It turns out that urban heat outputis far more effective than originally thought and it certainly is in a positionto be leveraged by the jet stream just as El Nino is leveraged. That is still a long was from a completeanswer. That will take decades ofobservation and analysis to make clear.
It is also the one factor thathas hugely modified our temperature collecting protocol and makes our historicaldata pretty dicey since it is impossible to properly correct with anythingother than a fudge factor.
We discussed this several yearsago and reviewed quite a bit of heated material. My sense is that it is part of an envelop ofinteracting variables that far too difficult to safely resolve into a usefulpredictive tool set. Since then we haveseen global temperatures flat line for fifteen years completely delinking fromthe CO2 hypothesis which was fuzzy anyway. However it flat lined at a warmer state so the present plateau is aplausible half degree above the prior state. All this fits nicely with out Holocene expectations after our recoveryfrom the Little Ice Age.
It is warmer and that is goodnews. The bad news is that it could now getcooler or worse, precipitously cooler as it is wont to do. If one of my conjectures were to hold up, weare a few centuries away from that.
Study finds energy use in citieshas global climate effects
by Staff Writers
http://www.terradaily.com/reports/Study_finds_energy_use_in_cities_has_global_climate_effects_999.html
The heat generated by everyday energy consumption in metropolitan areasis significant enough to influence the character of major atmosphericcirculation systems, including the jet stream during winter months, and causecontinental-scale surface warming in high latitudes, according to a trio of climateresearchers that includes Ming Cai, a professor in
Led by Guang Zhang, a research meteorologist at Scripps Institution ofOceanography at the University of California, San Diego, the scientists reportin the journal Nature Climate Change that waste heat released in major citiesin the Northern Hemisphere causes as much as 1 degree C (1.8 degrees F) ofcontinental-scale winter warming in high latitudes of the North America andEurasian continents. They added that this effect helps to explain the disparitybetween actual observed warming in the last half-century and the amount ofwarming predicted by computer models that only include anthropogenic greenhousegases and aerosols.
The study, "Energy Consumption and the Unexplained Winter WarmingOver Northern Asia and
Cai, Zhang and Aixue Hu of the National Center for Atmospheric Researchin Boulder, Colo., considered the energy consumption - from heating buildingsto powering vehicles - that generates waste heat release. The world's totalenergy consumption in 2006 was 16 terawatts (one terawatt equals 1 trillionwatts). Of that, 6.7 terawatts were consumed in the 86 metropolitan areasconsidered in this study.
"The burning of fossil fuel not only emits greenhouse gases butalso directly effects temperatures because of heat that escapes from sourceslike buildings and cars," Hu said.
The release of waste heat is different from energy that is naturallydistributed in the atmosphere, the researchers noted. The largest source ofheat, solar energy, warms the Earth's surface. Atmospheric circulationsdistribute that energy from one region to another. Human energy consumptiondistributes energy that remained dormant and sequestered for millions of years,mostly in the form of oil or coal. Though the amount of human-generatedenergy is a small portion of that transported by nature, it is highlyconcentrated in urban areas.
"The world's most populated metropolitan areas, which also havethe highest rates of energy consumption, are along the east and west coasts ofthe North American and Eurasian continents, underneath the most prominentatmospheric circulation troughs and ridges," Cai said. "Theconcentrated and intensive release of waste energy in these areas causes anoticeable interruption to normal atmospheric circulation systems, leadingto remote surface temperature changes far away from the regions where the wasteheat is generated."
The authors report that the influence of urban heat can widen the jetstream at the extratropics, or area outside the tropics. They add that theheating is not uniform. Partially counterbalancing it, the changes in majoratmospheric systems cool areas of
The study does not address whether the urban heating effect disruptsatmospheric weather patterns or plays a role in accelerating global warming,though Zhang said drawing power from renewable sources such as solar or windprovides a societal benefit in that it does not add net energy into theatmosphere.
Zhang said the climate impact this research studied is distinct fromthe so-called urban heat island effect, an increase in the warmth of citiescompared to unpopulated areas caused by land use changes. Such island effectsare mainly a function of the heat collected and re-radiated by pavement,buildings and other urban features.
"What we found is that energy use from multiple urban areascollectively can warm the atmosphere remotely, thousands of miles away from theenergy consumption regions," Zhang said. "This is accomplishedthrough atmospheric circulation change."
They also find observational evidence indicates that the waste heatcan be the "missing forcing" that would account for the discrepancybetween the observed temperature change and that is simulated in computermodels forced only by anthropogenic greenhouse gases and aerosols. Theysuggest that the influence of energy consumption should be considered, inaddition to heat-trapping gases and aerosols, as necessary anthropogenicfactors in computer models to predict the future climate.
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