Weather has begun behaving unpredictably since the beginning of the year. Last year too, people of this region including Bangladesh saw frequent changes in weather. There were repeated depressions in the bay, cyclones, heavy rainfall and floods. Bangladesh will have to be prepared for the same this year too, according to weather forecasts.
There is a warm wind over the Bay of Bengal and will remain until April. As a result, Bangladesh will experience its impact throughout the year. Amidst winter, summer, drought, rain, depression, cyclone and floods, this will have a strong impact on the overall agriculture and fisheries production. This will change import and export equations and can cast a shadow on development activities.
All this has been predicted by the World Meteorological Organization (WMO), meteorological offices of Bangladesh and India, and several climate experts.
Weather and climate trends indicate that this unusual behaviour of the nature in the country has been increasing gradually for more than a decade. Due to rainfall, floods, storms and tidal surges, people from the coastal regions up to the north, all suffered more than they did three years ago.
Impact of La Nina
La Nina is an atmospheric condition in the Pacific. Usually the water becomes heated in the central equatorial Pacific every six to eight years and this spreads to the Bay of Bengal after passing the Indian Ocean via the Arabian Sea. Huge clouds form over these seas. As a result, extreme rainfall occurs in the countries along the seas. Clouds hamper the movement of cold wind during the winter. Consequently, the temperature rises and remains higher than normal during winter.
According to the observation of Bangladesh Meteorological Department, the temperature was 1° Celsius higher than normal temperature throughout December and January during this winter. It was 1° Celsius higher in cities. The Pacific and Indian Ocean countries including Australia, New Zealand and India have already issued La Nina warning.
A La Nina warning issued the US-based Columbia University on 14 January said La Nina will remain active over the vast coastal area from Pacific Ocean to the Bay of Bengal. Consequently, countries in this region will have to be prepared to tackle extra heat and rains.
United Nation’s Food and Agriculture Organization also forecasted the same, stating that hotter weather will occur till April this year, affecting people’s lives and agriculture.
Climate expert and professor of the University of Hawaii in the US, Rashed Chowdhury, told Prothom Alo that as a positive effect of the year-long coronavirus pandemic, it had been expected that the rise in global temperature would fall, but this did not happen.
Besides, water vapour and cloud are blowing more towards Bangladesh since November due to La Nina. As a result, more rainfall will occur and early floods are likely.
A damp winter
Half the Bangla month Magh is over. Spring will arrive with the month of Falgun within a few days. Before that, acute cold was likely in January, but that didn’t happen this time due to La Nina. This condition keeps the Bay of Bengal warm. Wind from the sea is making the sky cloudy and decreasing the cold. The weather becomes more damp than dry. There have already been drizzles in certain places.
Senior meteorologist at the Bangladesh Meteorological Department, Abdul Mannan, told Prothom Alo clouds have started forming in the sky since November when it was time for acute cold. Consequently, there was no severe cold wave anywhere in the country. The cold wave didn’t last even for a week because of La Nina.
More low pressure likely
According to the India Meteorological Department, 2020 was one of the warmest years in the history of the Bay of Bengal. The sea temperature remained between 24 and 26° Celsius during summer. Since May last year, sea temperature fluctuated between 27° and 32° Celsius. As a result, four major cyclones -- Amphan, Goti, Nisarga and Nivar – hit the coastal regions. Amphan wreaked havoc in Bangladesh and the Indian state of West Bengal, Nisarga on Gujarat of India, and Goti and Nivar hit the south coast of India.
A report of India Meteorological Department said more depression and low pressure will form in the Bay of Bengal and the India Ocean. But these are unlikely to turn into a strong cyclone. As a result, no powerful cyclone is likely to hit Bangladesh this time, unlike that of the past three years.
Meteorologist of the Bangladesh Meteorological Department, Bazlur Rashid, told Prothom Alo more depressions and low pressure may occur in the Indian Ocean and the Bay of Bengal. This may increase rainfall in Bangladesh. Research indicates there may be an increase in low pressure.
According to the experts working on long term weather forecast, more rainfall is likely in March-April because of La Nina. As a result, early floods may hit. Bangladesh faced such an early flood in 2017, destroying crops in haor areas.
More nor'westers and lightning
In Bangladesh, nor'westers and lightening occur more from March to May. According to meteorologists, this may happen more than usual because of La Nina. Intensified heat will create more depression and low pressure in the sea and it may increase lightning strikes in those three months.
Climate experts said only innovating paddy varieties that can adapt to the climate change will not be enough. The forecasting system for disasters including floods, cyclones and heavy rainfall must be improved
According to Bangladesh Meteorological Department, last year lightning occurred 20 per cent more than normal. Deaths caused by lightening were also 10 per cent more than the previous years, according to the disaster management and relief ministry.
Meteorologist Abdul Mannan said temperature will remain higher than normal in the mainland and the Bay of Bengal since January. That’s why more lightening may strike, he added.
Fear of more floods
In 2018, Bangladesh Meteorological Department and the Norwegian Meteorological Institute conducted joint research on the impact of climate change in Bangladesh. It revealed that currently, more rainfall occurs at the beginning and at the end of the rainy season in Bangladesh.
Last year, rainfall was recorded higher than the usual. At the beginning of the rainy season, rainfall was 35 per cent higher than usual while it was 11 per cent more throughout the entire season. Crops were damaged at the beginning of the last year’s rainy season.
Last year, floods hit in five phases. This lasted for 41 days. The second-longest-lasting flood of the country reduced the production of aman paddy by 1.5 million (15 lakh) tonnes, resulting in exorbitant rise in rice prices in the country. The government was compelled to import rice after three years.
The Food and Agriculture Organization, in its La Nina forecast report, said the years of 2012 and 2017 were La Nina years. Heavy rainfalls caused floods in the South Asian countries in those years. So production of rice and wheat dropped and prices of these food grains increased. The UN organisation fears a repeat this year.
Regarding preparedness, professor of Bangladesh University of Engineering and Technology (BUET)’s Flood and Water Management Institute, Saiful Islam, told Prothom Alo other than La Nina, rise in global warming has increased floods. That’s why focus should be given on innovating paddy varieties that will ripen before floods arrive in April.
Climate experts said only innovating paddy varieties that can adapt to the climate change will not be enough. The forecasting system for disasters including floods, cyclones and heavy rainfall must be improved. At first, all will have to work to tackle climate change – limiting the global warming to 2° Celsius within this century. Like all countries, Bangladesh has to play a role in implementation of the Paris Agreement.
Professor emeritus at BRAC University, Ainun Nishat, told Prothom Alo the agriculture sector suffered maximum damage due to unusual behavior of weather last year. This time, the impact of weather and climate change must also be kept in mind in all plans including agriculture and development work to move ahead, he added.
*This report appeared in the print and online edition of Prothom Alo and has been rewritten in English by Hasanul Banna