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[Nagraj Adve]

This post of mine should also convince all - except those diehards on the
loony Right - that the Sun is not responsible for the ongoing phase of
global warming.
Naga

On 2 February 2012 08:13, Nagraj Adve <nagraj.adve at gmail.com> wrote:

> Enough excess energy - over half a watt per metre squared - to light up a
> 40 watt bulb in a middle class home.
> Naga
>
>
>  <http://www.nasa.gov/>
>
> *National Aeronautics and Space Administration <http://www.nasa.gov/>*
>
> *Goddard Institute for Space Studies <http://www.giss.nasa.gov/>*
>
> Go to Main Content (press
> 2)<http://www.giss.nasa.gov/research/news/20120130b/#content>
> Go to Site Navigation (press
> 3)<http://www.giss.nasa.gov/research/news/20120130b/#mnav>
>
> *Goddard Space Flight Center <http://www.nasa.gov/centers/goddard/>
> Sciences and Exploration Directorate <http://sciences.gsfc.nasa.gov/sed/>
> Earth Sciences Division <http://sciences.gsfc.nasa.gov/610/>*
>
> *Research News*
>
> *Earth's Energy Budget Remained Out of Balance Despite Unusually Low Solar
> Activity*
>
> Jan. 30, 2012
>
> A new NASA study underscores the fact that greenhouse gases generated by
> human activity — not changes in solar activity — are the primary force
> driving global warming.
>
> The study offers an updated calculation of the Earth's energy imbalance,
> the difference between the amount of solar energy absorbed by Earth's
> surface and the amount returned to space as heat. The researchers'
> calculations show that, despite unusually low solar activity between 2005
> and 2010, the planet continued to absorb more energy than it returned to
> space.
>
> James Hansen, director of NASA's Goddard Institute for Space Studies (GISS)
> in New York City, led the research. *Atmospheric Chemistry and
> Physics*published the study last December.
>
> [image: conceptual image of the
> sun]<
> http://www.giss.nasa.gov/research/news/20120130b/619626main_solarcycle0281.jpg
> >
>
> A prolonged solar minimum left the sun's surface nearly free of sunspots
> and accompanying bright areas called faculae between 2005 and 2010. Total
> solar irradiance declined slightly as a result, but the Earth continued to
> absorb more energy than it emit throughout the minimum. An animation of a
> full solar cycle is available
> here<http://svs.gsfc.nasa.gov/vis/a020000/a020100/a020133/>.
> (Credit: NASA Goddard's Scientific Visualization Studio)
> + View larger image<
> http://www.giss.nasa.gov/research/news/20120130b/619626main_solarcycle0281.jpg
> >|
> TIFF
> format<
> http://www.giss.nasa.gov/research/news/20120130b/619627main_solarcycle0281.tif
> >
>
> Total solar irradiance, the amount of energy produced by the sun that
> reaches the top of each square meter of the Earth's atmosphere, typically
> declines by about a tenth of a percent during cyclical lulls in solar
> activity caused by shifts in the sun's magnetic field. Usually solar
> minimums occur about every eleven years and last a year or so, but the most
> recent minimum persisted more than two years longer than normal, making it
> the longest minimum recorded during the satellite era.
>
> Pinpointing the magnitude of Earth's energy imbalance is fundamental to
> climate science because it offers a direct measure of the state of the
> climate. Energy imbalance calculations also serve as the foundation for
> projections of future climate change. If the imbalance is positive and more
> energy enters the system than exits, Earth grows warmer. If the imbalance
> is negative, the planet grows cooler.
>
> Hansen's team concluded that Earth has absorbed more than half a Watt more
> solar energy per square meter than it let off throughout the six year study
> period. The calculated value of the imbalance (0.58 Watts of excess energy
> per square meter) is more than twice as much as the reduction in the amount
> of solar energy supplied to the planet between maximum and minimum solar
> activity (0.25 Watts per square meter).
>
> "The fact that we still see a positive imbalance despite the prolonged
> solar minimum isn't a surprise given what we've learned about the climate
> system, but it's worth noting because this provides unequivocal evidence
> that the sun is not the dominant driver of global warming," Hansen said.
>
> According to calculations conducted by Hansen and his colleagues, the 0.58
> Watts per square meter imbalance implies that carbon dioxide levels need to
> be reduced to about 350 parts per million to restore the energy budget to
> equilibrium. The most recent measurements show that carbon dioxide levels
> are currently 392 parts per million and scientists expect that
> concentration to continue to rise in the future.
