Follow up to Questions on Deaths from Extreme Cold and Extreme Heat

The post The Deadliest U.S. Natural Hazard: Extreme Cold has generated a number of questions. Mr.. Goklany has graciously supplied a followup which I have posted below. – Anthony

by Indur  Goklany

A few readers have raised a number of questions including what deaths are covered under the categories of “extreme cold” and “extreme heat” in my blog. The estimates I provided are only supposed to include deaths that are directly due to exposure to extreme cold or heat, that is, hypothermia and hyperthermia.  They do not include deaths that may be associated with cold or hot weather but are attributed to other primary causes, e.g., the flu, heart attacks (e.g., coronary thrombosis), strokes (e.g., cerebral thrombosis), accidents caused by ice, etc. Professor William Keatinge has a very readable piece here (see pp.47-52) that briefly discusses the different mechanisms by which heat or cold may kill directly and indirectly.

Had I had accounted for the deaths associated with hot and cold weather, the numbers would have been have been much higher (particularly for cold weather).  The UK Office of National Statistics (ONS) probably has the most easily accessible and up to date information on excess winter mortality. The following figure from the UKONS shows that there were 25,300 excess winter deaths in England and Wales from December 2007 to March 2008.

uk-excess-winter-deaths

Excess winter mortality (EWM) is calculated as “winter deaths occurring in December to March minus the average of non-winter deaths (April to July of the current year and August to November of the previous year).”  Honestly, UKONS could have been clearer about how precisely EWM was computed: Did they compute EWM using aggregate deaths over the 4-month winter period and subtracting from that aggregate deaths during the remaining 8-months of the year, or did they compute the difference between the average monthly difference in mortality for the 4-month winter period and the 8-month non-winter period and multiply by 4?  In any case, either way, more people die in winter than during other seasons]

UKONS notes that “the number of extra deaths occurring in winter varies depending on temperature and the level of disease in the population, as well as other factors.”

Considering that global temps were higher in 1998-1999 than in subsequent years, offhand I don’t see any correlation with global temps and EWM, nor should it be expected.  First, any correlation would be with local temps (no teleconnections).  Moreover trends would be confounded by changes (improvements mainly) in adaptive capacity, housing stock, insulating characteristics of clothing, greater income and affordability for energy, etc.

Having more deaths in winter is not just a UK phenomenon

Healy (2003) looked at excess winter deaths for EU-14 from 1988-97. His results, summarized in the table below, show:

.

  • Portugal has the highest seasonal variation in mortality in Europe, with a winter increase of some 28% above the average mortality rate, equivalent to 8,800 premature winter deaths each year.
  • Ireland has an increase of some 21%, or 2,000 excess winter deaths annually.
  • Spain: 21%, 19,000 excess annual deaths.
  • The UK: 18%, or 37,000 annual excess winter deaths.
  • Greece: 18%, or 5,700 premature winter deaths annually.
  • Italy: 16%, or 27,000 excess deaths.

healy-2003-excess-winter-deaths

Healy’s results indicate that:

  • Mean winter environmental temperature and mean winter precipitation are positively associated with levels of relative excess winter mortality in Europe. “A highly significant regression coefficient of 0.27 is found (p<0.001) with regard to environmental temperature.”
  • Overall level of relative humidity is also positively associated with excess mortality across Europe:a significant regression coefficient of 0.23 (p=0.02) is reported. The relationships between mean winter rainfall and excess deaths is also found to be significant (a regression coefficient of 0.54, p<0.001).
  • There is a “paradox of excess winter mortality”, namely, “higher mortality rates are generally found in less severe, milder winter climates where, all else equal, there should be less potential for cold strain and cold related mortality. This result indicates that the typical, inverse relation normally found between cold exposure and rates of (all year) mortality does not hold for excess winter mortality”, perhaps due to differences in housing standards, noting that “countries with comparatively warm all year climates tend to have poor domestic thermal efficiency. Because of this, these countries find it hardest to keep their homes warm when winter arrives. This is especially the case in Portugal, Spain, and Ireland, where winter temperatures are comparatively mild and excess mortality rates in winter are very high. Conversely, countries with severe climates-such as those in Scandinavia-have to maintain high levels of thermal efficiency, as temperatures demand that houses must retain warmth.” I would also speculate that physiological acclimation, and differences in wealth during the 1988-97 period may also have played a role.

