Reducing Climate Change Uncertainty By Figuring Out Clouds 249
Most climate scientists agree that the Earth's climate is getting warmer, but models predicting the severity of the temperature rise span a (relatively) broad range. One big reason for this is the difficulty in modeling things like cloud cover and how different air masses mix and move around each other.
"Specifically, they have differences in how water-rich air at the bottom of the atmosphere gets mixed with the layers immediately above it. In some cases, this mixing increases rapidly as the temperature rises, effectively drying out the lower atmosphere and suppressing cloud formation there. This in turn would enhance the warming effect. In others, the increase in mixing is more gradual, limiting the impact of warming on clouds. The former produces a higher climate sensitivity; the latter a lower one. ... So, the authors turned to the atmosphere, using data to determine the relative importance of these processes (abstract). In the end, they find that the models that dry out the lower atmosphere more quickly are likely to get the process right. And, in these models, the mixing increases the drying rate in the lower atmosphere by about five to seven percent for each Kelvin the Earth's temperature increases. In contrast, the rate of evaporation, which adds moisture to the lower atmosphere, only increases by two percent for each Kelvin. Thus, the lower atmosphere dries out, cloud formation there is suppressed, and the planet warms even further. How much more will it warm? Quite a bit."
Re:But I heard (Score:3, Interesting)
Good Science tends to be rather aware of its limitations.
Bad Science Journalism tends towards dogmatic assertions of absolutism just as much as many religious folk.
"Error bars", "p-values", "uncertainty values/ranges" are the norm in Science, not the exception.
Here you're juxtaposing two separate issues. First "the science is settled" appears to be a remark or jab at the idea that the overwhelming consensus among relevant Scientists and relevant peer-reviewed studies is that global average temps are increasing and that human activity has played a measurable, significant part of that. Second, the projections for how much temp increase by 2100 and 2200 are not exact at all. They're given as a range with a corresponding uncertainty. Supposedly, this latest study/model serves to narrow that range. It's just like the difference between someone telling you it will snow tomorrow and you'll get between 1 and 47 inches vs. another person saying between 4 to 5 inches. Both predictions are somewhat uncertain but one is less so.
Re:Models vs models (Score:2, Interesting)
What are you talking about? Neglecting transient fluctuations (which are admittedly large enough to partially mask the still-small trend), global warming has been drastically worse that the worst-case scenarios predicted several decades ago predicted, probably in large part because human fossil fuel consumption has also been exceeding the worst-case scenario assumptions. Just because we haven't yet reached the predicted "apocalypse" doesn't mean we can't see it coming - it was never predicted to start to really manifest obviously until well into this century, and the earliest.
Don't make the mistake of confusing the well-established "broad overview" science with the often disproved theories on the details that may exacerbate or moderate the problem. Trends are far easier to predict - you can fairly accurately predict how a crowd will move using extremely simple models that can't even begin to predict the movements of an individual within that crowd.
At this point nobody in the scientific community is predicting global warming - you don't predict it's going to start raining when you're already getting wet. The evidence is in, GW is real and getting rapidly worse. What's being studied now is the details that may lead to ways we can "cheat" our way out of the problem, or at least get a more detailed prediction of what's actually coming once things get so bad that the politicians are forced to give up their oil-industry funded blinders and deal with the crises surrounding them. Because if you can get even 5-10 years warning that a region is going to start experiencing massive flooding and drought then you have a chance to start building the necessary dams now, instead of waiting until your budget is stretched thin by dealing with crisis after seasonal crisis.