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Environment & Energy
In reply to the discussion: Don't believe the extremists: No Big Changes In Leaked Draft AR5 Report [View all]Nederland
(9,976 posts)33. Here you go...
http://www.agu.org/journals/ms/ms1208/2012MS000154/2012MS000154.pdf
Yet, the span between the coldest and the warmest model is almost 3 K, distributed equally far above and below the best observational estimates, while the majority of models are cold-biased. Although the inter-model span is only one percent relative to absolute zero, that argument fails to be reassuring. Relative to the 20th century warming the span is a factor four larger, while it is about the same as our best estimate of the climate response to a doubling of CO2, and about half the difference between the last glacial maximum and present. To parameterized processes that are non-linearly dependent on the absolute temperature it is a prerequisite that they be exposed to realistic temperatures for them to act as intended. Prime examples are processes involving phase transitions of water: Evaporation and precipitation depend non-linearly on temperature through the Clausius-Clapeyron relation, while snow, sea-ice, tundra and glacier melt are critical to freezing temperatures in certain regions. The models in CMIP3 were frequently criticized for not being able to capture the timing of the observed rapid Arctic sea-ice decline [e.g., Stroeve et al., 2007]. While unlikely the only reason, provided that sea ice melt occurs at a specific absolute temperature, this model ensemble behavior seems not too surprising when the majority of models do start out too cold.
Yet, the span between the coldest and the warmest model is almost 3 K, distributed equally far above and below the best observational estimates, while the majority of models are cold-biased. Although the inter-model span is only one percent relative to absolute zero, that argument fails to be reassuring. Relative to the 20th century warming the span is a factor four larger, while it is about the same as our best estimate of the climate response to a doubling of CO2, and about half the difference between the last glacial maximum and present. To parameterized processes that are non-linearly dependent on the absolute temperature it is a prerequisite that they be exposed to realistic temperatures for them to act as intended. Prime examples are processes involving phase transitions of water: Evaporation and precipitation depend non-linearly on temperature through the Clausius-Clapeyron relation, while snow, sea-ice, tundra and glacier melt are critical to freezing temperatures in certain regions. The models in CMIP3 were frequently criticized for not being able to capture the timing of the observed rapid Arctic sea-ice decline [e.g., Stroeve et al., 2007]. While unlikely the only reason, provided that sea ice melt occurs at a specific absolute temperature, this model ensemble behavior seems not too surprising when the majority of models do start out too cold.
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Don't believe the extremists: No Big Changes In Leaked Draft AR5 Report [View all]
Nederland
Dec 2012
OP
And there's no sign that we are deviating from the highest-carbon scenarios.
GliderGuider
Dec 2012
#11
They don't even assess drought. Hopefully that's changed before AR5 is finished.
joshcryer
Dec 2012
#15
Which is how I'm beginning to think the IPCC should conduct it's business as well.
AverageJoe90
Dec 2012
#63
Nope, sorry - and the Chicken Little cartoon was the last straw - hot-button for me
hatrack
Dec 2012
#90
Isn't it perhaps possible that methane may not have as much of a impact.....
AverageJoe90
Dec 2012
#61
You aren't allowed to allude to that "possibility" without a leaked IPCC AR5 snippet to back you up
NoOneMan
Dec 2012
#64
He is not qualified according to the criteria Rajendra Pachauri claimed was used
Nederland
Dec 2012
#84