Remember when I measured the UHI in Reno, NV? It seems the normally alarmist “Climate Central” is just now getting around to recognizing UHI, but of course, they have to put in the obligatory disclaimer that it cannot possibly contribute to the global warming signal. Well, they are just flat wrong about that, but that’s what they are paid to say.
New Study on Urban Heat Islands and Climate Change Shows Most Large U.S. Cities Getting Hotter Faster than Rural Areas
Since 1970, summer temperatures have been rising. While exact rates of warming differ between regions, most cities have been heating up faster than adjacent rural areas all across the United States. The concrete and asphalt surfaces in city buildings, roads, and infrastructure hold more heat and release that heat more slowly than vegetation and organic surfaces. This is known as the Urban Heat Island (UHI) effect. Climate change then takes that heat and makes cities even hotter.
In a new report, Climate Central analyzes how UHI and climate change have affected 60 of the biggest American cities since 1970. The study examines the difference between average summer temperatures in urban areas and nearby rural areas. Some cities had much higher temperature differences: 23 different cities experienced single days that were an astonishing 20°F warmer than the rural areas around them.
With more than 80% of Americans living in cities, these urban heat islands, combined with rising temperatures caused by increasing heat-trapping greenhouse gas emissions, can cause serious health effects for hundreds of millions of people during the hottest months of the year. Heat is the number one weather-related killer in the United States, and the hottest days, particularly days over 90°F, are associated with dangerous ozone pollution levels that can trigger asthma attacks, heart attacks and other serious health impacts.
The study ranks the 60 cities by the intensity of their heat island effect, shows how heat drives air pollution (ozone levels) in nearly every city analyzed, lists cities that have far more days over 90°F than adjacent rural areas, and shows how most cities are warming faster than the surrounding rural areas.
analysis of summer temperatures in 60 of the largest U.S. cities found that:
- 57 cities had measurable urban heat island effects over the past 10 years. Single-day urban temperatures in some metro areas were as much as 27°F higher than the surrounding rural areas, and on average across all 60 cities, the maximum single-day temperature difference was 17.5°F.
- Cities have many more searing hot days each year. Since 2004, 12 cities averaged at least 20 more days a year above 90°F than nearby rural areas. The 60 cities analyzed averaged at least 8 more days over 90°F each summer compared to adjacent rural areas.
- More heat can increase ozone air pollution. All 51 cities with adequate data showed a statistically significant correlation between higher daily summer temperatures and bad air quality (as measured by ground-level ozone concentrations). Temperatures are being forced higher by increasing urbanization and manmade global warming, which could undermine the hard-won improvements in air quality and public health made over the past few decades.
- In two thirds of the cities analyzed (41 of 60), urbanization and climate change appear to be combining to increase summer heat faster than climate change alone is raising regional temperatures. In three quarters (45 of 60) of cities examined, urbanized areas are warming faster than adjacent rural locations.
- The top 10 cities with the most intense summer urban heat islands (average daily urban-rural temperature differences) over the past 10 years are:
- Las Vegas (7.3°F)
- Albuquerque (5.9°F
- Denver (4.9°F)
- Portland (4.8°F)
- Louisville (4.8°F)
- Washington, D.C. (4.7°F)
- Kansas City (4.6°F)
- Columbus (4.4°F)
- Minneapolis (4.3°F)
- Seattle (4.1°F)
- On average across all 60 cities, urban summer temperatures were 2.4°F hotter than rural temperatures.
Urban heat islands are even more intense at night. Over the past 10 years, average summer overnight temperatures were more than 4°F hotter in cities than surrounding rural areas.
Urban heat measured by satellite in Louisville, Ky. Click image to enlarge.
Several independent studies have shown that urban heat islands (in the U.S., and around the world) do not bias global warming measurements, ruling out the possibility that rising global temperatures have been caused by urbanization alone.
Research suggests that urban planning and design that incorporates more trees and parks, white roofs, and alternative materials for urban infrastructure can help reduce the effects of urban heat islands.
But rising greenhouse gas emissions are projected to drive average U.S summer temperatures even higher in the coming decades, exacerbating urban heat islands and their associated health risks.
Source: http://www.climatecentral.org/news/urban-heat-islands-threaten-u.s.-health-17919
Unfortunately they fail to mention that in the winter the UHI makes the cities warmer which is a huge benefit.
I wish I had more UHI last winter when we were suffering with unbearable cold to the point where even with the furnace running constantly the house was too cold. $$$ in winter but less AC this summer so some balance in cost.
Warmer in the winter is much more preferred especially since there are more cold weather deaths than hot!!
Given the heat holding capacity of all infrastructure, be it of concrete, brick, steel, bitumen, wood, etc. etc. is many times that of air, and thus many many times that of the trace gas CO2 has anyone calculated the relative capacity of all global infrastructure existing today, including such things as the pyramids where the stone has been bought to the surface, as opposed to that of atmospheric CO2?
Lovin Spoonful
The graphic at the top of the post seems confusing. 17.0 Degrees …is that Fahrenheit or Celsius? Also -7 Days…what does the negative number mean?
You know, it occurs to me that only a myopic alarmist could claim that UHI does not contribute to global warming—when they claim that exact thing about CO2, when both achieve that effect by analogous mechanisms. The pavement/concrete absorbs solar radiation (both short- and long-wave, in the case of concrete and pavement), and then re-radiates it as long-wave radiation (ok, simplification, because depending upon albedo, parts of the ‘concrete jungle’ can reflect the short-wave). So does CO2. It is this exact effect of CO2 that is why the alarmists continue the hue and cry about it.
