Claim: 'global warming has been amplified in cities', ignores infrastructure increase

Heat waves becoming more prominent in urban areas, research reveals

For past four decades, global warming has been amplified in cities, warns UCLA geographer

From the University of California – Los Angeles

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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143 thoughts on “Claim: 'global warming has been amplified in cities', ignores infrastructure increase

  1. Just exactly for how long have people headed out of cities for cooler climes during summer months? I’ve been doing it for as long as I remember, but I can’t remember much before my birth in 1958.

    • Tom Crozier
      Just exactly for how long have people headed out of cities for cooler climes during summer months? I’ve been doing it for as long as I remember, but I can’t remember much before my birth in 1958.

      The roman Emperors, their families, (and the other rich Roman and Greeks who could afford two houses (er, palaces) did it back before Christ was born. One in the city for its conveniences and access to power and influence and politics, one in the hills during the hot months of the year.
      Later, in the 1870’s, the “city club” members who could afford it built “country clubs” out in the country for the same reason. A few in Pittsburgh, for example, bought an old lake and dam upstream of Johnstown PA for their “country club”, and decided to put a “fish trap” across their old dam’s drainage canal … Rains came, and the lake level rose; maintenance bills came but the needed inspections and repairs were not done, and hundreds were killed when the dam broke.
      All because of UHI.
      But today, the Johnstown tragedy would be blamed on CAGW (or the rich), not on poor maintenance by the rich.

    • I saw the diary of my grandmother where she did the same though I have an earlier reference to it in days when we would not have even rated London as a big town.

    • The British in India decamped from the lowlands and headed for the hill stations every summer building railways into the mountains for the purpose. In the USA the good people of Tucson used convict labour to build the road to the top of Mount Lemmon where they built the little town of Summerhaven to escape the heat.

  2. Since cold waves kill more people than heat waves, can we assume that the mortality due to temperature in cities is lower than in rural areas?

  3. It is hard to know what to make of this. A study about how people who swim more than others have a higher incident of ear infections would make about as much sense as this study about “urban heat.” Did I miss the part in the paper that states that a high percentage of Stevenson screens reside in urban areas?

    • JimS, you hit it right on the head! The alarmists have been claiming that UHI is not significant. This study supports what we have been saying for a long time. UHI is producing warming bias in the surfac sensor temperature records. And this is why we perfer to use the satallite records; which due to excluding UHI bias, show less warming than do the ground based temperature records.

  4. So how does this fit in with the usual warmist position that UHI has no noticeable effect on local temperature ?

    • exactly right… finding fits perfectly with UHI… In Melbourne Australia UHI has been shown to be as much as 6 degrees(C)… which also fits with the finding that minimum temperatures (overnight) are increasing but maximums generally are not.
      Cheers
      J

      • Quite right, Jim!And, the socialist government planners can only see cramming more people into concrete edifices in the cities as a salute to their silly religion. Wendell Cox was right, urban ‘sprawl’ is better than aggregation in the cities.

      • It’s called “New Urbanism” and “Smart Development”. If you want to get a project through in a jurisdiction which subscribes to this nonsense, remember to emphasize “Livable, Walkable, Sustainable, and Green” in your presentation to the Council.

      • It’s also called “Smart Growth”. I don’t know a single developer, including myself, who hasn’t lost his butt initiating one of these projects. The trick is to buy it from the third guy who went broke or died trying to get the permits. The last one I did took 16 years, after the first and second guys, both of whom are now dead; in fact the partner with whom I pulled it off on the third try is dead.
        Now that I think about it, the guys we sold it to, #4 in the chain of title, still haven’t completed the project.

  5. So, instead of UHI temperature readings causing an exaggeration in global warming, global warming is causing UHI. Is that what they are trying to claim?

    • Quite so. Global warming is man made, and is worse in cities, also man-made. Can you see a pattern here? Well man-made things are causing UHI.

      • So Carbon Dioxide is an intelligent molecule then. It knows how to selectively target urban areas for extreme heat and precipitation. Does it do it out of revenge? Or is it thanking humans for setting it free from its fossil-fuel prison? After all, it is also making winds more gentle in the urban areas where humans tend to live. So perhaps CO2 is more intelligent than most climate scientists and knows that a little more nighttime warmth and a little more moisture are actually good things. I’m just worried about what it might do to us if it ever gets “wind” that humans have designated it as “carbon polution” and are out to eliminate it. I sure hope that message takes a long time to get well mixed into the atmosphere. Next ice age, here we come! /Sarc

      • The hotter the day, the more heat the cars’ and buildings’ air-conditioning pumps to the out-of-doors, which in turn causes them to increase the air-conditioning, which … well, we now know what causes man-made global warming. \sarc

    • Louis, you hit the nail on the head!
      The cart is officially put before the horse. These guys have endless illogical explanations about the simple weather. I say we escort all of them to the nearest sanitarium for mental health issues.

