Extreme weather events in India on the rise
In the 29 years from 1986 to 2015, India has recorded several weather extremes --- such as an increase in warm days and nights and a rise in extremely severe cyclonic storms over the Arabian Sea --- that were a result of human-caused climate change.
By the end of the 21st century, the number of warm days and warm nights in India is likely to be 55-70% higher compared to the average number between 1976 and 2005, according to the worst climate change scenario listed in the country’s first national climate change assessment by the ministry of earth sciences.
And the frequency of summer heat waves is likely to be three to four times higher and their duration, likely to double .
The report, to be released on Tuesday said that in the 29 years from 1986 to 2015, India has recorded several weather extremes --- such as an increase in warm days and nights and a rise in extremely severe cyclonic storms over the Arabian Sea --- that were a result of human-caused climate change.
Rapid changes in India’s climate will put stress on ecosystems, agricultural output and freshwater resources, and also cause damage to infrastructure, the report, available on publishing platform Springer and seen by HT, added.
“These portend serious consequences for the country’s biodiversity, food, water and energy security, and public health…higher temperatures, extreme weather events, and higher climate variability have been associated with an elevated risk of heat strokes, cardiovascular and neurological diseases, and stress-related disorders,” the report said.
Under all climate change scenarios, the extremes will only intensify. For example, temperatures of the warmest day and the coldest night of the year increased by 0.63 degree Celsius and 0.4 degree Celsius, respectively, in the 29-year period.
“India has witnessed a rise in average temperature; a decrease in monsoon precipitation; a rise in extreme temperature and rainfall events, droughts, and sea levels; and an increase in the intensity of severe cyclones, alongside other changes in the monsoon system. There is compelling scientific evidence that human activities have influenced these changes in regional climate,” the report, drafted by scientists from Indian Institute of Tropical Meteorology said.
The number of warm days have increased by about 9.9 per decade and warm nights by 7.7 per decade, the report said. Cold nights have decreased by 3.3 per decade during this period. Warm days or nights are those when maximum and minimum temperatures are over the 90th percentile.
“Heat action plans need to be further developed and calibrated. We need to track what kind of changes in health impacts we are seeing…In the long term, our infrastructure needs to be heat-resistant or mortality will increase; cool roofs, efficient cooling should be a part of policy,” said Dr Dileep Mavalankar, director, Indian Institute of Public Health Gandhinagar, Gujarat.
India’s average temperature has risen by around 0.7 degree Celsius during 1901–2018, which may not reflect these extremes. The largest increase in the annual mean temperature of more than 0.2 degree Celsius per decade was observed in some areas of north India between 1986 and 2015. The warming is much weaker in the southern peninsula.
With increase in air temperature, sea surface temperature over the Indian Ocean has already risen abnormally by 1 degree Celsius in the 64 years between 1951 and 2015 compared to the global average sea surface warming of 0.7 degree Celsius. The frequency of extremely severe cyclonic storms (ESCS) over the Arabian Sea has increased during the post-monsoon seasons of 1998–2018. Most models are projecting a higher sea surface warming in the Arabian Sea than the Bay of Bengal. Oxygen concentrations and marine phytoplankton have declined in the recent decades.
“It’s a first for India. The Intergovernmental Panel on Climate Change produces such reports for global impact assessment. This national report can help policymakers in different sectors specially health and agriculture. We plan to do this review every four to five years,” said M Rajeevan, secretary, the ministry of earth sciences.
The report has also underlined that climate change has already skewed the monsoon patterns with rains decreasing by 6% between 1951 and 2015. The Indo-Gangetic Plains and Western Ghats have recorded the highest declines, but the frequency of extreme rainfall (over 150 mm) has increased by 75% between 1950 and 2015 in central India. There is a shift towards more frequent dry spells (27% higher than the 1951-1980 period) and more intense wet spells during the summer monsoon season. High elevations of the Tibetan Plateau recorded severe warming as high as 0.5 degree Celsius per decade, according to the report.
The projections in the assessment report are based on the climate models used in the IPCC Fifth Assessment Report (AR5) and climate change modeling studies using the IITM Earth System Model (ESM) and CORDEX South Asia datasets.
The report has warned of a cascade of climate-related hazards, which will overlap. For instance, a region may experience an abnormally long or intense summer heat wave followed by intense monsoon floods that alternate with lengthening dry spells.
“Low-lying coastal zones, especially on India’s east coast, may witness rising sea levels damaging property and increasing groundwater salinity. A rise in cyclone intensities will likely result in increasing inundation from the accompanying storm surges that turn proximate agricultural lands and lakes saline, and imperil wildlife,” the report added.
The India Meteorological Department (IMD) released on Sunday a detailed report on Super Cyclone Amphan, which devastated parts of Sunderbans after it made landfall on May 20. The IMD report said tidal waves as high as 15 feet or around 5 metres inundated low-lying areas of the islands.