Global warming?

[Kathyan]

I read in the Mirror this morning that this winter has been the second warmest since 1659. The warmest was in 1868-69. So how come that Global warming is responsible for this years?

[jno]

I think long-term trends are more important than individual years' statistics; for me the really significant figures are those showing that most of the warmest years ever have come in the last decade. I don't know what happened in 1868, but it could have been a one-off due to freak weather - that's always possible. That doesn't seem true of this winter, though.

[kwicky]

Weather always comes in cycles. If we wait long enough there will be annother ice age.

Something interesting: If you take todays weather there is more than a 50% chance it will be the same tomorrow. That is why we get those weeks of prolonged droughts.

[jno]

it's not quite true that things always go in cycles. The planet started as a lump of moltem metal; it will end as a lump of ice. So the very long-term trend ought to be cooling. And yet the figures suggest it's currently as warm as any time in the last 10,000 years or so (sorry, can't find the link to bear this claim out, but I think it was a NASA report). That to me clearly indicates something out of the ordinary is going on.

[jake-the-peg]

The climate is changing.

That's not just the odd hot year here or there and not just what the temperature might be doing in the UK.

As jno says it's the overall trend that's important.

If you don't believe it you'll have to come up with a pretty convincing explanation of where all the glaciers are going!

[Lonnie]

The climate is always changing.
There's no doubt about Global warming, the Met office says that this summer comming, will be hotter than last years.

I did put a warning about this in Gardening, but it all depends if you go there or not.

Global Warming is caused by lack of Ice, which is needed to cool the planet down, as time goes on, with more plants being grown, more Methane escaping into the atmosphere, No matter what we humans do or not do, Global warming will happen.

[newtron]

Jno, I think you fell into the same trap you warned Kathyan about. You are correct in saying that the earth is cooling on a very large time scale. This very large time scale is in terms of billions of years. Comparing temperatures over the last 10,000 years, which is a much smaller time scale (5 orders of magnitude difference), does not necessarily say anything about the over-all cooling trend. As for how climate change affects us, we are interested in the 1000 to 10,000 year time scale. Paleo-climate data suggests that the climate does change in a semi-cyclic manner on this time scale, as kwicky said.

[jake-the-peg]

I think you're talking about Milakovitch cycles

http://en.wikipedia.org/wiki/Milankovitch_cycl es

It's true that the Earth's climate would change without us but it's also equally true that biological organisms can have a significant effect on climate - this has been pretty much accepted since James Lovelock came up with Daisy World to answer his critics on the Gaia hypothesis.

However similarly you cannot explain the amount of warming that we are currently seeing by any known natural cycles, solar activity, vulcanism etc.

This was acknowledged by the US Congress' own committee on climate change.

Consequently even the US Government accepts the need to reduce emissions - even if they are persuing what many people think is a blind alley in carbon sequestration.

[newtron]

Hi Jake, I'm not arguing that global warming is not caused human activity. I was just pointing out that jno begins by rightfully saying that you cannot relate yearly temperature fluctuations to global climate change because of the differences in scale, but then turns around and makes the same mistake by suggesting that temperature change due to the long-term cooling trend of the earth has been altered based on temperature variations over a 10,000 year period.

[newtron]

http://www.answers.com/topic/2000-year-tempera ture-comparison-png

[kwicky]

Those graphs certainly show a cyclic pattern. The last 50 years do show an accelerated growth towards a hotter climate but if true to form a return to the norm will surely happen although the mean value may be above those of the past. There must be so many variables influencing our weather I would suggest there are forces to control this equilibrium.

[jno]

I was in error, newtron - it's the hottest not in 10,000 years but in a million years.

http://environment.guardian.co.uk/climatechang e/story/0,,1881461,00.html

Still a different order of magnitude, no doubt, but a quite sufficient period of time to warrant the conclusion that something's up.

[newtron]

Fair enough jno.

[skyhi9921]

i read it in either the mirror or the daily mail that it is coz of the plants that global warming is happening this was written by a scientist cant remember exactly how it worked though