Yes I beileve the world is warming up, but I do not believe that it is entriely (or necessarily even mostly) to do with human efforts. But then my father is one of the scientists that was arguing against it for years, so I'm biased.
I certainly don't think we can combat it. I think cutting the use of fossil fuel, which is running out anyway, will effectivly reduce emissions, which may be making things worse. But the effects of smog and cloud cover are so little understood that it's difficult to say what the effects will be.
I believe it is happening in a large part because of the presence of people, particularly CO2 and CH4 emissions and deforestation.
Here's the supporting evidence I mainly use to convince myself.
The concentration of CO2 has increased in fifty years by 50ppm to 350ppm from 300ppm almost linearly. From 1850 to 1950 there was a slower increase from about 290ppm. 300ppm is a concentration which has not been exceeded for the past 0.5My.
Industrial countries emit around 10Pg (peta-grams, 10^15) of CO2 a year. Around 5Pg of CO2 is emitted a year through land use change such as burning forests. There are around 2750Pg of CO2 in the atmosphere, meaning that human changes are around 0.5% of the atmospheric CO2 a year.
The processes which exchange carbon between the atmosphere and the sea, and the atmosphere and the land are both currently biased toward deposition from the atmosphere of around 1-2% of the total annual exhange, suggesting geohistorically high CO2 concentrations in the atmosphere. The total nett loss of CO2 equivalents from the atmosphere to natural processes is around 11Pg/y.
The nett loss of 11Pg/y by natural processes from the atmosphere is close to the annual human input to the atmosphere of 15Pg/y, and slightly lower. The figures are so similar that, for me, I would need compelling evidence that this isn't the mechanism, and that other, yet unknown processes, are occuring which happen to cancel out to leave the impression of human causation.
An additional formulation is that this isn't a process of judicial blame, a process of "whose fault". If we didn't emit these CO2 emissions then, whatever the source of the initial warming, our actions would have a massive cooling effect, causing the atmosphere to lose CO2 to the ground and sea by natural processes.
It also suggests to me that the natural processes maintain a dynamic equilibrium between the atmosphere and the land/sea, and that the atmospheric concentration needs to increase further, so that the equilibrium shifts until the natural deposition processes proceed at a rate of 15Pg/y. It's difficult to predict what kind of an increase in CO2 would cause the deposition rate to match. The most-likely "best" case though is that the current concentration is sufficient, in time to increase deposition of CO2 to 15Pg/y. At current concentrations of CO2, the Vostok ice core suggests a 4-5 deg C temperature rise over present temperatures from three separate eras at slightly less than current concntration, all within about 10% of that temperature rise figure. I'd extrapolate 6 celcius at current unprecidented concentrations, but 5 degrees, the minimum plausible, is still quite a lot!
The vostok core suggests that past eras of warming have been caused by concentrations of CO2 rising from a baseline of around 220 to around 280ppm. The 280ppm of the pre-industrial start is already near the top of the range. We're now close to 350ppm.
5Pg of CO2 is around 1ppm. Annual human output puts about 2ppm into the atmospheric buffer. The CO2 data suggests that concentrations have been rising by around 1ppm annually. In 1950 we were putting around a quarter to a half of that into the atmosphere annually, around 0.5ppm-1ppm, the current rate of the deopsition processes.
I don't think there's much room for doubt at the moment to be honest, a five to six degree rise, then who-knows-what?
I think the causation argument is daft. I think that even the most natural-origins people would acknowledge the correlation between CO2 concentration and temperature. I think that most acknowledge that the CO2 causes the temperature rise, because it's exactly what even simple bulk models of gasses predict. It could always be a coincidence caused by fairies, or whatever, but isn't that always the way? I think that the argument as to whose straw broke the camel's back between the owners of various straws, and as to who is to be blamed is a bit daft. We are placing a CO2 load on the atmosphere. Even if the current increase is being caused by goblins, it's best to take our additional load off if we don't want to fry.
I wasn't suggesting that it isn't the most commonly supposed mechanism. It's more that I'm trying to cultivate a habit of avoiding making definite statements about causation on topics about which I am insufficiently informed :)
A couple of years back I asked a friend who works as a climatologist for the Met office what he thought of Bjorn Lomborg. The answer was predictable, although unexpectedly considered and polite.
Do I believe in the greenhouse effect (ie the theory that the production of CO2 and certain other gasses will cause a substantial increase in temperatures)? Yes. I think you'd be hard pressed to find many scientists who don't believe that the theory is at least probably correct. It seems almost certain that an increase in the planet's temperature will be an inevitable consequence of the production of greenhouse gasses.
But do I believe that the Earth is currently getting hotter (in a noticeable/measurable) way? Weather patterns are so naturally variable that it's impossible to tell. I think you'd be hard pressed to find many meteorologists who would be prepared to state categorically that the Earth is currently getting warmer (though I may be out of date on this).
What's clear is that the Earth certainly will get a lot warmer unless we make radical changes to the way we treat the environment.
Problem is, the much-publicised 'global warming' is only one of several phenomena associated with climate change. There's good evidence to suggest that we in the northern hemisphere might experience global cooling, as the gulf stream may cease to function properly due to the icecaps melting.