What fraction of the problem is due to influenza?

Donaldson and Keatinge (2002), estimate this to be around 2-3% based on a daily record of deaths in southeast England from 1970 to 1999 for all causes and for influenza. However, others believe it could be higher, perhaps 19% [see Fleming et al. (2002), and Donaldson/Keatinge reply).  Whatever the number is, it’s going to fluctuate wildly from year to year and depend on, among other things, the accuracy of official forecasts about which strain each year’s flu vaccine should primarily guard against.

References:

Donaldson, GC; Keatinge, WR. 2002. Excess winter mortality: influenza or cold stress? Observational study. British Medical Journal. January 12; 324(7329): 89-90.

Healy, JD. 2003. Excess winter mortality in Europe: a cross country analysis identifying key risk factors. Journal of Epidemiology and Community Health 57:784-789

Fleming, DM et al. and Donaldson, GC; Keatinge, WR  2002. Excess winter mortality: Method of calculating mortality attributed to influenza is disputed. British Medical Journal. June 1; 324(7349): 1337.

About these ads

21 thoughts on “Follow up to Questions on Deaths from Extreme Cold and Extreme Heat

  1. One of the “other factors” in the UK could be the way money is handed out to pensioners to supplement their heating bills if there is a cold snap.
    They are entitled to cold weather fuel payments if the temperature drops below 0C (or is forecast to do so) for a continuous period of seven days.

    Due to the sprialling energy costs this year it must have crippled many pensioner’s budgets and put them in a situation of having to forego or limit the time the heating is on. I don’t think I would survive too well in a house that is close to freezing for a period of seven days.

    Woe betide them if it drops down below 0C for six days, lifts above for one and then drops again.

  2. This is fascinating-and verifies some things I’v e held.BTW I prefer a Cold climate myself-being a Downhill skier since eight years…

  3. I would also like to include this list of percent of all deaths by month in Canada for 2006. You can get a time series off of Statistics Canada website as well. I’ve ordered them from highest to lowest.

    Month of death 2006
    Month of death, December 9.0
    Month of death, March 8.9
    Month of death, January 8.8
    Month of death, October 8.6
    Month of death, November 8.4
    Month of death, May 8.4
    Month of death, April 8.2
    Month of death, February 8.1
    Month of death, August 8.0
    Month of death, September 7.9
    Month of death, July 7.9
    Month of death, June 7.8

    I don’t know if there is a good trend there, but it looks like to me that warm months are at the bottom. I believe February is below April and May only due to the number of days.

  4. Indur, thanks for the analyses! At the other “extreme”, it appears that the ipcc “scientists” rely upon non-scientific thinking which is specifically directed toward goals other than those of real science and meant to influence those who think pre-scientifically. In other words, the ipcc “science” is no more than propaganda.

  5. This was an excellent followup to the original cold vs. warm fatalities post. Thank you very much.

    The extra depth of the analysis raises additional questions, one of which would be; how does one account for the differences between countries with aging populations (higher national average age, such as the U.S. with its large number of baby boomers) and countries with high birthrates and a lower national average age? Is it a wash? Extreme temperatures affect the young and old the most.

    I think I’ll take a look at that EU chart and and see if I can find anything on the average or median national ages of those countries.

  6. There is a “paradox of excess winter mortality”, namely, “higher mortality rates are generally found in less severe, milder winter climates where, all else equal, there should be less potential for cold strain and cold related mortal

    There is also the general lack of preparedness and skill at dealing with cold in warm climates. For example, the first rain of the season in California results in a higher accident rate than in other more, um, ‘experienced’, climes.

