Rise Temperature Between 1960 to 2009

We know that global warming has taken place because millions of temperature measurements have been taken over many decades from all points on the earth. The measurement of global warming is of a wide variety of statistics over a period of time and therefore can be quite difficult to explain and understand.

The global average air temperature shows a linear trend of 0.74 [0.56 to 0.92] °C
for the 100-years from 1906-2005

This sounds like a small increase and is easily misinterpreted

For example some would say that when 2006 is described as being "the hottest in Britain since 1659" (when temperatures began to be recorded in central England)  it simply means that it was as warm in 2006 as it was in 1659 and there wasn't any worry about global warming then, so why is there now?

	Hottest since 1659 means that was when temperatures started to be recorded - not that 1659 was the 2nd hottest year ever.
	Past record years have come pretty much at random and certainly not in groups. The fourth hottest year in Britain since 1659 was 1949, 8 of the 10 hottest years since 1860 have all occurred in the last decade.
	Daily variations in temperature can commonly be from 5°C to 10°C which makes the average 0.74°C rise difficult to spot by the individual in the shorter term.
	Some parts of the world are showing the effects of warming more than others. The Northern hemisphere for instance appears to be warming more than the Southern hemisphere, possibly because there is more land in the north and more sea in the south

Northern hemisphere average annual temperatures compared to the 1961-1990 average