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Urbanization affects thermometers

29 May 2019 | Science Notes

Common sense tells you that cities are hotter than the surrounding countryside because asphalt and cement absorb heat and machinery emits it, and as the city grows the warming effect grows too. Which is a problem in measuring global warming because most long temperature records come from places people live, aka cities. So part of the warming trend, perhaps even most, is from urbanisation not greenhouse gases. A new UK study adds a bit of important detail: so-called “urban heat islands” tend to raise the daily minimum but not the maximum, and the result has been to add about 1.5 degrees to the average temperature in UK cities since 1990. Wait, isn't that the amount that spells catastrophe?

For a long time, whenever people asked about the quality of the data on which the global warming panic is based, their questions would be waved away with the claim that the experts make "adjustments" to clean up the numbers and remove things like urbanisation bias. Curiously, the adjustments all seem to add warming, not take it away; an objection that itself gets waved away with increasing impatience. But the use of data from urban centers matters, because there are many places around the world where the historical record consists of nothing but data from big cities.

Now we learn that urbanisation has added 1.5 degrees of warming to UK cities, on average, just since 1990. No doubt it is also true elsewhere; the UK just happens to be where the study was done. Reassuringly, this change in temperature readings did not bring about the apocalypse, but you never know, maybe the next 1.5 degrees really will be the death of us all.

If so, it won't have been greenhouse gases, it will be the extra heat in cities. Made worse by the current insistence on "densification" in urban areas in the name of, you guessed it, fighting climate change. But if the aim of global climate policy is to prevent experiencing one or two degrees of warming, wouldn't it be easier just to tell people to get out into the countryside a bit more often?

Which brings to mind the point that today's hardcore green activists are a thoroughly urban crowd. They wouldn't dream of living anywhere that doesn't have a Starbucks on every corner and Uber on every street. They keep claiming global warming will make the whole planet uninhabitable, yet places we know are getting warmer keep attracting people.

One comment on “Urbanization affects thermometers”

  1. Excellent article. I have always thought that urbanization had a greater effect on global warming than that from an increase in CO2 levels. More studies need to be done to firm up a better understanding of the urbanization effects, particularly for the impact here in the USA.

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