    The roads have a lot of built up oils that make a nice slippery emulsion (not present in places like well washed Florida, in my experience). Lord help you at first snow… It’s like bumper cars on an inch of snow in areas that are not used to it. And forget black ice. They don’t even know what it is or why to look for it, or where (except for the ski crowd headed up I80 who get nagged at frequent intervals by road signs to remind them…)

    I have been substantially unable to get my family to regularly pack a coat & emergency kit in the car. Even when headed through a mountain pass that might block with snow. (The Grapevine is where I5 climbs over the mountains between L.A. and the central valley. It can snow closed, as it recently has. Many folks driving that pass take NO cold weather precautions, since they originate and end in relative warm spaces about 1 hour apart, and have never been stuck in the snow – yet…)

    My Dad, from Iowa, was ALWAYS prepared for cold, snow, freezing, mud,… He grew up in it.

  7. In the UK the highest death toll amongst vulnerable people (Elderly, poor etc) was always most prevalent during the winter months, and tended to peak December / March. In general terms 23% up on the rest of the year. All death causes appear to be exacerbated during this period, especially around Christmas and new year.

    So yes, too much cold is worse for you than too much heat.
    Stats here: http://www.erpho.org.uk/Download/Public/13356/1/Briefing%208%20winter%20deaths%20final.pdf

    We’re expecting another 6 inches of ‘Global Warming’ tonight with more to come over the next three days. Most unseasonable for our part of Vancouver Island so I’m told.

  8. In the previous thread, Tom in warm and apparently deadly Florida (04:49:36) observed that:”Having moved from New England to the ‘deadliest’ part of the US, I will say that I would rather take my chances here while being warm most of the year rather than spending half the year in the cold waiting for the summer.”

    And, in fact, some research supports Tom in Florida.

    Specifically, Deschenes and Moretti (2007) estimate that 8%-15% of the total gains in life expectancy experienced by the U.S. population over the past 30 years may be because of ongoing migration from the cold Northeastern states to the warmer Southern states. They also estimate that every year 5,400 deaths are delayed by changes in exposure to cold temperature induced by migration, and that older people benefit more than younger ones from such migration.

    Here’s a longer life to Tom. Happy Holidays!!

    Reference: Deschenes, Olivier and Moretti, Enrico, “Extreme Weather Events, Mortality and Migration” (2007). NBER Working Paper No. W13227. Available at SSRN: http://papers.ssrn.com/sol3/papers.cfm?abstract_id=998010.

    PS: I hope the above is not gibberish, because I’ve forgotten what little I knew of HTML.

  9. Indur, here’s some ironic anecdotal evidence:

    My grandfather, in upstate NY, died at the age of 93.
    From a stroke? Nope. From cancer? (he smoked cigars). Nope.

    He was shoveling global warming from his sidewalk. Heart attack? Nope.
    His neighbor backed out of his driveway, didn’t see him due to the snowbanks, and hit him.

  10. The UK, in the effort to reduce the excess winter mortality, pays everyone over 60 £250 tax free. Of course this means lots who do not really need it get it. Because the top rate of tax is 40%, in fact its effectively a payment of far more than £250 to the better off. Everyone over 80 gets a higher payment.

    Then there is an additional payment for people on some kinds of benefits if the temperature falls below freezing for seven consecutive days. This one does not come to everyone, only those on state benefits.

    Not sure when the Winter Fuel Payment started – could have been at the point in the chart which shows the sharp fall in excess mortality. It came in with the Labour government. It was generally reported in the past that hypothermia was a serious public health problem among the elderly, and there used to be lots of government messages about how to tell if your friend or relative is getting hypothermic, and what to do about it. They are not so noticeable now.

    The UK excess winter mortality is basically a house heating problem. If English houses were better insulated and less drafty, or if people had more money to heat them, it would vanish totally.

  11. Thank you, Indur, for the follow-up and graph. Warmer is so much better every way you look at it and it’s just amazing that the AGW faithful are against it.

  12. Thanks for the return to reality. That cartoon clip of the animal suicides due to global warming was quite a departure.

    I’d like to update and repost a note from a previous thread; its content may be more suited to this one.

    The lake where I walk every day after dropping my daughter for school was flash-frozen last week by 100-year record, -18 F. temperatures. The lake surface is a perfectly white plane of hoarfrost, except for the network of coyote and fox trails, each leading to and from dark blobs scattered across the surface. I counted three of these this morning. Out on the ice, up close to the dark blobs, I could see the frozen vertebra sticking up through, the bones stripped clean, and the trampled ring of feathers, light and gray as ash, of the Canada geese, their carcasses frozen in place where they died.

