Cloud watching
Richard Treadgold | December 21, 2011I am sent this snippet of correspondence that refers intriguingly to continuing research into the effect of clouds on the climate. No, I won’t say who’s speaking.
Your reference to clouds led me to the work of Prof Roger Davies, who holds the Buckley-Glavish chair in Climate Physics at Auckland U.
He is part of a global group triangulating cloud data from a dedicated satellite, and seems to be developing a view that clouds provide a natural thermostat function (which Richard Lindzen has previously speculated about).
This comes from a 2008 article “Watching the Clouds” in the science faculty magazine:
Over the past eight years of data, there has been little change in the clouds over much of the Earth. However two regions stand out as exceptions. Near the equator, where the high clouds that determine the greenhouse effect are especially numerous, the cloud cover has dropped in height, suggesting a lowering of their greenhouse effect, potentially to offset global warming.
In addition, the reflectivity of the Arctic has changed. In northern summer 2006, the reflectivity of the Arctic decreased significantly, due to less cloud cover and less ice in the area, both of which reflect sunlight. However, from the ground, only a moderate decrease in ice was seen compared to its normal summer melt. The following year, there was a significantly higher ice melt than predicted, despite the fact that satellite pictures were brighter than average, and much brighter than the previous summer, due to increased cloud.
But was the 2007 melt due to the darkness of 2006? Were the clouds of 2007 compensating for the low ice reflectivity to keep a balance? Right now, we don’t know enough to say.
Interesting, but Google shows up nothing recent. He generally seems to keep his head down.
/end snippet
The proper comparison of temperatures in the atmospheres of Venus and Earth, which I put forward over a year ago, provides the definitive, factual evidence against the greenhouse effect, and corrects everyone’s climate speculations, including about clouds. The thick clouds of Venus, which reflect much of the visible light from the Sun, nevertheless do not change the temperature-vs-pressure curve of that planet’s atmosphere, which (my simple analysis clearly shows) is essentially the same as the temperature-pressure curve of the Earth, when only their different distances from the Sun are taken into account. The only effect clouds can have, based upon this definitive evidence, is a cooling of the atmosphere (by about 5 °C) within the clouds themselves, but no effect well outside of the clouds. There are no climate or atmospheric science experts, unless and until my Venus/Earth analysis is confronted and generally accepted as the fundamental fact it is, providing a true consensus to replace the current smorgasbord of theoretical speculations.
“He generally seems to keep his head down.” seems to sum up the parlous state of science these days. If you can get funding and it is in the field of climate that doesn’t preach the correct sermon, then you have to keep it quiet.
Pretty sad state of affairs, really
It always seemed to me that a key question in the climate debate is how the earth reacts to any increase/decrease in temperature. Most things in nature have a bias in favour of stability – a tendency to return to the norm.
If a little heat produces a feedback of more heat, which in turn produces more, etc,etc I would have expected the planet would have burned up a billion or so years ago. But it’s still around, after many travails, so it seems more probable that any new heat would lead to a feedback which cancels that out and returns to the norm. A built-in thermostat.
Everybody seems to agree that the big unknowns in terms of feedbacks are clouds. They produce both warming and cooling effects, but which is the stronger?
Perhaps Prof Davies could tell us by now?
A couple of comments Australis.
As an automation engineer of many years I can heartily agree with you. This is indeed one of the fundamental problems with cAGW, that there are apparently positive feedbacks in the climate system, unbounded positive feedbacks no less. As you say, any such positive feedbacks would have led to climate instability and catastrophe well before the modern age. In fact, what we see is an extremely stable system that does not depart more than about 10C either side of a mean for most of the last five billion years.
On another note, Willis Eschenbach, wrote a piece on wattsupwiththat a few months ago on the effect of tropical cloud feedback to maintain a stable temperature. It looked quite reasonable. His last post on it was at http://wattsupwiththat.com/2011/06/07/further-evidence-for-my-thunderstorm-thermostat-hypothesis/
Update on the research:
http://tvnz.co.nz/technology-news/university-auckland-has-had-its-head-in-clouds-4736355
Here’s some more as well:
http://www.worldclimatereport.com/index.php/2012/02/08/a-significant-measure-of-negative-feedback-to-global-warming/
I’d check to see if this made the AR5 cutoff if I could be bothered but I can’t so I’ll just assume we wont read about there if past form is anything to go by.
“A paper published today in the Journal of Climate finds that relative humidity has been decreasing 0.5% per decade across North America during the 62 year period of observations from 1948-2010. Computer models of AGW show positive feedback from water vapor by incorrectly assuming that relative humidity remains constant with warming while specific humidity increases…..”Over 1/4 billion hourly values of temperature and relative humidity observed at 309 stations located across North America during 1948-2010 were studied…The averages of these seasonal trends are 0.20 C/decade and 0.07 hPa/decade which correspond to a specific humidity increase of 0.04 g/kg per decade and a relative humidity reduction of 0.5%/decade.“” [V. Isaac and W. A. van Wijngaarden 2012: Journal of Climate]
http://www.c3headlines.com/2012/02/climate-scientists-confirm-that-actual-atmospheric-water-vapor-levels-invalidate-global-warming-tipp.html