shenzhen Daily)

As reports of vehicle fires and sporadically smoldering infrastructure in the massive Chinese heatwave flared, suspicions emerged that Chinese officials are covering up what are potentially thousands of heat-related deaths.

According to Chinese news agencies, the official report is that about two dozen have died so far in Shanghai’s record-shattering heatwave. But similar heat in Europe and Russia resulted in tens of thousands of deaths over the past decade. At issue is the fact that China’s current record heat and humidity are at levels never before experienced in its weather history and that this event is even more intense than the deadly heatwaves of Europe and Russia. Add to this extraordinarily dangerous event the fact that more than 400 million people live in the region of China currently being socked by record heat and the vague reports coming out of China seem highly incongruent.

Never before has such high wet bulb temperatures hit a region of so dense a population. Yet China has only continued to report the vague ‘dozens’ estimate.  It was this discrepancy thatcaused WeatherUnderground Historian Christopher Burt to speculate that China may be covering up a catastrophic rash of fatalities:

Eastern China, where about 30% of the population of the country and 5% of the global population reside (approximately 400 million people) has undergone a heat wave unprecedented in its history. No one really knows how many have died as a result of the heat wave (Chinese news sources claim ‘about two dozen’), but statistically it is almost certain that many thousands must have perished as the result of the heat over the past month.

If Christopher Burt’s, quite rational, analysis ends up proving true, we can expect reports of fatalities to begin to slowly trickle out of China. Misreporting and under-reporting of Chinese heatwave casualties would also be yet one more instance of government officials and mainstream media downplaying and under-reporting the effects of catastrophic events related to human-caused climate change. Such under-reporting is yet one more manifestation of a dangerous and paralyzing denial that has so hampered an effective response to these increasingly dangerous and self-inflicted events.

Making such a call, however, is possibly premature as residents of this region are more acclimated to excessive heat than Europeans or Russians. As Burt notes:

One thing to keep in mind, however, is that it is ALWAYS hot and humid in eastern China during the summer (unlike Russia and Western Europe), so perhaps the population has learned to adapt to extreme heat.

The Ocean Heat Dome Expands to Cover Korea and Japan

Ocean Heat Dome Over China, Korea and Japan (Image source: NASA/Lance-Modis)

A sprawling heat dome high pressure system that has scorched a region stretching from coastal China to a large expanse of the Pacific Ocean shifted eastward into Korea and Japan over the weekend. Southern Japan saw temperatures surge into the 100s with Shimanto recording the highest temperature ever measured in Japan of 105.8 degrees Fahrenheit (41 degrees Celsius). Tokyo, meanwhile, broke the record for its hottest minimum temperature at 86.7 degrees Fahrenheit (30.4 C).

South Korea, over the same period, reported 8 deaths as temperatures soared to 102.2 degrees Fahrenheit (39 C) in Busan. Temperatures in Seoul hit the still hot, but more moderate, 90s (32 C +).

Both South Korea and Japan are surrounded on multiple sides by water. This geographic feature would usually provide a cooling effect as ocean temperatures are typically many degrees cooler than land temperatures. But, in this case, a massive heat dome is baking the ocean itself to unprecedented high surface water temperatures. As a result, a large area of open ocean now shows readings above 30 degrees Celsius ( 86 Fahrenheit). This extremely hot, near 90 degree water, has formed the central pulse of the current heatwave even as it has pumped extraordinarily humid air for such hot conditions over adjacent land areas. A shift to the north of this large and still growing region of extraordinarily hot ocean water led to the record steamy conditions over Japan and Korea during the past few days — both of which can expect little relief from the now, very hot, water.

Ocean Heat Dome Puts Asia in Hot Water (Image source: Weather Online)

Forecasts for Shanghai, Korea, and Japan call for slightly less sweltering temperatures in the upper 90s with more isolated readings in the 100s as clouds are expected to move in and increase chances of rainfall by later this week. A slight improvement but a welcome change, nonetheless. Meanwhile, hot ocean conditions create a risk for continued very hot temperatures for much of this coastal region.

Ocean Heat Dome Steams Coastal China: Shanghai to Near Very Dangerous 35 Degree Celsius Wet Bulb Temperatures This Week