(Well, no, the real reason they continue the hue and cry about CO2 rather than the REAL culprit, H2O, is that, quite aside from the fact that H2O is also a heat sink (Latent Heat, of both Fusion and Vaporisation) and a convective conductor of heat (water vapor, in thermals inside thunderstorms, acts as an express elevator to carry heat from the surface to the top of the Troposphere where it deposits it when the vapor changes back into a liquid in order to precipitate out as rain), it can’t be as effectively regulated as processes which produce CO2, so there’s no money in it. Follow the money. It explains most of the entire sordid affair, But the “greenhouse gas effect” of CO2 is the ostensible reason for the hullabaloo)
If a trace gas like CO2 can bear such a huge burden of the warming for which man is supposedly responsible since the industrial revolution, then how much is mankind’s paving of the globe responsible for? To say none—as it appears the alarmists have been claiming—is disingenuous at best, obstinate stupidity more likely—denial, actually, in truth.
Now—unlike them with their claims about CO2, I have never heard anyone of the Skeptic camp claim that there is some very high percentage of confidence that some percentage of all the warming since 1950 can be blamed on UHIE, but I think it’s been proven beyond doubt—how odd to discussing this here of all places—that so much heat collected to re-radiate through the nights in locales where surface temperature monitoring is also located will, ipso facto, skew the surface temperatures thus recorded, distorting the measurement, and effectively disqualifying that data for use in determining the mean global surface temp, lest it make it look like the earth is warming a lot faster than it perhaps is…QED.
But again, if you look at it, for the alarmists to claim that CO2 plays a huge role in warming, and deny that UHI has any—not even the skewing of the data—is an incredible, fabulous double standard.
There have been some studies previously. One I remember was an SPPI Original study by Dr. Edward Long. His study considered raw temperature readings, one rural and one urban station in each state. As I recall the difference was about .7̊F warming for urban stations.
Also it seems to me the problem could be resolved if we just used the REAL rural stations for the climate change.
A good example in the USCRN are the two stations near Stillwater, OK, one close to the city, the other about 3 kilometers further out in the rural area. The station closer to the city consistently reads 1̊F warmer.
It should (I suspect) have been tilde that stands for “approximately.”
I just love this
“Climate change then takes that heat and makes cities even hotter.”
Jibberish!
The UHI in Las Vegas is 7.3 F. Let’s assume no UHI only greenhouse effect. Assume 2 C per doubling of CO2. We have to quadruple CO2 to 1,200 ppm to get 7.3 F warming. Funny we worry more about GHE than UHI. 7.3 F warming is catastrophic! The gamblers are too busy to notice.
cirby says: August 20, 2014 at 10:50 am “Any motorcyclist knows all about UHI from practical experience. Perfectly comfortable in the city, freezing to death ten miles outside of town.”
Yup. (cept I haven’t died from it yet…)
I measure temperature in my garden in two places, one next to the house and the other in a secluded shady part. I can get up to 10C difference at times. Guess which one is the higher?
The thermal band of Landsat provides insight on UHI. I have generated thermal maps of several large cities in the USA and Australia. The maps can be found at the URL below.
http://www.mascookin.com/Mas_Cookin/Urban_Heat/Urban_Heat.html
I believe in global warming, but I think it is only in the cities. I live between two metro areas that are consistently 2-6 degrees F warmer than here at the house. Seems like a no-brainer to me….
copernicus34 says:
this is why meteorologists (at a higher percentage anyway) don’t believe in this GW crap.
Unfortunately, the Farmers Almanac meteorologist has bought into it completely 🙁
“Can you guys comment on the BEST papers and how they claim that these UHI account for little if not none of the recorded warming? Its obvious to me that UHI is a real thing, but what impact does it really have on the average warming trend, (or is warming still shown even with the UHI)?”
1. The number of stations that are in large urban areas is small.
2. almost half of the stations are in zero population areas.
3. The high figures you see in this post are atypical. Google UHI in large cities for a study of SUHI in 419 global large cities.
4. UHI is real, but average UHI is small. That is most of the doomsday studies you see that claim
7F or 4F are for the worst days. cloudless, windfree days.
5. Noise levels are still too high to find the small UHI signal. you can see spikes.. but over the
long term the signal is just not strong enough nor consistent enough to make a substantial
difference.
Working on some better techniques to isolate the problem. In the end I may find something.
in previous work we found a small signal in the US.. and a couple different areas.. but nothing
globally consistent.
Steven Mosher says:
August 21, 2014 at 3:14 pm
“Can you guys comment on the BEST papers and how they claim that these UHI account for little if not none of the recorded warming? Its obvious to me that UHI is a real thing, but what impact does it really have on the average warming trend, (or is warming still shown even with the UHI)?”
1. The number of stations that are in large urban areas is small.
4. UHI is real, but average UHI is small. That is most of the doomsday studies you see that claim
+++++++++++
This does not jive very well with what I’ve seen. I am sure people can produce graphs which show otherwise. I’ve seen many. And “what is small???”
The actual delta temperature claimed to be caused by CO2 is small too… we’re talking about small numbers blown up to create histerical conclusions. If you only used urban stations, there would barely be global warming to the degree BEST shows. Sorry but this Mosher post is disturbing to me.
Steven Mosher (August 21, 2014 at 3:14 pm)
2. almost half of the stations are in zero population areas.
does this statement apply just to US stations
>1. The number of stations that are in large urban areas is small.
is it impossible for urban sites to be badly situated
Let’s take one line from this article and use it correctly.
“Urban heat islands are even more intense at night. Over the past 10 years, average summer overnight temperatures were more than 4°F hotter in cities than surrounding rural areas.”
++++++
Over the last 10 years, the overall official “global” temperatures, which include these hot urban stations, have cooled slightly. But average summer overnight temperatures were more than 4°F hotter in cities [urban areas].
Is this admission that ONLY urban areas have warmed in the past 10 years. As if we didn’t know that?