UAH (University of Alabama, Huntsville) Microwave Sounder Unit (MSU) lower troposphere global temperature anomaly data for July 2008 was published today and has moved a bit above the zero anomaly line, with a value of 0.048, up from -0.114 in June 2008
The global UAH ∆T from June to July 2008 was .162°C
2008 1 -0.046
2008 2 0.020
2008 3 0.094
2008 4 0.015
2008 5 -0.180
2008 6 -0.114
2008 7 0.048
Click for a larger image
Reference: UAH lower troposphere data
Just like with the RSS global temperature anomaly data, I rather expected it to go up a bit, given that La Nina has diminished, plus the NH has a greater landmass than the SH, and we are in summer.
Click for a large image
Steve McIntyre of Climate Audit did an interesting graph that shows the difference between the NH and SH using the RSS data:
Figure 1. TLT3 20-80N minus TLT3 20-70S.
In general terms, the relative warming of the NH relative to the SH is something that we’re aware of, but isn’t the strength of the trend in the 30 years of satellite record astonishing? And this is nothing to do with UHI.
In comments, he proposes a some hints on a possible mechanism:
The N-S delta is very interesting in terms of historical fluctuations. The earth has small but interesting asymmetries in its poleward heat transfer, with a slight bias towards the north. In entropy terms, if the energy can find a pathway to be slightly biased north, then that’s a more efficient solution. With the same T^4 average and somewhat more efficient poleward distribution, you can increase the T^1 average, which is what we measure. A line of reasoning suggests that the ITCZ was further north in the MWP and south in the LIA.
See the complete article on Climate Audit here
Roger Pielke Sr. writes to me:
With respect to your posting on [RSS July Data]
Don’t forget that the effect of land mass and time of year is included in creating the annual variation of average tropospheric temperature, such that the anomalies are from the average for a given month. This means that in the RSS data, the increase in temperature was faster than average between June and July.
See my weblog on this subject at