    • The entire research can be summarized in terms of three items:
      1) 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
      2) “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,”
      3) said Dennis Lettenmaier, a co-author of the study and a UCLA geography professor
      Translated to the vernacular:
      1) if you are a hammer everything looks like a nail
      2) the drunk always looks for his missing keys under the street light
      3) those who can’t do proper statistical analysis teach geography
      There are clearly places on the earth [e.g. midtown Manhattan] where the technological heat input exceeds the natural heat input to the local environment by a large factor. What would have made the study semi-useful would have been to measure the correlation between kW/capita and kW/m^2 and the UHI effect

      • ‘most were located at airports close to urban areas, ‘
        Weather stations at airports are designed to be used to give information for flight movements and and out of the airport , they are not designed to give this information for the wider area , they are used in this way because ‘they are there’ not [because] they are good at it .
        Airports may not even be typical of the area they are sited in, modern airports tend to out of cities because that is where the free land is , but the surrounding area can still be rural. In fact very few areas have such big open areas of concert and tarmac in the way airports with their runways, pans taxi lanes, have . If you ever work at one you
        Its like using a weather station [on] top of a mountain to represent the weather conditions in the valley below mountain because it ‘there ‘ and not far away , and then expecting to get honest results.

      • WestHi – There are clearly places on the earth [e.g. midtown Manhattan] where the technological heat input exceeds the natural heat input to the local environment by a large factor.
        Back in 2010, I posted the following analysis on New York City power usage as it related to UHI.
        DD More February 26, 2010 at 7:22 am
        I could never understand how UHI was minimized. If you look at New York City as an example.
        Area, including water 468.9 sq mi ( 2,590,000 sq m)
        Power used (2008) 54,869 GW-hr
        (http://www.nyc.gov/html/planyc2030/downloads/pdf/progress_2008_energy.pdf)
        Watts/sq m = 2,416 total. The Mayor says 80 percent is used by buildings and therefore 100 percent ends up as heat loss. So the forcing is 1,933 W/Sq M
        The file also remarks that the city has seen a 23 percent increase in the last 10 years, which is close to the increase showing up in the charts.

        http://wattsupwiththat.com/2010/02/26/a-new-paper-comparing-ncdc-rural-and-urban-us-surface-temperature-data/#comment-329553
        Well it should be updated a little. Clarifying the 80 percent used by buildings was for lighting and heat, so by next day at the same temperature it was all turned to waste heat. I heard later that Reliability concerns require that 80% of the City’s peak load be met with in-City resources under a mandate from the New York State Reliability Council and the New York Independent System Operator.
        The original calculation would now be 54,869 GW-hr / year * 1.0 x 1.00E+09 W/GW x 8760 hr/yr = 6,263,600,000 W-hr / hr. that divided by 2,590,000 m^2 = 2418 W / m^2 each hour. But if you take at least 60 percent of power generated in the city generates 40 percent excess waste heat to convert to electrical power = 2418 x (1+ .24) = 3000 W / m^2 of extra energy being dumped in the air of New York City. And that is from electrical power alone, doesn’t include all the vehicle waste heat.
        So does 3,000 w / m^2 raise the temperature more than 100 ppm CO2?

  6. I have said this in the past. I am in a small town in rural Montana and there is a 6 degree temperature differential within four blocks of the two thermometers. One is surrounded by all cement and the other is elevated and above gravel and dirt. I call this the cold island effect. It is more noticeable the colder it gets.

    • In cars with digital thermometers, one can see the temperature rise going from country to urban areas – discounting those variables that add or subtract to the effect. (It would be interesting to digitally store the temps during a trip, and then plot them out, superimposed over a map of the route taken.)

      • noaaprogrammer
        Anthony did this experiment a few years ago using some of his temp and humidity monitors mounted on his car as he drove through his local town one evening all tracked but GPS the results were posted for us all to look at just how much the temp fell away from the middle of town.
        James Bull

    • I live 1 mile outside of a small rural town in Ohio (6,000 people) and during cold January, February mornings it is 12 degrees warmer in town than 1 mile outside of town. No elevation change either it is flat land for miles around.

