THE Rev Philip Foster (Letters, April 23) would have us believe that world temperatures are falling while CO2 levels are rising, and that there is no correlation between CO2 levels and world temperatures. In support of his argument, he presented misleadin

THE Rev Philip Foster (Letters, April 23) would have us believe that world temperatures are falling while CO2 levels are rising, and that there is no correlation between CO2 levels and world temperatures.

In support of his argument, he presented misleadingly selective data on surface temperatures and lower atmosphere temperatures measured by satellite. He claims that the surface temperature data are overestimated and less reliable than the microwave satellite data collected by US National Oceanic and Atmospheric Administration, NOAA, but he fails to support this with any evidence or authoritative source.

Professional meteorologists from the UK Met office and NOAA disagree with his claims. Here are the facts. No one denies that greenhouse gases in the atmosphere, and in particular CO2 have been increasing over at least the last century. Global surface temperatures have increased by 0.8 degrees C since 1910 and the rate of increase has been accelerating and has been 0.15 degrees C per decade over the last 50 years (see the NOAA website: http://www.ncdc.noaa.gov/oa/climate/globalwarming.html and the UK Met office website: http://www.metoffice.gov.uk/corporate/pressoffice/myths/2.html).

NOAA also operates the satellites that measure temperatures in the atmosphere. NOAA's data show that temperatures in the lower troposphere (the atmosphere between the surface and 10,000 feet) from 1979 up to March 2008 have increased by 0.177 degrees C per decade - similar to and compatible with the measurements of surface temperature (http://www.remss.com/msu/msu_data_description.html#msu_decadal_trends).

Furthermore, other observations are consistent with a warming world. The September Arctic Sea ice has shrunk between 1973 and 2007 by a massive 35 per cent. Glaciers have shrunk in the Asian High Mountains (Karakoram, Hindu Kush and Himalaya), Western North America, Alaska and Patagonia by huge amounts (see NOAA website above). Sea levels have been rising steadily since 1900.

Most professional meteorologists accept that global warming is caused, at least partly, by the increase in CO2 concentrations, but a very few disagree. That is legitimate. But to claim that there is no global warming and that there is no correlation between CO2 concentration and global temperatures over time is, as we have seen, simply false.

Dr ALEC MacANDREW

Balmoral Way

Eynesbury