Photograph by Peter Sandison.
The consequences of this warming are likely to be highly destructive. With more energy driving the Earth’s climatic systems and more heat affecting the polar ice caps, the frequency and severity of storms, floods and droughts will increase. Sea surges, crumbling coastlines, salt water intrusion
into groundwater, failing crops and the spread of endemic diseases such as malaria and dengue fever will take a heavy economic and social toll. The inundation of low-lying coastal areas and islands will displace entire societies and destroy areas like the Maldive and Galapagos islands.
There are likely to be hundreds of millions of environmental refugees – people fleeing from the intruding sea or from the deserts they have left in their wake. Scientists are cautioning governments that millions more will die worldwide because of the changes in global climate that we have unleashed.
Raising a storm
South Asia has already been particularly badly hit by the likely effects of climate change. In 1999, the super-cyclone that tore through Orissa – whose winds were 73 per cent faster than past cyclones in the region - killed over 10,000 people and destroyed the crops, cattle and livelihoods of millions more. Even more recently, well over 100 million people have been put at risk from the unusually severe drought in northern India, southern Pakistan and Afghanistan, as the rains have failed for successive years and as temperatures have reached intolerable levels.
If greenhouse gas emissions continue to rise in an unmitigated way, the UK Meteorological Office forecasts that by 2080, India will experience a rise in temperature of up to 70C, a decline in precipitation of up to three millimetres per day, reduction in annual river runoff by up to 75 per cent and a 20 per cent fall in food supply. The lives and livelihoods of 50 million people living on the coast will be threatened by sea level rise, which is expected to inundate low lying coastal areas including much of Bangladesh, islands in the Indian Ocean such as the Maldives, and parts of India, Pakistan and Sri Lanka. India is expected to have shorter monsoons and more intense downpours, further increasing the likelihood of damaging floods, especially as the intensity and frequency of cyclones in the Arabian Sea and the Bay of Bengal will increase. The melting of the Himalayan glaciers (which has already begun) will initially cause the glacier-fed rivers of northern India, the Indus, Ganges and others, to swell and flood, and then shrink to dangerously low levels, bringing severe water shortages affecting up to 500 million people.
Photograph by Hira Punjabi.
Wildlife in danger
While humanity is clearly going to be dramatically affected by such changes, the first impacts will, as always, be on wildlife, for whom the implications of climate change will be even more severe. The rate of human-induced climate change is occurring faster than nature has had to deal with for over ten thousand years, and there is a very real prospect that many natural ecosystems and individual species will not be able to adjust fast enough. Delegates to the 1987 Villach Climate Conference were of the opinion that a global mean temperature rise of about 10C per century was about the limit to which most ecosystems could adapt, a rate which will be far surpassed if global greenhouse gas emissions are not brought under control. Climate change will thus give rise to huge ecological instability, leading to vast animal migrations, population explosions (largely of micro-organisms), and sharp increases in the already alarming rate of extinctions.
Climate change is already suspected of having had a major impact on marine and terrestrial habitats and species in South Asia. In the Indian Ocean, 70 per cent of coral reefs – the second richest type of ecosystem in the world, harbouring one-quarter of all ocean species and at least 65 per cent of marine fish species – appear to have died. The principal culprit seems to be ocean warming, which causes coral polyps to expel the algae that live within their tissues, an action known as ‘bleaching’ because it turns the coral white. If the bleaching is brief, the coral can usually recover, but with rapid, sustained and pervasive ocean warming, bleaching of many reefs has persisted with fatal results, as coral cannot live for long without the expelled algae upon which they depend for nourishment. Bleaching is also thought to make corals more vulnerable to epidemics, which are further destroying Indian Ocean reefs. If the situation continues, nearly three-quarters of the ocean’s richest biome may disappear in 50 years.
The consequences of such coral loss are far-reaching, especially in combination with rising sea levels and increased storm intensity and frequency. Large stretches of the South Asian coast will lose the protection that reefs provide, making them more vulnerable to inundation.
