From PBS last night: From Rooftop to Alleyway, Chicago Fights Extreme Urban Heat With Greener Ideas
One of Chicago’s most beautiful and hidden gardens is located on top of City Hall, part of an effort to ‘green’ roofs in order fight rising temperatures. Hari Sreenivasan reports on the actions the city of Chicago is taking to mitigate climate change in an urban landscape.
Here’s the video report:
THOMAS PETERSON, Climatologist, National Oceanic and Atmospheric Administration: We look at temperature at rural stations and we look at temperatures at urban stations.
And we see if they are showing the same thing in the long-term trend variability and change. And they are showing the same thing in our record, both in the U.S. record and in the global record. What we find is when we account for the different factors that impact temperature at a location, we see that the temperature in urban sites is warming at about the same rate as temperature in rural sites.
From transcript at:
http://www.pbs.org/newshour/bb/climate-change/july-dec12/climate_10-09.html
======================================================
Dr. Peterson sidestepped the real seasonal heat issues for cities. It isn’t the trend, but the absolute temperatures. Heat waves born in urban heat islands aren’t so much about trends like 0.7C over the last century, but they are about the high temperature that day. Anybody who has ever watched a TV weather report or driven a car from downtown to the suburbs in the evening can see how cities are warmer and retain heat longer.
In a few days, I’ll be releasing a first ever live rural-urban temperature comparison project, never before done, that will help provide a near real-time window on this problem. Its something that should have been done a long time ago, and could easily have been done anywhere in NOAA and especially at NCDC. But NCDC’s Peterson and others don’t like the sorts of comparisons I’m about to make, which is why they don’t like to talk about the absolute temperature differences between urban and rural stations on national TV.
But I suppose his belief isn’t surprising, when you live in an homogenized data world, every temperature looks the same to them.
h/t to R. Cook
First you build a park on your roof, then you extend the roof to get more green area, then roofs from adjacent houses merge … and before you notice, you’re living in a cave.
But honestly, I am a fan of green roofs.
My roof’s been covered in green moss for ages, but I haven’t noticed any serious changes in temperature. Perhaps I should go and paint it white, or black, or something…
Albedo determines the percentage of solar energy absorbed by a surface (as heat). Greening a surface will in almost all cases decrease the albedo and hence increase the solar energy absorbed. That is increase the heat in the urban environment.
Greening decreases temperatures by increasing evapotranspiration (humidity).
Artificial rain would probably be cheaper and more effective.
Places with high and recent urbanization growth such as India and China should be able to provide all the data we’ll ever need about UHI
Interestingly enough, the local weather forecasts on our local BBC TV station, has started noting that temperatures in the countryside, will be a few degrees lower than the one’s on their charts, as we’re getting sub 10C overnight temperatures.
When I lived in the UK and watched local (midlands of England) weather forecasts there was a tacit assumption that it would be 3’C warmer in town that in the rural areas. UHI was never mentioned though.
All those air conditioned buildings pumping heat to the outside will also increase the UHI effect.
So what is this awful warming blamed on – the sunshine? – or 0.01% of the atmosphere?
Returning to the old way of “Turfing” our roofs may making it warmer indoors which may increase the demand for more Air Conditioning and increased fossil fuel use.
PS. Now that the “Hose-pipe ban” has been lifted in the UK the farmers find their potato – crops have rotted in the waterlogged soil. –
Water logged soil weighs a lot more than most “normal” roof coverings do so watch out for the possibility of collapsed roofs due to AGW in the future.
Seems like it would be difficult to get a good urban/rural comparison from official American records.. Nearly all of them are at airports, typically 10 miles away from dense cities. Airports have their own heat sources, but they’re not representative of mid-city temps.
Kindly rename UHI as “HI” as it significantly exists even in small towns and a comparison of small versus large cities is often used to discredit UHI as a cause of upward temperature trends.
Even small towns of 5000 people have undergone massive changes that have increased the temperature: trees are gone, single family homes are now high-traffic offices and multifamily, lawns have been replaced by black parking lots, traffic has increased. air conditiioning which was non-existant 50 years ago is now the norm, etc, etc, ….and towns are often located in valleys which trap this heat. Not uncommon to see them 5-10 degrees warmer than surrounding rural areas.
