Today’s Chicago Tribune asked Are farmers cooling Chicago’s summers? The article begins
Amid one of the warmest springs on record in Chicago, and renewed worries about our warming planet, how is that late summer days across the Midwest are cooling?
Evidently, David Changnon, a climatologist from UIUC NIU has been studying the changes in the local weather. Late summers are cooling but the dew point is higher. The article Chagnon’s theory about this particular non-ghg climate change phenomena.
“While we’re seeing fewer really hot days, we’ve created dew points in Chicago and around the Midwest that are unheard of,” Changnon said. “And it begs the question, ‘How the heck can we do that?'”
Changnon’s theory, backed by more than a decade of research, is that more densely planted corn and soybean fields scattered across the Midwest are changing the regional climate by releasing more water vapor into the atmosphere. The more water vapor that reaches the atmosphere, the higher the dew point, and the fewer extremely hot summer days.
In other words, while some still question whether people are to blame for changing weather patterns around the globe, farmers around the Midwest are already altering the region’s climate in significant ways, Changnon said.
“It’s a different type of human-induced climate change that has certainly played a role in the changes to Illinois’ weather,” said Jim Angel, a climatologist at the Illinois State Water Survey in Champaign. “It’s kind of an interesting way to look at all this.”
Interesting, but also crucially important, Changnon said, as climate scientists ponder two intriguing questions related to this research: Have Midwest farmers accidentally created a barrier to soften the most severe effects of global warming? And if so, can it be repeated elsewhere?
The article is a fun read. I have to admit, I never expected to read an article that suggested the densely planed corn fields of Illinois might result in cooler, but muggier late summer days in Illinos!
Nice to hear somewhere’s warm this spring!
We’re shivvering over here in Blighty! Forecasts of -4C in places tonight and daytime temps have struggled to get over 10C here in the Midlands.
Still, the paper adds more weight to Pielke (How does one pronounce his name?) Snr’s theories about human activities altering climate due to factors other than CO2 emmissions.
When that President chap of yours finds out, it’ll give him something else to tax!
Adam–
The past few weeks have been unusually cool, and we are running the furnace. Earlier on it was warm. Spring is always variable around here– but the trend has been for warmer springs.
One gram of living matter requires the transpiration of 100-1000g of water, which is released into the atmosphere.The living biomass is distributed non uniformly being several magnitudes higher on land then in the ocean ,and several magnitudes higher in the forests. Taking into account the leaf area, we can assume the leaf biomass is 4 times that of other land areas Therefore land and forest is an important part of the hydrological cycle.
I just wanted to point out that David Changnon is a professor of geography at Northern Illinois University at DeKalb IL, not UIUC.
Lucia, Since your neck of the woods is affected by El Nino (warmer conditions) I would expect that you should have had a warmer than usual winter this year… and now that El Nino is transitioning, I would expect things to cool, either to the average or below.
Jim Angel– Thanks. Fixed.
My friends from Illinois told me that spring there was “a week of mud between winter and summer”.
Changnon’s findings appear to confirm Roy Spencer’s hypothesis in his new book, The Great Global Warming Blunder: How Mother Nature Fooled the World’s Top Climate Scientists.
I’ve heard several older people observe that the irrigation in eastern Nebraska has raised the humidity and increased haze. If true, that could ultimately affect the weather a slightl bit. All of those center pivots pumping away make the country look like a Chinese checkerboard when viewed from a an airplane at 30K ft.
hmccard:
I thought Spencer was going on about unforced variability. This sort of thing is more in the Pielke line: land-use changes.
Carrot–
Yes. I think this is more “Pielke” than “Spencer”. It’s an interesting notion, and even more interesting if it turns out to be something useful.
Carrot eater and lucia,
I had in mind Spencer’s POV that clouds mask the underlying feedback mechanisms and whether or not the net effect is positive, negative or both. I also understood him to be questioning the conventional cilmate science thinking that warming absorbs water vapor therby forming clouds and that perhaps warming may directly cause the formation of clouds.
I interpreted Changnon’s research as showing that increased water vapor due to changes in land use caused a net cooling, Changnon didn’t speculate on whether or not late-day cloudiness and thunderstorms were caused by heating or high humidity. However, it appears to me that the net effect of the increase in relative humidity on temperature reflects the existence of a negative feedback mechanism.
Instead of UHI(Urban Heat Island), perhaps this is a case of RHI(Rural Humidity Island). BTW, Changnon is a nice guy. No heavy agendas.