Special Report on Climate Change: IPCC

The Intergovernmental Panel on Climate Change (IPCC) made public ‘The Special Report on the Ocean and Cryosphere in a Changing Climate’ which underlined the dire changes taking place in oceans, glaciers, and ice-deposits on land and sea at the United Nations Climate Summit underway in the United States.

• The published report is the last in a series of three reports on specific themes that IPCC has published namely:
  
  • Global Warming of 1.5° C: A special report, which was commissioned to specifically explore the scientific feasibility of the 1.5°C goal set in the Paris Agreement, on global warming.
  • Land and climate change: The report focuses on the contribution of land-related activities to global warming i.e how the different uses of land affect the emission of greenhouse gases.
• The report also updates the IPCC's 5^th Assessment Report — and summarises the disastrous impacts of warming based on current projections of global greenhouse gas emissions.

Key Findings of the Report

• Over the 21^st century, the ocean is projected to transition to unprecedented conditions with increased temperatures, further ocean acidification, marine heatwaves and more frequent extreme El Niño and La Niña events.
• Ocean Warming:
  
  • Global ocean has warmed unabated since 1970 and has taken up more than 90% of the excess heat in the climate system.
  • Since 1993, the rate of ocean warming and marine heatwaves have very likely doubled in frequency and intensity.
• Global Mean Sea-Level:
  
  • It has increased by 16 cm between 1902 and 2015, and that the rate of increase had doubled of late.
  • Between 2006 and 2015, the global mean sea level recorded an average rise of 3.6 mm per year, which was more than double of 1.4 mm per year recorded in the first 90-year-period of the 20th century.
  • Sea-level rise is not globally uniform and varies regionally. Regional differences, within 30 % of global mean sea-level rise, result from land ice loss and variations in ocean warming and circulation
• The Melting of Glaciers:
  
  • Between 2006 and 2015, the Greenland ice sheet lost ice-mass at an average rate of 278 billion tonnes every year (e.g. Okjokull glacier of Iceland), which was enough to result in a global sea-level rise of 0.8 mm per year. During the same period, the Antarctic ice sheet lost a mass of 155 billion tonnes on an average every year.
  • Snow cover outside these two poles, like the glaciers in the Himalayas, together lost an average of 220 billion tonnes of ice every year.
  • The melting glaciers are the dominant source of sea-level rise, exceeding the effect of thermal expansion of ocean water (due to rising temperatures).
• Since the mid-20^th century, the shrinking cryosphere has led to predominantly negative impacts on food security, water resources, water quality, livelihoods, health, and well-being, as well as the culture of human societies, particularly for Indigenous peoples.

Source: TH