The Earth is warming because of what humans have been doing to the atmosphere. Global Warming has a lot of effects many of which we've discussed here, but the most obvious one is, well, it gets warmer. At present, India is experiencing record breaking heat and people are dying.
It is very difficult to say how many people die from the heat in any region. We can use a standard approach used by epidemiologists to estimate this number. This involves simply looking at mortality rates as they change over time to try to detect a signal, an increase, associated with the variable in question. If all sources of mortality remain the same over a period of time, but a heat wave occurs during that period and with it comes an increase in mortality, then it is possible that those extra deaths are due to the heat. Nothing, of course, is that simple, but epidemiology has some fancy tools to try to tease out reasonable numbers.
I'm reminded of the Ituri Forest, where I worked for a few years. We kept track of births and deaths, and it became apparent that deaths tended to be seasonal. More people seemed to die during the annual "hunger season." This season occurred around June, when the first wet season crops (there are two wet seasons) were not ready, and the previous wet season's crops were mostly used up. At the same time, other crops were not abundant and wild foods (both plants and animals) tended to be hard to come by, as the forest experienced a coeval reduction in productivity of human edible foods. But the people who died during that period rarely seemed to die of hunger. They died of other things, such as infectious disease, but presumably these other causes of mortality were more effective when combined with food stress. One hunger season, two people died in a murder-suicide. An elderly couple lived in a small village, alone, with an orphaned grandchild. It was a bad hunger season for them since their village lacked the resources to produce enough food. It is believed the elderly woman, depressed by the hunger, harvested poisonous wild yams and made a meal of them, knowingly, and fed them to her family. She and her husband died, but the child vomited up the deadly meal and survived. Those were hunger-related deaths, but as is the case with many such deaths, were embedded in a much more complicated scenario.
Right now people in parts of India are dying of the heat, but many more than those known to die of heat stroke are also dying in this more complicated way. Indian heat waves are increasing in their frequency, being one third more common by the end of a study period covering 1961-2010, according to a 2014 study. The problem has become worse due to anthropogenic global warming, and it is made even worse in El Niño years. And, we seem to be entering an El Niño period. Changes in land use and urbanization are also probably contributing factors in India.
Heat wave related death spells produce numbers in the hundreds. Something like 500 people are known to have died directly of the heat over the last few days in India. But other deaths caused by multiple factors where heat is a sort of final straw would be in the thousands.
Right now, India is very hot, and some areas are expected to become even hotter over the next several days.
Fred Barbash at the Washington Post has a good writeup on the current situation there.
UPDATE: Jeff Masters has a current write-up of the heat wave in India. At present the death rate (which is certainly an underestimate) for India places it fifth in known historic deadly heat waves.
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Tragic news and reality. They were saying 400 plus dead the other night then risen to 800 and now over a thousand killed.
See : http://www.abc.net.au/news/2015-05-26/india-heatwave-kills-800-as-capit…
You'd think this would be headline news, the top story - like the Nepalese earthquake - wouldn't you? But it isn't - at least not here and not even on the usually very good ABC.
From my understand we are definitely in an El Nino phase according to NOAA, NASA & the Aussie Bureau of Meteorology among other reliable scientific sources :
http://www.bom.gov.au/climate/enso/
Plus seen at least one article online based on good science that suggests this is going to be a particularly strongand nasty one. Really not looking forward to summer here (Dec-Jan-Feb where I live) -well, except for the cricket season!
(But seriously, the implications for what's in store with bushfires, heatwaves and drought for us are pretty damn grim.)
These excess deaths are hard to attribute. Also we don't know how many of them were people sick enough they would have died soon anyway, and the heat stress just advanced the date. I suppose some studies may have been attempted to see if there is a negative echo following a heat related spike? Or is the noise too great to tell?
Omega, the 500+ number is not hard to attribute. Cause of death: Heat Stroke. End of story. Normally, in India, once records are finally collated after a heat stroke like this one, the number doubles or triples, so if it is 500 now, it is probably between one and two thousand.
The larger number, the many thousands (over a period of time) of heat related deaths are indeed difficult to attribute. Yet, those people are in fact dead, and there is an attribution of some kind for each of them. Epidemiology relies on that basic relationship between cause and effect and tries to tease it out. They generally do an OK job as long as you understand the basic caveats. This is nobody's first rodeo!
