How the world is threatned by massive change

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How the world is threatened by massive change

http://news.independent.co.uk/uk/environment/story.jsp?story=83044

By Michael McCarthy Environment Editor

12 July 2001

The effects of relentlessly rising global temperatures in the coming century are likely to be catastrophic for the world, the second volume of the new IPCC report spells out with more chilling confidence than ever before.

The key point to grasp from Impacts, Adaptation and Vulnerability is that so many terrible things might happen at once to a planet already under severe stress from rapid population growth, poverty and pollution.

Water supplies, agriculture, human health, wildlife, coastal cities, towns and villages and even whole national economies are all likely to be knocked off balance by climate change, the report predicts. Its 1,000-plus pages go into enormous detail about every continent.

Billions of people will to be affected directly. Societies may be able to bring about some limited adaptation, but the least able to adapt will be the poor developing countries in Africa, Asia, Latin America and the Pacific, who will be hit hardest. Their future is grim.

But do not just think of this as the future. The effects of a warming world are already vividly visible all around us and have been widely documented, the report says: across the globe now glaciers are shrinking, permafrost is thawing, ice on the sea, lakes and rivers is freezing later and melting earlier, and plant and animal behaviour is changing, with some species extending their ranges towards the poles and others declining. There are earlier dates for trees coming into leaf, insects emerging, and birds laying their eggs.

George W Bush take note: in its sober scientific language, the report insists that these phenomena are not accidental. "The observed changes in these systems are consistent in direction and coherent across diverse localities and/or regions... there is high confidence that recent regional changes in temperature have had discernible impacts on many physical and biological systems."

Yet the future that the report predicts is far worse. In the natural world, glaciers, coral reefs and atolls, mangrove swamps, northern and tropical forests, polar and alpine ecosystems, wetlands and grasslands may not just change, but "undergo significant and irreversible damage". Rare and endangered species will generally move close to extinction, and more will disappear, despite conservationists' efforts to save them.

For the human world the outlook is equally dire, not least for the fact that climate change will be imposing new interlocking stresses on human society – in an era of soaring population growth, falling incomes and rising pollution – all at the same time.

Among the most significant points are:

Water

Global warming threatens the world with a double whammy over water, the report predicts. Where there is currently enough, there is likely to be too much, in the shape of floods from increased rainfall; where it is badly needed, there is likely to be less, in the shape of droughts. The supercomputer models indicate that there will be heavier rainfall over areas such as northern Europe, including Britain, and lower rainfall over areas such as northern Africa or Australia.

"Flood magnitude and frequency could increase in many regions as a consequence of increased frequency of heavy precipitation events," the report says. It adds: "River flood hazard will increase across much of Europe" – a line that will be resonant to anyone driven out of their home by the floods following last winter's rains in Britain, the heaviest in southern England since at least 1727, and by some calculations, for 500 years or more.

But water shortage may be an even heavier burden to bear. Approximately 1.7 billion people, one-third of the world's population, already live in countries that are water-stressed, the report points out, and this figure is predicted to increase to five billion by 2025. In many of these countries, especially those in central Asia, north Africa and southern Africa, rainfall is likely to decrease further, and water quality is likely to become degraded through higher temperatures and pollutant run-off.

Agriculture

The implication of water shortage is simple: the failure of food supplies. The report predicts "a general reduction in crop yields in most tropical and sub-tropical regions for most projected increases in temperature, and a general reduction, with some variation, in potential crop yields in most regions in mid-latitudes, for increases in annual temperature of more than a few degrees C".

Across Africa, grain yields are expected to fall in many areas, with deserts growing; many countries of southern Asia are likely to see their yields fall also. In Latin America, yields may decrease to such an extent that "subsistence farming may be threatened".

The models predict some agricultural benefit from a warmer world. Timber-growing in some areas may for a time be more productive, and crops may be able to flourish in unaccustomed areas, such as northern Canada, but the report gives a warning at reading too much into this: "Benefits for crops would decline at an increasing rate and possibly become a net loss with further warming."

Health

As if flooding and the failure of food supplies were not enough, a greatly increased danger of disease will accompany them. There is likely to be a significant rise in the numbers of people exposed to vector-borne diseases such as malaria and dengue fever, and water-borne diseases such as cholera, which already impinge on up to 50 per cent of the world's population, the report says.

"Within their present ranges, these and many other infectious diseases would tend to increase in incidence and seasonality – although regional decreases would occur in some infectious diseases."

Disease itself is not the only health threat. "Projected climate change will be accompanied by an increase in heatwaves, often exacerbated by increased humidity and urban air pollution, which would cause an increase in heat-related deaths and illness episodes. The evidence indicates that the impact would be greatest in urban populations, affecting particularly the elderly, sick, and those without access to air-conditioning."

Human settlements

But the lack of food and water and health are not the only threats: the places where people live may be at risk directly. Climate change presents another bleak threat from water, the destructive power of the sea. Combine two expected phenomena, sea-level rise and the increase in violent storms, and you have a recipe for disaster on an unthinkable scale, especially in countries such as Bangladesh or Egypt where millions of people are living on land below sea level.

With a mid-range sea-level rise of 40cm, the report says, the mean annual number of people who would be flooded by coastal storm surges would increase by 2080 by between 75 and 200 million, depending on the preventive measures taken. Landslides may be as big a threat as flooding in some parts of the world.

Animals

Plants and animals, of course, will be every bit as affected as humans, and the resultant stresses will result in some of them going extinct. Modelling studies "continue to show the potential for significant disruption of ecosystems under climate change," the report says.

The change will happen too quickly for ecosystems to migrate, so the species composition within them will alter. As species are adapted to their ecosystems, this means big trouble for many of them.

"Many species and populations are already at high risk, and are expected to be placed at greater risk by the synergy between climate change rendering portions of current habitat unsuitable for many species, and land-use change fragmenting habitats and raising obstacles to species migration," says the report. "These pressures will cause some species currently classified as 'critically endangered' to become extinct and the majority of those labelled 'endangered or vulnerable' to become rarer, and thereby close to extinction, in the 21st century."

Throughout the 1,000 pages of predictions one theme is constant: it will be the poor of the world who will be hardest hit. Not only will climate disruption be greatest in the countries with lowest incomes – in water and food shortages, disease and natural disasters – the people who live there are those who can least afford adaptation and mitigation measures.

Will the rich countries be able to sit back and watch it all happen? Or is this coming collection of stresses on a battered planet be something with the power to overwhelm us all?

-- Swissrose (cellier3@mindspring.com), July 12, 2001


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