climate-report-predicts-hotter-rainier-days-summary

Context: India’s first-ever national forecast on the impact of global warming on the subcontinent in the coming century, expects annual rainfall to increase, along with more severe cyclones and also more droughts.

More on the news:

  • These projections are based on a climate forecasting model developed at the Indian Institute of Tropical Meteorology (IITM), Pune.
  • These projections will also be part of the next report of the Intergovernmental Panel on Climate Change (IPCC), expected to be ready in 2022.

Key Findings

  • Hottest day and Coldest night
    • From 1986-2015, the hottest day and coldest night have warmed 0.63°C and 0.4°C, respectively.
    • According to the report, by the end of the 21st century, these temperatures are projected to rise by approximately 4.7°C and 5.5°C, respectively, relative to the corresponding temperatures in 1976-2005.
    • However, these projections are under a hypothetical scenario where no steps are taken to curb global greenhouse gas emissions or the RCP 8.5 as it is called.
  • The frequencies of future warm days and warm nights
    • These are projected to increase by 55% and 70%, respectively, relative to the reference period of 1976-2005. 
    • Summer heatwaves in India are projected to be three to four times higher by the end of the 21st century.
  • Levels of fine particulate matter
    • The reports also note that aerosol loading or the levels of fine particulate matter that result from fossil fuel burning, fertilizer use as well as natural processes has substantially increased during the recent few decades.
    • Also, this trend in aerosol optical depth (AOD), is subject to seasonal variability. The rate of increase in AOD is significantly high during the dry months of December-March.
      • Aerosol Optical Depth (AOD) is the measure of aerosols (e.g., urban haze, smoke particles, desert dust, sea salt) distributed within a column of air from the instrument (Earth's surface) to the top of the atmosphere.

This high-emissions scenario The Representative Concentration Pathways (RCPs) 8.5 is frequently referred to as “business as usual”, suggesting that is a likely outcome if society does not make concerted efforts to cut greenhouse gas emissions.

 

Complex role of the aerosols

  • Aerosols play a complicated role in the environment. They absorb sunlight and reduce to some extent the heating of the land and ocean surface due to global warming. 
  • The aerosol concentrations also promote clouding and increased intense rainfall over smaller areas such as cities and urban agglomerations.
  • However, while a switch away from fossil fuels might reduce aerosol load, it may increase the greenhouse gas effect of increasing ground temperature, atmospheric water vapor, and rainfall.

Impacts associated with global warming:

  • According to the report, the projected rapid changes in India’s climate will place increasing stress on the country’s natural ecosystems, agricultural output, and freshwater resources.
  • An observed change of 0.7°C in average temperatures over India, had already registered a spike in extreme weather events over the region.
  • Rainfall patterns have changed drastically, with longer dry spells intermittent with heavy rainfall events. 
  • The frequency of very severe cyclones has increased over the Arabian Sea. 
  • Over the Himalayas, the glacier retreat is going at a fast pace. 
    • Glacier melt and ocean warming are raising the sea level across the Indian Ocean. 
    • Recent records also show a sea-level change of 3cm per decade along the Mumbai coast while it is above 5cm per decade along the Kolkata coast. 

Conclusion:

  • With the temperatures projected to rise by 2.7°C by 2040 and 4.4°C by the end of the century, India should be ready to face a further increase in the intensity, frequency, and extent of these extreme weather events.

The Intergovernmental Panel on Climate Change (IPCC)

  • It is the United Nations body for assessing the science related to climate change.
  • Background
    • Created in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP).
  • Objective 
    • The objective of the IPCC is to provide governments at all levels with scientific information that they can use to develop climate policies. 
    • IPCC reports are also a key input into international climate change negotiations.
  • The IPCC is an organization of governments that are members of the United Nations or WMO. It currently has 195 members. 
  • Thousands of people from all over the world contribute to the work of the IPCC. For the assessment reports, IPCC scientists volunteer their time to assess the thousands of scientific papers published each year 
    • to provide a comprehensive summary of what is known about the drivers of climate change, its impacts and future risks, and how adaptation and mitigation can reduce those risks.

Source: https://www.thehindu.com/news/national/climate-report-predicts-hotter-rainier-days/article31845582.ece#:~:text=From 1986-2015, the hottest,corresponding temperatures in 1976-2005.

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