Heat waves becoming more prominent in urban areas, research reveals
For past four decades, global warming has been amplified in cities, warns UCLA geographer
The frequency of heat waves has increased dramatically over the past 40 years, and the trend appears to be growing faster in urban areas than in less-populated areas around the world, a new study suggests.
“Our findings suggest that urban areas are experiencing a kind of double whammy — a combination of general climatic warming combined with the heat island effect, wherein human activities and the built environment trap heat, preventing cities from cooling down as fast as rural areas,” said Dennis Lettenmaier, a co-author of the study and a UCLA geography professor. “Everything’s warming up, but the effect is amplified in urban areas.”
Lettenmaier and his co-authors studied 217 urban areas across the globe and found that prolonged periods of extreme heat increased significantly in 48 percent of them between 1973 and 2012.
The results, which were published today in the journal Environmental Research Letters, show that about only 2 percent of those urban areas experienced a significant decline in heat waves. And the change was more dramatic at night: Almost two-thirds of the urban areas showed significant increases in the frequency of extremely hot nights.
“The fact that the trend was so much stronger at night underscores the role of the heat island effect in urban areas,” Lettenmaier said. “You have heat being stored in buildings and in asphalt, concrete and other building materials, and they don’t cool down as quickly as they would outside of the urban area. This effect was likely exacerbated by decreasing wind in most of the urban areas.”
The study is one of the first to focus solely on the extent of extreme weather in urban areas globally and to examine disparities between densely populated and less-densely populated areas.
Lettenmaier collaborated with researchers at the Indian Institute of Technology Gandhinagar, Northeastern University and the University of Washington. The team obtained daily observations for rain, air temperature and wind speed from the National Oceanic and Atmospheric Administration. The researchers identified about 650 urban areas with populations greater than 250,000 and then refined the list to the 217 locales based on the areas’ proximity to weather stations with complete weather records and NOAA data — most were located at airports close to urban areas. Although the researchers would have liked to have more data for urban areas in Africa, Lettenmaier said the report provides as close as possible to a representative sample of changing weather conditions in the world’s cities.
For each of the locales in the study, the researchers identified extremes for temperature, precipitation and wind, calculated heat and cold waves, and pinpointed individual extremely hot days and nights.
The study defined heat waves as periods in which the daily maximum temperature was hotter than 99 percent of days for the four-decade period and in which those temperatures were sustained for a consecutive period of six or more days. (The median length of heat waves was eight days.) It found that the average number of heat waves per year increased by over 50 percent during the period.
Of the five years with the largest number of heat waves, four were the most recent years for which data was available: 2009, 2010, 2011 and 2012. Urban areas in South America experienced the greatest increase in frequency of heat waves, followed in order by those in Africa, Europe, India and North America.
Researchers also found other striking examples of climate change within urban settings. Sixty percent experienced a significant decline in extreme windy days, 17 percent experienced a significant increase in daily precipitation extremes, and 10 percent experienced a significant increase in maximum annual precipitation.
“Urban areas make up a relatively small part of the global land area, but over half the world’s populations now live in them, so the trend is troublesome,” said lead author Vimal Mishra, an assistant professor of civil engineering at IIT Gandhinagar. “The combination of higher temperatures and lower wind in particular is not a good combination for human health and well-being. This should concern everyone.”
The increase in precipitation could damage cities’ infrastructure, which could also mean large economic losses, Mishra said.
Using a separate data set of 142 pairs of urban and non-urban areas, the researchers found that the frequency of heat waves grew 56 percent more quickly in urban settings than in surrounding areas that were less populated. Urban areas experienced 60 percent fewer extremely windy days than non-urban areas.
“In urban areas, buildings are disrupting the air flow, which affects not only the immediate area of buildings, but apparently the larger regional wind fields,” Lettenmaier said. “The reduction in wind may well be exacerbating the heat island effect.”
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Millions?
Even more CO2 lingering…. 🙂
Oh my Good Lord……….What if it’s gazillions???
It’s worse than we thought….
Another dumb study. How much were these Muppets paid?
Concrete and Tarmac absorb more heat than trees and grass, what a surprise!
Does anyone not think having lots of plants, trees and grass in urban areas is a good idea? I thought not. So we’re all agreed we don’t need to spend loads of money on academics to tell us lies about Global Warming and the bl00dy obvious about how to make cities nicer places to live in. Much easier paying some gardeners instead!
Duh?
Most weather stations are urban or airport. Dennis Lettenmaier manages to stay within the AGW script, when he should be pointing out that the global temperature measurements are “too high” because of UHI. I don’t think that’s honest.
