The Indian Ministry of Earth Sciences recently published the first Assessment of Climate Change over the Indian Region. It is reportedly the country’s first-ever national forecast on the impact of global warming on the subcontinent in the coming century.
These projections are based on a climate forecasting model developed at the IITM (Indian Institute of Tropical Meteorology) – Pune.
This is a remarkable step for India’s policy framework with respect to climate change as existing projections are put in the context of historical trends in monsoon rainfall, floods, land and ocean temperatures, droughts and Himalayan warming & glacier loss.
Observed Changes in Global Climate
- The global average temperature has increased by approximately 1°C since pre-industrial times. According to the report, the warming’s magnitude and rate cannot be explained by natural variations only and must necessarily take into consideration changes due to human activities.
- As per the findings, emissions of greenhouse gases, aerosols and changes in land use and land cover (LULC) during the industrial period have substantially altered the atmospheric composition, and are thus primarily responsible for the present-day climate change.
- Warming since the 1950s has already contributed to:
- Weather & climate extremes globally like heat waves, droughts, heavy precipitation, and severe cyclones
- Changes in precipitation and wind patterns
- Warming and acidification of the global oceans
- Melting of sea ice and glaciers
- Rising sea levels
- Changes in marine & terrestrial ecosystems
Projected Changes in Global Climate
- Global climate models project a continuation of human-induced climate change during the 21st century and beyond.
- If the current GHG emission rates are sustained, the global average temperature is likely to rise by nearly 5°C, and possibly more, by the end of the 21st century.
- The report further added that even if all the commitments made under the 2015 Paris agreement are met, it is expected that global warming will exceed 3°C by the end of the century. However, it is to be noted that temperature rise won’t be uniform across the planet
- Temperature Rise Over India
- By the end of the 21st century, average temperature over India is projected to rise by approximately 4.4°C relative to the recent past (1976–2005 average)
- In response to an increase in surface temperature and humidity, amplification of heat stress is expected across India.
Indian Ocean Warming
- According to the findings, Sea surface temperature (SST) of the tropical Indian Ocean has increased by 1°C on average during 1951–2015.
- During the 21st century, SST and ocean heat content in the tropical Indian Ocean are likely to continue to rise, as per the report.
- Changes in Rainfall
- The summer monsoon precipitation (June to September) over India has decreased by around 6% (from 1951 to 2015).
- There has been a shift in the recent period toward more frequent dry spells and more intense wet spells during the summer monsoon season.
- The frequency of localized heavy precipitation occurrences has increased globally.
- With continued global warming and anticipated reductions in anthropogenic aerosol emissions in the future, CMIP5 models project an increase in the mean and variability of monsoon precipitation by the end of the 21st century.
- The overall decline in seasonal summer monsoon rainfall during the last 60–70 years has led to an increased propensity for droughts over India.
- Climate model projections indicate a high probability of an increase in the frequency, intensity and area under drought conditions in India by the end of the 21st century under the RCP8.5 scenario.
Sea Level Rise
- Sea levels have risen globally due to the continental ice melt and thermal expansion of ocean water.
- At the end of the twenty-first century, steric sea level in the North Indian Ocean is projected to rise by approximately 300 mm relative to the average over 1986–2005 under the RCP4.5 scenario.
- There has been a significant reduction in the annual frequency of tropical cyclones over the NIO basin since the middle of the twentieth century (1951–2018).
- Climate models project a rise in the intensity of tropical cyclones in the NIO basin during the 21st century.
Changes in the Himalayas
- Several areas of Hindu Kush Himalayas (HKH) have experienced a declining trend in snowfall and also retreat of glaciers in recent decades.
- By the end of the twenty-first century, the annual mean surface temperature over the Hindu Kush Himalayas (HKH) is projected to increase by about 5.2°C under the RCP8.5 scenario.
The report concluded that there is compelling scientific evidence that human activities have influenced these changes in regional climate. Human-induced climate change is expected to continue apace during the twenty-first century. In order to have accurate future climate projections, it is indispensable to develop strategic approaches for improving the knowledge of Earth system processes and to continue enhancing observation systems and climate models.