It describes longer growing season but less productivity.

Havent found a retraction! Is it still current thinking in certain corners of NASA?

http://earthobservatory.nasa.gov/Newsroom/NasaNews/2000/200002211661.html

RELEASE NO: 00-23

URBAN SPRAWL REDUCES ANNUAL PHOTOSYNTHETIC PRODUCTION

A study of the impact of urbanization and industrialization over the past seven years using satellites shows that annual photosynthetic productivity can be reduced by as much as 20 days in some areas where urbanization is intense, not unlike turning the lights off in a greenhouse during the growing season.

The study also reveals that urbanization may be creating vast heat islands that can actually lengthen the growing season, but do not improve the productivity of the land..

NASA Goddard Space Flight Center (Greenbelt, Md.) researcher Dr. Marc L. Imhoff presents his findings during a news media briefing at the 2000 American Association for the Advancement of Science (AAAS) Annual Meeting

According to Imhoff’s research, urbanization and industrialization have resulted in the development of mega-cities and urban and suburban sprawl. The environment is altered as a result of replacing land cover with roads, housing, and commercial and industrial structures…

..A most interesting finding according to Imhoff was that urbanization seems to elongate the growing season, yet still reduces the overall productivity of the land. “…. “This could be demonstrating a profound urban heat island effect and have implications in climate change, especially in the northern Hemisphere where urban development is most intense.”

For supporting images: http://svs.gsfc.nasa.gov/search/Keywords/URBAN.html

This text derived from http://www.gsfc.nasa.gov/news-release/releases/2000/00-23.htm

REPLY: Anne, nice try, but no. I’m not measuring the waste heat of the car in front of me. I purposely chose that time of night because there was so little traffic, and I was careful to avoid any cars ahead.

Anthony, perhaps you didn’t notice, I was answering Ric Werme, not commenting on your article. I was well aware that you drove at night.

“Everyone acknowledges the reality and the scale of UHI…”

Half right, John.

The problem is the scale. The UN/IPCC incorrectly minimizes the effect of the UHI influence. The UHI effect is present, and that effect is much greater than the UN/IPCC assumes in its computer modeling.

If the UN/IPCC were honest about the effect of the UHI adjustment, the scientific community would see that the only credible measurements are those that rigorously adjust for external influences, preferably by siting surface stations well away from urban heat sources.

Crossing Westminster Bridge yesterday after the famous snow… the pavement was divided by a clear line down the middle, bone dry roadside, dripping wet riverside. Mind you, there could be a “fan” effect as well as warming from cars.

REPLY: “Seems improbable”, but the fact is that even stations in the absolute middle of nowhere are affected by microsite biases that are not accounted for. The fact is that rural vs urban categorizations have been shown to be wholly unrepresentative of the measurement environment around the thermometer. For example, here’s a “rural” station, which is badly polluted.

Miami, AZ USHCN station shown here

And there are plenty more where that came from.

The rural -vs- urban assignment is essentially useless for determining potential bias impact on the thermometer. Where large scale UHI might not be can easily be replaced or even be greater in bias by local site issues. Just moving the thermometer to an improper setting can dwarf UHI effects.

And, none of theses studies by Hansen, Jones, Parker, et al even touch on it. The are absolutely clueless about the measurement environment because they never look at the experiment in progress themselves. Any scientist that doesn’t look at where the data is gathered and assure themselves of it’s integrity, relying on the face value of the data aloine is not truly a scientist in my book.

As for that 2% well, we see the problem elsewhere too, as the US system is supposedly the best. Do you really think that the same sorts of problems I’ve documented only exist in the USA? Seems improbable that would be true. Human folly is universal. – Anthony

Ric Werme (05:07:28) :

A little more seriously, I don’t have hard data, but I’ve noticed that between my usual parking place at work (shaded in the afternoon, at the bottom of a short hill going up to self-storage place) and the Turnpike heading north, I’ll see a 2-3 F rise. Some of it may be from sun, the temperature sensor is in the exterior rearview mirror, but I think most is from the hillside and car being in the shade at work.

How is traffic? I have done some quick calculations on how much heat a car dumps, and it is not negligable. May be you are just measuring the waste heat of the car in front of you.

That ranks a high 2nd on my list of culprits. The road is asphalt, widened from 4 lanes several years ago. Traffic does move at or above the speed limit now. That, combined with solar warming during the afternoon is likely significant.

