https://www.commondreams.org/headline/2013/12/31-1
[Something to look forward to in 2014 and subsequent years. Not!]
Published on Tuesday, December 31, 2013 by Common Dreams
'Worst' of Climate Predictions Are the Most Likely: New Study
Groundbreaking research on cloud behavior and global warming says
'catastrophic' increase of 4°C or more by 2100 should be expected
- Jon Queally, staff writer
New research predicts that global temperatures will likely rise at least
4°C by 2100 and potentially more than 8°C by 2200 if carbon dioxide
emissions are not reduced and serious actions by governments and society
are not taken.
New research by a team of scientists looking at the impact of cloud
behavior on planetary climate change says that "the worst" and
"catastrophic" predictions offered by previous studies on the rate of
global warming this century are much more likely than the less severe
scenarios offered by others.
According to Dr. Steven Sherwood, lead author of the study and a
specialist in climate and cloud formations at the University of New
South Wales in Australia, cloud patterns in an increasingly warming
world are likely to exacerbate global temperature increases overall, not
mitigate warming as some models have suggested.
"This study breaks new ground twice," Sherwood explained in an interview
with the Guardian. "First by identifying what is controlling the cloud
changes and second by strongly discounting the lowest estimates of
future global warming in favor of the higher and more damaging estimates."
The research predicts that global temperatures will likely rise at least
4°C by 2100 and potentially more than 8°C by 2200 if carbon dioxide
emissions are not reduced and serious actions by governments and society
are not taken.
Such drastic increases, Sherwood told the Guardian would be
"catastrophic rather than simply dangerous."
Specifically, the study looked at how already warming temperatures
impact the ability of clouds to form at high altitudes, because that
ability can greatly impact the way in which large clouds help the planet
reflect or absorb the sun's heat. One of the long-acknowledged
shortcomings of other climate computer models—which drive much of the
work of climate change predictions—is the difficulty of accurately
projecting cloud behavior under complex, future conditions.
By tackling that problem, say Sherwood and his colleagues, their
research "cracks open one of the biggest problems in climate science."
As the Syndey Morning Herald reports:
Will Steffen, an adjunct professor at Australian National
University and a member of the Climate Council, said the paper was
''right out on the forefront of the sort of research we need to do on
clouds''.
''The more we get research like from [Professor Sherwood] and his
group, the more confidence we'll have in being able to say where in that
range [the temperature increase] is likely to fall.''
The CO2 level of the atmosphere in 2012 was 393 parts per million,
or 41 per cent higher than in pre-industrial times, the World
Meteorological Organisation said. The level is rising at an accelerating
rate - more than two parts per million a year - as humans burn more
fossil fuels and cut down forests.
Global temperatures have risen about 0.8 degrees since about 1880,
with system lags and air pollution reflecting sunlight partly explaining
why the rise has not been higher. ''We've been hoping for the best and
not planning for the worst,'' Professor Sherwood said.
''And now it's looking like the best is not very likely.''
In 2012, a study by the World Bank—an institution not typically known
for sounding the alarm over industrial, human-caused global
warming—also said that a 4°C temperature rise was not only possible, but
likely if humanity did not change course. According to Kim Yong Kim, the
bank's president, the resulting impacts of a planet that warm would
likely "make the world our children inherit a completely different world
than we are living in today."
And those kinds of warnings only mirror the consistent and nearly
unanimous consensus of the international scientific community when it
comes to temperature increases that exceed the 2°C increase that world
governments have set as the benchmark not to exceed this century. The
problem, of course, is that no agreements or promises have resulted in
actual emission reductions. In fact, annual global emissions continue to
increase even as the warnings escalate.
====================================================================
http://phys.org/news/2013-12-cloud-mystery-global-temperatures-4c.html
Cloud mystery solved: Global temperatures to rise at least 4C by 2100
[on-line article includes video]
Global average temperatures will rise at least 4°C by 2100 and
potentially more than 8°C by 2200 if carbon dioxide emissions are not
reduced according to new research published in Nature. Scientists found
global climate is more sensitive to carbon dioxide than most previous
estimates.
The research also appears to solve one of the great unknowns of climate
sensitivity, the role of cloud formation and whether this will have a
positive or negative effect on global warming.
"Our research has shown climate models indicating a low temperature
response to a doubling of carbon dioxide from preindustrial times are
not reproducing the correct processes that lead to cloud formation,"
said lead author from the University of New South Wales' Centre of
Excellence for Climate System Science Prof Steven Sherwood.
"When the processes are correct in the climate models the level of
climate sensitivity is far higher. Previously, estimates of the
sensitivity of global temperature to a doubling of carbon dioxide ranged
from 1.5°C to 5°C. This new research takes away the lower end of climate
sensitivity estimates, meaning that global average temperatures will
increase by 3°C to 5°C with a doubling of carbon dioxide."
The key to this narrower but much higher estimate can be found in the
real world observations around the role of water vapour in cloud formation.
Observations show when water vapour is taken up by the atmosphere
through evaporation, the updraughts can either rise to 15 km to form
clouds that produce heavy rains or rise just a few kilometres before
returning to the surface without forming rain clouds.
When updraughts rise only a few kilometres they reduce total cloud cover
because they pull more vapour away from the higher cloud forming regions.
However water vapour is not pulled away from cloud forming regions when
only deep 15km updraughts are present.
The researchers found climate models that show a low global temperature
response to carbon dioxide do not include enough of this lower-level
water vapour process. Instead they simulate nearly all updraughts as
rising to 15 km and forming clouds.
When only the deeper updraughts are present in climate models, more
clouds form and there is an increased reflection of sunlight.
Consequently the global climate in these models becomes less sensitive
in its response to atmospheric carbon dioxide.
However, real world observations show this behaviour is wrong.
When the processes in climate models are corrected to match the
observations in the real world, the models produce cycles that take
water vapour to a wider range of heights in the atmosphere, causing
fewer clouds to form as the climate warms.
This increases the amount of sunlight and heat entering the atmosphere
and, as a result, increases the sensitivity of our climate to carbon
dioxide or any other perturbation.
The result is that when water vapour processes are correctly
represented, the sensitivity of the climate to a doubling of carbon
dioxide - which will occur in the next 50 years – means we can expect a
temperature increase of at least 4°C by 2100.
"Climate sceptics like to criticize climate models for getting things
wrong, and we are the first to admit they are not perfect, but what we
are finding is that the mistakes are being made by those models which
predict less warming, not those that predict more," said Prof. Sherwood.
"Rises in global average temperatures of this magnitude will have
profound impacts on the world and the economies of many countries if we
don't urgently start to curb our emissions.
====================================================================
Nature Journal reference (includes abstract and purchase information):
http://www.nature.com/nature/journal/v505/n7481/full/nature12829.html
--
Darryl McMahon
Failure is not an option;
it comes standard. (But, so does optimism.)
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