As they say in the Real Estate business — Location, Location, Location
1) Boston has had a daily temperature record since March 1872 with sporadic data before
such as by Paul Bradley, Chief Justice of Massachusetts — records from 1738-50 in Boston; John Winthrop, Harvard College Professor, covering 1742-78 — in Cambridge
2) From 1870 until 1929 the temperature was recorded a few meters above sea level, and about 1 km NW of the edge of Boston Harbor:
a) initially @ur momisugly the Old State House on the corner of State and Devonshire Sts.
b) Tuesday, November 1, 1870 — “Time of observation, 8 AM; ‘height’ of barometer, 29.72 inches; ‘height of attached thermometer, 52F; reduced barometer (sea level), 29.655 inches; temperature (outdoor), 44�; temperature of the wet bulb, 38�; direction of wind, west; velocity of wind, 3 mph; pressure of wind (1 lbs. per square foot), .044; amount of cloud, 1/4.” — the first official Weather Bureau observation taken in Boston
3) Jan. 10, 1871 — The Boston Weather Bureau office was moved to “103 Court Street, Room No.10”
a) Aug.12, 1875 the Equitable Bldg., corner Milk and Devonshire Sts., “Room No.65,
4) October 1, 1884, the Office was relocated to the Boston Post Office and Subtreasury Building and Courthouse on the block of Milk, Congress, Pearl and Water Streets, where it was to remain for 45 years until 1929
4a) From June 7, 1929 to Sept.29, 1933 Young’s Hotel served as interim quarters
5) October 15, 1926 — The station at Logan Airport established at U.S. Army Hangar No.1 until
b) April 1, 1927 temporarily located on the 8th floor of the Army Base in South Boston for 7 months
c) Nov. 1, 1927, until July 1, 1929, Army “shacks” housed the airport station
6) Jan. 1, 1936 — Official synoptic and climatic observations for Boston were shifted to the Airport Station
a) Nov.22, 1951 relocated to the Toutwell Building (Gate No.11)
b) December 5, 1963 moved to the General Aviation Administration Building on Maverick Street
c) July 1987 moved to the three story Massachusetts Technology Center on Harborside Drive — still there today
However while the station has recorded its data at Logan for nearly 80 years — the short gravel strip surrounded by grass and a lot of water has given way to 2,384 acres (965 ha) with six runways and acres of parking and buildings. Meanwhile the location within the airport has moved from the center to one edge of the harbor
http://www.erh.noaa.gov/box/NWShistory.html
so which location is the the one for you Boston?
waiiiiiit. So they’re trying to claim that the Urban Heat Island that they’ve spent thirty years claiming DOESN’T exist is actually a symptom of global warming and not a mass of heat generating appliances, structures and materials?
Correct me if I am wrong but there are far fewer reporting temperature stations now than there were 30 years ago and from what I saw most of the ones no longer in service where in rural sites. Most of what is left is heavy towards being sited on airports or other urban areas so I have two questions.
One, I wonder if the data correction algorithms are now removing or adjusting the cool stations instead of removing UHI. Two, is enough being subtracted for UHI as things get more congested around the temperature sensors?
You have to wonder when the last time was they actually went through their computers and audited what they are really doing. Changes get made and things sometimes do not get removed.
A big part of me wonders what the real temperatures have been doing. Are we going to be blindsided by something the governments know that we do not.
I no longer know what is really going on other than someone wants the money in my wallet without giving me something in return.
It’s worse than we thought!
But Einstein predicted it.
“proximity to weather stations with complete weather records and NOAA data — most were located at airports close to urban areas.”
As soon as I read that, I quit wasting my time. WX records from airports and NOAA? NOAA? Surely this was written for the Onion.
On the plus side, UHI effect in large northern cities just might keep large ice sheets from getting a foothold over vast areas of the continent.
Suggest we begin constructing domes over the most substantial UHI as formerly used at Amundsen–Scott South Pole Station
then when the ice comes back — we’ll have a chance to save some of the world’s major cities
Go stand next to the ‘out-door’ unit of an AC system on a hot day and describe how it feels….then multiply the effect by the hundreds of thousands of such units in every city.
Mods – as I have retired from flying and no longer stay completely up to date with aviation technology, I wish to use my real name from now on. It’s Tom Crozier. I live in Ventura, California and Granada, Nicaragua. -bonanzapilot
Pierre: It’s all about your wallet. Here in California the government bureaucrats are panicking because Gas Tax revenues are falling off due to the adoption of hybrid and all electric vehicles and increased telecommuting. Even the State subsidies to Teslas are probably going to be withdrawn. The “green” movement appears to be falling under the weight of its own success.
Am I missing something here? This makes absolutely no sense. Local UHI effects affect…what???
