It turns out that urban heat output
is far more effective than originally thought and it certainly is in a position
to be leveraged by the jet stream just as El Nino is leveraged. That is still a long was from a complete
answer. That will take decades of
observation and analysis to make clear.
It is also the one factor that
has hugely modified our temperature collecting protocol and makes our historical
data pretty dicey since it is impossible to properly correct with anything
other than a fudge factor.
We discussed this several years
ago and reviewed quite a bit of heated material. My sense is that it is part of an envelop of
interacting variables that far too difficult to safely resolve into a useful
predictive tool set. Since then we have
seen global temperatures flat line for fifteen years completely delinking from
the CO2 hypothesis which was fuzzy anyway.
However it flat lined at a warmer state so the present plateau is a
plausible half degree above the prior state.
All this fits nicely with out Holocene expectations after our recovery
from the Little Ice Age.
It is warmer and that is good
news. The bad news is that it could now get
cooler or worse, precipitously cooler as it is wont to do. If one of my conjectures were to hold up, we
are a few centuries away from that.
Study finds energy use in cities
has global climate effects
by Staff Writers
The heat generated by everyday energy consumption in metropolitan areas
is significant enough to influence the character of major atmospheric
circulation systems, including the jet stream during winter months, and cause
continental-scale surface warming in high latitudes, according to a trio of climate
researchers that includes Ming Cai, a professor in Florida State
University
Led by Guang Zhang, a research meteorologist at Scripps Institution of
Oceanography at the University of California, San Diego, the scientists report
in the journal Nature Climate Change that waste heat released in major cities
in the Northern Hemisphere causes as much as 1 degree C (1.8 degrees F) of
continental-scale winter warming in high latitudes of the North America and
Eurasian continents. They added that this effect helps to explain the disparity
between actual observed warming in the last half-century and the amount of
warming predicted by computer models that only include anthropogenic greenhouse
gases and aerosols.
The study, "Energy Consumption and the Unexplained Winter Warming
Over Northern Asia and North America ,"
appears in online editions of the journal on Jan. 27. The study was funded in
part by the National Oceanic and Atmospheric Administration's Climate Program
Office.
Cai, Zhang and Aixue Hu of the National Center for Atmospheric Research
in Boulder, Colo., considered the energy consumption - from heating buildings
to powering vehicles - that generates waste heat release. The world's total
energy consumption in 2006 was 16 terawatts (one terawatt equals 1 trillion
watts). Of that, 6.7 terawatts were consumed in the 86 metropolitan areas
considered in this study.
"The burning of fossil fuel not only emits greenhouse gases but
also directly effects temperatures because of heat that escapes from sources
like buildings and cars," Hu said.
The release of waste heat is different from energy that is naturally
distributed in the atmosphere, the researchers noted. The largest source of
heat, solar energy, warms the Earth's surface. Atmospheric circulations
distribute that energy from one region to another. Human energy consumption
distributes energy that remained dormant and sequestered for millions of years,
mostly in the form of oil or coal. Though the amount of human-generated
energy is a small portion of that transported by nature, it is highly
concentrated in urban areas.
"The world's most populated metropolitan areas, which also have
the highest rates of energy consumption, are along the east and west coasts of
the North American and Eurasian continents, underneath the most prominent
atmospheric circulation troughs and ridges," Cai said. "The
concentrated and intensive release of waste energy in these areas causes a
noticeable interruption to normal atmospheric circulation systems, leading
to remote surface temperature changes far away from the regions where the waste
heat is generated."
The authors report that the influence of urban heat can widen the jet
stream at the extratropics, or area outside the tropics. They add that the
heating is not uniform. Partially counterbalancing it, the changes in major
atmospheric systems cool areas of Europe by as
much as 1 degree C, with much of the temperature decrease occurring in the
fall.
The study does not address whether the urban heating effect disrupts
atmospheric weather patterns or plays a role in accelerating global warming,
though Zhang said drawing power from renewable sources such as solar or wind
provides a societal benefit in that it does not add net energy into the
atmosphere.
Zhang said the climate impact this research studied is distinct from
the so-called urban heat island effect, an increase in the warmth of cities
compared to unpopulated areas caused by land use changes. Such island effects
are 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 areas
collectively can warm the atmosphere remotely, thousands of miles away from the
energy consumption regions," Zhang said. "This is accomplished
through atmospheric circulation change."
They also find observational evidence indicates that the waste heat
can be the "missing forcing" that would account for the discrepancy
between the observed temperature change and that is simulated in computer
models forced only by anthropogenic greenhouse gases and aerosols. They
suggest that the influence of energy consumption should be considered, in
addition to heat-trapping gases and aerosols, as necessary anthropogenic
factors in computer models to predict the future climate.
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