Air Conditioning May Be Causing Global Warming

But maybe not the way you think. 

Via Anthony Watts, Oregon State Climatologist George Taylor sends in a picture of one of the official temperature measuring sites that feed into the databases that are used to track global temperature. 

Here is the official temperature plot from "rural" Forest Grove.  Note the "global warming" that really takes effect around 1984.


Of course, this change might (just call me a holocaust-denying skeptic) be due instead to the fact that the adjacent building installed an air conditioner about 1984 that vented hot air on the thermometer.  If you have never seen one, the vented white box on about 4 foot legs and the small white cylinder on the metal pole next to it are the weather station station. 


Of course, setting the measurement station on a pad of hot asphalt and next to a reflective building are also best practices for getting a thermometer to read high.  The aptly name Mr. Watts has been running a great series on temperature measurement issues in his blog - just keep scrolling.

Update: Andrew Watts found the location on Google maps when I could not, probably because I was looking for a semi-rural area outside of town.  But apparently, this is one of the fastest growing communities in Oregon, and, like with many measurement spots over the last 100 years, a hotter urban environment has enveloped the measurement point.  The location is on the left, and I zoomed straight out on the right, so the location is still in the center.


In 1900, this thermometer was measuring the temperature of miles and miles of pasture.  Today, it is measuring the temperature of acres of asphalt in the middle of a growing city.


  1. jens:

    The airconditioner hypothesis would have made more sense if:

    1) the "spike" continued to be at or over the 1984 levels
    2) there was some information that this airconditioner was moved or shutdown in 1985.

  2. Anthony:

    Its not the spike, its the plateau that maintains after that date.

  3. dearieme:

    When I was a schoolboy, the recording of the burgh's weather was left in my hands for part of one summer. (I suppose that it was normally done by a teacher and that he was away on holiday.) Looking back after decades of experience with experimental measurement, I am inclined to think that my readings might be the only ones I would ever trust. They are the only ones where I can currently be sure that there were no blunders, no guesses and no changes in the neighbourhood of the instruments.

  4. George Potts:

    This reminds me of a hearing test I recently took in a "sound proof" room at a local HMO. I mentioned to the tester that the noise from an air conditioner that was running to cool this room was making it difficult to hear some of the generated testing tones. She responded that the room got too hot without the air conditioner running. Ergo, this room, with all its expensive sound-proof baffling was made pointless by thoughtlessness.

  5. SuperMike:

    You must be one of those bloggers working for the oil companies to ruin the planet. Why do you hate eskimos, pacific islanders, polar bears and walruses too much to admit the truth? Two legs bad, four legs good!

  6. dearieme:

    By golly, George, an international phenomenon - I had an identical experience in a British National Health Service hospital.

  7. Bob:

    It fits with this...

    Study: California being warmed by urbanization
    Wed Mar 28, 2007 5:46 PM ET
    By Dan Whitcomb

    LOS ANGELES (Reuters) - Average temperatures across California rose slightly from 1950 to 2000, with the greatest warming coming in the state's big cities and mostly caused by urbanization -- not greenhouse gases -- authors of a study released on Wednesday said.

    The study found that average temperatures in California rose nearly 2 degrees Fahrenheit (nearly one degree Celsius) in the second half of the 20th century, led by large urban centers such as San Francisco and Southern California.

    "Everybody's talking about the carbon coming out of the SUV exhaust or the coal plant, but in the past 50 years in California the bigger impact has been urbanization and suburbanization," said Bill Patzert of NASA's Jet Propulsion Laboratory, one of the study's authors.

  8. Mike:

    Air conditioners do not create an increase in temperature because. All they're designed to do is move heat around. Air conditioners push the undesirable hot air from inside your house back outside again. Heat is constantly and spontaneously moving as long as there is a difference in temperature (Laws of Thermodynamics). People like air conditioners because they don't want to wait for this to happen spontaneously and for their impatience they it will cost them energy (literally and figuratively). If air conditioners did increase the globe's overall temperature they would be in violation of the most basic of all laws - the law of conservation of energy. That would make for some interesting science fiction.

  9. Captain Arbyte:

    Mike, air conditioners DO increase temperature because they are not perfectly efficient. (And they have to be, because they operate on thermodynamic principles.) They move heat from one area to another AND emit heat from inefficiency. The energy transformed into waste heat comes from the electricity powering the unit.

  10. Agammamon:

    Plus the AC does increase the temperature of the outside, which is what is important here.

    The thermometer measures the temp of its surface, which is being increased by the heat pumped out of the nearby building.

    On a related note, this just gives more credence to the enviro-loony groups that want us to live in caves - its all this asphalt, buildings, and motors that are heating up the planet.

  11. la petite chou chou:

    But don't you find the most ironic part of it is that big cities tend to be really liberal with lots of environmental groups (like Portland, Oregon) but these cities are nothing but concrete as far as the eyes can see.

    Also, thanks for the clarification captain. As we know, heat is the result of work being done. In this case basically, making cool air by pulling hot air through cold coils, which are only cold because of the electricity working to do such.

    Wikipedia says "In the vapor-compression refrigeration cycle, heat is transferred from a lower temperature source to a higher temperature heat sink. Heat naturally flows in the opposite direction, and due to the second law of thermodynamics work is required to move heat from cold to hot. A food refrigerator or freezer works in much the same way; it moves heat out of the interior into the room in which it stands."

  12. Grey Swan:

    Mike - Air conditioners do increase the total heat energy in the world. They do not simply push air around, but rather use a large amount of energy that is tranformed into heat. Put an airconditioner in a room with no exhaust and it will get much hotter.

    While urban centers do create there own climate zones, that in no way disproves global warming. A simple look at our worlds poles or a Nothern Hemisphere Winter will suffice. These are different effects, but one does not negate the other. Also, global warming does not mean everywhere will get hotter (like California), it means places will get hotter on average.

    Grey Swan

  13. Pete:

    Windows has a bird's eye view of the location in case anyone's interested. Just click on "Hybrid" for the satelite/street view, and bird's eye for a fly-over view. It may be one of those things you have to view in IE, though.

  14. Gogeiger:

    Geiger-Air conditioning includes both thecooling and heating of air.
    It also cleans the air and controls themoisture level.
    Air Conditioning Contractors Directory for Cincinnati,
    Prescreened Home Improvement Professionals for Cincinnati.

  15. Julie Pew:

    I think my air conditioner makes my yard alot hotter. I really don't think it is my imagination. However, it gets between 111 and 118 here in the summer and I live in a mobile home, and I don't think I could survive without it.

  16. air conditioning Ontario:

    but no one cares, until its too late.