Guest Essay by Kip Hansen – 30 June 2022
The esteemed journal Science carries this story from Latin America in Climate section:
Extreme temperatures in major Latin American cities could be linked to nearly 1 million deaths
“An increase of 1°C could mean thousands of additional deaths on very hot days, according to a new study” by Rodrigo Pérez Ortega
It leads with:
“In mid-January, the southern tip of South America suffered its worst heat wave in years. In Argentina, temperatures in more than 50 cities rose above 40°C [ 104°F ], more than 10°C [ 18°F ] warmer than the typical average temperature in cities such as Buenos Aires. The scorching heat sparked wildfires, worsened a drought, hurt agriculture, and temporarily collapsed Buenos Aires’s electrical power supply. It also killed at least 3 people, although experts estimate the true number might be much higher.
With climate change, heat waves and cold fronts are worsening and taking lives worldwide: about 5 million in the past 20 years, according to at least one study. In a new study published today in Nature Medicine, an international team of researchers estimates that almost 900,000 deaths in the years between 2002 and 2015 could be attributable to extreme temperatures alone in major Latin American cities. This is the most detailed estimate in Latin America, and the first ever for some cities.”
There is a study! A real study published in nature medicine authored by Josiah L. Kephart and eleven others. “City-level impact of extreme temperatures and mortality in Latin America” [ .pdf here ].
Let’s start with the abstract and compare it to the lede in Science.
“Climate change and urbanization are rapidly increasing human exposure to extreme ambient temperatures, yet few studies have examined temperature and mortality in Latin America. We conducted a nonlinear, distributed-lag, longitudinal analysis of daily ambient temperatures and mortality among 326 Latin American cities between 2002 and 2015. We observed 15,431,532 deaths among ≈2.9 billion person-years of risk. The excess death fraction of total deaths was 0.67% (95% confidence interval (CI) 0.58–0.74%) for heat-related deaths and 5.09% (95% CI 4.64–5.47%) for cold-related deaths. The relative risk of death was 1.057 (95% CI 1.046–1.067%) per 1 °C higher temperature during extreme heat and 1.034 (95% CI 1.028–1.040%) per 1 °C lower temperature during extreme cold. In Latin American cities, a substantial proportion of deaths is attributable to nonoptimal ambient temperatures. Marginal increases in observed hot temperatures are associated with steep increases in mortality risk. These risks were strongest among older adults and for cardiovascular and respiratory deaths.”
One of the amusing things we see right off is the use of Large Numbers: 15,431,532 deaths, 2.9 billion person-years of risk. Well, they have a huge population over a very large area (1.5 continents) over 13 years during which 15.4 million people died. But what of the results?
The excess death fraction of total deaths was 0.67% (95% confidence interval (CI) 0.58–0.74%) for heat-related deaths
The excess death fraction of total deaths was 5.09% (95% CI 4.64–5.47%) for cold-related deaths
Bottom Line: Excess Death Fraction for cold-related deaths is 7.5 times higher than for heat-related death.
And for Relative Risk (RR) change per 1°C change in highest/lowest temperature?
The relative risk of death was 1.057 (95% CI 1.046–1.067%) per 1 °C higher temperature during extreme heat and 1.034 (95% CI 1.028–1.040%) per 1 °C lower temperature during extreme cold.
Bottom Line: While the study makes a big deal about the difference in these two RRs, with a difference of only 0.023 – they are in terms of medical science, often considered identical.
There is no reason, however, to believe that this small difference is not real. It may just show that human bodies have a different limit responses to small changes at highest and lowest temperatures when averaged across a large enough population.
At every turn in this paper, the authors make the attempt to make heat the villain despite the far greater risk of dying from cold:
“Overall, a substantially higher proportion of deaths is attributable to ambient cold than to ambient heat, which corroborates findings from similar analyses in other settings. A 2021 analysis by Zhao et al. estimated temperature–mortality associations in 750 locations from 43 countries (including 66 locations in Latin America and the Caribbean), and extrapolated these estimates glob ally at 0.5° × 0.5° grid size (approximately 55 × 55 km2 at the equator) using meta-predictors. The Zhao et al. study reported global EDFs of 8.52% for cold and 0.91% for heat for all-age, all-cause mortality. This global EDF for cold (8.52%) is almost twice our estimated EDF for cold within Latin American cities (4.71%).”
And
“A 2017 study, which included 32 locations in Mexico, Brazil and Chile, projected that, under multiple climate-change scenarios, midcentury decreases in cold-related mortality would approximately counterbalance increases in heat-related mortality, yet by the end of the twenty-first century overwhelming heat-related mortality would cause a substantial net increase in temperature-related excess mortality.”