I haven’t noticed a similar effect on cloudy days – then again, I haven’t looked, I should, though there is something to be said for watching traffic, not thermometers.

REPLY: Anne, nice try, but no. I’m not measuring the waste heat of the car in front of me. I purposely chose that time of night because there was so little traffic, and I was careful to avoid any cars ahead.

Anne and I are talking about Nashua NH at 1730 and a sensor in a external rearview mirror (black housing), not Reno at night with good equipment.

Nobody here is saying UHI accounts for all the recent warming. Please correct your representation of skeptics as saying “The apparent rise of global average temperatures is actually an illusion due to the urbanization of land around weather stations, the Urban Heat Island effect”. People here just note that surface records have been shown to be suspect regarding UHI, and that this evidence suggests the IPCC corrections are way too small.

My take is that truly rural stations tend to show either no trend, or a cooling trend over the las 100 years, while those closer to urban areas show mostly a warming trend. Then adjustments occur, for no logical reason, on those rural stations, making the trend change based on other stations up to 1500km distant. Completely ludicrous. It tells me that even if UHI isn’t a major factor in the surface record, GW aint global.

‘fewer cells’ should read ‘fewer stations.’

Apologies.

No I do not make that that assumption. In GISTEMP, for example, the contribution of each grid cell to the global mean is identical (after weighting for latitude band) regardless of the number of stations within it. So the contribution of a cell with relatively dense station coverage (eg Reno, presumably) and that of a grid cell with fewer cells (e.g.in rapidly-warming Siberia) to the global mean is identical.

I always thought ‘Bollocks’ was a British coinage. Interesting to see it is used over the pond.

REPLY: Still bollocks. Even with such cell weighting, the majority of stations are still being impacted by ubanization though city scale UHI as well as microsite urbanization issues, thus UHI is contributing to the signal on a broad scale, and .05 doesn’t begin to cover it.

I can say with certainty, that the overwhelming majority of stations we’ve studied so far are affected with urbanization issues, either on a city scale and/or microsite scale. only 4% of stations surveyed are truly pristine.

As surfacestations.org has shown, even remote stations can suffer from localized urban effects. So while IPCC, Hansen, Parker and other armchair data jockeys claim they have it under control, the simple fact is they have absolutely no idea of the magnitude of the local effects nor have they even lifted a finger to study the issue. They just dismiss it with a wave of the hand.

Parker’s ridiculous “cool parks” statement demonstrates his complete lack of understanding of the measurement system and it’s problems, thus rendering his conclusions moot. – Anthony

I know this from first hand temp readings with 2 Nimbus NTL thermometers with an accuracy of .02 degrees that I had up several years ago while living in the country 15 miles from Fresno. I had several thermometers up at the same time just to verify each other as I didn’t believe them at first. Also one can easily look at the NWS Hanford Regional Temperature Roundup to see the UHI effect for themselves.

It’s so upsetting that some try to be so smart and in doing so miss the obvious. Some just don’t know how to objectively take a step back and look at the big picture. Some are just to prideful, which clouds their judgement. Sorry for the rant, just wanted to present my thoughts. Thank You again for your work Anthony.

“Adelaide is 1.5C hotter today than it was almost 100 years ago. This is altering the coastline and climate, new research shows.”

“The metropolitan urban jungle is trapping the day’s warmth after sunset more than before.
The heat radiates at night and keeps temperatures higher than if the heat could dissipate into the atmosphere.”

“University of Adelaide researchers have found this heat is drawing the afternoon sea breeze into land more quickly than in previous decades making sea breezes stronger”

“The breezes affect the size of waves in Gulf St Vincent. That affects the movement of sand and sediment along the gulf, causing beach erosion.”

The research was undertaken by Civil, Environmental and Mining Engineering honours students.

If, according to the IPCC, UHI effects are negligible and local:

* this research appears to show that UHI has added at least 1C to Adelaide’s average temperature which is around the same increase attributed to CO2

* how ‘local’ is ‘local’ – the effects of the Adelaide UHI cover St Vincent Gulf which is 90 miles long and 45 miles wide?

* Adelaide is a coastal city in South Australia with a population of approx 1 million. What effect do much larger cities have on weather patterns and climate that is blamed on CO2?