World's
climate could cool first, warm later
NewScientist
2009
Forecasts
of climate change are about to go seriously out of kilter. One of the world's
top climate modellers said we could be about to enter one or even two decades
during which temperatures cool.
"I am not one of the sceptics," insisted Mojib Latif of the Leibniz Institute
of Marine Sciences at Kiel University, Germany. "However, we have to ask the nasty
questions ourselves or other people will do it." Few climate scientists go as
far as Latif, an author for the Intergovernmental Panel on Climate Change. But
more and more agree that the short-term prognosis for climate change is much less
certain than once thought. Earth
cools, and fight over warming heats up
Wall
Street Journal 2009
Two
years ago, a United Nations scientific panel won the Nobel Peace Prize after concluding
that global warming is "unequivocal" and is "very likely" caused by man. Then
came a development unforeseen by the U.N.'s Intergovernmental Panel on Climate
Change, or IPCC: Data suggested that Earth's temperature was beginning to drop. A
few years of cooling doesn't mean that people aren't heating up the planet over
the long term. But the cooling wasn't predicted by all the computer models that
underlie climate science. That has led to one point of agreement: The models are
imperfect. "There is a lot of room for improvement" in the models, says Mojib
Latif, a climate scientist in Germany and co-author of a paper predicting the
planet will cool for perhaps a decade before starting to warm again -- a long-term
trend he attributes to greenhouse-gas emissions. "You need to know what you can
believe and can't believe from the models." The
goal of climate models is to project how rising greenhouse-gas emissions will
interact with natural forces to affect the global temperature. The models are
technological marvels. Using supercomputers, they divide the world into grids
of roughly 4,000 cubic miles apiece. The grids are stacked, one on top of the
other, up through the atmosphere. The
models are only as good as the information they are fed. One big uncertainty is
ocean temperature. Oceans trap huge amounts of heat, and they process by which
they release it over time affects the temperature of the planet. The
success of the models also depends on the soundness of their assumptions. The
effects of clouds, for example, are unclear. Depending on their shape and altitude,
clouds can either trap heat, warming the earth, or reflect it, cooling the planet.
The way that greenhouse gases affect cloud formation -- and how clouds in turn
affect temperature -- remains a subject of debate. Different models treat these
factors differently. Supercomputers
Provide Simulation of Abrupt Climate Changes
Oak
Ridge National Laboratory 2009
At
the Department of Energy's Oak Ridge National Laboratory, the world's fastest
supercomputer for research is simulating abrupt climate change and shedding light
on an enigmatic period of natural global warming in Earth's relatively recent
history. The findings could provide great insight into the fate of ocean circulation
in light of continued glacial melting in Greenland and Antarctica. More
accurately depicting the past means clearer insights into climate's outlook. "The
current forecast predicts the ocean overturning current is likely to weaken but
not stop over the next century," according to one of the researchers. "However,
it remains highly uncertain whether abrupt changes will occur in the next century
because of our lack of confidence in the model's capability in simulating abrupt
changes. |
| | Comment... Computer
Model Shortcomings
Nearly
every week we hear a new alarming warning about our climate future. These warnings,
however, are based upon climate models that even the scientists themselves say
are significantly unreliable and incomplete. Moreover,
climate models cannot anticipate what has yet to be discovered. For instance,
computer models in the 1990s did not anticipate the importance of the El Nino
– Southern Oscillation that transfers heat between the oceans and the atmosphere
and, as we now know, was probably responsible for the hottest year on record,
1998. The bullet
points that follow are concerns expressed in the climate model chapter of the
IPCC's Climate Report 2007. After
reading the scientists own words do you think we should restructure our energy
economy based upon computer models? - ...important
deficiencies remain in the simulation of clouds
and tropical precipitation. (p591)
- The
shortwave impact of changes in boundary-layer clouds, and to a lesser extent mid-level
clouds, constitutes the largest contributor to inter-model differences in global
cloud feedbacks. The relatively poor simulation
of these clouds in the present climate is a reason for
some concern. (p593)
- Climate
models exhibit different strengths and weaknesses, and it is not
yet possible to determine which estimates of the climate change cloud
feedbacks are the most reliable.
