IS GLOBALWARMING REAL?

The warming of the earth through natural events isn’t in doubt but there is debate as to how much human activities have contributed to globalwarming.

NATURAL GLOBALWARMING

Since the creation of Earth some 4,567 million years ago it has gone through many warming and cooling cycles. The current cycle is one of warming, this began 18,000 years and has warmed Earth by approximately 9°C; it’s this warming which brought about the end of the last ice age some 10,500 years ago (note 1).

On a much larger time-scale, the world is in a general cooling phase and has been for about 50 million years, this in itself is part of a much larger cycle of long term cooling and warming.

It’s thanks to the natural greenhouse effect that our planet is habitable, without it the world would be some 33°C colder.

MAN-MADE GLOBALWARMING

If there were no life on Earth it would still be warming. Of concern is the unprecedented rise in temperatures over the last 150 years or so, as can be seen on the graphs below.

In recent years there has been much debate about the human contribution to globalwarming and consequent climate change. The IPCC (note 2) has conducted the most detailed examination of climate change to date and concludes that human cause is ‘very likely’ [BBC News].

AWARENESS2007, AN UNPRECEDENTED RISE IN TEMPERATURE

As we’ve established, the world is currently in a warming phase which has seen temperatures rise by 9°C during the course of the last 18,000 years. Most of this rise happened during the first 8,000 years of this period and was the cause of the glacial retreat. For the last 10,000 years temperatures have remained more or less the same and the glacial retreat has been halted.

Over the course of the current warming phase, the rise in temperatures has been the equivalent of 0.0005°C per year, this can be considered to be the natural variation in the earths temperature. Such small changes have very little effect over periods of tens or hundreds of years but over longer periods the effects are dramatic.

The last 200 years has seen a rise in temperatures far in excess of that which would be expected.

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