      • Jared,
        That is due to the RHRE, or Rural Heat Rejection Effect, for which you are personally responsible. Either pay up or move into town, where it is warmer. Your masters demand it. (See Al Gore to sign up.) Sarc/off
        (And take your bleeping thermometer with you…)

      • Remember though that our small little town in the middle of nowhere is considered rural where UHI should not even register. I doubt any of the Gavin’s or Hansen’s of the world have ever done a field study in a true rural place. They have blind faith in the omniscience of their flawed computer algorithm. Hey Gavin, do an actual field study in a truly rural place in the middle of January. Tell us again how UHI is negligible. I forgot your algorithm is infallible.

  7. This result is about as significant as stating “empirical evidence shows that daily temperature ranges are far greater in desert environments than they are in coastal environments”.
    Duh.
    “Dark is most prominent at night”

    • Don’t laugh. I once worked for a company whose industrial engineers did a study trying to figure out why the night shift used more flashlight batteries than the dayshift. Should have been a gov’t grant proposal.

  8. Someone in the past reported here on the difference between urban and rural temperature readings. It would be very interesting to do that again for 2014, “the warmest year on record.” I’m curious about how much difference there is in both the raw data and the adjusted data. I would be very surprised if the rural areas are not being adjusted upward to make them more closely match nearby urban readings. Anyone willing to take that on?

    • There must be a reason why their study 650 urban areas was winnowed down to 147 rural/urban pairs there at the end. That’s because rural stations aren’t condusive to their lie. So inspite of “Urban areas make up a relatively small part of the global land area” it’s the rural stations that get closed up, discontinued, deleted from the network.

  9. I wonder what this means for a city such as Vancouver, BC. The hottest of the hot days in that city is still about 10 C cooler than a city like Spokane WA. The hottest temperatures I have ever experience was 40 C in Winnipeg during a stop over for 4 hours in 1988, and 40 C on a tennis court in Spokane WA in the late 1970’s. I also experience great heat while traveling through Osoyoos a couple of decades ago whereupon a nice large iced drink solved that problem.
    The summer heat of Spokane is such an alien experience to me having spent most of my live on the south west coast of British Columbia, so much so that I was amazed at how hot it still was late into the evening when visiting family there. While planning a swimming adventure out of town at a French named lake Coeur d’Alene in Idaho, the temperatures dropped on the day of the outing so much that it was too cold to swim.
    I ride my bike a lot and get to experience local micro-climates and have discovered, for instance a noticeable cooling when I approach the entrance to Hyde-Creek Park, several blocks before the entrance. Note the Creek is dried up in summer so the cooling is from the mass of trees. I have experience cool spots while riding on the dike and noted the coolness was related to the proximity of the river to the edge of the dike.
    I am working on a very complex computer model to more scientifically determine for example the global average temperature of the earth. Several years more work to do. Gotta go, a couple more years of study still to do also.

  10. “Urban areas experienced 60 percent fewer extremely windy days than non-urban areas.”
    Winds aloft or down between the tall buildings? Vertical “winds” or horizontal winds? As every pilot who’s been there knows, on sunny days you hit a major updraft as you pass over the parking lot on short final to RWY’s 25 R&L at LAX.

    • And for some reason I’ve never understood, as you depart LAX on a warm day, it gets cooler once you cross the beach and head out over the Pacific. /s

  11. Looking forward to the audit of the Bureau of Met in Australia. I can see the skyscrapers from my farm where we are always several degrees cooler than the official thermometer.
    ACO2 hasta cause cooling. ☺

    • Its not going to be an audit, its going to be a “forum” whatever that means, i guess a bunch of BOM friendly people are going to sit around and chat about those nasty malicious rumours and decide that no such thing actually occurred, then they will write a report and the ABC will yell nya nya na na na, Iwe told you so…….

