global warming?
I’ve often wondered at how little global warming gets a mention in the New Scientist mag which I try to buy and read each week, considering it’s supposedly the biggest issue facing the planet and we need hard and ongoing scientific data to keep as alert to the issues and possible solutions. The February 12 issue, four days before the Kyoto Protocol came into effect, has at last come to the party, and I’ll use that as a starting point to try to get a grip on the phenomenon.
One of the problems of the stuff in NS is that it's come out of a conference on dangerous climate change, what they call 'outlier' predictions of horrendous warming, up to 11 degrees C, so much of the reporting is skewed towards the dire. I'll try to keep a level head.
Some things are beyond contention. The amount of carbon dioxide in the atmosphere is increasing. Concentrations are currently about 35% above pre-industrial levels. About half of this increased CO2 since the industrial revolution is being absorbed by the oceans, increasing their acidity. It’s naturally assumed that the effect of this increased acidity on complex ecosystems will be substantial, though not easy to predict. It’s very likely that worldwide coral growth will be affected, and presumably this is already happening.
It’s also beyond doubt that there is a greenhouse effect as a result of carbon dioxide and water vapour in the atmosphere trapping the infrared radiation emitted by the earth’s surface. Recent measurements have shown that infrared radiation - in the 13 to 19 micrometre wavelength range, which is the part of the infrared spectrum trapped by CO2 – has escaped from the atmosphere less and less in the past thirty or so years. This unescaped radiation would be stored in the atmosphere as heat.
With all the uncertainty, though, it’s hardly surprising we have some individuals and groups claiming that the effects will actually be beneficial. Of course it’s always worth noting who's putting out certain interpretations and who’s backing them.
The UN’s Intergovernmental Panel on Climate Change (IPCC) has often been criticised by global warming sceptics for ignoring alternative interpretations and scenarios as it tries to build a consensus that can lead to effective action in terms of curbing emissions, but some scientists at a recent conference in Exeter, England, are advancing the idea that alternative scenarios, which present an even worse picture of the problem, may turn out to be correct.
They’ve pointed to ‘dangerous extreme’ events, such as the 2002 heat wave in Europe that killed an estimated 30,000 people (I missed that one), which they argue are rendered more likely by incremental changes to average climate conditions.
Probably the most important and controversial feature of climate change research concerns ‘tipping points’, the triggering of irreversible climatological changes, such as the melting of the polar ice caps, which will lead to a substantial rise in sea levels.
Looking at Antarctica, the East Antarctic ice sheet sits on land, but the land of the West Antarctic is below sea level, and the ice sheet above it appears to be slipping into the sea and breaking up. Predictions have been made in the past about this scenario, with claims that the whole process could be completed in 200 years, but they have been either disputed or dismissed. More recently alarm bells have begun to chime again, but more research needs to be done.
The difficulty of course is that not only can sceptics dispute that polar ice is melting, they can also dispute the causes of such melting, as well as the likely effects. On global warming generally, Robert Mendelsohn of Yale Uni argues that the benefits are offsetting the damages, particularly for North Americans and Northern Europeans. The official line of the US government is that climate change science is ‘uncertain’, which of course means business as usual.
Temperature records going back 150 years indicate that 19 of the 20 warmest years, in terms of average global temperature, have occurred since 1980. A reasonable point could be made here that 150 years is hardly a long time. In Robin Stirling’s book, The Weather of Britain, he pointed out that the weather has fluctuated much more over larger periods. There was the Little Ice Age of a few centuries ago (I remember reading about it in Virginia Woolf’s Orlando), when parts of the Thames were covered in metres of ice, and there is some evidence that in Roman times Britain was a few degrees celsius warmer than it is today.
It’s also questionable whether human activity alone is responsible for the upward trend of temperatures in recent years – in fact it’s now generally agreed that solar cycles are at least partially responsible. The changing frequency of volcanic eruptions also has an effect, but scientists are more or less agreed that, in the past thirty years at least, neither of these two factors should have played a part in the 0.5 degree increase in global temperature. So even sceptics accept that human activity has effected some climate change, even if they disagree on its effects.
The picture that’s beginning to emerge from my explorations, shallow though they might be, is quite muddled and a little unconvincing. I don’t see any clear reason as yet to side with the catastrophists, though I would err on the side of caution in assuming that increased CO2 emissions are likely to increase global temperature, with the follow-on effect of causing sea levels to rise due to thermal expansion and the melting of glaciers.
