The April edition of Birmingham University's newsletter BUZZ incudes comment from climate researcher Chris Kidd that,
"Despite these warmer temperatures and recent news of further ice-shelf melting, global temperatures do appear to be cooling after reaching a peak in 1998.
Since then the temperatures steadied and have fallen over the past couple of years: in fact, Antarctica saw its greatest recorded extent of ice in 2007, unlike the dwindling Arctic sea ice.
As for the summer, seasonal forecasting is best left to computer models to get wrong, but it would seem that we could be in for an 'average' summer: cool and showery."
Let's hope Jo Abbess, the activist who recently insisted the BBC change a story that mentioned some global cooling, doesn't try and get this article changed!
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Dr Chris Kidd is from the Climate and Atmospheric Research Group, in the School of Geography, Earth and Environmental Sciences, University of Birmingham, and he is not a climate skeptic.
At the time of writing the April Edition was not yet available online.
This Story was edited by Jennifer at 9.30am on April 10.
Ivan, I wrote: “There has been direct evidence from satellites for quite a few years now of changes in the infrared radiation emitted to space at the top of the atmosphere” [TOA].
You have twisted this to make it appear that I was making a claim about temperature changes in the troposphere. I made no such claim; perhaps the issues of changes in OLR and temperature changes are confused in your own mind. Be that as it may, and as you have referred to upper-atmosphere temperature trends, I refer you to the paper by Vinnikov et al., J. Geophys. Res., v.111, D030106 (2006). From the abstract: “The observations [of temperature trends] at the surface and in the troposphere are consistent with climate model simulations. At middle and high latitudes in the Northern Hemisphere, the zonally averaged temperature at the surface increased faster than in the troposphere while at low latitudes of both hemispheres the temperature increased more slowly at the surface than in the troposphere.” So, how do you reconcile that with Lindzen’s claim in the link you provided? In fact, Lindzen’s data seem to conflate trends for the stratosphere (where cooling is expected) with those for the lower atmosphere (where warming is expected). It is far from clear to me how Lindzen explains the actual changes in TOA OLR, and reconciles these with what happens lower down. If the stratosphere cools, and the lower atmosphere warms, in response to increased GHGs, then somewhere in between the atmosphere must neither warm nor cool.
Louis Hissink: there have been a variety of satellite measurements of outgoing longwave radiation (OLR) since the 1970s. They measure the radiation going out to space so your question as to the “position [of] the top of the atmosphere [TOA]…in km…)” is slightly misconceived. The measurements began with the IRIS on Nimbus 4 in 1970. See Hanel et al., Appl. Optics, v.10(6),p.1376 (1971). According to Harries, who surveyed satellite data from 1970 through 1997: “Using IRIS and IMG, we have observed global and regional change of OLR(nu) between 1970 and 1997 which is consistent with increased concentrations of CO2, on average a higher surface temperature, and increased concentration of CH4.” (J.E. Harries, 'The Impact of Satellite Observations of the Earth’s Spectrum on Climate Research' in Meteorology at the Millennium (Academic Pr., 2002).
A measurement of a reduction in OLR to space, at the characteristic frequencies of emission of GHG molecules (CO2, methane, water) is direct physical evidence for a “greenhouse effect”. The influence of increased carbon dioxide on atmospheric temperatures is to cool the stratosphere [thus reducing the OLR] and mesosphere and to warm the lower atmosphere and the surface. (Houghton, The Physics of Atmospheres.)
Joe de V. says: "Do those people who say the Sun is not the main influence in Global Warming have figures showing minute variation in this huge number Over the last 100 years?"
What they argue is that the solar irradiance variations (which are only directly measured during the satellite era, from ca.1979) are not large enough to explain the observed surface temperature trend. The maximum peak-to-peak solar irradiance variation is approx. 0.2 W/m^2. The greenhouse-gas (GHG) forcing over the same period is somewhat larger. So, UNLESS one wishes to maintain that climate sensitivity to solar forcing is much greater than to forcing by GHGs (an assertion which raise its own set of issues), then one is forced to conclude that solar forcing accounts for less than 50% of the late 20th century change. Climate scientists do not, of course, deny a major, determining influence by the sun in earlier epochs.