  12. ‘…Lettenmaier said. “You have heat being stored in buildings … they don’t cool down as quickly… This effect was likely exacerbated by decreasing wind in most of the urban areas.”’
    Well, that’s it, we should all sleep on the ground. What do these morons expect? Don’t live in a private home. But don’t live in a building. Don’t live in the city. But don’t live in the country. But, definitely don’t live in a suburb. Don’t drive. Don’t fly. Don’t use your AC. Don’t use your washing machine. Don’t even buy a washing machine unless it’s a front loader. Don’t use a dryer. Don’t use electricity when we don’t think you should use electricity. Don’t have a pet dog. Don’t eat beef. In fact, don’t eat meat. Don’t drink soda pop. But don’t drink water. Don’t flush your toilet. Don’t take a shower unless it’s a dribble.
    Enough alright already. The U.S. Constitution does not tell the citizens what they can’t do. It is a blunt statement on what the damn government cannot do. It’s about time we demand that these, “first of its kind”, “unique”, “new approach”, and so on, and so on, “revolutionary” studies stop sucking up our hard earned money.

  13. They got it at the end. “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.” Or call it no breeze.

    • Yes! Walls block wind ! Who knew ?! …Maybe the Great Wall of China was really built to cause” Climate Change” !… /sarc …

      • Maybe it was! The ancient Chinese were pretty bright and maybe their wives were complaining about the cold…

  14. Has Dennis Lettenmaier ever heard of the Urban Heat Island effect? That is one reason the “data” has been adjusted to show global warming. I don’t think Dennis Lettenmaier has been reading his WUWT to being kept up-to-date on the subject…

  15. “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.”
    Increases is flights? Those places are busy with mega space heaters.

    • Used to be called the “Air Field”, then it was called the “Air Port”, now it’s the “Air Terminal”. Apparently caused by Global Warming.

    • Where I live in Canberra, I am about 400 meters from a BOM weather station. I always use to a direct reference to it from the BOM website. Unfortunately, in the last two years an elder care facility was completed about 150 meters away. I have noticed an increase in the average temps. So much for no UHI influence.
      Interestingly, the “official” weather appears to reported from the airport. Who lives at the airport??

  16. Too many people, crammed into not enough space. Cars everywhere. Tall buildings everywhere. Every bit of green space is covered with concrete or asphalt. What on earth did they expect? Agenda 21, is not a good plan…..

  17. So the more people, cars, buildings, increased energy use and waste within a concentrated area the greater the heat signature for that specific area .Who would have ever thought this, what a startling discovery.
    Next up for a critical scientific break-through relates to the studies that are close to determining whether night follows day or day follows night.

  18. Has anyone ever calculated the heat generated by braking systems, whether by automobile/truck/train or aircraft?
    At YYZ (1990’s) the smell of burning rubber from aircraft tires hitting the runway was never far away.
    APU exhaust goes with the flow.

    • Aircraft manufacturs have calculated brake and associated hydraulic fluid temperatures and their effects on performance since at least the days of the B-29; but don’t tell Bill Nye. He would suffer debilitating cognitive dissonance in spite of the fact he once worked for Boeing. 😉

    • Has anyone ever calculated the additional heat generated by plonking a PC on everyone’s desk, many of them left running 24×7? Maybe the pause is down to the emergence of fondle slabs /sarc.

    • Automobiles and trucks release a large enough amount of heat from the exhaust and the cooling system that heating from brakes would be a minor effect. This is even more pronounced by modern aircraft where the heavy braking is done by thrust reversers on the engines. Modern electric trains tend to use regenerative braking where much of the energy released by braking is turned back into electricity,
      That said a large road even when there is no traffic tends to a hot place in summer especially when it has a black asphalt surface. Even in the UK I have seen melting tar on roads in summer.

    • Don’t need to calculate it, the energy to “generate” the heat comes from burning the fuel to make the vehicle move in the first place, and we measure that.

  19. In addition to infrastructure development, over the past few decades there has been a vast deployment of HVAC systems, electronics and wires/cables of all types. All of these produce heat, which adds to the impacts caused by infrastructure/albedo modifications. I’m noting the exhaust out of my laptop as I write this!

    • Good point. As I write my computer system’s power supply indicates a draw of 175 watts, and some of those are definitely generating heat.

      • Good point. As I write my computer system’s power supply indicates a draw of 175 watts, and some of those are definitely generating heat.

        Rather, ALL of those 175 watts are generating heat. But, on a winter’s night, those 175 watts are “replacing heat” not otherwise needed in the house that come from your furnace. On a summer’s afternoon, those 175 watts added indoors to an air conditioned space would be adding to your street’s electricity needs. However, to get those 175 watts inside your house on your lap, the power company needed to generate some 195 to 205 watts depending on where your house is. To generate those 200 watts at the end of the power station transformer, the power company needed to create 400 to 500 watts in their boiler or gas turbine.
        You, yourself, are also adding heat just by sitting there … about 100 watts per person.

