Scientists worry about increasing westerly winds bringing more winter rain, as global warming raises evaporation from the Mediterranean Sea
A sudden heavy snowfall threw life out of gear in Kashmir this March. Snow up to several feet fell on most of the valley, whipping up blizzards and triggering avalanches on the steeper mountain slopes. At least 17 deaths have been reported. Around 2,000 homes have been damaged, roads have been blocked and electricity has been disrupted in many parts of the state.
The unusually late and unusually heavy winter rain in northern, central and western parts of India did not affect everyday life in the same way, but the economic costs will be very high. The rain spoilt standing crops ready for the harvest in large swatches of Maharashtra, Madhya Pradesh, Punjab, Haryana and Uttar Pradesh. Planners fear a spike in food prices in the coming weeks, just at the time when it will hurt the ruling party the most, as India goes to the polls in April and May.
While the recent wet weather has been unexpected, experts say it is not unseasonal, at least not in Kashmir. “If you really look into the curve of snow cover, there is always a sudden peak in snow cover in the month of March,” says Anil Kulkarni, glaciologist at the Indian Institute of Science’s Divecha Centre for Climate Change in Bangalore. “It is more a part of climate variability.”
This shock has been due to the massive quantity of snow that has been dumped into Kashmir. The snowfall might have been caused by one of several atmospheric phenomena.
Winter rain and snow in the Himalayas is brought by western disturbances, cyclonic circulations that develop over the Mediterranean Sea and move east. Once it hits the Pir Panjal range of the Himalaya, the westerly winds get deflected in two directions, explains A.L. Ramanathan, professor at New Delhi’s Jawaharlal Nehru University School of Environmental Sciences. One stream blows along the Karakoram mountains towards Ladakh. The other flows south of the Karakoram and into Kashmir.
Ramanathan says the excessive snow in Kashmir could be caused by the westerlies not having enough momentum to make the journey into Ladakh but getting concentrated as one stream into Kashmir. “This time, I think, the elevation of the circulation is less and it is not crossing the Karakoram and because of that it is coming only to Kashmir and other regions there.”
Another possibility Ramanathan puts forward is an influence by winds from the Arabian Sea. At the end of winter the westerly winds, which should normally be weakening, are sometimes reinforced by moisture-bearing winds from the Arabian Sea. As these winds climb along the Himalayan slopes the moisture can be deposited as intense snowfall in the lower regions of Kashmir.
Govindswamy Bala of the Divecha Centre for Climate Change also thinks that the current weather in Kashmir could fall within the normal climate variability of the region but he does not discount the influence of climate change in a warming Himalaya.
“Warmer atmosphere can hold more water vapour. Even just pure thermodynamics will tell you that the water vapour content of the atmosphere will go up by 7% for every degree of temperature change. This is a very well-known fact. So the amount of water contained in the atmosphere is more. So when we get a rainfall event or a snowfall event the quantity is going to be more.”
In general, rainfall and snowfall in the Himalayas might be showing more variation in the last decade than before. “We are analysing in the westerlies from different meteorological stations in the Pir Panjal range. We found that 10 to 15 years back there was higher westerly precipitation. Now it is fluctuating,” says Ramanathan. His data shows that the westerlies earlier brought uniformly higher precipitation. Now they come in strongly at the start of winter bringing large amounts of rain and snow, quieten down mid-winter and then become re-energized again towards the end of the season. He says this may be due to changes in local microclimates.
The past year has been witness to many weather surprises. Bala says that while no single weather event can be pinned down to being caused by climate change, if the pattern repeats often in coming years it can definitely be attributed to climate change. Climate change also magnifies intense weather making it more destructive. “When weather conditions are leading to a very heavy event, even a 10% boost of that because of climate change could be extremely damaging and could lead to a disaster.”