Brightness temperatures derived from the Meteosat data show a planetary trend of global cooling of upto 2K/decade since 1984.
One wonders why this data has not been publicised earlier.
In general, the Atlantic Ocean, Africa and Europe show a negative temperature trend, varying between zero and -2 K/decade.
Andries Rosema, Steven Foppes and Joost van der Woerd, Meteosat Derived Planetary Temperature Trend 1982-2006, Energy & Environment, Volume 24, Number 3 – 4 / June 2013, 381-396, doi:10.1260/0958-305X.24.3-4.381
The paper is behind a paywall at the Journal but a pdf version is available (via climategate.nl): Rosema et al Meteosat data 1984-2006
From the author’s conclusions:
The amazing finding of the present study is that we do not observe global warming in the period 1982-2006, but significant cooling. …
The satellite data are from a reliable origin supported by the European meteorological community. Their accurate calibration has received due attention and efforts from Eumetsat. Our processing of these data has been simple and straight forward, involving only noon and midnight image composition, averaging and a filter to eliminate cloud effects. We have created similar planetary temperature change images for the unfiltered, 10, 20 and 30 day filtered data, clearly showing convergence towards the longer filters, indicating that cloud influences were effectively removed.
Moreover, we do observe significant temperature increase at some locations which are due to human interventions, and which are quantitatively in line with the theoretically expected effects of these interventions. Therefore we believe the observed planetary temperature decrease for most of the hemisphere to be real.
The cloud filtered temperature change patterns, in figure 2c, indicate that the largest decrease occurs in the more cloudy regions of the hemisphere: the tropics and the temperate zones, while in the desert belt the temperature decrease is much smaller. This suggests that cloudiness changes could be the mechanism behind the observed global cooling since 1982: an increase in cloudiness would decrease global radiation and increase rainfall and evapotranspiration. Both effects tend to decrease the surface temperature.
While their conclusions about cloud cover as the determining mechanism are plausible – but as yet unproven – their general observations are quite significant:
In general, the Atlantic Ocean, Africa and Europe show a negative temperature trend, varying between zero and -2 K/decade. Remarkable, is a large area in southern Africa, mainly Zimbabwe and Mozambique, where the temperature decrease is even larger and in the range of -2 to -3 K. Also note the temperature decrease of Lake Chad and Lake Nasser, probably due to an increase in their surface areas. There are also some spots that show a substantial temperature increase, in particular in SE Iraq (figure 3a) and NW Tanzania (figure 3b).
They see a general reduction of temperature everywhere except in two small areas of Iraq and Tanzania:
- SE Iraq- An exceptional location which shows a strong temperature increase of some 5K in the period of 20 year. This increase took mainly place in the period 1993-1995 and reflects the draining of the marshes at the confluence of the Ephrata and Tigris under the regime of Sadam Hussein.
- NW Tanzania, south of Lake Victoria. There is a temperature increase of 1.3 K in 20 year. This location is in a strongly developing mining area. Decrease in vegetation cover and reduced evapotranspiration may have caused this temperature increase.
ABSTRACT
24 year of Meteosat hourly thermal infrared data have been used to study planetary surface temperature change. Thermal infrared radiation in the 10.5-12.5mm spectral window is not affected by CO2 and only slightly by atmospheric water vapor. Satellite thermal infrared data have been converted to brightness temperatures as prescribed by Eumetsat. Hourly brightness temperature images were then composed to corresponding noon and midnight temperature data fields. The resulting data fields were cloud filtered using 10, 20 and 30 day maximum temperature substitution. Filtered data were subsequently averaged for two 10 yearly periods: 1986-1995 and 1996-2005. Finally the change in brightness temperature was determined by subtraction. In addition nine locations were selected and data series were extracted and studied for the period 1982-2006. Our observations point to a decrease in planetary temperature over almost the entire hemisphere, most likely due to an increase of cloudiness. Two small areas are found where a considerable temperature increase has occurred. They are explained in terms of major human interventions in the hydrological balance at the earth surface.
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