Urban warming 'as important as AGW'

Tuscon, Arizona (Credit: © John Miller / Fotolia)

Whilst the possible warming from AGW in the last 100 years can be measured in tenths of a degree, a new study suggests that warming from urbanisation may be even more significant:

In the first study to attempt to quantify the impact of rapidly expanding megapolitan areas on regional climate, a team of researchers from Arizona State University (ASU) and the National Center for Atmospheric Research has established that local maximum summertime warming resulting from projected expansion of the urban Sun Corridor [the four metropolitan areas of Phoenix, Tucson, Prescott and Nogales] could approach 4 degrees Celsius. This finding establishes that this factor can be as important as warming due to increased levels of greenhouse gases. Their results are reported in the early online edition (Aug. 12) of the journal Nature Climate Change.


“The actual contribution of urban warming relative to summertime climate change warming depends critically on the path of urbanization, the conversion of natural to urban landscapes, and the degree to which we continue to emit greenhouse gases,” said Alex Mahalov, a co-author and principal investigator of the National Science Foundation grant, “Multiscale Modeling of Urban Atmospheres in a Changing Climate,” which supported the research.

“As well as providing insights for sustainable growth of the Sun Corridor and other rapidly expanding megapolitan areas, this research offers one way to quantify and understand the relative impacts of urbanization and global warming,”said Mahalov, the Wilhoit Foundation Dean’s Distinguished Professor in ASU’s School of Mathematical and Statistical Sciences. (source)

The abstract is here.


  1. Thanks. Very useful. Also, cause for regret.
    I have been professionally involved in passive climatic design for something like 35 years, mostly with regard to the tropics, where heat is the issue, and cold little more than a novelty. (Except perhaps in the current Australian winter.)
    The regret comes from reading phrases like these:
    “However, pinning precise figures on the relative contribution of each effector is difficult” (the referenced article).
    Ok. Those of us who are practitioners in this field never got around to providing precise figures. Too busy getting positive results.
    Mea culpa. Failed to anticipate that a bunch of know-nothings would invade the territory.
    (Links from referenced article)
    “White Roofs May Successfully Cool Cities, Computer Model Demonstrates “.
    Whaaat … Expletives deleted. Classic “rediscovering the bleedin’ obvious” this one.
    “Water Evaporated from Trees Cools Global Climate, Researchers Find”.
    Lost count of the occasions on which I have demonstrated this to be correct, along with some other novelties, such as:
    Individual large trees can redirect natural airflow if type and placement relative to windows is correct. (Corollary here is, single trees are vulnerable to cyclonic winds. Trees on the edge of tree belts are also vulnerable.)
    Tree planting in belts (can be savanna woodland, doesn’t need to be dense) raises the boundary layer. Extensive belts can significantly modify the micro-climate, even the level of precipitation if large enough, but don’t overlook the build-up of fuel load.

  2. James Hein says:

    “First study?” what about:

    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, D14113, 12 PP., 2011 doi:10.1029/2010JD015452
    Observed surface warming induced by urbanization in east China

  3. But isn’t it amazing that this urban heat has NO EFFECT on the land thermometers in the expanded urban areas

    (according to BEST, anyway) 😉

  4. That’s not how I read that abstract. It is urban sprawl they want to prevent. This is why Agenda 21 is such a useful tool in what is called in the US the Regional Equity Movement. I know from reading the new economics foundation’s work in the UK that the idea is international. I do not know the specific vehicles in Australia apart from ICLEI and IBM’s Smarter Cities Initiatives globally. That pushes the System of System mentality that takes evolved, unplanned social institutions and cultivates the idea that they can be redesigned and implemented by political fiat. Just need to cultivate consensus among enough transformed “New Thinkers.”

    It is no accident Arizona State runs the largest center for Sustainability in the US. Which of course has little to do with the environment or temps and everything to do with control and money.

    I know from my work involving what is really going on in Australian education that this cultivated Newmindedness and non-Axemakers Mind is relevant here as well. Moreover this link will show the fit with the Regional Equity Movement so that readers can be on the look out for that statist tool as well.


    I have mentioned before that Australia is a part of the Belmont Forum and thus the Future Earth Alliance mentioned in the post. It is located in Sweden and works with the UN agencies to transform Western societies and economies around Sustainability. Including personal behaviors and how people think. Or whether they can.

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