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  • 'Phenomenal' temperature rises threaten India


[CHANDIGARH] India is likely to become  "phenomenally" hotter and could also become considerably wetter due to global warming, according to initial projections by climate researchers.

Scientists at the Pune-based Indian Institute of Tropical Meteorology (IITM) used two models to forecast the impact of global warming. Both models predict that the country's temperatures will rise significantly until the end of the century. But the two models differ on the effect on monsoon rains.

One global climate model predicts that temperatures in India are likely to rise by 2 to 3 °C by the end of the century if greenhouse gas concentrations increase by 1 per cent each year.

Rupa Kumar Kolli, head of IITM's climatology and hydrometeorology division, who presented the findings at the Indian Science Congress in Chandigarh this week, says the increase could have serious consequences for crop growth and weather patterns, given that India's temperature has risen by only 0.4 to 0.6 °C over the past century.

The other model – a high-resolution regional climate model developed under joint Indo-UK collaboration – also projects a general warming over India. The IITM team has yet to run the regional model up to the end of the century, but an analysis up to 2050 indicates a temperature rise of between 1 and 2 °C, in line with estimates of the global model.

The two models, however, come up with different conclusions about the impact of global warming on India's monsoon rainfall – the most crucial weather element that is the lifeline to the country's agriculture and central to the livelihoods of 70 per cent of the country's population.

The global model predicts a 10 per cent increase in monsoon rainfall over the next century. In contrast the regional model predicts that rainfall will remain at current levels up to 2050.

Both models indicate a weakening of the link between El Niño, the warming of eastern Pacific waters that affects global weather patterns, and the monsoon. Kolli says the weaker link has already been evident in India over the past two decades. "This is now being considered an early signal of possible global warming effect on monsoon variability," he says. 

Global warming, however, is not expected to affect the link between La Niña, or the cold sea surface temperatures in tropical Pacific waters, and the Indian monsoon.

IITM is also running the regional model against 10 to 15 scenarios based on differing patterns of human behaviour that are likely to lead to an increase in the use of fossil fuels and concentrations of greenhouse gases and aerosols.

While greenhouse gases such as oxides of carbon, nitrogen and sulphur increase atmospheric temperatures by trapping heat, aerosols – tiny atmospheric particles produced naturally through volcanic eruptions, dust storms and fires, or through human activities such as fossil fuel burning – cool the air by scattering and blocking the Sun's radiation to the earth.

Large cities in India and China are recording an "alarming" increase in aerosols due to human activities, creating "hotspots" for climate change, warns A. Jayaraman from the Ahmedabad-based Physical Research Laboratory, which is studying the likely impact of aerosols on India's climate.

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