Assessment of Climate Change over Indian Region

Recently, The Ministry of Earth Sciences released the first ‘Assessment of Climate Change over the Indian Region.

• The projections, based on modelling conducted by the Indian Institute of Tropical Meteorology (IITM), Pune and they are for the decades which will lead to the end of the 21st century.

Key Highlights of the assessment: 

A)Temperature

• Surface air temperature over India has risen by 0.6°C per year during 1901-2018.
• Regions of North India have undergone warming more than the South.
• The frequency of warm days is projected to increase by 55% and that of warm nights by 70%, both are relative to 1976- 2005.
• The average duration of heatwaves during April-June is projected to double in the coming decades and their frequency to rise by 3 to 4 times as compared to 1976-2005.
•  By the end of the 21st-century average temperature over India is projected to rise by 4.4°C which is relative to the average temperature during 1976-2005.
• Sea surface temperatures on the tropical Indian Ocean have been rising by an average 1°C annually over 1951-2015.

B)Monsoon

• Annual rainfall over India showed a declining trend during 1951-2015 and the reduction ranged between 1-5 mm over central India, Kerala and the far Northeast regions.
• Contrarily, precipitation increased over J&K and Northwest India.
• The coming decades are projected to witness a considerable rise in the mean, extreme and inter-annual variability of rainfall associated with the monsoon.

C)Droughts and floods

• The frequency and intensity of both heavy rainfall events and dry days have gone up Since the 1950s.
• These trends are prominent over Central India and South Peninsular regions during the southwest monsoon (June-September) and northeast monsoon (October-December) respectively.
• There is an increase in the area under drought along with frequency and severity during 1951-2016.
• Flood risks are higher over the east coast, West Bengal, eastern Uttar Pradesh, Gujarat, Konkan and cities like Mumbai, Chennai and Kolkata.
• Projections suggest an increase by one or two events per decade over Central and Northern India. Eastern India could face two more droughts per decade compared to what was experienced during 1976-2005, while the Southern Peninsula is projected to experience one or two droughts fewer.

D)Sea level

•  The sea level over the North Indian Ocean (Arabian Sea and Bay of Bengal) rose by 3.3 mm per year, which is in tune with the Global Mean Sea Level (GMSL) rise during 1993-2015.
• A risk of inundation looms over Andhra Pradesh and Ganga-Brahmaputra-Meghna delta basins in an extreme climate scenario.
• Some 340 million coastal residents of the North Indian Ocean and its islands would be exposed to coastal hazards by 2030.

E)Tropical cyclones

•  Severe Cyclonic storms in the Arabian Sea are gaining more strength and the trend is projected to continue. The number of extremely severe cyclonic storms formed in the Arabian Sea has increased in the last 20 years.

F)Himalaya snow cover

• The Hindukush Himalayas have warmed at an average 0.2°C per decade, leading to a decline in snow cover during the last seven decades and glaciers in the last four to five decades.
• The Karakoram Himalayas have reported an increase in snowfall during winter.
• The Hindukush Himalayas is projected to be warmer by 2.6-4.6°C by the end of the century.

Cause & effect:

• The main contributor to climate change is anthropogenic activities which are pushing up concentrations of greenhouse gases and this has led to rise in temperature and atmospheric moisture content.
• A higher concentration of water vapour, in turn, leads to intense rainfall during monsoon.
• Heating leads to vaporisation, which is directly linked to decreasing soil moisture, resulting in droughts and this can lead to a reduction in food production and in the availability of potable water.
• Rising sea levels would make India’s big cities vulnerable to erosion and damage to coastal projects.