Whilst looking for something else I came across this piece on Cloud Climatology on the NASA GISS website. As one of the premier research institutes in this field they don’t seem to think we know enough. Here are some quotes:
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•Clouds cool Earth's surface by reflecting incoming sunlight.
•Clouds warm Earth's surface by absorbing heat emitted from the surface and re-radiating it back down toward the surface.
•Clouds warm or cool Earth's atmosphere by absorbing heat emitted from the surface and radiating it to space.
•Clouds warm and dry Earth's atmosphere and supply water to the surface by forming precipitation.
•Clouds are themselves created by the motions of the atmosphere that are caused by the warming or cooling of radiation and precipitation.
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Right now, we do not know how important the cloud-radiative or cloud-precipitation effects are and cannot predict possible climate changes accurately.
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When contemporary models are given information about Earth's present condition — the size, shape and topography of the continents; the composition of the atmosphere; the amount of sunlight striking the globe — they create artificial climates that mathematically resemble the real one: their temperatures and winds are accurate to within about 5%, but their clouds and rainfall are only accurate to within about 25-35%. Such models can also accurately forecast the temperatures and winds of the weather many days ahead when given information about current conditions.
Unfortunately, such a margin of error is much too large for making a reliable forecast about climate changes, such as the global warming will result from increasing abundances of greenhouse gases in the atmosphere. A doubling in atmospheric carbon dioxide (CO2), predicted to take place in the next 50 to 100 years, is expected to change the radiation balance at the surface by only about 2 percent. Yet according to current climate models, such a small change could raise global mean surface temperatures by between 2-5°C (4-9°F), with potentially dramatic consequences. If a 2 percent change is that important, then a climate model to be useful must be accurate to something like 0.25%. Thus today's models must be improved by about a hundredfold in accuracy, a very challenging task. To develop a much better understanding of clouds, radiation and precipitation, as well as many other climate processes, we need much better observations.
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In 1974 an international conference of investigators in Stockholm highlighted the need for greater understanding of clouds as one of the two biggest obstacles to further progress in climate research. The second was inadequate knowledge of ocean currents. Recent comparisons of the predictions made by various computer climate models show that the problem has not gone away. In some models, for instance, clouds decrease the net greenhouse effect, whereas in others they intensify it.
https://isccp.giss.nasa.gov/role.html#COMP_MODS
The summary of those points is that we have no idea if the current series of climate models is accurate and the potential errors are much bigger than the potential changes. Nice to know what our policy makers are basing their policies on ?
Best regards
Roger
