Above: NOAA Satellite IR image showing UHI of New York, Philadelphia, Baltimore, and Washington, DC
Above: A trend comparison slide from my tour, courtesy of my friend, former California State Climatologist Jim Goodridge.
Simon at ACM writes:
So reads the headline on the ABC website, as if it’s something we don’t know. Obviously, as cities increase in size, the Urban Heat Island (UHI) effect will also increase. However, the latest “research” bolts this on to the IPCC’s incorrectly exaggerated warming predictions, to give some even scarier scenarios:
Dr Richard Betts, a climate scientist at the UK’s Met Office, and colleagues, report their findings in the journal Geophysical Research Letters [although I cannot find the article there right now].
Betts and colleagues found not only do cities retain more heat than rural areas do but hot cities will grow even hotter as the climate warms and cities grow.
By mid-century, night-time temperatures in cities could rise by more than 5.6°C, they say.
At stake are the comfort and health of people who live in cities around the world, especially those who don’t have access to air-conditioning.
“If you’ve been exposed to hot temperatures during the day and you expect relief over night, that becomes increasingly difficult as temperatures at night get warmer,” says Betts. “We have to prepare to live in a warmer world.”
In a concrete jungle, roads and buildings absorb sunlight and trap heat, which also flows as waste out of cars, air-conditioning units and even just the breathing of millions of people crammed into a busy grid of streets.
As a result, cities create their own, warmer microclimates – a phenomenon called the urban heat island effect.
Unfortunately, this is another GIGO* case, where the results from the IPCC’s incomplete models, which vastly overstate the sensitivity of the climate, are plugged into further models of UHI effects (which may or may not be accurate). However, satellite temperatures are continuing to diverge from the IPCC’s predictions, which means that research based on them is the stuff of fairytales.
Read it here.
* Garbage in, garbage out
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How does this story reconcile with the temps in Vegas? Seems their model doesn’t work there. I wonder why?
Las Vegas Temperatures
Temperatures in Las Vegas
Month High F. (c) Low F. (c)
January 57 F. (13.8) 34 (1.11)
February 63 (17.2) 34 (1.11)
March 69 F. (20.5) 44 (6.6)
April 78 (25.5) 51 (10.5)
May 88 F. (31.1) 60 (15.5)
June 100 (37.7) 69 (20.5)
July 106 F. (41.1) 76 (24.4)
August 103 (39.4) 74 (23.3)
September 95 F. (35) 66 (18.8)
October 82 (27.7) 54 (12.2)
November 67 F. (19.4) 42 (5.5)
December 58 (14.4) 34 (1.11)
Michael said: How does this story reconcile with the temps in Vegas? Seems their model doesn’t work there. I wonder why?
Regardless of their accuracy, the models are modeling global climate not local weather. They can’t be applied to individual sites.
Hu McCulloch says:
June 26, 2010 at 7:25 am
If the climate establishment could bring itself to recognize the reality of the UHI, it could get busy fighting beastly hot urban summers with effective and inexpensive local recommendations, rather than crusading for ruinously expensive and probably ineffective CO2 controls.
———————————-
From papers I’ve read it’s clear that scientists do believe in the reality of UHI and works hard to correct the data for biases from the UHI effect. the UHI is just another example of how humans are changing the climate.
I’ve always suspected AGW was actually AUHIW. This article provides further evidence that those of us who think that way may be correct.
jeff brown says: June 26, 2010 at 11:42 am
” the UHI is just another example of how humans are changing the climate.”
Daniel says: June 26, 2010 at 11:28 am
“Regardless of their accuracy, the models are modeling global climate not local weather. They can’t be applied to individual sites”
So, which is it; a large number of local sites, or the global climate?
Boris Gimbarzevsky,
Interesting observation that people perceive generalized heating due to living in urban and growing urban areas and do not spend appreciable time in the countryside and thus fail to witness the differences in nightfall temperature drop between urban vs rural environment.
I live in a far different enviroment than Vancouver Canada; the American desert southwest and have been conducting UHI data collections. I live in a densly populated and thoroughly urbanized neighborhood; but it is only 7 or 8 minutes from an Indian reservation (Native American) boundary that is abruptly rural and has not been subject to sudden development.
My plan is to take a full year of data by taking a consistant route and at the same time – early evening. So far I am showing roughly 5 degrees F change between urban and rural and have been taking data since March. I don’t claim what I am doing is scientifically rigorous – it’s just fun and interesting to me.
Another thing I have noted from downloading temperature from local recording stations I can find “Global Warming” just by picking temperature stations showing rapid urbanization that I have witnessed since living here; while I can find other stations that I know have no such rapid growth and there is little or no “Global Warming” even if the station is not rated as being perfectly sited. Again, I am not making any kind of claim of certitude, completeness, or novelty – it’s just that it is amazingly easy to see UHI (for yourself) by directly measuring it from a moving vehicle or by looking at temperature trends from rapidly developing areas during the period of development.
Daniel says:
June 26, 2010 at 10:44 am
“Does the UHI affect the temperatures recorded by the satellites?”