Local UHI affects (1) local temperature, obviously, (2) local temperature trends because urbs grow therefore UHI grows, (3) regional temperatures and trends because they consist of local t&ts, (4) regional temperatures because of infilling, (5) regional temperatures because of UHI component of adjustments/homogenisations, (6) global temperatures and temperature trends because of all the above.
They affect the local temperature sensors. Which are then used to adjust the data from all the nearby rural stations.
Oh my. Another paper discussing the obvious.
Many cars have external temp sensors. (They are used to adjust fuel/air stoichiometry by computerized engine controls for max efficiency and min pollution, not your amusement.) For those that feed into driver displays, anyone can examine UHI under any weather conditions just by driving urban transects. The data is good to about 1 degree (engines are not that sensitive to climate change). A winter evening in Phoenix was used in essay When Data Isnt in ebook Blowing Smoke. Even shows TOBS. The later evening return was cooler. duh! Total delta UHI about 6 F.
Did not have the wind comditions since cars make their own; obviously not the major deal.
Improperly homogenizing UHI is the biggest failing in the land data sets. Explained in the essay.
Good troll repellant. Thanks Anthony; needed a night off.
Bubba, they’re all still tucked up warm in bed under a warm bridge next to a warm road.
And in case you wondered why the bridge above bore signage reading “roadway on bridge freezes first” it’s because; oh wait, I don’t need to explain it to you, you aren’t the author of this article.
Since when does heating observed in urban areas translate to global warming. We all know about UHI – but that is, by definition, local.
As per my earlier comment (January 29, 8:51pm) : Local UHI affects (1) local temperature, obviously, (2) local temperature trends because urbs grow therefore UHI grows, (3) regional temperatures and trends because they consist of local temps&trends, (4) regional temperatures because of infilling, (5) regional temperatures because of UHI component of adjustments/homogenisations, (6) global temperatures and temperature trends because of all the above.
Every station is used to calculate the global average.
If UHI is causing some of those stations to read too hot, then that will cause the average to read too hot.
And that’s before we get to the “homogenization” algorithms that adjust rural stations to better match the urban ones.
THE STUPID HURTS SO BAD😱😱😱
UHI – WHICH PART OF THAT DIDN”T THEY GET??
AS for “blocking the wind”, have they never been in a large downtown with high rises? The wind increases speed and tends to howl a lot. It also increase the skin heat transfer coefficient to increase building heat losses.
Do they not know bldgs have “unoccupied setback set points” that activate the interior perimeter heating systems to offset those skin losses?
And morning warm-up sequences to also bring the bldg back to a “occupied” set point?
Many bldgs have leaky envelopes the exacerbate the issues.
Watch the nightwalk videos on http://www.betterbricks.com.
Yes, that is me in the videos.
I forgot to add all those high rise buildings that turn their HVAC systems on 24/7 when it gets cold out to compensate for envelope failures, due to a lack of maintenance.
Just sit right back
And you’ll hear a tale
A tale of a fateful trip,
Started by the misanthropic lot,
Aboard this tiny ship.
The mate was a flighty flailin’ lad,
The Skipper a knave for sure,
Five passengers set sail that day,
For an eco-detour,
An eco-detour.
The climate started getting warm,
The tiny ship was tossed.
Due to the miscarriage of the feckless crew
The Akademik Shokalsky would be lost.
The Akademik Shokalsky would be lost.
The ship set ground on the shore
Of this uncharted UHI
With Michael Mann,
The Skipper too.
algore the millionaire
but not his wife,
DiCaprio the movie star,
Professor Lettenmaier and HotWhopper Sou,
Here on Urban Heat Isle.
So this is the tale of our castaways,
They’re here for a long long time.
They’ll have to make the best of things,
It’s an urban clime.
The first mate and his Skipper too
Will do their very best,
To make the others mis’erble
In their UH-island mess.
No phone, no lights, no motor car,
Not a single luxury
The warmunists all want it
As primitive as can be.
So join us here on WUWT my friends,
You’re sure to get a smile,
From all the climate refugees
Here on UH-Isle!
Hilarious. 🙂
I’ve read it all. A study devoted almost solely to UHI ignores … UHI.
To study increasing heat waves in cities is to ignore UHI.
That is of course logical.
If there has been a change in maximal temperatures it might be a good sign. Global dimming due to aresols is been a Kinese problem nowdays. It has not always been that way.
Global brigthening is a new sign thanks to sulfur diminishing. Clean air act?
“17 percent experienced a significant increase in daily precipitation extremes, and 10 percent experienced a significant increase in maximum annual precipitation.” So would it be fair to say insignificant rainfall differences?