Mangroves and coastal wetlands are very sensitive to sea level rise, as their location is closely linked to the present sea level. With them will disappear a unique ecosystem, home to birds, mammals, crustacean and fish populations, as well as an invaluable breeding habitat, regulator of tidal flows and a filter for sediments and pollutants. The World Wide Fund for Nature predicts that among the victims of the flooding of mangroves is the Bengal tiger in the Sundarbans.
Gone too will be the protection from storms and floods that mangroves provide to coastal areas. If the sea level rises by one metre by 2100 – as has been predicted by the UN’s Intergovernmental Panel on Climate Change - hundreds of thousands of square kilometres of coastal wetlands and other lowlands in South Asia will be inundated – including the ecologically-rich Andaman and Nicobar islands, the Seychelles and Maldives.
Freshwater aquifers and soil will be contaminated with sea-salt, threatening entire water supplies and ecosystems.
Natural forests are also under severe threat from climate change. Rising temperatures and sea levels, and changes in precipitation patterns are expected to put at risk one-third of the world’s forests, and with them many of the species they harbour. Particularly vulnerable are forest systems on remote islands, and fragmented forests surrounded by agricultural or urban development, such as India’s Western Ghats, as the species they support have no opportunity for migration. Some Himalayan forest systems are thought to be equally vulnerable to climate change. In a warmer, drier world, forests from the lower slopes are likely to climb higher up but forests near the tree line will be squeezed into smaller areas or even disappear altogether.
Record high temperatures and the failure of winter rains were responsible for the destruction through fire of hundreds of hectares of natural forest in the Garhwal Himalayas in India and in eastern and central regions of Nepal from March to May last year. This risk will only increase with further climate change. The forest fires in Sankhuwasabha and Ilam in Nepal claimed red pandas, leopards as well as monkeys, deer, bear and other species. The Mountain Natural Resources Division of the International Centre for Integrated Mountain Development based in Kathmandu pins the blame on global warming for creating the conditions that led to the fires. Global warming, it says, is already putting a tremendous strain on the fragile Himalayan ecology.
Photograph by Peter Sandison.
Global warming and disease
Warmer conditions could also increase the threat to forests by expanding the range of pests and diseases. This already appears to be taking place in India, where increased temperatures and humidity in sal forests – the second largest in the country after teak – have led to a heavy infestation of a dark metal-brown beetle known as the sal heartwood borer, whose larvae eat their way into the heartwood of sal trees. As a result, over three million sal trees are sick and dying all over India, from Raja Bhatkhowa in West Bengal to Palamau in Bihar, Mandla in Madhya Pradesh, Dehra Dun in Uttar Pradesh and Nahan in Himachal.
As their habitats are lost, reduced or altered because of climate change, animal species will struggle to adapt and survive. Described in the New Scientist as “the first clear victim of global warming,” Edith’s checkerspot butterfly is vanishing from southern latitudes and low altitudes in Canada, western USA and Mexico, as conditions are too warm for the host plant on which it depends. Similarly, the golden and harlequin toads have become locally extinct in the rainforests of Costa Rica because of decreased rainfall, and there have been sharp declines in the numbers of the Adelie penguin in Antarctica because of a reduction in pack ice.
The species thought to be most vulnerable to climate change are those that are high in the food chain, especially when there is limited suitable habitat for them to migrate into. This is sadly true for the Bengal tiger. The reduced precipitation that climate change is predicted to bring about in northern and central India is likely to produce a significant deficit in soil moisture in the deciduous forests that are home to India’s last remaining tigers in such reserves as the Kanha and Pench National Parks. This climatic change is likely to result in an increase in tree mortality in these reserves and a shift towards tropical dry forest types, which are more open and far less productive for tigers.
Photograph by Ashok Captain.
There is, therefore, serious reason to be concerned about climate change and its impact on both the natural and human worlds. If yet more damage is to be avoided, it is vital that industrialised countries act fast to reduce their greenhouse gas emissions. They must also help to ensure that developing countries do not repeat the mistakes of the west, by enabling them to avoid further dependency upon fossil fuels, a pernicious and unnecessary addiction that threatens to change for the worse the world that we know and love.
by Simon Retallack, Sanctuary Asia, August 2000.