How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic


A 205-Year History of Mean Sea-Level Pressure From India
Reference
Allan, R.B., Reason, C.J.C., Carroll, P. and Jones, P.D.  2002.  A reconstruction of Madras (Chennai) mean sea-level pressure using instrumental records from the late 18th and early 19th centuries.  International Journal of Climatology 22: 1119-1142.

What was done
Using data from various sources, the authors present a time series of monthly mean sea-level pressure for the city of Madras (now Chennai), India for the period 1796-2000.

What was learned
Temperature, precipitation and other climate variables are largely controlled by patterns of atmospheric circulation, especially in the mid-latitudes.  Thus, decadal to centennial changes in atmospheric circulation or pressure may signify similar-scale changes in global or regional climate.  With these facts in mind, we plotted the annual sea level pressure time series - derived from the author's monthly data presented in Appendix B of their paper - for evidence of climate change.  As can be seen from the resulting figure, higher pressure dominated the first 50 years of the record, followed by about 50 years of lower pressure.  Since 1900, however, the pressure has deviated but little from the 200-year average of 1007 hPa.  In addition, the data indicate that the annual mean sea level pressure was 44% more variable during the first 75 years of the record (1796-1870) than it was during the remaining 130 years (1871-2000).

What it means
Our simple analyses of the authors' data support the findings of Slonosky et al. (2000), who analyzed surface pressure data from 51 stations scattered throughout Europe and the eastern North Atlantic over the past 200+ years and found that atmospheric circulation over Europe was "considerably more variable, with more extreme values in the late 18th and early 19th centuries than in the 20th century."  Hence, it grows ever more clear that as the earth has recovered from the global chill of the Little Ice Age, the variability of atmospheric circulation - and, hence, weather - has lessened, which finding is in direct contradiction of climate-alarmist predictions of increasing weather extremes due to global warming.

Reference
Slonosky, V.C., Jones, P.D. and Davies, T.D.  2000.  Variability of the surface atmospheric circulation over Europe, 1774-1995.  International Journal of Climatology 20: 1875-1897.


Reviewed 9 October 2002