So what evidence is there of sea levels rising currently, and if there are rises, are they within normal fluctuations?
The IPCC has predicted a global rise in the sea level of approximately 1 metre in the twentieth century [on what data are these predictions based?]. The sea level rose by 20-30cms in the twentieth century, threatening the islands of Tuvalu and the Maldives, though again it’s uncertain that CO2 emissions are primarily responsible. America’s EPA predicts a rise between 30 inches and six feet in the course of the century. It’s an inexact science, to say the least, and this makes the taking of measures to ward off global warming quite a difficult proposition. How can we hammer away at CO2 emissions via the Kyoto protocol if we can't agree on the impact of CO2 emissions on global climate change? There’s no doubt that much global warming scepticism is self-serving and opportunistic, but many sceptics have a valid point considering the number of variables and the lack of consensus on the causes, effects and extent of global warming. There’s no doubt that some groups behave with missionary zeal and are quick to blame all impacts on wealthy fossil fuel-consuming nations, and there's also no doubt that the science of climate change is enormously complex and open to manipulation.
My tentative conclusion is that global warming is occurring, and some of it is due to human activity. The consequences of such warming are largely unforeseeable at this stage, as is the extent of the warming and whether it’s within ‘natural limits’. As to consequences, a point made by Julian Hunt is worth pondering, on the distinction between hazard and vulnerability, hazard being the actual phenomenon and vulnerability being the effect on the community. This distinction was tragically illustrated in the recent tsunami, which so massively affected vulnerable and impoverished coastal communities. If we were able to better predict events related to global warming, such as heat waves, obviously the vulnerability of communities would be greatly reduced.
I'm sure much of the science in this debate is beyond me, but I'm smart enough to recognise that the only real consensus in this debate is that there has been a global warming over the past hundred years, and that the amount of CO2 in the atmosphere has increased quite a bit (from 280 to 380ppm in the past 250 years or so). And that there is quite probably a causal link there. The best article i've so far come across in my search (that's to say the one that most agrees with my tentative conclusions) is this from Rob Lyons. It's a pleasure to find a new site like Spiked.
Another reason for scepticism is that temperatures tend to be measured in cities, where there's been much local warming in the past century or so. There are counter-claims that these local effects have already been factored in, but the debate in this area, as in global warming generally, will continue to run and run.
So, I feel more informed but not more certain.
One of the problems of the stuff in NS is that it's come out of a conference on dangerous climate change, what they call 'outlier' predictions of horrendous warming, up to 11 degrees C, so much of the reporting is skewed towards the dire. I'll try to keep a level head.
Some things are beyond contention. The amount of carbon dioxide in the atmosphere is increasing. Concentrations are currently about 35% above pre-industrial levels. About half of this increased CO2 since the industrial revolution is being absorbed by the oceans, increasing their acidity. It’s naturally assumed that the effect of this increased acidity on complex ecosystems will be substantial, though not easy to predict. It’s very likely that worldwide coral growth will be affected, and presumably this is already happening.
It’s also beyond doubt that there is a greenhouse effect as a result of carbon dioxide and water vapour in the atmosphere trapping the infrared radiation emitted by the earth’s surface. Recent measurements have shown that infrared radiation - in the 13 to 19 micrometre wavelength range, which is the part of the infrared spectrum trapped by CO2 – has escaped from the atmosphere less and less in the past thirty or so years. This unescaped radiation would be stored in the atmosphere as heat.
With all the uncertainty, though, it’s hardly surprising we have some individuals and groups claiming that the effects will actually be beneficial. Of course it’s always worth noting who's putting out certain interpretations and who’s backing them.
The UN’s Intergovernmental Panel on Climate Change (IPCC) has often been criticised by global warming sceptics for ignoring alternative interpretations and scenarios as it tries to build a consensus that can lead to effective action in terms of curbing emissions, but some scientists at a recent conference in Exeter, England, are advancing the idea that alternative scenarios, which present an even worse picture of the problem, may turn out to be correct.
They’ve pointed to ‘dangerous extreme’ events, such as the 2002 heat wave in Europe that killed an estimated 30,000 people (I missed that one), which they argue are rendered more likely by incremental changes to average climate conditions.
Probably the most important and controversial feature of climate change research concerns ‘tipping points’, the triggering of irreversible climatological changes, such as the melting of the polar ice caps, which will lead to a substantial rise in sea levels.