[ Yes, that 2017 study finding uses RCP8.5. – kh ]
The Pérez Ortega study we are looking at today summarizes its findings in this table:
I have written about Cause of Death and its uses in studies more than once: Cause of Death: A Primer and Cause of Death: Follow-up. This study is not about heat deaths or cold deaths. It is about All Cause Deaths with details about the major causes: Cardiovascular Deaths, Respiratory Deaths, and Respiratory Infection Death with breakouts for All Ages and Ages 65+.
This study does not even consider categories of deaths caused by extremes of temperature, hot or cold. There are cause of death codes for excessive natural heat “2022 ICD-10-CM Diagnosis Code X30 Exposure to excessive natural heat” and cold “2022 ICD-10-CM Diagnosis Code X31 Exposure to excessive natural cold”. Quite simply, they did not count people killed by heat or people killed by cold, at all, not one.
The question the study asks and tries to answer is “Do more people than normal die in Latin America when it is unusually hot or when it is unusually cold?”
What they fail to ask and fail to analyze are the most likely culprits in the issue itself: what are the poverty and development levels in the cities studied? Surely poverty and lack of development — lack of electricity, lack of clean water, lack of appropriate housing and lack of even basic healthcare and social support have far more impact on the extreme numbers of “temperature related deaths” than the temperatures themselves.
BOTTOM LINE: While it comes as no surprise, this study confirms that more people die when ambient temperatures are at extreme levels (much higher or much lower than usual) for the locality. This study confirms that far more die when it is unusually extremely cold than when it is unusually extremely hot. This is a fact affecting older people (65+) more than younger people and these excess deaths are a result of heart (cardiovascular) and breathing (respiratory) problems – but do not from directly from the heat or cold itself.
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Author’s Comment:
Readers here already know that cold kills far more than heat. This study finds this to be true once again. The authors have made feeble attempts – not based on their own study but on speculative RCP8.5 studies – to claim that this will cause more, not less, future deaths if general climates continue to warm.
As with all studies that use All Cause mortality, there is no “cause” found, only various vaguely related correlations. All Cause Mortality is one of the absolutely worst indicators to be used in such studies and is used, quite frankly, because it is easy. Cause of Death is hard, complicated, complex, and records of ICD-10 codes are unreliable (doctors are in a hurry or doctors lie…). It is hard to determine the real causes of individual deaths but easy to determine and count dead bodies.
We already knew that more people, particularly (us) old folks die when it is very hot or very cold. We already knew that far more die when it is very cold than when very hot. I am not convinced that this study found anything that makes mankind more knowledgeable or anything that will help policy makers in nations or localities set better policy to make a better world. In that sense, this study is “useless”.
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All this is moot – by far most deaths are caused by poverty, caused in main part by a lack of inexpensive abundant energy.
Greg61 ==> You are absolutely correct — lack of development mostly due to “no real government”.
I expect that one factor that is not being considered in studies like these is the effects of an aging population. It is well known that people tend to survive much longer now than decades ago, even more so in developing countries than in fully developed countries. The ability of the human body to regulate its own internal body temperature becomes degraded, in part due to reduced blood circulation, other health issues, and the heavy use of certain medicines. This factor affects tolerance of both heat and cold.
A little over century ago, in 1920, the average life expectancy for women was 54.6 years, compared to 78.9 years today. That’s a humongous change – an increase in life expectancy of 44%!
So if more people are living longer, but normal aging makes them more susceptible to illness or death due to extreme heat or cold, then those deaths really cannot be considered “excess deaths” since in prior decades such people wouldn’t have lived long enough to die of such a cause. A method of calculating “net excess deaths” would be necessary to properly characterize what is happening.
Duane ==> Age is a factor taken into account — but not “adjusted for”. They are just counting bodies….dead ones.
It may be “well known,” but it is an Urban Legend. Because of hygiene, vaccinations, and antibiotics, far fewer children die now than previously. Far fewer young women die in child birth, and wars take far fewer lives of men of military age. Thus, the average life expectancy from birth has increased. However, look at an actuarial table and see the remaining expected years for a 55-year old woman in 1920 and compare that to a 55-year old today. You won’t see a 44% increase. If one makes it through the high-risk years, the increased life expectancy is only marginal.
I’ve always found 75 a very pleasant temperature but when it hits 76 I feel like I’m going to die.
But not to worry – the WHO will control this too. It’s almost in their hands now. Come to poppa.
marlene ==> The WHO is a massive out-of-control bureaucracy. At the regional level and local levels, their smaller units actually do good work. Partnered with PAHO (Pan-American Health Organization) in the Dominican Republic for several years with good results.