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timeasmymeasure
no subject
Date: 2004-08-18 10:52 am (UTC)no subject
Date: 2004-08-18 11:12 am (UTC)no subject
Date: 2004-08-18 04:34 pm (UTC)no subject
Date: 2004-08-18 11:08 am (UTC)no subject
Date: 2004-08-18 12:08 pm (UTC)Here's the supporting evidence I mainly use to convince myself.
The concentration of CO2 has increased in fifty years by 50ppm to 350ppm from 300ppm almost linearly. From 1850 to 1950 there was a slower increase from about 290ppm. 300ppm is a concentration which has not been exceeded for the past 0.5My.
Industrial countries emit around 10Pg (peta-grams, 10^15) of CO2 a year. Around 5Pg of CO2 is emitted a year through land use change such as burning forests. There are around 2750Pg of CO2 in the atmosphere, meaning that human changes are around 0.5% of the atmospheric CO2 a year.
The processes which exchange carbon between the atmosphere and the sea, and the atmosphere and the land are both currently biased toward deposition from the atmosphere of around 1-2% of the total annual exhange, suggesting geohistorically high CO2 concentrations in the atmosphere. The total nett loss of CO2 equivalents from the atmosphere to natural processes is around 11Pg/y.
The nett loss of 11Pg/y by natural processes from the atmosphere is close to the annual human input to the atmosphere of 15Pg/y, and slightly lower. The figures are so similar that, for me, I would need compelling evidence that this isn't the mechanism, and that other, yet unknown processes, are occuring which happen to cancel out to leave the impression of human causation.
An additional formulation is that this isn't a process of judicial blame, a process of "whose fault". If we didn't emit these CO2 emissions then, whatever the source of the initial warming, our actions would have a massive cooling effect, causing the atmosphere to lose CO2 to the ground and sea by natural processes.
It also suggests to me that the natural processes maintain a dynamic equilibrium between the atmosphere and the land/sea, and that the atmospheric concentration needs to increase further, so that the equilibrium shifts until the natural deposition processes proceed at a rate of 15Pg/y. It's difficult to predict what kind of an increase in CO2 would cause the deposition rate to match. The most-likely "best" case though is that the current concentration is sufficient, in time to increase deposition of CO2 to 15Pg/y. At current concentrations of CO2, the Vostok ice core suggests a 4-5 deg C temperature rise over present temperatures from three separate eras at slightly less than current concntration, all within about 10% of that temperature rise figure. I'd extrapolate 6 celcius at current unprecidented concentrations, but 5 degrees, the minimum plausible, is still quite a lot!
The vostok core suggests that past eras of warming have been caused by concentrations of CO2 rising from a baseline of around 220 to around 280ppm. The 280ppm of the pre-industrial start is already near the top of the range. We're now close to 350ppm.
5Pg of CO2 is around 1ppm. Annual human output puts about 2ppm into the atmospheric buffer. The CO2 data suggests that concentrations have been rising by around 1ppm annually. In 1950 we were putting around a quarter to a half of that into the atmosphere annually, around 0.5ppm-1ppm, the current rate of the deopsition processes.
I don't think there's much room for doubt at the moment to be honest, a five to six degree rise, then who-knows-what?
Figures courtesy of UNEP and others.
no subject
Date: 2004-08-18 12:08 pm (UTC)no subject
Date: 2004-08-18 12:13 pm (UTC)no subject
Date: 2004-08-18 12:28 pm (UTC)no subject
Date: 2004-08-18 06:54 pm (UTC)no subject
Date: 2004-08-18 12:58 pm (UTC)no subject
Date: 2004-08-18 02:08 pm (UTC)Do I believe in the greenhouse effect (ie the theory that the production of CO2 and certain other gasses will cause a substantial increase in temperatures)? Yes. I think you'd be hard pressed to find many scientists who don't believe that the theory is at least probably correct. It seems almost certain that an increase in the planet's temperature will be an inevitable consequence of the production of greenhouse gasses.
But do I believe that the Earth is currently getting hotter (in a noticeable/measurable) way? Weather patterns are so naturally variable that it's impossible to tell. I think you'd be hard pressed to find many meteorologists who would be prepared to state categorically that the Earth is currently getting warmer (though I may be out of date on this).
What's clear is that the Earth certainly will get a lot warmer unless we make radical changes to the way we treat the environment.
-roy
no subject
Date: 2004-08-19 12:03 am (UTC)no subject
Date: 2004-08-19 02:29 am (UTC)http://news.bbc.co.uk/1/hi/sci/tech/3266833.stm
and
http://news.bbc.co.uk/1/hi/sci/tech/2840137.stm
The trend for the planet as a whole seems to be of temperature increase though:
http://news.bbc.co.uk/1/hi/sci/tech/3570602.stm
http://news.bbc.co.uk/1/hi/sci/tech/3559426.stm
http://news.bbc.co.uk/1/hi/world/europe/3929507.stm
http://news.bbc.co.uk/1/hi/world/europe/3922579.stm
http://news.bbc.co.uk/1/hi/sci/tech/3572532.stm
...just since July!