Greg,
I don't think the direct heatstroke deaths are the issue (now probably around a thousand). By excess deaths, I mean deaths that aren't from heatstroke/dehydration, but other causes that spike, just like your hunger-season deaths, other causes get a boost because of stress. These are likely to outnumber direct heat related deaths by several fold. But, these are mainly among the infirm population, and my question is how long they would have lived without the additional stress.
A big factor, is to have active public policies to get vulnerable populations cooled off. Chicago learned this after the disastrous heat wave (in 95 IIRC) which killed several hundred. Now they set up cooling centers, and have people check on the elderly to find out if they need to be brought to one. Many oldfolks don't have AC -or are too afraid of the electric bill to use them. Oftentimes fear of crime prevents them from opening windows, and so their dwellings can become very hot during a long heatwave.
Yes, and therein lies the problem that adaptation hides part of the cost of climate change.
In colonial India, in 1900, the British army suffered more deaths annually from heatstroke than malaria.
The 61 % rise in indigenous heat related deths in this century may however be driven as much by urban population growth - and its feedback on the urban heat island effect as decadal temperature trends.
Little wonder America's near universal air conditioning is such an immgration draw !
Russell, you just stepped on your own argument.
Changes in land use are changes in context grating against acclimatization. That is certainly part of the problem in India. The British colonial army going to India is a context against acclimatization.
You can't explain away one thing without explaining away the other, an the british-south asia link is much much stronger. Epidemiologists have looked at heat death in India. We know that heat island and migration explain only part of it.
The chances are heat related deaths can be cut down to fairly low levels, but good civil policies. So the real issue with AGW won't the an increase in heat related deaths, we know how to adapt. The issue will be theeconomic cost of that adaptation, both direct. Especially in terms of reduced productivity. One adaptation will be, that all outdoor work stops (by law) at a given temperature/heat index. {I read China was cheating, and you could see it in reported maximum temperatures staying a half degree below the threshold}. There might even be mitogating interventions here, some form of personal cooling probably, which will allow some outdoor activities to continue safely.
Although human activities have added to the global warming, that contribution is minor compared to the natural glaciation cycles which occur on about 80,000 to 140,000 year cycles. Saying that the recent temperatures are record breaking only represents short term data. It has been at least as hot before during previousl interglacial periods.
See these sources:
http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm
http://www.eoearth.org/view/article/154612/
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No. Orbital geometry has been shown to relate to the coming and going of "ice ages" (an oversimplification) only when CO2 levels are well below 350ppm or so. We have shifted CO2 levels to 400ppm and rising, so this is no longer a factor. CO2 levels are higher now then they have been in millions of years, and temperatures are climbing above any likely temperature of that same period. It was not warmer globally during prior interglacials. This difference in temperature is entirely human cause (though, again it is a bit more complex than that). You have bought into a fallacy perpetuated by climate science deniers. But now you know that so you can learn more stuff and get closer to what is really happening!
-gtl]
Death toll now over 2,000 :
http://www.abc.net.au/news/2015-05-30/india-reels-under-heatwave-as-dea…
.. and rising still every day.Temperatures of 48 degrees Celsius (118 Fahrenheit) in one Southern Indian city or so I heard on the news the other day.
This catastrophe is almost going unmentioned here and yet it shouldn't. In six months time or so, it maybe our turn and then we'll no doubt hear no end of it. Because it will be us not them. I hate to think what's coming then and what these poor individuals are going through.
@9. Omega Centauri : "One adaptation will be, that all outdoor work stops (by law) at a given temperature/heat index."
Thing is, this isn't always possible given things like bushfires that parts of our world - like mine - experience because of heat wave conditions. Think firefighting and medical emergencies and a lot of unethical employers that have workers in no position to say no even when their health is on the line.
PS. Think also about nights - rows of consecutive nights - where the temperature never drops below say 25 Celsius (77 F) or more for extended periods. Where a lot of people (raises hand) find it hard to sleep and suffer as a result. Think about the implications of that. We can take some actions to adapt and we will - but these actions also have consequences and side effects (think power bills that are just unaffordable for many especially the poorest & most vulnerable among other things) and aren't always all that effective.
Yes, we can try to legislate and try to adapt but it still a huge problem and has a huge impact on a lot of people and cannot always be done. Even in wealthy First World lands like Australia and the United States.