2007-07-24

Cynical me

Half of the UK is underwater. So what does the BBC start reporting?
Human-induced climate change has affected global rainfall patterns over the 20th Century, a study suggests.

Researchers said changes to the climate had led to an increase in annual average rainfall in the mid-latitudes of the Northern Hemisphere.
I mean, I believe in the whole human-caused global warming thing, but this is a bit too "convenient".

"It's raining because of global warming" may not necessarily be true.

1 comment:

Dave Lankshear said...

Hi OSO,

You're absolutely write in that weather does not automatically indicate evidence of climate change, even freakish weather.

It's only when these events increase statistically over time that we can say they are probably down to a change in longer-term climate.

However, if I can go on a round about way to get back to your point.... (indulge me a little).

Tim Flannery writes that the Mesopotamian civilizations flourished because of climate change caused by a minor wobble in the Milancovitch cycles. This smallish wobble, not even enough to lead to a noticeable ice-age or conversely, reduction of ice cover, "increased sunlight by 7% to the Northern Hemisphere. This enhanced the rainfall of Mesopotamia by 25 to 30%, markedly alterting the ratio of rainfall to evaporation, and increasing the overall moisture available to plants sevenfold. What was once a desert was transformed into a verdant plain that supported dense farming communities. After 3800 BC, however, Earth's orbit reverted to its former pattern and rainfall dropped off, forcing many farmers to abandon their fields and wander in search of food." (Paqe 66)

He then goes on to show how some climate specialists have argued that the rise of these ancient civilization city-states resulted from the following loss of water and concentration of people, and the need to innovate and irrigate and establish agricultural accountants so to speak... which leads into Blainey's argument as to why writing developed in the first place. In other words, climate generosity and then deprivation let our numbers flourish, and then privations forced us into the hierarchical city state with power structures, writing, organization, and culture.

Or, more simply, climate change started civilization.

Now that was only 7% change in sunlight, which in reality is a rather minor forcing in today's climate. (Over longer term Milankovitch cycles it is profound, but we are not approaching one of those for a while.)

7% in a minor forcing.

But CO2 is a much more powerful forcing. The atmosphere is very sensitive to changes in this tiny percentage gas. Yet we have already increased CO2 30% above anything we've seen in the natural Milancovitch cycles over the last MILLION years!

30% in a more significant forcing compared to the 7% change in a smaller forcing. Admittedly, the effects will be different because that 7% was a local sunlight event whereas CO2 is global... but you see what I mean. Co2 shifts are radical, even though they are tiny amounts. (I liked the climatologist in the ABC's response to "The Swindle"... "If I injected a tiny particle of ebola virus into your body, even though it was tiny the effects would be profound. You would die.")

So, in summary: one weather event does not a climate change make, but I would not be surprised if this 1 in 60 year event becomes a 1 in 5 year event if we don't beat this thing.

Thanks for your indulgence. ;-)