Looking at Antarctica, the East Antarctic ice sheet sits on land, but the land of the West Antarctic is below sea level, and the ice sheet above it appears to be slipping into the sea and breaking up. Predictions have been made in the past about this scenario, with claims that the whole process could be completed in 200 years, but they have been either disputed or dismissed. More recently alarm bells have begun to chime again, but more research needs to be done.
The difficulty of course is that not only can sceptics dispute that polar ice is melting, they can also dispute the causes of such melting, as well as the likely effects. On global warming generally, Robert Mendelsohn of Yale Uni argues that the benefits are offsetting the damages, particularly for North Americans and Northern Europeans. The official line of the US government is that climate change science is ‘uncertain’, which of course means business as usual.
Temperature records going back 150 years indicate that 19 of the 20 warmest years, in terms of average global temperature, have occurred since 1980. A reasonable point could be made here that 150 years is hardly a long time. In Robin Stirling’s book, The Weather of Britain, he pointed out that the weather has fluctuated much more over larger periods. There was the Little Ice Age of a few centuries ago (I remember reading about it in Virginia Woolf’s Orlando), when parts of the Thames were covered in metres of ice, and there is some evidence that in Roman times Britain was a few degrees celsius warmer than it is today.
It’s also questionable whether human activity alone is responsible for the upward trend of temperatures in recent years – in fact it’s now generally agreed that solar cycles are at least partially responsible. The changing frequency of volcanic eruptions also has an effect, but scientists are more or less agreed that, in the past thirty years at least, neither of these two factors should have played a part in the 0.5 degree increase in global temperature. So even sceptics accept that human activity has effected some climate change, even if they disagree on its effects.
The picture that’s beginning to emerge from my explorations, shallow though they might be, is quite muddled and a little unconvincing. I don’t see any clear reason as yet to side with the catastrophists, though I would err on the side of caution in assuming that increased CO2 emissions are likely to increase global temperature, with the follow-on effect of causing sea levels to rise due to thermal expansion and the melting of glaciers.
So what evidence is there of sea levels rising currently, and if there are rises, are they within normal fluctuations?
The IPCC has predicted a global rise in the sea level of approximately 1 metre in the twentieth century [on what data are these predictions based?]. The sea level rose by 20-30cms in the twentieth century, threatening the islands of Tuvalu and the Maldives, though again it’s uncertain that CO2 emissions are primarily responsible. America’s EPA predicts a rise between 30 inches and six feet in the course of the century. It’s an inexact science, to say the least, and this makes the taking of measures to ward off global warming quite a difficult proposition. How can we hammer away at CO2 emissions via the Kyoto protocol if we can't agree on the impact of CO2 emissions on global climate change? There’s no doubt that much global warming scepticism is self-serving and opportunistic, but many sceptics have a valid point considering the number of variables and the lack of consensus on the causes, effects and extent of global warming. There’s no doubt that some groups behave with missionary zeal and are quick to blame all impacts on wealthy fossil fuel-consuming nations, and there's also no doubt that the science of climate change is enormously complex and open to manipulation.
My tentative conclusion is that global warming is occurring, and some of it is due to human activity. The consequences of such warming are largely unforeseeable at this stage, as is the extent of the warming and whether it’s within ‘natural limits’. As to consequences, a point made by Julian Hunt is worth pondering, on the distinction between hazard and vulnerability, hazard being the actual phenomenon and vulnerability being the effect on the community. This distinction was tragically illustrated in the recent tsunami, which so massively affected vulnerable and impoverished coastal communities. If we were able to better predict events related to global warming, such as heat waves, obviously the vulnerability of communities would be greatly reduced.
I'm sure much of the science in this debate is beyond me, but I'm smart enough to recognise that the only real consensus in this debate is that there has been a global warming over the past hundred years, and that the amount of CO2 in the atmosphere has increased quite a bit (from 280 to 380ppm in the past 250 years or so). And that there is quite probably a causal link there. The best article i've so far come across in my search (that's to say the one that most agrees with my tentative conclusions) is this from Rob Lyons. It's a pleasure to find a new site like Spiked.
Another reason for scepticism is that temperatures tend to be measured in cities, where there's been much local warming in the past century or so. There are counter-claims that these local effects have already been factored in, but the debate in this area, as in global warming generally, will continue to run and run.
So, I feel more informed but not more certain.
posted by Stewart at 9:08 pm
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