    • Well obviously the CO2 generated by its production and transportation to job sites lingers overhead, creating the UHI.

  20. 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!

  21. 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 @ 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?

  22. 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?

  23. 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.

  24. “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.

  25. 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

  26. 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.

  27. 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.

    • 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.

  28. 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.

      • 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.

  29. 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.

  30. 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.

  31. 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!

  32. Claim: ‘global warming has been amplified in cities’, ignores infrastructure increase.

    I’ve read it all. A study devoted almost solely to UHI ignores … UHI.

  33. 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?

  34. “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?

  35. 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.

  36. 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.

  37. 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.

  38. Did somebody’s taxes seriously just pay for “UHI is real – especially at night”?
    I spent last June sleeping with just a sheet, in Sydney. I wouldn’t try that in the bush even near Cairns!

  39. Glad they could identify that mankind is simply using too much energy that is converted into heat in confined urban centres. Not enough to cause global warming – but enough with careful fudging of temperatures and careful limitations on the true effect and thus using incorrect adjustments for UHI to create the illusion of global warming.
    Switching from one kind of fuel to another, say fossil to solar, has no effect upon the energy use and thus heat release at point of use – be it heating, air conditioning etc. or any domestic appliances.
    So with the current way of assembling and ‘homogenising’ global temperatures a complete replacement of fossil with wind and solar will show no change at all to ‘global warming’. Only when correct adjustments for UHI are used and the constant manipulation of data to reduce earlier temperatures is brought to an end will we see an end to ‘global warming’. (That is unless we see temperatures fall in the next 20 years or so as the solar minimum has its predicted effect.)
    As a random thought I wonder if anyone has ever run calculations, on a national scale, for the heat generated due to resistance by the distribution of electricity ? If heat release to atmosphere were ever to replace CO2 as the scientivist and political campaigning tool behind energy (and economic) policies then I suspect that the use of fossil fuels at or near the point of use would create lower heat energy release than remote generation (of whatever kind) distributed over massive distances. Just a thought.

  40. One aspect of the religion of Global Warming, is that it requires it’s adherents to believe that everything in the world is constant, except for CO2.
    Thus, the idea that the cities they are studying have gotten bigger and more developed over the last 40 years just never occurs to them.

  41. On the subject of the role of urban areas on the temperature trends, see also
    Montandon, L.M., S. Fall, R.A. Pielke Sr., and D. Niyogi, 2011: Distribution of landscape types in the Global Historical Climatology Network. Earth Interactions, 15:6, doi: 10.1175/2010EI371. https://pielkeclimatesci.files.wordpress.com/2011/02/r-344.pdf
    We also conclude that most of these land use types (including urban areas) have a significant warming due just to a change in the vertical distribution of heat near the surface and not a deeper layer warming. This subject is discussed in
    McNider, R.T., G.J. Steeneveld, B. Holtslag, R. Pielke Sr, S. Mackaro, A. Pour Biazar, J.T. Walters, U.S. Nair, and J.R. Christy, 2012: Response and sensitivity of the nocturnal boundary layer over land to added longwave radiative forcing. J. Geophys. Res., 117, D14106, doi:10.1029/2012JD017578. Copyright (2012) American Geophysical Union. http://pielkeclimatesci.files.wordpress.com/2013/02/r-371.pdf
    Other papers include
    Georgescu, M., G. Miguez-Macho, L. T. Steyaert, and C. P. Weaver (2009), Climatic Effects of 30 Years of Landscape Change over the Greater Phoenix, AZ, Region. Part I: Surface Energy Budget Changes, J. Geophys. Res., doi:10.1029/2008JD010745. http://www.agu.org/journals/pip/jd/2008JD010745-pip.pdf
    Georgescu, M., G. Miguez-Macho, L. T. Steyaert, and C. P. Weaver (2009), Climatic effects of 30 years of landscape change over the Greater Phoenix, Arizona, region: 2. Dynamical and thermodynamical response, J. Geophys. Res., doi:10.1029/2008JD010762, http://www.agu.org/journals/pip/jd/2008JD010762-pip.pdf
    Georgescu, M. et al 2012: Summer-time climate impacts of projected megapolitan expansion in Arizona. Nature Climate Change. doi:10.1038/nclimate1656. http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1656.html
    and my post of this paper
    https://pielkeclimatesci.wordpress.com/2012/08/16/new-paper-summer-time-climate-impacts-of-projected-megapolitan-expansion-in-arizona-by-georgescu-et-al-2012/
    [Thank you for the (extended) list of papers, your time in researching and writing them, and your time responding here. .mod]

  42. In this study, a city is a city. There is no mention of urban area. Are you suggesting UHI is greater in the middle of a 10-km square city than in a 5-km square city? Is there a critical area required for UHI to be significant?

