Impact of climate change

Subject: Geography

Context:

The first ‘Assessment of Climate Change over Indian Region” report by Ministry of Earth Sciences warned about India’s climatic vulnerabilities and stressed for need of mitigations.

Findings:

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, where warming has been mainly during winters.
• In coming decades, the average duration of heatwaves during April-June is projected to double, and their frequency to rise by 3 to 4 times compared to 1976-2005.

Monsoon

• During 1951-2015, annual rainfall over India showed a declining trend. 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 monsoon.

Droughts and floods

• Since the 1950s, the frequency and intensity of both heavy rainfall events and dry days have gone up.
• Flood risks are higher over the east coast, West Bengal, eastern Uttar Pradesh, Gujarat, Konkan and cities like Mumbai, Chennai and Kolkata.
• The Himalayan flood basins are projected to greater floods, due to the faster glacial and snow melting. Major flooding events are projected over the Brahmaputra, Ganga and Indus.

Sea level

• During 1993-2015, 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.

Tropical cyclones

• 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.

Himalaya snow cover

• During the last seven decades, the Hindukush Himalayas have warmed at an average 0.2°C per decade, leading to a decline in snow cover and glaciers in the last four to five decades. The Karakoram Himalayas have reported an increase in snowfall during winter.

Cause & effect

• The main contributor to climate change is anthropogenic activities pushing up concentrations of greenhouse gases. 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. This can lead to reduction in food production and in availability of potable water, the report says.
• Rising sea levels would make India’s big cities vulnerable to erosion and damage to coastal projects.