-
Significant uncertainties...are associated
with the representation of clouds, and in the resulting cloud responses to climate
change. (p601)
- Models
continue to have significant limitations,
such as in their representation of clouds, which lead to uncertainties
in the magnitude and timing, as well as regional details, of predicted climate
change. (p601)
- Cloud
processes affect the climate system by regulating the flow of radiation at the
top of the atmosphere, by producing precipitation, by accomplishing rapid and
sometimes deep redistributions of atmospheric mass and through additional mechanisms
too numerous to list here. (p602)
- Realistic
parametrizations of cloud processes are a prerequisite
for reliable current and future climate simulation (p602)
- Outside
the polar regions, relatively large errors
are evident in the eastern parts of the tropical ocean basins, a likely symptom
of problems in the simulation of low clouds.
The extent to which these systematic model errors affect a model’s response to
external perturbations is unknown, but may
be significant. (p608)
- Given
that clouds are responsible for about half the outgoing SW radiation, these errors
are not surprising, for it is known that cloud processes are among
the most difficult to simulate with models.
(p610)
- ...many
climate models overestimate surface absorption
of solar radiation partly due to problems in the parametrizations of atmospheric
absorption, clouds and aerosols. (p618)
- The
role of polar cloud feedbacks in climate sensitivity ...remain
poorly understood. (p637)
- Modelling
assumptions controlling the cloud water phase (liquid, ice or mixed) are known
to be critical for the prediction of climate sensitivity. However, the evaluation
of these assumptions is just beginning (p638)
|
Climate
models have mischaracterized the effects of soot
Stanford
Univ. 2010
The
quickest, best way to slow the rapid melting of Arctic sea ice is to reduce soot
emissions from the burning of fossil fuel, wood and dung, according to a new study
by Stanford University. The
analysis shows that soot is second only to carbon dioxide in contributing to global
warming. But, he said, climate models to date have mischaracterized the effects
of soot in the atmosphere. Because of that, soot's contribution to global warming
has been ignored in national and international global warming policy legislation,
he said. | Predictions
of coal, CO2 production flawed, says latest research
Univ.
of Texas 2010
The
CO2 emission estimates used for government policy decisions
assume unlimited coal and fossil fuel production for the next 100 years, an unrealistic
premise which skews climate change models and proposed solutions, according to
new research published by Tad Patzek, chair of the Petroleum and Geosystems Engineering
Department at The University of Texas at Austin. Based
on widely accepted studies predicting coal production will peak and decline after
2011, Patzek warns climate change predictions should be revised to account for
this inevitable peak and decline.
"Governments worldwide are basing their policy decisions on the uninterrupted
increase of coal and oil production worldwide," says Patzek. "These policy decisions
will be inherently in error, and will lead to expensive and false technological
solutions." |
| Global
Warming:
Our Best Guess Is Likely Wrong
Rice
University 2009
No
one knows exactly how much Earth's climate will warm due to carbon emissions,
but a new study suggests scientists' best predictions about global warming might
be incorrect. The
study, which appears in Nature Geoscience, found that climate models explain only
about half of the heating that occurred during a well- documented period of rapid
global warming in Earth's ancient past. Uncertainties
in Climate Model Cloud and Water Vapor Processes
Dr.
Roy Spencer 2009
The
climate model equations are only approximations of the physical processes that
occur in the atmosphere. While some of those approximations are highly accurate,
some of the most important ones from the standpoint of climate change are unavoidably
crude. This is because the real processes they represent are either (1) too complex
to include in the model and still have the model run fast on a computer, or (2)
because our understanding of those processes is still too poor to accurately model
them with equations. This is especially true for cloud formation and dissipation,
which in turn has a huge impact on how much sunlight is absorbed by the climate
system. The amount of cloud cover generated in the model in response to solar
heating helps control the Earth’s temperature, so the manner in which clouds change
with warming is of huge importance to global warming predictions. Climate modelers
are still struggling to get the models to produce cloud cover amounts and types
like those seen in different regions, and during different seasons. .
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