    • UHI can never be measured quantitatively, there is no possible control. Attempts are made, such as a bicycle with recording thermometer passing linearly through city from a distant rural starting point.
      The point is that urban thermometers are measuring the temperatures of underground steam pipes, or concrete, or air conditioner exhausts. What would the temperature of Manhattan Island be without the city??
      It’s impossible to know. Is it 1C, 2C or 5 C in January or July???
      Urban temps must be rejected in assessments of global temps.
      When only rural temps are plotted, global warming is zero. The decade of the 1930s remains the warmest decade in the time of thermometers.

  43. I didn’t see a link to the actual paper so here it is:
    http://iopscience.iop.org/1748-9326/10/2/024005/article
    The study period (1973-2012) coincides with a recognized warming trend globally. Indeed, 1973 essentially coincides with the end of a multi-decade cooling trend. Urban population (and therefore urban infrastructure) has increased tremendously since 1973. Therefore, finding anything other than an increase in urban heat waves would have been shocking.
    In addition, the authors provide an important caveat when they state: “Increasing and declining trends in temperature extremes may be associated with natural climate variability, anthropogenic climate warming, and land use/land cover (Kiktev et al 2003, Alexander et al 2009, Min et al 2011b, Avila et al 2012, Coumou and Rahmstorf 2012). Here we simply report the aggregate effect on urban extremes and have not attempted to quantify their separate contributions.”

  44. Simply an acknowledgement of UHI with no relationship to CAGW other than exaggerating it due to poor siting of measurement stations.

  45. I have to wonder about Detroit’s local climate. That would seem to be a good test case for urban heat islands being amplified hypothesis.
    Think about it.
    Perhaps someone could suggest it to the researchers…

  46. “Everything’s warming up, but the effect is amplified in urban areas.”

    Well done to captain obvious. This has been covered to death on WUWT.

  47. Give’em a break! The scamps just found out about UHI effect, got excited, then needed to tell everyone what they “discovered.”

  48. Almost two-thirds of the urban areas showed significant increases in the frequency of extremely hot nights.
    If you install underfloor heating the concrete floor becomes a thermal mass, buildings, concrete, more buildings, more concrete, nothing to do with CO2, it`s all to with population growth.
    From 1950 to 1990, Melbourne, the capital city in the Australian state of Victoria, had a population increase from 1.5 million to about 2.5 million. Within the city (where the weather observations are taken), buildings progressively became higher and these blocked wind, cast shadows and, via the thermal properties of newer building materials, changed the daily patterns of heat flow. Other factors such as increased motor traffic and the increase in use of air conditioning in buildings probably also caused additional heat energy.
    http://mclean.ch/climate/Melbourne_UHI.htm

  49. “Urban areas make up a relatively small part of the global land area, but over half the world’s populations now live in them AND 3/4 OF THE WORLDS WEATHER STATIONS ARE SITUATED WITHIN THEM, so the trend is troublesome,” said lead author

  50. The authors of this paper missed their calling, they should have been police detectives:
    “Yes, the deceased committed suicide . . . by shooting himself in the head seven times.”

  51. I’m encouraged by this “heat island” panic. The warmists have fallen back (hugely) to the only “confirm-able” effect of the much-touted but bogus “warmist” position. Yes – the cities are getting warmer, but not from CO2. Just concrete & infrastructure growth. And all the E-windmills and carbon sequestration plans in the world aren’t going to change it. Pity its wrecking the used-to-be science of climate studies.

  52. “For past four decades, global warming has been amplified in cities, warns UCLA geographer”
    Yes, poor people flock to citie, and have greater access to energy. In addition, there are more sewer systems now, removing standing water and reducing the amount of “latent heat” from evaporation.
    Just reduce allowable energy usage by having rolling power blackouts, as happened years ago in California under Governor Gray Davis, eliminate the sewer systems, and you’ll get plenty of
    case of cholera, malaria, a mass exodus from cities, and reduced warming in cities and the “paradise on earth” the UCLA geographer is striving for.

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