4 ms·

Since we're talking about a deadly heat-wave, people will certainly ask what global warming has to do with this. Roughly speaking, global temperatures have incr

by scythe 5y ago

Since we're talking about a deadly heat-wave, people will certainly ask what global warming has to do with this. Roughly speaking, global temperatures have increased by about 1 degree Celsius over the past century. So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. But it's also important to recall that the human sensitivity to excessive heat depends on humidity. Because the vast majority of the heat burden from global warming is stored in the oceans, and evaporation rates are determined by sea surface temperatures, global warming tends to increase wet-bulb temperatures just as much as dry-bulb temperatures [1]. Since heat waves tend to occur under dry (sunny) conditions, the wet-bulb temperature anomaly is probably smaller than the dry-bulb anomaly, and global warming may play a larger role, perhaps 20%. It's also important to remember that the human sensitivity to heat stress has an extremely rapid onset. Under reasonable conditions (shade/hydration/ventilation), a Tw of 28 C is uncomfortable, but brief exposure (a few hours, while working) rarely causes health issues [2]. The risk of exertional heat injury doubles at 30 C, doubles again at 32 C, and doubles again at 34 C. Above Tw = 35 C, extended survival is not possible [1]. Historically, wet-bulb temperatures on Earth almost never exceeded 31 C [1]. So, are the people who die in this heat wave dying because of global warming? Probably some of them. Considering what we have learned about heat stress, it seems plausible that the "rebrand" of global warming to "climate change" was a mistake. [1] S. C. Sherwood and M. Huber, An Adaptability Limit to Climate Change Due to Heat Stress, Proc. Natl. Acad. Sci. U.S.A. 107, 9552 (2010). [2] X. P. Garzon-Villalba, A. Mbah, Y. Wu, M. Hiles, H. Moore, S. W. Schwartz, and T. E. Bernard, Exertional Heat Illness and Acute Injury Related to Ambient Wet Bulb Globe Temperature, Am. J. Ind. Med. 59, 1169 (2016). [2 note] Wet-bulb globe temperature is an adjustment that incorporates sun exposure into heat stress calculations. However, sunlight is easily mitigated. Because humans avoid such conditions, there is not much evidence on human exposure to in-shade Tw above 32 C.

PheonixPharts 5y ago
> So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. That is not remotely how global warming works.
- scythe 5y ago
  It's basically just bad phrasing. Granted, obviously global warming is not responsible for a deviation of a daily temperature from the average over that year or other near-term comparison. But it's not unreasonable to simply say "it would have been about one degree cooler 150 years ago".
  - polotics 5y ago
    It is unreasonable because it is completely incorrect! Lower & wetter lows, and much much higher much wetter highs is what CO2-induced climate disruption has triggered. "It" would not have been one degree cooler, this is a completely invalid way of thinking about the predicament.
Beltalowda 5y ago
> Since we're talking about a deadly heat-wave, people will certainly ask what global warming has to do with this. Roughly speaking, global temperatures have increased by about 1 degree Celsius over the past century. So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. I don't think it's quite that simple; the average temperature has increased by 1°C, but that doesn't mean there can't be spikes, or even that some areas can actually become colder due to different weather patterns. The climate is a complex system with a lot of feedback loops.
- scythe 5y ago
  >I don't think it's quite that simple; the average temperature has increased by 1°C Yes, there are regional variations. But India sits right near the average. So this isn't a real problem for my analysis. See: https://commons.wikimedia.org/wiki/File:Map_global_warming_2010-2019.png https://commons.wikimedia.org/wiki/File:Map_global_warming_2...
  - Beltalowda 5y ago
    But that only describes average temperature increases for a particular area? I'm not talking about regional variations, I mean that "an average increase of n°C" doesn't mean "it's now always n°C warmer than 100 years ago". If much of the year is only 0.5°C warmer and the occasional heat-wave several degrees warmer, then you can still end up with an average that's much lower than the top of the heat-wave spike. I believe in some areas winters are actually even cooler than before and summers warmer (don't know if that's also the case in India). Averages are a really poor way to understand most things.
    - scythe 5y ago
      >I mean that "an average increase of n°C" doesn't mean "it's now always n°C warmer than 100 years ago". If much of the year is only 0.5°C warmer and the occasional heat-wave several degrees warmer, then you can still end up with an average that's much lower than the top of the heat-wave spike. These ideas are statistically possible, but that doesn't mean that they're physically reasonable. A 1 C increase is proportionally an 0.3% increase in the actual temperature. You don't expect a whole lot of nonlinear effects by default. The effect I'm concerned with comes mostly from heat stored in the ocean, which is not that unstable. Now, if you want to talk about fires or hurricanes or something, sure, that's complicated. Most of the things that would cause increased variability do not apply. Moving snow lines don't matter because it's India (and not near the mountains). Wind isn't that important because temperature gradients are small at the equator. Cloud cover is very low in India in April and it isn't high right now (we're talking about a local atmospheric high, that's not cloudy). Changes in albedo, kinda-maybe, but it's the end of the dry season so things are already as brown as they get. Changes in evaporation/precipitation, again, it's the end of the dry season in India. You could make a case for shifts in the tropopause or whatever but that's why I said "probably" and not "definitely". Most of my post was about the fact that a +1 C contribution to a +10 C excess temperature is more important than it sounds at first. I don't feel like combing through Indian temperature records to prove a lazy ceteris paribus, but if we were in a bar I'd bet ten bucks that I'm within a factor of two.
Workaccount2 5y ago
>So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. Bruh...
- Lendal 5y ago
  I feel bad because he spent a lot of time building up a case for it to be ruined from it all resting on this one really shaky foundation. I feel like this probably happens often in science.
  - scythe 5y ago
    It's not that shaky. Averages are averages. A very-long-term average is not that unpredictable. People just don't like hearing that their selfishness is getting people killed, so they demand unachievable standards of evidence.
radicaldreamer 5y ago
Comical disinformation with [citations] to throw you off... "So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly." Literally LOL

