From the University of Maryland Center for Environmental Science, somebody finally gets it. We’ve changed our local climates significantly, and the plants have figured this out long ago.
Mid-Atlantic suburbs can expect an early spring thanks to the heat of the big city
If you’ve been thinking our world is more green than frozen these days, you’re right. A recent study has found that spring is indeed arriving earlier – and autumn later – in the suburbs of Baltimore and Washington, D.C. The reason? The urban landscape traps heat in the summer and holds it throughout the winter, triggering leaves to turn green earlier in the spring and to stay green later into autumn. The result is a new, extended growing season.
Scientists used high-resolution satellite data collected over the past 25 years to look at the number days that trees have green leaves in the forests of the Mid-Atlantic. The study found that urban heat islands affected the growing season in areas within 20 miles of the city. As a result, gardeners may have more time to grow their vegetables and plant new varieties.
The longer growing season also has a profound impact on forests. Forests are, in effect, the world’s air filters. Green leaves on trees turn carbon dioxide – a greenhouse gas that traps heat in our atmosphere – into oxygen. Carbon dioxide also helps trees grow since they use energy from the sun to convert the gas into plant matter. A longer growing season could change how quickly forests grow and increase the amount of carbon dioxide taken out of the atmosphere.
“Everything changes when the leaves turn green,” said the study’s lead author Dr. Andrew Elmore of the University of Maryland Center for Environmental Science. “Trees start pumping water into the atmosphere. They take carbon dioxide out of the atmosphere. They make sugars and build plant tissue. It’s as if the entire landscape goes from exhaling to inhaling.”
The study also pinpointed other factors that influence the timing of spring and autumn in areas outside the influence of urban heat islands, including the elevation of the landscape, proximity to tidal water, and cold air drainage in small valleys.
Not all forests are the same, however, and predicting which forests will grow faster during a longer growing season requires detailed satellite measurements. This study is the first to apply high-resolution satellite data to the problem. “We are trying to understand how forests function so we can understand how they might respond to global warming,” said Dr. Elmore. “With more detailed data, we can do better job of predicting what might happen to a forest impacted by urbanization, for instance.”
The study, “Landscape controls on the timing of spring, autumn, and growing season length in mid-Atlantic forests,” was published in the February issue of Global Change Biology by Andrew Elmore and Steven Guinn of the University of Maryland Center for Environmental Science, Burke Minsley of the U.S. Geological Survey, and Andrew Richardson of Harvard University.
UNIVERSITY OF MARYLAND CENTER FOR ENVIRONMENTAL SCIENCE
The University of Maryland Center for Environmental Science unleashes the power of science to transform the way society understands and manages the environment. By conducting cutting-edge research into today’s most pressing environmental problems, we are developing new ideas to help guide our state, nation, and world toward a more environmentally sustainable future through five research centers—the Appalachian Laboratory in Frostburg, the Chesapeake Biological Laboratory in Solomons, the Horn Point Laboratory in Cambridge, the Institute of Marine and Environmental Technology in Baltimore, and the Maryland Sea Grant College in College Park. www.umces.edu
UPDATE: kadaka writes in comments-
Paper found, can be freely downloaded, 3.25MB pdf.
This is an Accepted Article that has been peer-reviewed and approved for publication in the Global Change Biology, but has yet to undergo copy-editing and proof correction. Please cite this article as an “Accepted Article”; doi: 10.1111/j.1365-2486.2011.02521.x
http://andrew.elmore.cc/pubs/Elmore_gcb2521.pdf
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Although the article does not directly say it, it is also likely that increased CO2 concentration in urban areas has played a role in extending the growing season. It cannot be said because that gets too close to admitting that additional CO2 has some beneficial effects.
“We’ve changed or local climates” = our local?
“A longer growing season could change quickly forests grow ” = change how quickly?
[Thanks, fixed -w]
The study found that urban heat islands affected the growing season in areas within 20 miles of the city.
Perhaps we need to redefine ‘rural’ WRT UHI. It is easy to conceive of a rural site, unchanged, with the exception of a city only 10 miles away. That the encroachment of effect from UHI has a 20 mile radius, should exclude many sites thought to be unaffected.