No. It’s Urban Heat. Satellites can’t detect Urban Heat. They only detect Rural Heat.
My normal June afternoon at work, and I live through it every year.
http://farm5.static.flickr.com/4048/4706726429_883f766e38_b.jpg
Anthony,
Thanks for the laugh about the UHI “add on”.
Dramatic slide by Goodridge, but I think some of the context is over my head. For example, why do the horizontal scale and curves start at 1860 when the data seems to start around 1905? And has the story changed or continued the same since 1996? If you came to Tokyo, I’d be sure to come to your talk and ask the questions in person, but Australia is a bit far, even from here.
Cheers.
I’ve worked with data from some of the most rural and isolated weather stations in regions I’ve studied. Places that look great even in Anthony’s scrapbook. Yet they have been warming at the same rate as the cities. There also are non-thermometer indicators that show similar trends in these regions, ruling out UHI as an explanation.
Scientists who have done larger-scale analysis looking for UHI effects on anomaly trends from USHCN or GHCN station data have reached much the same conclusion, in published studies that I’ve seen. Since these weather-station trends also tend to agree with trends derived from satellites, buoys at sea, biological indicators and other sources, UHI again looks unsupported as an explanation for the observed warming trend.
Obviously, the UHI explanation has strong emotional appeal to many on this website. But this is a hypothesis that should be easy to test directly. Where are the data, and the analysis, showing that among stations and datasets contributing to GISTEMP, or HadCRU, the adjusted temperature-anomaly trends from urban stations are rising faster than those from stations way out in the country?
If someone found such results, and they stood up to scrutiny, that would definitely be publishable. Unless that happens, it’s the dog that didn’t bark.
[REPLY – I have; they will. I use USHCN raw, gridded data over the last 30 years and GISS classifications as to urban, suburban, and rural. I expected to find urban sites to warm faster from 1979 – 1998 and cool faster from 1998 – 2008. But instead I find urban sites just plain warm faster to 1998 and cool slower after that. And this is UHI, not microsite issues: urban microsites actually average slightly superior to suburban and rural. ~ Evan]
Andrew30 says:
June 26, 2010 at 12:32 pm
“So, which is it; a large number of local sites, or the global climate?”
From the field I work in (which isn’t climatology or meteorology), I know that if I have a large enough number of data points, I can get the overall picture. But that doesn’t mean I can use the overall picture to determine what’s happening at a particular point. I see meteorology as doing short-term predictions at local levels (‘local’ can be pretty big, of course), and climatology as doing long-term predictions at larger (sometimes global) levels. With quite a bit of overlap….
DirkH says:
June 26, 2010 at 12:41 pm
“No. It’s Urban Heat. Satellites can’t detect Urban Heat. They only detect Rural Heat.”
So if the UHI doesn’t affect satellite data, and the satellite data is accurate, that would seem to be the data to use. I guess the problem would be how far back we have satellite data. I think I’d use the satellite data (over land) and compare it to the land-based (or other non-satellite) measurements to determine the adjustments needed to the land-based readings to account for the UHI (or any other) effect.
Where do they get these people who think that this could possibly pass for real science. Sheesh, a 2 year old could dream this up.
Daddy daddy, why do greenhouses have roofs?
It’s the only way to keep the heat in … sigh.
Evan writes,
“[REPLY – I have; they will. I use USHCN raw, gridded data over the last 30 years and GISS classifications as to urban, suburban, and rural. I expected to find urban sites to warm faster from 1979 – 1998 and cool faster from 1998 – 2008. But instead I find urban sites just plain warm faster to 1998 and cool slower after that. And this is UHI, not microsite issues: urban microsites actually average slightly superior to suburban and rural. ~ Evan]”
I look forward to reading your paper. Why the split at 1998?
Why would we have to wait a 100yrs to find out if we are going to become extinct from rising UHI. If a city were to grow from a couple of million to ten million, then it would become like NYC – hey uhi is high but NYers aren’t going extinct. Doesn’t Mexico city have 40 million?! Anyway I have a survival strategy for those who may be alarmed. Wait for it! …. Leave town. Also, there is growing evidence that warming has stalled since the peak 12yrs ago (or 70yrs ago if you accept that the dustbowl 1930s was warmer still) and could be heading back down. NYC could become a warm island vacation spot.
The irony is that urban heat drives the use of AC which is what made necessary all those coal-fired power plants. That, and the desire of yankees to move to semi-tropical climates.
Highs have been running 95-100 the past two weeks in my neck of the woods. But, it’s 75 inside my house. The 1800 MW of nuclear power six miles away that I help produce means I’m not part of the imagined global warming problem!
Discovery news has also just discovered UHI.
http://news.discovery.com/earth/urban-cities-warming-heat.html
Has anyone actually calculated the cumulative UHI effect from all the cities across the globe? Taking into account the net global effect of all the concrete, asphalt, and general LW radiation emissions and heat sources in and around the thousands major cities?