A less than cretinous person would have come to a different conclusion. The logical one is that temperature measurements in a city are useless for taking with reference to climate as they are dominated by infrastructure.
As for the clean air acts this was quantified by engineers who did the original measurement for the now climate scientists as producing a one degree step function over five years given the imperfections of the Stevenson screen for sub degree measurements in clean air. This was back in the late sixties.
and doesn’t the wildlife love it.
Park life: the wildlife of Britain’s cities | Urban wildlife …
http://www.theguardian.com › Environment › Wildlife
18 May 2012 – Far from destroying the British love of nature, our cities have become urban oases for wildlife, says naturalist Stephen Moss.
http://static.skepticalscience.com/pics/hadcrut-bias3.png
Looking at the above graph, why would it be that land surface measurements have heated at well more than twice the rate (~0.8 C versus ~0.3 C) of sea surface temperatures since 1980 (and 1940)?
—–
http://onlinelibrary.wiley.com/doi/10.1029/2007JD008465/abstract
[E]xtraneous (nonclimatic) signals contaminate gridded climate data. The patterns of contamination are detectable in both rich and poor countries and are relatively stronger in countries where real income is growing. We apply a battery of model specification tests to rule out spurious correlations and endogeneity bias. We conclude that the data contamination likely leads to an overstatement of actual trends over land. Using the regression model to filter the extraneous, nonclimatic effects reduces the estimated 1980–2002 global average temperature trend over land by about half.
—–
http://onlinelibrary.wiley.com/doi/10.1002/joc.971/abstract
During winter (December 2001–March 2002), the urban area averaged 2.2 °C warmer than the hinterland. The population has grown from about 300 residents in 1900 to more than 4600 in 2000. In recent decades, a general increase of mean annual and mean winter air temperature has been recorded near the centre of the village, and a concurrent trend of progressively earlier snowmelt in the village has been documented. Satellite observations and data from a nearby climate observatory indicate a corresponding but much weaker snowmelt trend in the surrounding regions of relatively undisturbed tundra.
—–
http://link.springer.com/article/10.1007%2Fs00704-013-0894-0
Daily minimum temperature (Tmin) and maximum temperature (Tmax) data of Huairou station in Beijing from 1960 to 2008 are examined and adjusted for inhomogeneities by applying the data of two nearby reference stations. Urban effects on the linear trends of the original and adjusted temperature series are estimated and compared. Results show that relocations of station cause obvious discontinuities in the data series, and one of the discontinuities for Tmin are highly significant when the station was moved from downtown to suburb in 1996. The daily Tmin and Tmax data are adjusted for the inhomogeneities. The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization
—–
http://www.sciencedirect.com/science/article/pii/S1352231099001314
[I]n the climate of Poland the occurrence of the UHI is the most important feature of urbanized areas. Over 80% of nights are characterized by surplus heat in towns, amounting to 2–4°C, and sporadically to 8°C and more.
—–
http://www.sciencedirect.com/science/article/pii/S0034425709003174
On a yearly average, urban areas are substantially warmer than the non-urban fringe by 2.9 °C
—–
http://www.tandfonline.com/doi/abs/10.1080/01431169208904271#.UyMwZoXLLEw
The results indicate that urban heating is attributable to a large excess in heat from the rapidly heating urban surfaces consisting of buildings, asphalt, bare-soil and short grasses. In summer, the symptoms of diurnal heating begin to appear by mid-morning and can be about 10°C warmer than nearby woodlands.
—–
http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291097-0088%28199608%2916:8%3C935::AID-JOC64%3E3.0.CO;2-V/abstract
The long-term mean annual temperature record (1885 –1993) shows warming over the past century, with much of the warming occurring in the most recent three decades. However, our analyses show that half or more of this recent warming may be related to urban growth, and not to any widespread regional temperature increase.
—–
http://onlinelibrary.wiley.com/doi/10.1029/2010JD015452/abstract
[R]apid urbanization has a significant influence on surface warming over east China. Overall, UHI effects contribute 24.2% to regional average warming trends. The strongest effect of urbanization on annual mean surface air temperature trends occurs over the metropolis and large city stations, with corresponding contributions of about 44% and 35% to total warming, respectively. The UHI trends are 0.398°C and 0.26°C decade−1. The most substantial UHI effect occurred after the early 2000s, implying a significant effect of rapid urbanization on surface air temperature change during this period.
—–
http://onlinelibrary.wiley.com/doi/10.1002/joc.1420/abstract
The heating effect due to urbanization was found to penetrate about 600–800 m height in the atmosphere over the city, and the two surface heat island cells were found to combine aloft.
No mention of AlGore’s $90 trillion urbanization project?
I need a drink.