I wonder if trees put more water out than they take in? They split water to make O2 as part of photosynthesis. And they require water for growth. Here in New Orleans it is particularly obvious because we have a lot of warm weather but the plants all have a huge growth spurt after a heavy rain.
Water is released as starch and cellulose are synthesized by the plant though, so I don’t know what the net balance is.
How long did it take them to figure out what residents who’ve lived in those areas knew for years?
This is ridiculous: the Team and the IPCC have clearly stated UHI is grossly overstated and should be ignored as a factor in interpreting historical temperature data.
Look at what Wikipedia, the font of all knowledge on global warming, has to say about UHI:
“Despite concerns raised about its possible contribution to global warming, comparisons between urban and rural areas show that the urban heat island effects have little influence on global mean temperature trends”.
The fact that most temperature monitoring stations are located in urban areas is therefore irrelevant.
Paper found, can be freely downloaded, 3.25MB pdf.
http://andrew.elmore.cc/pubs/Elmore_gcb2521.pdf
I see the ‘local UHI warming’ effect every year. Dandelions always bloom 5 to 7 days earlier outside my office window than at my lower density neighborhood 4 miles away. 42N
ABC News ran a report Wednesday on their nightly news broadcast saying it was green house gases causing our early spring, and spring would be earlier and earlier as greenhouse gas emissions rise and the world continues to warm.
The same broadcast they also had a story on this year’s mild and dry winter, caused by the same culprit, AGW.
“Carbon dioxide also helps trees grow …”
Perhaps just a wee bit understated?
palm slaps forehead.
Another hey its reality study…
Yes warmer temps help plants grow which in turn means more, bigger plants… which in turn means more CO2 being used and converted to O2… also means more food produced. Why can’t I get 100k in grants to state well known facts?
“We are trying to understand how forests function so we can understand how they might respond to global warming,” said Dr. Elmore.
Yup, he just had to say that. But urbanization is not “global warming.” Oh, well. At least this was based on actual observation, no models to be found.
Notice that the map is in growing days not in delta T. However a change from a growing season of 150 days to a growing season of 210 days (2 months) is a heck of a lot for a distance of about 10 miles.
Apologies for the off-topic question, or if this serious issue has been dealt with somewhere else (impossible to read it anyway!), but what’s up with the the pale grey, all-caps and sans-serif microscript in the comments section? It’s as if someone combined all typographical boo-boos which make texts unreadable. Screen reading speeds are already lower by as much as 30% compared to traditional black type on white paper and the added tiny point size, harder to read sans-serifs and the low contrast between type and screen background make me suspect a psy-ops from the Warmies. Would have DeSmog’s mark of “sophistication,” methinks.
On the other hand, I think this alarming typographical blight appeared first on Willis’ article. That’s enough evidence to collectively blame Willis, I rather than to flog the Warmist dead horse. Blaming Willis is a hallowed custom here and results in colourful zingers from him which make for much better reading then the anemic whining and sniffling from the Warmies.
Great article! However, the cities themselves appear to be coded in gray with no growing season indicated. But the suburbs do tend to be oranger than the rest of the map. Contrary to the caption, there is no actual red on the map that I can find.
Another problem is that the cities tend to be at lower elevations than most of the countryside, and therefore run warmer already. A better map would adjust for altitude. As you go west, the elevation rises rapidly, but if the Delmarva peninsula is relatively flat it may be the best comparison. What’s its max elevation? For some reason, there is also a lot of gray in the western hills.
OT, but one thing that has always bothered me is whether Delmarva has an older geographical name that isn’t based on the colonies that happened to split it.
What grows when is the only accurate indicator of of climate change, And the trees say: “its the UHI stupid!!”
You only have to listen to any Weather Forecast. Every one states that the temperatures will be higher in the Cities and large towns than in the countryside. Usually at least a couple of degrees difference..
Coutrysides always have the Frost first. It is so obvious and yet so ignored.
Wha…wha happen’? Did WUWT consumer relations just hit a switch upon my kvetching or am I suffering from post-Purim effects. I’d rather deal with the traditional snakes on the walls.
