The Oil Drum | Heat over the heartland

169 comments on Heat over the heartland

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RickD on August 2, 2006 - 10:59am

Question: How does the amount of asphalt in a city now vs 1920's affect temps?

I would think that it would be the temps in the city go up quite a bit...even if the countryside stays the same.

Maybe checking cities doesn't give the whole picture.

Thoughts?

Rick

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tate423 on August 2, 2006 - 11:13am

I don't know about most cities but here in STL, we have an entire grid of temps across the entire metro area. So I see the variations all over the city. Having said that, here in STL I know our "official" weather is taken at the airport, which is not even in the "city" of St. Louis. That airport I'm sure has a type of heat island effect, expecially with the new runway just openend and the density of the surrounding area (BOEING is on the other side).

I don't think the airport was there during the dust bowl days, but you'll have to take my word for it b/c I wasnt around. We also have a lot of weather instruments (radar etc) set up in the rural areas so I'm sure the readings are different there too. I think it's hard to be accurate on temps when so many other variables seem to shift the focus a bit each time until you're off course entirely.

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tate423 on August 2, 2006 - 12:16pm

All of you missed the point. I wasn't saying the HIE affects GW, but rather the readings on the ground. Prior to the inception of the airport I don't know where they got the official temps. Let's even go far and say they took readings in the same spot and decades later an airport gets built and when you look at the temps, they appear to be masked as higher b/c of HIE. My only point is that temps need to be consistent in their location to really be accurate.

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gettingwarm on August 2, 2006 - 11:14am

The Urban heat island effect is not related to GW. See Real Climate:

http://www.realclimate.org/index.php?p=44

Remember that the areas that are warming the most, as predicted by GW theory, are the poles. Temperatures up 3 to 5 degrees.

My brother lives in Anchorage, AK where the summer temperatures are much higher than even 20 years ago. And you can watch the snow pack dissapear from the Chugach Mountains.

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step back on August 2, 2006 - 2:37pm

Just to clarify further here, Global "Warming" does not mean it is getting hotter in your neighborhood.

The Global "Warming" phraseology is an unfortunate one that stuck before people realized it may send "wrong messages".

The increased trapping of solar energies by CO2 and other GHG's leads to Climate Change. Part of that Climate Change is the melting of the ice caps. Part of that Climate Change is the shift of annual rain patterns.

When rain fails to come to the MidWestern states, we have a dust bowl.

Yes it does make us pause and re-think the wisdom of the crowds regarding the biofuel strategy.

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Don Sailorman on August 2, 2006 - 11:17am

There is a Huge Fudge Factor (HFF) in estimating the heat island effect of growing cities when it comes to estimating the true amount of global warming.

The fact is, nobody is sure exactly how to do it--except for the ones who are surely doing it wrong.

Based on casual empiricism, my PSI (Personal Sweat Index) tells me that common estimates of the impact of urban heat islands is off by roughly a factor of two; in other words, spreading cities matter (I think but cannot prove) roughly twice as much as the most commonly quoted estimates.

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Wharf Rat on August 2, 2006 - 11:21am

The Surface Temperature Record and the Urban Heat Island
william @ 6:33 pm

There are quite a few reasons to believe that the surface temperature record - which shows a warming of approximately 0.6°-0.8°C over the last century (depending on precisely how the warming trend is defined) - is essentially uncontaminated by the effects of urban growth and the Urban Heat Island (UHI) effect. These include that the land, borehole and marine records substantially agree; and the fact that there is little difference between the long-term (1880 to 1998) rural (0.70°C/century) and full set of station temperature trends (actually less at 0.65°C/century). This and other information lead the IPCC to conclude that the UHI effect makes at most a contribution of 0.05°C to the warming observed over the past century. continues...
http://www.realclimate.org/index.php/archives/2004/12/the-surface-temperature-record-and-the-urban-h eat-island/

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DrPaul on August 2, 2006 - 4:24pm

Seems that using average data is part of the problem here. The temp on Aug 1 may be hotter than the temp on Aug 1 during the dust bowl. If we have an extremely cold winter, or another season is colder than normal, it may wash out the extremes we see.

How about a series of highest recorded temperatures for cities?

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porsena on August 2, 2006 - 7:22pm

Like SC (comment further below), I too have trouble with using annual average temperatures to talk about heat waves, though I've used them myself for other purposes. It's the extremes of heat (and cold) that kill people. Most of the deaths are among the ill and the elderly, just as it would be in nature.

For species less adaptible than ours, the extremes in temperature (and precipitation) are much more important than the annual averages in affecting the health and reproduction of natural populations. Plants and animals are affected, like us, by drought, blizzards, heat waves, etc. The effects tend to be most pronounced towards the edges of their geographic distributions.

I haven't run across a summary measure for heat waves, which is not to say there isn't one. However, I have looked at the annual highest temperature for 36 representative climate monitoring stations in British Columbia, where I live, for the period 1950-2001. Only about a third of the locations show evidence for any increase in the maximum temperature. The increase at those locations is about a degree Celsius in 50 years.

Reasonably complete data sets are pretty rare in my experience, especially when looking at locations with records back into the 19th century. The outcome of even simple analyses can be affected by how the missing data are treated. Temperature records have been kept in BC for about 150 years, but the analysis back to 1950 is probably the best that can be done with confidence.

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