by scythe 5y ago

PheonixPharts 5y ago

> So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. That is not remotely how global warming works.

scythe 5y ago
It's basically just bad phrasing. Granted, obviously global warming is not responsible for a deviation of a daily temperature from the average over that year or other near-term comparison. But it's not unreasonable to simply say "it would have been about one degree cooler 150 years ago".
- polotics 5y ago
  It is unreasonable because it is completely incorrect! Lower & wetter lows, and much much higher much wetter highs is what CO2-induced climate disruption has triggered. "It" would not have been one degree cooler, this is a completely invalid way of thinking about the predicament.

Beltalowda 5y ago

> Since we're talking about a deadly heat-wave, people will certainly ask what global warming has to do with this. Roughly speaking, global temperatures have increased by about 1 degree Celsius over the past century. So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. I don't think it's quite that simple; the average temperature has increased by 1°C, but that doesn't mean there can't be spikes, or even that some areas can actually become colder due to different weather patterns. The climate is a complex system with a lot of feedback loops.

scythe 5y ago
>I don't think it's quite that simple; the average temperature has increased by 1°C Yes, there are regional variations. But India sits right near the average. So this isn't a real problem for my analysis. See: https://commons.wikimedia.org/wiki/File:Map_global_warming_2010-2019.png https://commons.wikimedia.org/wiki/File:Map_global_warming_2...
- Beltalowda 5y ago
  But that only describes average temperature increases for a particular area? I'm not talking about regional variations, I mean that "an average increase of n°C" doesn't mean "it's now always n°C warmer than 100 years ago". If much of the year is only 0.5°C warmer and the occasional heat-wave several degrees warmer, then you can still end up with an average that's much lower than the top of the heat-wave spike. I believe in some areas winters are actually even cooler than before and summers warmer (don't know if that's also the case in India). Averages are a really poor way to understand most things.
  - scythe 5y ago
    >I mean that "an average increase of n°C" doesn't mean "it's now always n°C warmer than 100 years ago". If much of the year is only 0.5°C warmer and the occasional heat-wave several degrees warmer, then you can still end up with an average that's much lower than the top of the heat-wave spike. These ideas are statistically possible, but that doesn't mean that they're physically reasonable. A 1 C increase is proportionally an 0.3% increase in the actual temperature. You don't expect a whole lot of nonlinear effects by default. The effect I'm concerned with comes mostly from heat stored in the ocean, which is not that unstable. Now, if you want to talk about fires or hurricanes or something, sure, that's complicated. Most of the things that would cause increased variability do not apply. Moving snow lines don't matter because it's India (and not near the mountains). Wind isn't that important because temperature gradients are small at the equator. Cloud cover is very low in India in April and it isn't high right now (we're talking about a local atmospheric high, that's not cloudy). Changes in albedo, kinda-maybe, but it's the end of the dry season so things are already as brown as they get. Changes in evaporation/precipitation, again, it's the end of the dry season in India. You could make a case for shifts in the tropopause or whatever but that's why I said "probably" and not "definitely". Most of my post was about the fact that a +1 C contribution to a +10 C excess temperature is more important than it sounds at first. I don't feel like combing through Indian temperature records to prove a lazy ceteris paribus, but if we were in a bar I'd bet ten bucks that I'm within a factor of two.

Workaccount2 5y ago

>So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly. Bruh...

Lendal 5y ago
I feel bad because he spent a lot of time building up a case for it to be ruined from it all resting on this one really shaky foundation. I feel like this probably happens often in science.
- scythe 5y ago
  It's not that shaky. Averages are averages. A very-long-term average is not that unpredictable. People just don't like hearing that their selfishness is getting people killed, so they demand unachievable standards of evidence.

radicaldreamer 5y ago

Comical disinformation with [citations] to throw you off... "So a simple answer is that global warming is responsible for about 1 degree of the 10-degree heat anomaly." Literally LOL