Urban Heat Island Effect Can Be Up To 9°C , Says NASA

We know that more and more temperature stations have been sited in urban areas over the last few decades, and surely this has had an impact on the measurement of the globe’s temperature. But not to worry, say scientists, the raw data have been homogenized in order to compensate for this.

Elevated temperatures in urban environments. (Photo: NASA)

Have they compensated enough? Just how much uncertainty is in the land-based temperature record for the last 50 years? A new report from NASA shows some results that I think are surprising.

Summer land surface temperature of cities in the Northeast were an average of 7 °C to 9 °C (13°F to 16 °F) warmer than surrounding rural areas over a three year period, the new research shows. The complex phenomenon that drives up temperatures is called the urban heat island effect.

Dr Marc Imhoff, leader of the study, says that urban areas located in forested regions have a much more pronounced urban heating effect than in desert areas. Adjustment is neither an easy nor accurate task (emphasis added):

However, accurate comparisons have long eluded scientists because ground-based air temperature sensors tend to be unevenly distributed and prone to local bias. The lack of quantifiable definitions for urban versus non-urban areas has also hindered comparisons

But thanks to satellites, progress is being made in understanding the urban heat island effect. Satellite data have been used to compare various urban settings. Ping Zhang, a scientist at Goddard and a lead author of the research:

This, at least to our knowledge, is the first time that anybody has systematically compared the heat islands of a large number of cities at continental and global scales,”

Research by NASA scientists shows that compact urban areas have a higher urban heat  island effect that sprawling cities, and depend greatly on the surrounding environment, as mentioned above.

Taking the UHI effect has been the subject of much controversy over the years. This new study shows that it may have been significantly understated, at least in some areas.

Providence, R.I.; Washington, D.C.; Philadelphia, Pa.; Baltimore, Md.; Boston, Ma.; and Pittsburgh, Pa.; had some of the strongest heat islands of the 42 northeastern cities analyzed.

Let’s look at some temperature records:

These 3 examples have all trended upwards over the last 30 or 40 years. The actual siting and history of each station would have to be examined individually. So one can imagine what a mess this is and how arbitrary all this could be. Here we can be thankful for satellites.

The warming indeed is man-made, but in a different sense. The urban warming is what has impacted people in the summertime, especially at night.

The U.S. Environmental Protection Agency estimates that, between 1979 and 2003, heat exposure has caused more than the number of mortalities resulting from hurricanes, lightning, tornadoes, floods, and earthquakes combined.

It is the lack of cooling at nighttime, rather than high daytime temperatures, that poses a health risk,” said Benedicte Dousset, a scientist from the University of Hawaii who also presented data about heat islands at the AGU meeting.

Urban planners will have to take this into account when designing cities in the future. Trees, trees and more trees can help a lot. Meanwhile, all this leaves James Hansen with a pile of almost useless data.


23 responses to “Urban Heat Island Effect Can Be Up To 9°C , Says NASA”

  1. Ed Caryl

    That study must be a great source of embarrassment to Hansen. It will take years to undo and recorrect all the surface station data.

    1. Mervyn Sullivan

      Ed, not just a great source of embarrassment to Hansen but also to Dr Phil Jones of the Climate Research Unit, University of East Anglia … it shows these experts’ research that UHI has negligent effect is in tatters!

      1. Brian H

        That’s “negligible”, but negligence is definitely involved! 😉

  2. Bernd Felsche

    So NASA tells us what we should already know; from the lessons of city planners of the 18th, 19th and early 20th century.

    e.g. Paris and Berlin’s wide avenues and generous parks were no accident.

    We’ve also known that the UHI compensation has been deeply flawed ever since it started because of the simplifications; with the most-likely result being that the error in assumption is greater than any real change in temperature.

    1. Brian H

      There must be climate wreckers burrowing in the bowels of NASA, trying to undermine the Enlightened Leadership of the Great Hansen!

      Go for it, guys!


  3. Paddy

    I seem to recall that the GCM assumption for UHI is warming by 0.5C. If my recollection is correct, why isn’t Hansen in irons doing the perp walk into a paddy

    1. Brian H

      Frrriennndssszz, in Hoigh Playces! Plus a direct tap into the BigBucks artery of the FEDGOV. Same deal that keeps the execrable Mann moored in place.

  4. Gator

    I have been saying this for over 20 years! I live in the “rural” and observe the disparity of temperatures every day. The UHI more than accounts for any linear warming graphed. Go to the site below, pick a rural location not effected by a marine bias whose site has not changed in a century, and voila! No warming! In fact, some sites show a slight cooling over the past 100 years. This is why when demographics are studied on belief in AGW, rural dwellers over 40 are the most likely to be skeptical.


