In the current issue of Science News is a article about clouds and it confirms that clouds are the single biggest unknown in climate models. Everybody agrees that clouds warm things through the greenhouse effect at night and cool things by reflecting sunlight during the day, and everybody agrees that the cooling effect is larger than the heating effect, but they disagree about just how much larger and on if we will have more clouds in the future or less. And a recently discovered fact complicates things further, clouds made of ice crystals and water droplets reflect light about equally but the ice crystal clouds have a stronger greenhouse effect than water clouds. As a result of all this confusion and uncertainty are rampant.
Back in 2007 the United Nations issued a report on climate change, it said that by 2100 things would be between 2 and 4.5 degrees warmer than now, a rather large amount of uncertainty; but after spending millions of dollars and 7 years of hard work they just issued a new report, and their uncertainty has actually INCREASED. Now they say between 1.5 and 4.5. The article also notes somewhat apologetically (Science News is a honest magazine but always leans toward the environmentalist view) that after 3 decades of increasing temperatures since 1998 the worldwide temperature has been roughly constant, and no climate model in 1998 predicted this. They conclude by saying "scientists say they need at least 20 to 30 years to determine if clouds respond to global warming the way simulations predict". I have to say all this doesn't exactly give me confidence that I should bet my life on the fact that although they make lousy 17 year predictions climate models make wonderful 100 year predictions. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.