The Heat is On

OUR PLANET 9.3 - Climate Change

The Heat is On


explains that the decisions taken at Kyoto
will affect the world for millennia

dry land

The greenhouse effect is very simple. We are increasing emissions of greenhouse gases and thus their concentrations in the atmosphere are going up. As these concentrations increase, the temperature of the Earth rises. This, in turn, leads to changes in the patterns of precipitation and to sea-level rise. And as temperatures, precipitation and sea level change, there is reason to worry about adverse effects on ecological and socio-economic systems, and on human health.

There is now a discernible human influence on the Earth's climate system. If there is no global agreement to try and limit greenhouse-gas emissions, the temperature of the Earth is expected to increase between 1.0 and 3.5oC over the next century. Such a rate of change has not been experienced at any time during the past 10,000 years.

Greenhouse gases last for a long time in the atmosphere. Their long-lived nature means that, if we wait for cause and effect to be established with certainty, the world's climate will inevitably change. And if we do not like that new world, it will take us not years, not even decades, but centuries to reverse the damage. Policy makers must recognize that there is scientific uncertainty in the climate issue. But they must also realize that if they wait for perfect knowledge, it will take hundreds of years to undo the harmful effects. The full ramifications of those changes will primarily be felt by future generations.

The evidence now shows that the temperature has gone up all over the globe. Precipitation patterns have also changed. In some parts of the world, especially in Africa, it has become much drier. However, not only the amount of rainfall, but also its type, has changed. More is now falling in extremely heavy downpours and far less as light rain. It may seem paradoxical, but a warmer world would be expected to have both more floods and more droughts.

Nineteen countries around the world are already under stress for lack of water. This figure is expected to double by the year 2025 even if the climate does not change. With climate change, and the accompanying alterations in precipitation patterns, there will be even greater difficulties with water resources in even more parts of the world.


Dieback and extinction

One-third of all forest species - and two-thirds in the boreal forests of the northern hemisphere taiga - could change in a world warmed by a doubling of carbon dioxide (CO2) concentrations in the atmosphere. Coral reefs could probably keep pace with sea-level rise, but they cannot live in a world that is two or three degrees warmer, and there would be significant die-back.

The present rate of extinction for birds, animals and plants is already between 50 and 100 times the natural one. If the current rate of deforestation in the tropics continues this would go up, potentially, to 1,000 to 10,000 times the natural extinction rate within the next 30 years. This would, to say the least, be a major experiment on our ecological systems. Climate change would place yet additional stress on these systems.

As genetic and species diversity is lost, and the types of ecosystems are changed, the goods and ecological services which are so important to sustainable development would be threatened. For example, the bio-geochemical cycling of the Earth will alter. This will in turn change inputs of CO2, methane and nitrous oxide and hence have a feedback effect on the Earth's climate system.

Global agricultural production is not expected to be threatened in a warmer world. But there will be more production in the high latitudes of the northern and southern hemispheres and far less in the tropics and sub-tropics where there is already famine. In a world with doubled CO2 concentrations harvests in these areas would fall by up to 30 per cent, particularly in Africa and Latin America.

Our best estimate of sea-level rise is 50 centimetres over the next century. It could be as high as 1 metre, or as low as 15 centimetres. But once the process is set into motion, it cannot be slowed down in anything less than a few millennia. A sea-level rise of up to 1 metre will displace tens of millions of people in the low-lying deltaic areas of Bangladesh, Egypt and China. Bangladesh could lose as much as 18 per cent of its land surface and suffer a significant decrease in agricultural productivity. Whole cultures, such as small-island states, could be wiped out.

woman working

Vulnerability to change

Though most of the emissions of greenhouse gases have been put into the atmosphere by the developed world, it is the developing countries that are particularly vulnerable to climate change. The costs would be extremely significant for some parts of the world. Deforestation and agricultural and industrial processes all affect greenhouse-gas emissions. Land-use policies and practices have a major effect on climate change, and they have altered considerably. Between 1961 and 1988, for example, the amount of arable land in Latin America increased by 36 per cent while the amount of forests and woodlands fell by 11 per cent. There are very similar trends in Africa and parts of Asia.

Industrialized countries would not escape altogether. Large segments of the Everglades in Florida, for example, would totally disappear if sea levels rose by 1 metre. There would also be a significant change in the structure of forests of the east coast of the United States. Neither sugar maples nor beeches would survive. At present, beech trees range all the way from Florida up to Canada, but in a world with doubled CO2 concentrations they would be restricted to Canada, and the situation would be very similar for sugar maples.

In fact all this is almost an optimistic view of the world of the future. Limiting the concentrations of CO2 to just a doubling will be an extremely difficult task. To achieve this, the governments of the world will have to agree on some fairly strict limitations on greenhouse-gas emissions in Kyoto. If they do not, there is no reason to believe that the concentrations will not triple or quadruple.

The extent to which climate will change in the future will depend on, among other things, the number of people on the Earth in the next few decades, economic growth rates, energy prices, and what policies are adopted to try and get new energy technologies into the marketplace.

The very rapid rise in the world's population since the 1800s - and the increase projected for the future - is an extremely important factor. It is now recognized that empowering women, through education and enabling them to get credit for microenterprises, is absolutely critical in reducing population growth.

The insatiable appetite for energy services is another key driving force. Countries in North America and Europe, for example, could produce and use energy much more efficiently and much more cleanly. Increased energy consumption in developing countries is absolutely essential if poverty is to be alleviated. Hence the challenge is to meet the energy services needs in the most environmentally friendly manner.

The bottom line is that meeting human needs, with present practices, is causing environmental degradation. And the environmental degradation then threatens our ability to meet human needs. A holistic approach is required, concentrating on meeting human needs while protecting the local, regional and global environment. Only then can the vision of sustainable development be realized.


Redoubling efforts

At the time of the negotiation of the Montreal Protocol - which will protect society against the harmful consequences of stratospheric ozone depletion - there were some sceptics who pointed out uncertainties in the ozone computer models and argued that the world should wait for much better knowledge before taking action. These sceptics were absolutely right about the models. They were inaccurate: they significantly underestimated the effects of human activity on stratospheric ozone. Hence, even with the Montreal Protocol - and all the strengthening amendments and adjustments to it of the past 10 years - we will have to live with stratospheric ozone depletion over most of the globe for at least another 50 years. Some of the same sceptics are now saying that we do not know enough about climate change to take action to combat it.

There are, of course, many scientific uncertainties - but there is no doubt that humanity is affecting the global environment. We must therefore redouble our research efforts. But, even more important, we must redouble our efforts at moving towards political solutions.

Science can only inform policy makers. It cannot and should not make decisions. It will take political will to protect the Earth's climate system. Kyoto is a milestone, testing the ability of governments to address this complex, but critical, global issue.

Dr. Robert Watson is Director of the Environment Department of the World Bank and Chairman of the Intergovernmental Panel on Climate Change.

Complementary articles in other issues:
Issue on Climate & Action 1998
Issue on Small Islands 1999
Claude Martin: Millennial warning (Looking forward) 1999
Ismail Serageldin: Beating the water crisis (Water) 1996
James D. Wolfensohn: Crucibles of development (Human Settlements) 1996
John Houghton: Danger signal (Atmosphere) 1996

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