“With climate change, heat waves and cold fronts are worsening“
From the linked article:
“Finally, one group of researchers, led by Nicholas Leach, a graduate student at the University of Oxford, is betting that detailed weather forecasting models can give a more precise picture of global warming’s role in weather than coarser climate models. They simulated the 2021 Pacific Northwest heat wave with the world-leading model of the European Centre for Medium-Range Weather Forecasts. After lowering carbon dioxide levels and removing human-driven heat from the ocean, the model reproduced a similar heat wave, although the highs were 2°C or so cooler than in the actual event, the team reported last month at the EGU meeting. The model’s many runs for each scenario will allow them to assess whether climate change made the heat wave more likely. But WWA’s statement that the event was “virtually impossible” without warming was likely an overreach, Leach says. “We don’t find that in our model.””
Seems rational that extra CO2 forcing in theory could intensify the heatwave but not make it more likely. The main problem is that they don’t have a theory for heatwaves, just the assumption that weather variability is chaotic gurgling of the climate system, often leading to assumptions of a warming climate making the weather gurgle more furiously. A study of historic major heatwaves of the last 1000 years should make it clear that they have nothing to do with the state of the global climate.
I contend that major European heatwaves are completely impossible without their discrete solar forcing, as well as brief Saharan plumes under negative NAO conditions like in summer 2019, which is irrational to attribute to rising CO2 forcing (as Friederike Otto has done), as that is expected to increase positive NAO conditions.
This covers four out the five hottest UK summers in the last 50 years:
https://docs.google.com/document/d/e/2PACX-1vQemMt_PNwwBKNOS7GSP7gbWDmcDBJ80UJzkqDIQ75_Sctjn89VoM5MIYHQWHkpn88cMQXkKjXznM-u/pub
“<i> CO2 forcing in theory could intensify the heatwave</i>”
Cliff Mass reported on the heat in Washington State of June 2021.
Roughly speaking, he said the CO2 forcing was insignificant.
Yes probably nearer to 0.2°C than 2°C.
Wait just a dang burn minute. If climate change results in slight increase in average temperature due mostly to less cold winters and nights, then climate change should be effectively reducing cool temperature mortality. This must surely off-set any increase in heat related deaths. They certainly cannot argue that Climate change both increases hot temperatures and decreases cold temperatures. — Well they can I suppose, but they’d look like idiots.
Rick C ==> The authors looked to Zhao 2017 to show that under RCP8.5 the situation would reverse, with heat killing more than cold. Totally invalid, of course. With RCP8.5 widely considered impossible.
I can see CO2 having the most effect in hot dry conditions with low humidity in daytime. It doesn’t have the heat capacity to retain heat at night like water vapour does, so it would speed up cooling of the atmosphere at night, probably giving a warmer dusk but a colder dawn.
Ulric ==> CO2 does not have minute to minute, day to day effects.
That was day to night, not day to day. As the surface warms, greenhouse gases absorb and re-radiate more longwave infrared. That changes hour to hour. Less water vapour means relatively more absorption by CO2, like where their absorption bands overlap. Unlike CO2, water vapour absorbs significant amounts of solar shortwave, in the near infrared. So atmospheric water vapour lowers potential daytime surface temperatures while CO2 will raise them.
The study blamed urbanization for part of the increase in ambient temps. How much of that increase was caused by the UHI effect? If the increase in temps is 3 degrees and 5 degrees of that is caused by UHI, then the non-urban area is actually cooling.
DomK31 ==> When they point to urbanization, they mean the same thing: UHI
Kip: UHI has nothing to do with climate change.
DomK31 ==> Of course not — urbanization — always always — leads to UHI. Even in Roman times….
One might argue that with more people dying from extreme cold than from extreme heat, the optimal temperature is warmer than at present. That is, when the excess deaths are equal, then any change would be away from the optimal.
Clyde ==> The whole concept studied is a FAKE — they study ALL CAUSE DEATHS .
I’m 68 and I still smoke.
I’m under no illusion that smoking has had no adverse effect on my health.
But if I die by being being hit by a truck crossing the street, the rabid anti-smoking crowd … er … anti-tobacco crowd (Smoking pot is OK.) will claim I was crossing the street to buy a pack of cigarettes.
Planned brownouts, blackouts that cut off heat and AC because a Green-Dream grid can’t supply reliable energy to protect from the weather has nothing to do with these “climate” deaths. Nor does age. Without Man’s CO2, we’d all live forever!
Justice Kagan is as clueless as RCP8.5.
Astounding.
How many migrated to Antarctica in the period of the study to get away from the oppressive heat?
dont worry they are working on a vaccine