7 June 2009
One of the most frequent myths I hear about climate is that the “satellites show cooling”. This myth lingers on in spite of the fact that the initial discrepancies have been reconciled. Don’t just trust me on this, read the report from the U.S. Climate Change Science program:
There has been a lot of interest in satellite measurements of the troposphere because most climate models show it should warm significantly, and perhaps more than the surface in some regions (especially the tropics). The reasons for this are latent heat. Here is a simple explanation of how latent heat warms the air.
If you want to turn a pan of water on the stove into water vapor, what do you do? Well you can wait a few weeks and the warmth of the air will do it for you, or you can add heat. A lot of heat. Boil it away. Here is the most important thing- when that water condenses back to a liquid, ALL the heat that went into boiling it off, will be released back into the air. The vapor had heat locked up inside it.
You may think a thunderstorm cools the air, and if you are under it on the ground, it does! In reality though, a thunderstorm releases tremendous amounts of heat high in the atmosphere. This is also how hurricanes form. The release of latent heat expands the air and drops the pressure. Lower pressure sucks in more muggy air into thunderstorms and the cycle continues until a deep tropical storm forms.
Some of the most interesting research in Climate is called fingerprinting. One of the top experts is Dr. Ben Santer of Lawrence Livermore National Laboratories. I had the chance to meet him at a climate seminar in Chicago in April. Fingerprinting answers questions like “how do we know it’s the carbon dioxide and not the sun causing the Earth to warm?”.
Take a look at the graphs below- courtesy of Dr. Santer. You can use climate models to simulate the response of the planet to different forcings. You can model the response of temperatures in the atmosphere to the changes in the sun over the last century. You can do the same for volcanos and aerosols from pollution and do it for Ozone and increasing greenhouse gases.
Notice, that if it were just the sun causing the temperature rise, we would see warming throughout the atmosphere. If it’s greenhouse gases, we see warming in the troposphere and cooling in the stratosphere. The last panel is an estimate of all the forcings, modeled from the real world.
So what do we see in the real world?? The stratosphere (above the troposphere) is cooling and the Troposphere below is warming.
Actually measuring the temperatures of the troposphere and stratosphere has turned out to be very difficult.
The Advanced Microwave Sounding Unit (AMU) on NOAA satellites sees a little of both layers and separating this out is not easy. Using radiosondes launched on balloons is not easy either, because the sensors have changed over the years. At first, it looked liked the troposphere was cooling. Turns out that better sun shields on the sensors caused this.
The first satellite measurements of the troposphere were made here in Huntsville by Dr. John Christy at UAH. At first the data looked like it showed cooling, but as you can read in the above report, the errors were spotted. The Remote Sensing Systems (RSS) group in California and others were instrumental in finding the errors.
The hordes of people who spend their time reading these junk science sites that deny climate change, and call it a hoax, have jumped on any inconsistencies they could find. Science meanwhile did what it always does. It kept looking for the truth. Slowly but surely the truth has shown itself, and the predictions made by the climate models, and Anthropogenic Global Warming theory have once again shown to hold.
The final funeral for the doubters can be planned now. Order the flowers, and pay the preacher to say something nice over the deceased he never knew. Why? Because yet another paper has shown using a different method of looking at the data, that indeed the stratosphere is cooling and the Troposphere is warming. The abstract and the site is below:
Why were scientists so sure that the early measurements were wrong. Easy, the laws of Physics said otherwise. Neil deGrasse Tyson the renowned astrophysicist said it best. “The laws of Physics are real- everything else is just opinion.”
Why can’t I write brilliant things like that!
Reconciling the differences- US Climate Sci. Program (Linked above)
Personal Communication Dr. Ben Santer LLNL
Global Warming- Understanding the Forecast by David Archer
IPCC A.R. 4 2007
Addendum 22 Nov 2009:
Dr. Christy has emailed me and included a new paper he and others have just published in GRL. To understand what this paper is about some quick background.
Climate model and basic physics indicate that the troposphere should warm more than the surface as greenhouse gases increase. The factor is probably around 1.2 for the globe as a whole. The satellite temperature data from UAH (Christy’s group) does not show this, while another groups data comes much closer. (RSS).
The paper by Christy and Klotzbach et al. reasons that this is due to a bias caused by not only increasing greenhouse gases, but also land use and cloud cover/moisture changes caused by urbanization. The merits of this idea will be debated in the peer review ad nauseum, and a geek like me will read it all avidly. There has been some criticism of his paper already (see below). This is likely to be the most controversial part of their paper since there has been a lot of published science that shows the corrections for urban stations are good. See Watts Wrong With That? – Plenty.
What I should make clear here is that after my communication with Dr. Christy, it’s clear he does not believe the discrepancies have been resolved satisfactorily and I have changed this blog post to put on this addendum.
I wrote this post above in response to the very often heard claim that ”The satellites show cooling, not warming!
This is not true and the paper that has just been published does not make that claim. The paper acknowledges that one of the reasons for the discrepancy may be increasing greenhouse gases.
The satellites show warming in the troposphere and cooling in the stratosphere (Cooling is what you would expect with increasing greenhouse gases in the stratosphere and this has been documented.)
If you want to get to the nitty gritty of it all then read 2009_Klotzbach_etal. There are several critiques in the bogosphere that I suspect will end up as comments in the journals. The one I think makes most sense is by James Amman, a climate scientist working in Japan. Another interesting note on it is by Dr. Michael Tobis here. He brings up a point that I feel requires an explanation by the authors. That may be the subject of a newer post.