Maybe call it LTBCHI – “Little Town Big City Heat Island”
Even in the countryside there is a big difference in the amount of heat absorbed/radiated from different land surfaces. As a farm student I had to bicycle home several miles in the evening, and there was a very noticeable difference when passing by stubble fields ( light fawn colour ) which were quite cool, compared with fields that had been ploughed (dark brown ) which gave off a noticeable amount of heat. The ploughed fields had obviously absorbed a lot of radiation during the day, but would they lose all that extra during the night?
Which temperature would be the one to record as the correct rural temperature, stubble or plough?
Would the average temperature of the different land surfaces over 24 hours be the same?
If there was one hour of very hot sunshine in the afternoon, but the rest of the day was cool, would the average taken by adding the max and min temperatures for the day and dividing by two be skewed?
Green rooves are at the heart of a local business kerfuffle. Sod roofs are a local cultural tradition and so are the goats used to mow the grasses. A business has effectively servicemarked the use of goats and, with the connivance of the courts, demands royalties on goats mowing roofs.
Kasuha says:
October 10, 2012 at 1:35 am
I’ve always been tempted to live in a cave. Save lots on cooling costs, humidity control might be an issue. With the large panel televisions you could have closed circuit TV from the top of the hill and have a view too!
An underground house is an okay compromise too.
“Greening” the roof top at city hall at great expense and maintenance cost sounds like a good idea to combat the heat citywide since the Amazon jungle is so chilly.
Dear Anthony
I was going to compliment you and your work and bring in Professor Manley who had adjusted the CET because of urban devevlopment.
I went to Wikipedia to get a reference.
Manley, G., 1953. “The mean temperature of central England, 1698-1952.” Quarterly Journal of the Royal Meteorological Society, 79, (340), 242-261.
Manley, G., 1974. “Central England temperatures: monthly means 1659 to 1973.” Quarterly Journal of the Royal Meteorological Society, 100, (425), 389-405.
Both links are to the RMS site and state page not found?
Conspiracy or Cock up or The Team?
Sometimes I have to drive to and through Raleigh from where I live. Raleigh isn’t as big as other major metro areas, but it does exhibit the UHI effect nicely, especially on cool days. Last year I had to drive through Raleigh. When I left home I carefully watched the temperature on my car. The temperature was 4F higher in Raleigh than when I left that morning. Considering it takes me 45 minutes to get to central Raleigh, this wasn’t just the normal heating of the day. After I passed Durham on I-40, the temperature began to fall again. Returning home that evening, I noticed the same effect. If the UHI effect is live and well in a big suburb like Raleigh/Durham, how much more so in places with bigger downtowns.
I like the Idea of Green roof as long as the engineering can prevent dry rot and collapse.
My mother’s family pioneer NW Kansas home is still standing- it is a sod house,,,,
“every temperature looks the same to them.”. Yes. They are all shaded monetary green.
Sounds like an expensive annual replanting scheme will be required in Chicago with its freezing temperatures in the winter (enough to kill off the green roofs) and boiling heat in the summer? Or am I wrong, coming as I do from the UK with a much more moderate climate?
A couple items: 1. Chicago is a very odd city. 2. PBS is about to lose their Govt. subsidy. 3. Chicago also wants to put a violence tax on ammunition.
Now let me get this straight. The brokest city in the brokest county in the second brokest state in the brokest country in the history of the planet has a “Green Projects Administrator”?
Where do I get my money back?
polistra says:
October 10, 2012 at 4:35 am
Seems like it would be difficult to get a good urban/rural comparison from official American records.. Nearly all of them are at airports, typically 10 miles away from dense cities. Airports have their own heat sources, but they’re not representative of mid-city temps.
______________________
Assertions backed up by data?
****
In a few days, I’ll be releasing a first ever live rural-urban temperature comparison project, never before done, that will help provide a near real-time window on this problem. Its something that should have been done a long time ago, and could easily have been done anywhere in NOAA and especially at NCDC. But NCDC’s Peterson and others don’t like the sorts of comparisons I’m about to make, which is why they don’t like to talk about the absolute temperature differences between urban and rural stations on national TV.
****
Cool, Anthony! Maybe this can start a new trend (get it?)
Seriously, this’ll be interesting.
Grumpy says:
October 10, 2012 at 7:01 am
Sounds like an expensive annual replanting scheme will be required in Chicago with its freezing temperatures in the winter (enough to kill off the green roofs) and boiling heat in the summer? Or am I wrong, coming as I do from the UK with a much more moderate climate?
______________________
Why worry about the cost?
The government pays for it, after all.
Shucks, I forgot my sarc tag.