>
> [image: graph of the sun's total solar
> irradiance]<
> http://www.giss.nasa.gov/research/news/20120130b/619624main_solar_irradiance_graph.jpg
> >
>
> A graph of the sun's total solar irradiance shows that in recent years
> irradiance dipped to the lowest levels recorded during the satellite era.
> The resulting reduction in the amount of solar energy available to affect
> Earth's climate was about .25 Watts per square meter, less than half of
> Earth's total energy imbalance. (Credit: NASA/James Hansen)
> + View larger image<
> http://www.giss.nasa.gov/research/news/20120130b/619624main_solar_irradiance_graph.jpg
> >
>
> Climate scientists have been refining calculations of the Earth's energy
> imbalance for many years, but this newest estimate is an improvement over
> previous attempts because the scientists had access to better measurements
> of ocean temperature than researchers have had in the past.
>
> The improved measurements came from free-floating instruments that directly
> monitor the temperature, pressure and salinity of the upper ocean to a
> depth of 2,000 meters (6,560 feet). The network of instruments, known
> collectively as Argo, has grown dramatically in recent years since
> researchers first began deploying the floats a decade ago. Today, more than
> 3,400 Argo floats actively take measurements and provide data to the
> public, mostly within 24 hours.
>
> [image: Argo float and
> ship]<
> http://www.giss.nasa.gov/research/news/20120130b/619622main_Arvor_pourquoi_pas05b.jpg
> >
>
> Data collected by Argo floats, such as this one, helped Hansen's team
> improve the calculation of Earth's energy imbalance. (Credit: Argo Project
> Office <http://www.argo.ucsd.edu/pictures.html>)
> + View larger image<
> http://www.giss.nasa.gov/research/news/20120130b/619622main_Arvor_pourquoi_pas05b.jpg
> >
>
> Hansen's analysis of the information collected by Argo, along with other
> ground-based and satellite data, show the upper ocean has absorbed 71
> percent of the excess energy and the Southern Ocean, where there are few
> Argo floats, has absorbed 12 percent. The abyssal zone of the ocean,
> between about 3,000 and 6,000 meters (9,800 and 20,000 feet) below the
> surface, absorbed five percent, while ice absorbed eight percent and land
> four percent.
>
> The updated energy imbalance calculation has important implications for
> climate modeling. Its value, which is slightly lower than previous
> estimates, suggests that most climate models overestimate how readily heat
> mixes deeply into the ocean and significantly underestimates the cooling
> effect of small airborne particles called aerosols, which along with
> greenhouse gases and solar irradiance are critical factors in energy
> imbalance calculations.
>
> "Climate models simulate observed changes in global temperatures quite
> accurately, so if the models mix heat into the deep ocean too aggressively,
> it follows that they underestimate the magnitude of the aerosol cooling
> effect," Hansen said.
>
> Aerosols, which can either warm or cool the atmosphere depending on their
> composition and how they interact with clouds, are thought to have a net
> cooling effect. But estimates of their overall impact on climate are quite
> uncertain given how difficult it is to measure the distribution of the
> particles on a broad scale. The new study suggests that the overall cooling
> effect from aerosols could be about twice as strong as current climate
> models suggest, largely because few models account for how the particles
> affect clouds.
>
> [image: map showing global reach of Argo
> floats]<
> http://www.giss.nasa.gov/research/news/20120130b/619618main_Argo_chart.jpg
> >
>
> A chart shows the global reach of the network of Argo floats. (Credit: Argo
> Project Office <http://www.argo.ucsd.edu/index.html>)
> + View larger image<
> http://www.giss.nasa.gov/research/news/20120130b/619618main_Argo_chart.jpg
> >
>
> "Unfortunately, aerosols remain poorly measured from space," said Michael
> Mishchenko, a scientist also based at GISS and the project scientist for
> Glory, a satellite mission designed to measure aerosols in unprecedented
> detail that was lost after a launch failure in early 2011. "We must have a
> much better understanding of the global distribution of detailed aerosol
> properties in order to perfect calculations of Earth's energy imbalance,"
> said Mishchenko.
>
> *Reference*
>
> Hansen, J., Mki. Sato, P. Kharecha, and K. von Schuckmann, 2011: Earth's
> energy imbalance and implications<
> http://pubs.giss.nasa.gov/abs/ha06510a.html>.
> *Atmos. Chem. Phys.*, *11*, 13421-13449, doi:10.5194/acp-11-13421-2011.
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