  5. DirkH

    NASA produces the satellite maps so Hansen can have weather stations relocated to the warmest places. They need to up the ante to keep the warming going…

    1. Brian H

      Speaking of relocated stations, here’s a graph from Tim Ball to blow your liddle mind(s):

      I did the ‘rithmetic: in the year of the great Station Slaughter, the average bounced up by >1.9°C. Correlation may not be causation, but …

  6. Hugh Roper

    Thanks for this useful link. These NASA people can produce good new work when they try. One could go further and point out that most land surface weather stations are in or close to places where people have removed vegetation and built houses, workplaces and roads. The resulting so-called UHI effect is unlikely to be confined to large cities; it is potentially present almost everywhere that people live, travel and work. I suspect that trying to remove or allow for this very real urbanisation (or ‘built environment’) effect in order to measure ‘real’ changes in global, regional – or even local – mean surface temperature is futile and ultimately pointless.
    There are other good reasons for disregarding the whole concept of global mean surface temperature, not least that the concept seems to have no clear physical meaning. Temperature is an intensive quantity and so cannot be summed or averaged. This applies to ‘anomalies’ (variations from an expected value) as well as to actual temperature measurements. The highly regarded (by both mainstream climate scientists and dissident ones) blog http://www.scienceofdoom.com has a post on
    “Why Global Mean Surface Temperature Should be Relegated, Or Mostly Ignored”

  7. ThomasJ

    Big txs, PG! Linking this to http://www.theclimatescam.se.

    Viele Gruesse aus der z.Zt. eiskalten Bestkueste Schwedens!


  8. Mike Davis

    Phil Jones knew this in 1990 when he wrote the paper about how UHI does not affect temperatures and I believe Tom Karl wrote another one about the same thing. This surface temperature scam has been going on since the late 70s.
    Maybe next they will finally realize the sea surface temperature records are worthless also.

  9. Sunsettommy

    I see this UHI effect everyday when I drive to work and back home from work.

    It is coolest between the two cities.

  10. Gary H

    Just a couple of weeks back, I had a little fun when David Letterman interviewed his mom on his late nite show. In the end he quizzed her on GW – where she stated she didn’t really belive in it.. and Letterman buried his head in hands — crowd laughing. She lives in Indianapolois –


    – yep temps rising there a bit. Here’s my stab.. It’s a fun exercise – and it works ofen.

    David Letterman and his mom, on Global Warming The video:


    The Transcript: From the November 24 Late Show:

    DAVID LETTERMAN: How are things in Indianapolis?

    DOROTHY LETTERMAN: Things are very nice. It’s been unseasonably warm.

    DAVID LETTERMAN: How warm. How warm has it been? Like 20 degrees warmer than it should be?

    DOROTHY LETTERMAN: About, yes, and it’s very windy.

    DAVID LETTERMAN: Yeah, well, that’s that climate change. It’s the global warming. You know that, mom? Do you believe in the climate change, in the global warming?

    DOROTHY LETTERMAN: Not really. [audience laughter as David Letterman’s facial expressions show his disapproval]

    The evidence abounds..

    Perhaps Letterman’s mom is a lot more informed than is he!

    Yes Dave, most of us intelligent and observant folks do understand the urban heat island effect; large metropolitan cities, do indeed generate a lot of heat and do absorb a lot of solar energy and do warm as they grow over the decades – perhaps like Indianapolis (even though we’d love to see the 1850-60’s plotted on that chart??).

    On the other hand, maybe in the suburbs where Mrs. Letterman lives, Dave, there is little evidence of a warming trend!

    South of Indianapolis, it’s getting cooler: Shoals Highway 50 Bridge

    West of Indianapolis, there’s no warming trend: Greencastle

    East of Indianapolis, it’s getting cooler: Cambridge City

    North of Indianapolis, it’s looking cooler, as well: Delphi 3nne

    The only thing hot around there is the hothead himself, David Letterman.

    (;~/ gary

    1. Brian H

      His mom is intelligent; Davie just has a smart mouth. BIG difference.

  11. Lawrie

    I think the AGW scientists honestly thought that no one would notice the detail. They figured we would all accept the science view as gospel and most did until a few discovered the odd mistake. Since then a lot of educated people are on their case and the fudges are no longer acceptable.

    There must be some scientists working in NASA and UEA who are not comfortable with the lies and who eventually will start to speak out if for no other reason than to preserve their own integrity.

    When the scam finally collapses who will employ a Jones or a Hansen? They will be damaged goods and so will any scientist who followed them on the AGW track.

  12. Intressant formulering av NASA | The Climate Scam

    […] rapporterar NoTricksZone att NASA i en nyligen publicerad rapport medger att den urbana värmeeffekten (UHI) kan vara upp […]

  13. Tommy

    I posted a comment on this at Huffington Post. It seems unable to get past the moderators. I also scanned all the major alarmist blogs to see if they covered it…nada. As such, you know it’s a big story when certain outlets refuse to cover it, or even allow it to be discussed. I’m not really surprised. When I first became interested in the topic, I noted quickly how sites like RC stifled my questions. I was told that was the best site on the subject, and quickly saw they were up to something. Ironically, that’s what caused me to dig deeper, and uncover lots of things they probably wish I hadn’t seen.

    1. Brian H

      If you read the Climategate Emails, you’d know that RC was specifically set up by and for The Team to cover for them, and to delay or suppress disagreement and inconvenient data. It was planned from the get-go.

  14. notrickszone.com

    Urban heat island effect can be up to 9 C2 B0c nasa.. Dandy 🙂

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