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Global warming - hype or doom?

Floods in Bangladesh, hurricanes in the West Indies and Florida, melting ice-caps. Dave Toke tries to separate fact from fiction in the greenhouse debate.

There can be little doubt that human-inspired global warming is happening. Any other reading would require a completely new geographical theory of the relationship between carbon dioxide levels, climate, and the way the Earth’s natural systems have worked since the formation of the planet. So it is not just a question of how recent temperature measurements show global warming, which they certainly do. The evidence of links between climate and carbon dioxide levels is written on the history of the planet since it was formed. To deny it you virtually have to re-invent geography and geology as subjects.

The problem is that by chucking so much carbon dioxide and other gases which trap heat we are fiddling with a mechanism that is fundamental to the Earth’s ecosystem.

Human-induced increases in atmospheric carbon dioxide levels began with large scale burning of tree coverage. Ten thousand years ago, for example, practically the whole of the UK was covered by trees (so much for the ‘naturalness’ of the British landscape!). However, even using the year 1800 as a base, carbon dioxide levels have increased from around 275 parts per million to over 360 parts per million today, a change of around 30 per cent. That is a big increase given the effect of carbon dioxide levels on climate.

In addition to changing atmospheric concentrations of carbon dioxide and other ‘greenhouse’ gases, there are various short term and longer term influences on climate. These include changes in the way the Earth ‘wobbles’ on its axis as it circles the Sun, the short term impact of dust thrown up by volcanoes and the occasional big meteorite strike, and changes in the amount of sunshine.

However we can see the big effect on climate by comparing temperatures on Earth to the moon. Despite being the same distance from the sun the temperature on the moon itself is around 35 degrees C lower than the Earth – this difference indicates the heating impact of the greenhouse gases.

Besides the comparison with the moon, another planetary comparison can be made between Venus and Mercury. Mercury, which has no atmosphere, is much closer to the Sun, yet its surface temperature is actually cooler than that of Venus. Venus, of course, has a thick atmosphere which includes a lot of carbon dioxide.

There are other potential explanations of global warming waiting in the wings. The ‘solar cycle’ theory is one. This says that changes in the levels of sunshine account for recent changes in temperature. The UN-backed Intergovernmental Panel on Climate Change (IPCC) says that it takes all these influences into account, and its models suggest that human influences generate the large bulk of the changes in temperature over the last 100 years.

As time goes on there is less questioning about the record of increases in global temperature in recent decades. All of the hottest global years in recorded history have occurred since 1990 and the 20th century was the hottest century over the past thousand years. Less is known about short-term variations in temperature before around 1000 AD because of shortages of tree-ring data.

Estimates of future temperature increases made by the IPCC average on the most plausible scenarios in the two to three degrees over the next 100 years. Median projections for sea levels come in at around 40 to 50 centimetres over the next 100 years. These figures depend on various assumptions, and certainly some influences, such as the rate of melting glaciers and ice caps, are subject to considerable uncertainty. Because warmer air holds more moisture rainfall is likely to rise, which is associated in many models with an increase in hurricanes and violent storms.

Of course we might be less lucky than the median estimates made by the IPCC. Scenarios (like the film The Day After Tomorrow) that involve the triggering of a big freeze in the northern hemisphere because of the diversion of the Gulf Stream, are cast by many as alarmist. However the problem is that we are making such a big change to our ecosystem, we have to ask ourselves, just how much of a risk do we want to take?

We are going to experience significant increases in sea levels. This is not good news for rich countries which will have to spend a lot more on flood defences for heavily populated areas and organise a retreat from other low-lying zones. It will be disastrous for developing countries with large river delta populations and positively terminal for many small island states. One sixth of the votes in the UN General Assembly come from small island states.

What we can say with reasonable certainty is that rising sea levels and shifting rainfall patterns offer the possibilities of severe disruption of human societies as well as the type of biodiversity patterns (birds, animals, plants) to which we have become accustomed. The longer that we delay taking radical counter-measures, then the worse will be the outcome.

While US policy makers, driven by Republican scepticism of ecological doomsayers, are being obliged to recognise the probability of human-induced global warming, they tend to argue that the cost of combating the problem is greater than the problems that will be caused. In a much publicised general assault on environmentalist priorities, Bjorn Lomborg in his book The Sceptical Environmentalist said that environmentalists have exaggerated environmental threats. He argues that money would be much more cost-effectively spent on providing clean drinking water for poor Africans rather than reduction of carbon dioxide emissions. The UN Johannesburg Conference on the environment endorsed this logic in 2002. On the other hand why are these two items alternatives to each other? One might as well pose spending money on educating people about state-of-the-art energy efficiency techniques rather than invading Iraq!

Perhaps this brings home the point. Tackling global warming may not be that costly if people take the problem seriously in their own lives, as well as if Governments take it seriously in their own day-to-day activities. Citizens could became experts in energy efficiency the way that people are now experts in DIY. It continues to amaze me that if you work in an office or industry you will be expected to go on all sorts of professional training schemes, yet there is not a single training scheme for (the very many) people who make workplace decisions about what energy systems or new buildings to order. There are already a lot of low-carbon technologies, ranging from making sure housing estates run on energy efficient energy generation systems to using super energy-efficient (but still zippy) motor vehicles. This Government has set a target of reducing carbon dioxide emissions by 50 per cent by 2050. Arguably, even this target is not good enough. Nevertheless, a target is there, but the means of achieving this target are still to be made clear.

The global warming problem may not be that difficult or expensive to solve, given the low-carbon technologies that already exist. The problem is attitudes. Perhaps therefore a bit more doomster-mongering might not go amiss in order to grab people’s attention.

A major problem is the solutions, about which there is fierce debate among the interest groups. Curbing carbon dioxide emissions is the biggest single priority. Options which can achieve this include energy efficiency, renewable energy sources and nuclear power as non-fossil sources. There is, and could continue to be, an increasing trend to using natural gas in place of higher-carbon fuels coal and oil leading to reductions in carbon dioxide emissions in countries such as the UK.

Many of us do not relish the prospect of a world becoming dependent on nuclear power which would itself lead to uranium resource crises and geopolitical problems such as we see surrounding oil in the Middle East. We have heard about wars for oil. What would wars for nuclear power be like? In that case we could simply be swapping one dangerous problem from another.

The nuclear power industry sense that there is a competition for funds to subsidise non-fossil sources and so are helping the campaign against wind power which is by far the cheapest renewable energy at present capable of large-scale implementation. Organisations like Friends of the Earth and Greenpeace have thus put resources into backing wind power. Any greens that decide to equivocate in the face of opposition run a very severe risk of losing credibility in their anti-global warming strategies. We have to give enthusiastic and well-resourced backing to various other renewable energy technologies, including solar power, biofuels, wave power and tidal power. Either that, or we shall encourage nuclear power.

Of course the great sleeping resource is energy efficiency. If only everybody was an expert in energy efficiency techniques we would be making very good progress in curbing rises in energy demand, because then much more energy efficient equipment and buildings would be put into use. However, as yet there is not even an accredited energy efficiency training scheme for the vast number of people who take energy equipment and building procurement decisions in commerce, industry and the public services.

Yet this would be a very cheap way of making significant progress. It is a measure of our complacency and lack of real motivation to tackle the challenge of climate change that we have so far failed even to ensure people go on energy efficiency training schemes. Indeed, the sheer economic sense of energy efficiency measures, as well as the declining cost of renewable energy sources, make a nonsense of claims made by people like Bjorn Lomborg that countering global warming is too expensive.