The graph above shows the temperature changes of the lower troposphere from the surface up to about 8 km as determined from the average of two analyses of satellite data. The UAH analysis is from the University of Alabama in Huntsville and the RSS analysis is from Remote Sensing Systems. The two analyses use different methods to adjust for factors such as orbital decay and inter-satellite difference. The best fit line from January 2002 indicates a declining trend. Surface temperature data is contaminated by the effects of urban development. The Sun's activity, which was increasing through most of the 20th century, has recently become quiet, causing a change of trend. The green line shows the CO2 concentration in the atmosphere, as measured at Mauna Loa, Hawaii. The ripple effect in the CO2 curve is due to the seasonal changes in biomass. There is a far greater land area in the northern hemisphere than the south that is affected by seasons. During the Northern hemisphere summer there is a large uptake of CO2 from plants growing causing a drop in the atmospheric CO2 concentration.

Cool periods in 1984 and 1992 were caused by the El Chichon and Pinatubo volcanic eruptions. The temperature spike in 1998 was cause by a strong El Nino.

Natural climate change is much stronger than any effect from carbon dioxide.

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