Future prospects - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 327

Figure 11.3. UAH globally averaged satellite-based temperature measurements of the lower
atmosphere. 6
other aberrations from human activity. However, the availability of satellite data
only goes back as far as 1979 and, therefore, has only limited implications for
understanding the long-term effects of CO 2 . Contrary to the picture presented by
Hansen et al. (2010) in Figure 11.2 , the measurements on tropospheric tempera-
ture provide a very different picture (as shown in Figure 11.3 ). These results
suggest that temperatures were stable from 1980 until the advent of the giant El
Nin˜ o of 1998, after which a new temperature plateau was reached about 0.3 C
higher than prior to the 1998 El Nin ˜ o.
Temperature data of the Earth based on surface measurements suggest that
over the past 120 years, temperatures have risen the most in northern latitudes,
with a smaller rise in the tropics, and an even smaller increase in southern
latitudes. There was an initial temperature rise from about 1890 to 1940, a tem-
perature dip from 1940 to about 1978, and a sharper rise after 1978 (see Figure
11.4 ) .
The dip from 1940 to 1978 was seized upon by global-warming naysayers as
evidence of a lack of connection between CO 2 growth and temperature rise.
However, several studies have concluded that sulfate aerosols and particulates
reflect incident sunlight, producing a cooling effect. Global-warming alarmists
then argued that the cooling observed from 1940 to 1978 was due to an increase
in aerosol production from power plants that overwhelmed the greenhouse effect,
but that the cleanup of power plants starting around 1978 reduced aerosol produc-
tion after that. This was challenged by naysayers, and there remains uncertainty
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