[REPLY – It affects the temperature level beyond any real question. The real issue is any effect it has on the trend (sic). FWIW, In the last 30 years, USHCN raw data shows cities warming faster from 1979-1998 and cooling slower from 1998 – 2008. Suburban trends lie between urban and rural (GISS designations used). So at least for US cities there appears to be some effect on trend; at any rate, the data is consistent with that hypothesis. ~ Evan]
I often wonder if there is not a real AGW out there, which everyone – especially the alarmists – are ignoring.
Over the past 60 years, there has been an approximate rise of 500% in the amount of land under irrigation – see page 31 0f: http://www.iwmigiam.org/info/GMI-DOC/GIAM-world-book.pdf
In the year 2000, the global area under irrigation was ~4 million sq. kms (400 million hectares, or ~one billion acres), now it is probably ~5 million sq.kms.
Irrigated areas make up only a small part of the world’s surface area, but their local impact on humidity and therefore temperature should be significant. I can only guesstimate the amount of additional water vapour which is now being added annually to the atmosphere, but if you assume 1.5 metres (60 inches) of rainfall equivalent and one third of this is evaporated, then:
(500-80) * (1.5*0.33333) = an increase of 20 billion tonnes of water evaporation in a relatively small part of the Earth’s surface, which must have a significant and measurable upward impact on temperatures in and around the irrigated regions of our planet.
Then, of course, there is the changing albedo of the irrigated areas, compared with what was there before irrigation. Presumably, the surface of the irrigated areas is on average darker than previously and therefore is more heat absorbent, further adding to local temperature anomalies.
Gneiss says:
June 26, 2010 at 3:50 pm
“Where are the data, and the analysis, showing that among stations and datasets contributing to GISTEMP, or HadCRU, the adjusted temperature-anomaly trends from urban stations are rising faster than those from stations way out in the country?”
Here is one;
I look forward to reading your paper. Why the split at 1998?
I’m just a humble co-author. (But, yes, the split was made at my particular insistence.) The split at 1998 is very important because from 1979 – 1998 there is a distinct warming trend and from 1998 – 2008 there is a distinct cooling trend.
Also, regarding microsite issues, one would expect that if a badly sited station will warm faster during a warming phase, it will also cool faster during a cooling phase (as the effect “undoes” itself “on the way back down”).
It is therefore very important that both periods be considered in tandem.
Discovery news has also just discovered UHI.
Yeah, I love the spin.
Not, gosh, UHI is disproportionately affecting temperature readings. Maybe the warming trend has been exaggerated as a result.
But OMIGOD! AGW makes UHI worse! It’s positive feedback, man! We’re all gonna die!
“Daniel says:
June 26, 2010 at 3:52 pm
[…]
DirkH says:
June 26, 2010 at 12:41 pm
“No. It’s Urban Heat. Satellites can’t detect Urban Heat. They only detect Rural Heat.”
So if the UHI doesn’t affect satellite data, and the satellite data is accurate, that would seem to be the data to use. ”
Daniel, i hate to bring it to you, but after reading up on thermodynamics, i have to correct myself: Heat is heat, whether urban or rural, and no thermometer or satellite can find out the difference between urban and rural heat. Sorry for any confusion caused.
Evan Jones wrote,
“I’m just a humble co-author. (But, yes, the split was made at my particular insistence.) The split at 1998 is very important because from 1979 – 1998 there is a distinct warming trend and from 1998 – 2008 there is a distinct cooling trend.”
A good reviewer would take a close look at that choice. 98 was an El Nino year which stands out on the graph, and as an outlier affects the averages in its neighborhood. But is there a physical rationale for splitting the periods before and after, or a statistically significant shift in slope? Are your conclusions stable if you choose a different cut-point, say 1997 or 1999, or (better) the whole modern series? If not, they’re depending on one outlier, and reading “trends” from a very short time series.
Which leads to another question. Where do you see that distinct cooling trend? Looking at monthly GISTEMP anomalies, the 1978-1997 and 1998-2008 periods both have similar, statistically significant and positive slopes.
NCDC slope remains positive but drops slightly below significance (not surprising in such a short series) for 1998-2008, then becomes significantly positive again looking at 1998-present. HADCRU slope becomes nonsignificant after 1998, but is still weakly positive (and steepens if we look 2998-present instead of 1998-2008). Of course these are simple tests.
That should have been if we look 1998-present, not 2998-present.
Alexander K says:
June 26, 2010 at 6:42 am
To Al Gore’s Holy Hologram; sadly, Rickets and Tuberculosis, formerly associated with Victorian overcrowding and poverty, are on the rise again in UK cities…..
_____________________________________________________________________
The rickets problem in the EU at least can be laid at the door of the UN, WTO and Codex Alimentarius. The USA adds vitamin D to the milk sold in stores and made it available very cheaply to school children and the poor. When I went to school milk was $0.02 a carton and soda and candy was not available on school property like it is today.
Codex Alimentarius views vitamins as “hazardous” to your health and sets the maximum dosage allowed at far below what some consider the minimum required by the human body. There is a real controversy raging on the subject of Codex Alimentarius food, farming and vitamins that rivals that around AGW. I have not had a chance to disentangle the mess dealing with the Codex portion, but the food safety/farming issues are as bad and as corrupt as the AGW hoax.