Winnipeg Free Press - PRINT EDITION

Warmer winter? Thank Tokyo

Heat from big cities may warm Manitoba

  • Print

WASHINGTON -- Heat rising up from cities such as New York, Paris and Tokyo might be remotely warming up winters as far away as Manitoba, North Dakota and Alaska, a surprising study theorizes.

In an unusual twist, that same urban heat from buildings and cars may be slightly cooling the autumns in much of the Western United States, Eastern Europe and the Mediterranean, according to the study published Sunday in the scientific journal Nature Climate Change.

Meteorologists have long known cities are warmer than rural areas, with the heat of buildings and cars, along with asphalt and roofs that absorb heat. That's called the urban heat island effect, and it's long been thought the heat stayed close to the cities.

But the study, based on a computer model and the Northern Hemisphere, now suggests the heat does something else, albeit indirectly. It travels about 800 metres up into the air and then its energy changes the high-altitude currents in the atmosphere that dictate prevailing weather.

"Basically, it changes the flow," said Guang Zhang of the Scripps Institution of Oceanography in La Jolla, Calif. He wrote the paper with Aixue Hu at the National Center for Atmospheric Research in Boulder, Colo.

This doesn't change overall global temperature averages significantly, unlike man-made greenhouse gases that cause global warming. Instead, it redistributes some of the heat, the scientists said.

The changes seem to vary with the seasons and by region because of the way air currents flow at different times of the year. During the winter, the jet stream is altered and weakened, keeping cold air closer to the Arctic Circle and from dipping down as sharply, Hu explained.

The computer model showed parts of Siberia and northwestern Canada may get, on average, an extra 0.8 to one degree Celsius during the winter, which "may not be a bad thing," Zhang said. The effect isn't quite as much in Manitoba and northern North Dakota, where temperatures might be about half a degree warmer (0.3 C).

In contrast, Europe and the Pacific Northwest are cooled slightly in the winter from this effect. The jet-stream changes prevent weather systems from bringing warmer air from the Atlantic to Europe and from the Pacific to the U.S. Northwest, thus cooling those areas a bit, he said.

The biggest cooling occurs in the fall, but Hu said he's not quite sure why that happens.

Several outside scientists said they were surprised by the study results, calling the work "intriguing" and "clever." But they said it would have to be shown in more than one computer model and in repeated experiments before they could accept this theory.

-- The Associated Press

Republished from the Winnipeg Free Press print edition January 28, 2013 A7

Fact Check

Fact Check

Have you found an error, or know of something we’ve missed in one of our stories?
Please use the form below and let us know.

* Required
  • Please post the headline of the story or the title of the video with the error.

  • Please post exactly what was wrong with the story.

  • Please indicate your source for the correct information.

  • Yes

    No

  • This will only be used to contact you if we have a question about your submission, it will not be used to identify you or be published.

  • Cancel

Having problems with the form?

Contact Us Directly
  • Print

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

You can comment on most stories on winnipegfreepress.com. You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

Have Your Say

New to commenting? Check out our Frequently Asked Questions.

Have Your Say

Comments are open to Winnipeg Free Press print or e-edition subscribers only. why?

Have Your Say

Comments are open to Winnipeg Free Press Subscribers only. why?

The Winnipeg Free Press does not necessarily endorse any of the views posted. By submitting your comment, you agree to our Terms and Conditions. These terms were revised effective April 16, 2010.

letters

Make text: Larger | Smaller

LATEST VIDEO

Inside peek at Real Pirates, new Manitoba Museum exhibit

View more like this

Photo Store Gallery

  • MIKE APORIUS/WINNIPEG FREE PRESS BUSINESS - cow on farm owned by cattle farmer Lloyd Buchanan near Argyle Wednesday afternoon -see Larry Kusch's story  January 04/2006
  • Marc Gallant/Winnipeg Free Press. Local- Korea Veterans Association stained glass window at Deer Lodge Centre. Dedication with Minister of Veterans Affairs Dr. Rey Pagtakhan. March 12, 2003.

View More Gallery Photos

Poll

Should Premier Greg Selinger resign?

View Results

View Related Story

Ads by Google