UHI, solar activity, CERN, natural variation – so much thrown out before looking around for what could be left. All to explain a short-term temperature rise in populated land areas where cooling exists elsewhere and the atmosphere and oceans show next to nothing in trend. There’s a Shakespeare comedy in here somewhere (Much Ado About Nothing X Midsummer Night’s Dream) – unless tragedy ensues.
It’s getting so obvious all the action is about to move to acidification. Their minds are made up. They just need the right excuses.
Hmm – big negative feedback – we aren’t supposed to talk about this sort of thing outside the house. The long-stalled climate science
http://wattsupwiththat.com/2012/03/07/under-the-radar-the-nas-report/
could sure use more engineers who deal with negative feedback in nearly all systems.
“We are trying to understand how forests function so we can understand how they might respond to global warming,” said Dr. Elmore.
And yet they still can’t make the leap that this same UHI is why urban weather stations showed warming. Rural stations showed little to no warming. They are halfway there. Keep going with the thought process guys.
Since the study area is near the ocean and tends to be more humid than other areas, say Arizona, Colorado or parts of California, I wonder if the affect is more pronounced there. I think that it’s possible that some urban areas, Denver for example, where large masses of cold, dry air blow in and the temps stay below freezing for longer periods, may not see the same effect. YMMV.
It is easy to prove to yourself that UHI is real. Simply go to Google and type in “your local city, Wunderground temperature”, then scroll down to the bottom and you will find a number of temperature measurement stations near you. You can study the individual measurement stations by clicking on the name of each station; among other things a location map will appear. You can try this for several weather conditions and times of day but you will find the temperature range to be about 5 degrees F. By studying the data you can eliminate any station(s) that is/are obviously incorrect.
There are also flyover data, including Paris France, showing how UHI rises and then drops as one flies over buildings then parks and open areas. The UHI impact lasts for 25 miles or so.
The problem that I see is many of the temperature measurement stations used by the Climatologists are located in and near cities, airports and other developed locations. The UHI effect decreases as one leaves the developed areas, reaching normal climate temperature in 25 miles or so. The temperature data in the UHI areas is then homogenized by Hansen et al. This number fiddling spreads the UHI effect over an area much greater than 25 miles. Hansen makes so makes so many numeric mistakes, I no longer trust him to do anything correct. Stephen McIntyre has wiped his butt many times yet Hansen never seems to learn to review his work.
I’m calling BS on this. Since I live here, I feel I can comment. The whole area is filled with asphalt roads and red brick buildings. They definitely trap heat on warm summer nights. However, when winter rolls in with any sort of wind, we basically do what the prevailing wind does. Our temp just swung 30F in a couple days because of a warm front. And went right back down with the cold front last night. I’m downtown, so, I get the maximum heat island effect. I’m saying that the heat island doesn’t work by averages…. it only works under specific conditions. If you have a low wind day with a hot sun, and a low wind night, the town will be warmer. If a wind comes up at night with a low temperature, you go almost as low as the suburbs fairly quickly.
You can see variations in temperature just driving a few miles. Some places are shaded by hills and don’t warm easily. Sometimes in winter, the bottoms of hills will freeze first. THe suburbs of Baltimore are anything but that, at this point. You have lots and lots of asphalt, huge traffic problems, and businesses popping up along major roads. So, the conclusion that the heat island of the suburbs is an extension of the city’s heat island is false. The suburbs would generate their own heat island even if the city were wooded.
The map that they have is a growing season map. The season length depends upon when you have a freeze. The longest seasons are near the water (no surprise) and the shortest seasons are on the tops of hills (get coldest first). This business about suburbs receiving the city heat island effect is nonsense and could easily be shown to be false by overlaying a season length anomaly map with a map of new construction along the I-95 corridor leading out of Baltimore. You will get a perfect match. I haven’t done this calculation, but, I have watched the relentless development of former farm & marsh land over the last 15 years.
Do me a favor and call BS on this with these authors. Ask them to overlay development with growing season anomaly.
I’d love to see an overlay of those areas where growing seasons have been lengthened because of UHI, and the official climate stations.