The IPCC synthesis report 2001, shows that the earth warmed between 1900 and 1940, then subsequently cooled between 1941 and 1965, but surface temperatures have been warming ever since (Fig 1.0). Data from millions of thermometer measurements taken from all over the world from as far back as 1860, allow calculation of average surface air temperatures. This data is believed to be the most useful when describing the state of the global climate. It can be seen that 1998 is the warmest year on record, with the ten warmest all occurring since 1990. Records show that global temperature has risen by approximately 0.6°C since the beginning of the 20th century, and 0.4°C of this warming has occurred since the 1970s (UKCIP, 2002). This indicates that global warming is occurring. However, many scientists are sceptical, and the issue is subject to debate on whether surface temperatures are rising or not.
Global- Average Surface Air Temperatures
The sceptics can be divided into two groups. Those that do not believe the climate is warming, and those who have the opinion that global temperatures are rising, but the observed increase is not anthropogenic. The latter argue that the rising temperatures are due to natural variation in climate as the world emerges from a mini-ice age (Kuo, Lindberg, and Thornson, 1990). They make the point that atmospheric concentration of CO2 has widely varied over time, the highest estimates being over twenty times higher than at present, and the lowest at approximately 18th-Century levels (Berner, 1997).
The two sceptical views are discussed – click on the links below:-
the climate is not warming
increase is not anthropogenic.
The UK Government accepts Climate Change: Read Tony Blair’s 2004 speech.
More than 80% civil engineers are now not only convinced that Climate Change is taking place: They also claim to be worried about it. More..