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Based on three years
of
observations from the SCIAMACHY instrument aboard ESA’s
Envisat, scientists
have produced the first movies showing the global distribution of the
most
important greenhouse gases – carbon dioxide and methane
– that contribute to
global warming. Careful monitoring
is essential to ensuring these
targets are met, and space-based instruments are new means contributing
to
this. The SCIAMACHY (Scanning Imaging Absorption Spectrometer for
Atmospheric
Chartography) instrument, for instance, is the first space sensor
capable of
measuring the most important greenhouse gases with high sensitivity
down to the
Earth’s surface because it observes the spectrum of sunlight
shining through
the atmosphere in ‘nadir’ looking operations. Dr. Michael Buchwitz
and Oliver Schneising from the
Institute of Environmental Physics (IUP) at the Although carbon
dioxide is the most important
greenhouse gas, methane molecules trap heat with an efficiency that is
20 times
larger than that of a molecule of carbon dioxide. Also, emissions from
methane
– the second most important greenhouse gas – may
significantly rise in the
future due to global warming if methane is released from currently
frozen
permafrost areas. The new methane data
also confirm findings from
another study in 2005 carried out by the Institute of Environmental
Physics
(IUP) at the "By comparing model
results with satellite
observations (assuming that most differences are primarily due to
shortcomings
of our current knowledge that has been included in the model), the
model is
continually adjusted until it is able to reproduce the satellite
observations
as closely as possible," Buchwitz said. "Based on this, we
continually improve the model and our knowledge of nature." Data from SCIAMACHY
is being provided to the GMES
Service Element for Atmosphere PROMOTE, which delivers policy-relevant
services
on multiple atmospheric issues to end-users. Feedback from these users
is
helping the scientists at the University of Bremen to improve their
algorithms
further, which is essential for reaching the accuracy level of 1
percent needed
for SCIAMACHY to retrieve information on greenhouse gas sources and
sinks. Buchwitz and his
colleagues used SCIAMACHY data
from the same period to retrieve the columns of carbon dioxide, which
occurs
naturally as well as being created through human activities, such as
the
burning of fossil fuels. As with methane,
there are significant gaps in the
knowledge of carbon dioxide’s sources, such as fires,
volcanic activity and the
respiration of living organisms, and its natural sinks, such as the
land and
ocean. By better
understanding all of the parameters
involved in the carbon cycle, scientists can better predict climate
change as
well as better monitor international treaties aimed at reducing
greenhouse gas
emissions, such as the Kyoto Protocol which addresses the reduction of
six
greenhouse gases including methane and carbon dioxide. With climate change
being the greatest
environmental challenge facing the world today, numerous studies and
results on
greenhouse gases will be presented at the 2007 Envisat Symposium in
Montreux,
Switzerland, from 23 to 27 April.
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