    There are more than 200 birds flocking in this lake, and winters, they usually huddle together at the east end, their bodies keeping the water open. Inexorably, it closes up. The manner of their deaths, no doubt awful, must take place slowly as their reservoir of energy is depleted. I had noticed some of the birds beginning to have trouble over a period of days as the temperatures dropped. As the lake was losing its surface heat in a blanket of rising steam, one goose stayed near shore, its head drawn down, and it became increasingly lethargic as others kept moving away to open water.

    It was still alive the next day, the water around it growing more visicid and slushy. It finally had difficulty lifting its head in response to the honks and movements of the other geeese. I think it was the third day when I saw its feathers, and those of other geese on the ice with the tracks of the predators leading to and from the site.

    Whatever natural reality that video may have captured, it seems silly to see any animal emulating human suicidal actions. The attempt at anthromorphism – to what end? – I would normally pass off as propagandistic crap which offers no insight whatsoever into the natural world or animal behavior, but as I said before, who knows? Maybe those geese consciously acknowledge that there was no way out, perhaps even watched the circling coyotes closing in.

    The Denver Post ran a story of a grim annual ceremony in which the city Mayor (one of whose talking points was ending the homeless problems of Denver) memorializes the anonymous homeless who have died by reading their names.

    This year, 164 names were called out, the most in the memorial’s 22 years. The annual ceremony is organized by the Colorado Coalition of the Homeless.

    “This weather (during the reading) is certainly fitting,” Hickenlooper said. “It’s cold. It’s damp. It’s heartless.”

    Jon Whitehawk, who said he is homeless, agreed. His friend, Jerry Rosendale, hung himself in a public garage near East Colfax Avenue and Tamarac Street last February.

    http://www.denverpost.com/news/ci_11265817

  13. TWC says that it’s snowed for 41 hours straight now at Logan airport.

    I heard one report that said the snow in Las Vegas was the first in a long time, then another that said since records started in 1936? So do we know if the snow in Las Vegas was the first ever recorded?

  14. E.M.Smith (04:37:24) :

    TWC says that it’s snowed for 41 hours straight now at Logan airport.

    I heard one report that said the snow in Las Vegas was the first in a long time, then another that said since records started in 1936? So do we know if the snow in Las Vegas was the first ever recorded?

    It snowed all day here in New Hampshire Saturday (I picked up my daughter at Logan Friday just after the snow started and had a miserable drive home. Too many cars, too few snow tires. Why do I bother?) Our “post-storm” snow was remarkably insubstantial, the 3.5″ over night had a fluff factor of 50X, about 5X fluffier than normal snow. Logan’s snow may have been ocean effect. All rather odd, but not terribly important.

    Today’s nor’easter will be a foot of denser snow, changing to rain at Logan.

    This AM I had 12″ snow on the ground, last year (which broke several records) I had 25″.

    The Las Vegas snow is not unique. http://icecap.us/ says “Heavy snow in Las Vegas occurs about once every 25-30 years – according to National Weather Service records, the most snowfall recorded in the Las Vegas Valley was 16.7 inches in January 1949, followed by January 1974 with 13.4 inches and January 1979 with 9.9 inches. A cold Pacific is usually the prerequisite for snow there, something clearly the case this year.”

  15. Our thanks to Mr. Goklany for his report on cross-sectional study on winter deaths. I wonder if there is a longitudinal study that associates deaths in a particular locality or climate with the winter severity over a number of years.

  16. At least, when it comes down to it, one media source isn’t afraid to tell the truth. Cbs2Chicago.com retails the cold hitting the Windy City and has this to say, courtesy of the National Weather Service no less:

    “But the worst danger was from the cold — exacerbated by 20-to-30 mile-per-hour winds that drove wind chills to 25 degrees below zero, or even lower, according to the National Weather Service. The mercury fell to minus-4 degrees Sunday night.”

Comments are closed.