IPCC’s SIXTH ASSESSMENT REPORT

IPCC’s SIXTH ASSESSMENT REPORT

Subject: Environment

About the Report:

• The IPCC’s Sixth Assessment Report is titled, “Climate Change 2021:The Physical Science Basis”.
• This has been published after the 5th report of 2014.
• According to the authors of AR6 report, warming of Indian Ocean will result in a rise in sea levels causing more frequent and severe coastal flooding across low-level areas.
• It will also result in intense and frequent heat waves and humid heat stress in the 21st century in South Asia.
• The planet was irrevocably headed towards warming by 1.5 degrees Celsius over pre-industrial times in the next two decades. Report highlights, even if the temperature is limited to 1.5 degree Celsius from pre-industrial levels, extreme weather events will be witnessed.
• Heatwaves, heavy rainfall events, and melting of glaciers is going to happen frequently, impacting countries like India.
• Report warned developed countries to undertake immediate, deep emission cuts and decarbonisation.
• The report recommended that countries strive to achieve net zero emissions — no additional greenhouse gases are emitted — by 2050.
• Human influence is the main driver of hot weather extremes (which have become more frequent and intense since the 1950s).

Other key takeaways of the report:

• Carbon dioxide (CO2) concentrations are the highest in at least two million years. Humans have emitted 2,400 billion tonnes of CO2 since the late 1800s. In fact, emissions have grown far more rapidly than expected in 1988, when the IPCC was established.
• The last decade was hotter than any period of time in the past 125,000 years. Global surface temperature was 1.09°C higher in the decade between 2011-2020 than between 1850-1900
• Sea-level rise has tripled compared with 1901-1971.
• The Arctic Sea ice is the lowest it has been in 1,000 years.
• Every additional 0.5 degree of warming will increase hot extremes, extreme precipitation and drought. Additional warming will also weaken the Earth’s carbon sinks present in plants, soils, and the ocean.

 Indian Scenario as per IPCC AR6

• India is the third largest emitter of carbon in the world.
• India will witness increased heat waves and flooding, which will be the irreversible effects of climate change.
• The current overall global warming trends are likely to lead to an increase in annual mean precipitation over India, with more severe rain expected over southern India in the coming decades.
• Changes in monsoon precipitation are also expected, with both annual and summer monsoon precipitation projected to increase. The presence of aerosols and particulate matter due to human activity have influenced rainfall events in the Indian subcontinent.
• In the Indian Ocean, the sea temperature is heating at a higher rate than other areas, and therefore may influence other regions.
• Coastal areas will see continued sea-level rise throughout the 21st century, resulting in coastal erosion and more frequent and severe flooding in low-lying areas.
• For India, it would increase pressure to agree to a net-zero target, a deadline by which it should be able to bring down its emissions to a level that equals the absorptions made by its carbon sinks, like forests.

IPCC on Volcanic Eruptions:

• Before the end of the century, there will be at least one large volcanic eruption, the scientists predicted based on their study of ancient climates and historical evidence.
• Such an eruption will reduce global surface temperature for several years, decrease land precipitation, alter monsoon circulation and modify extreme precipitation, at both global and regional scales.
• Large volcanic eruptions shoot aerosols (small particles) into the upper atmosphere. These reflect sunlight and induce a long-term cooling effect on the surface.
• Volcanoes are one of the two natural drivers that influence the Earth’s climate in the long-term. The other is the variation in solar irradiance.
• The albedo effect (increased reflection of sunlight) produced by the aerosols have shown to partially offset the warming in an atmosphere dense with greenhouse gases, according to some models.

 IPCC on Pollution:

• Intergovernmental Panel on Climate Change (IPCC)’s latest report certified that Air pollutants continue their meteoric rise across India and other parts of south Asia.
• The concentrations of lethal air pollutants such as sulphur dioxide (SO2), nitrogen dioxide (NO2), ammonia (NH3), ozone (O3) and Particulate Matter 2.5 are at their highest in south Asia, when compared to other parts of the world.
• Short Lived Climate Forcers (SLCF):  SLFCs are different from greenhouse gases like carbon dioxide, the effect of which on the climate endures till centuries. But the effects of these compounds are short-term. SLCPs include black carbon, methane, tropospheric ozone, and hydrofluorocarbons (HFCs) and are commonly associated with refrigeration, diesel-fueled vehicles, and solid-fuel cooking fires.
• They have a warming or cooling effect on the climate.
• The report by the IPCC noted that a major geographical shift had taken place in SLCFs from the 1950s to the 1980s. During this period, North America and Europe had dominated SLFC emissions. However, starting from the 1990s, Asia became the leading emitter due to strong economic growth in many of its countries.
• The major sources of PM2.5 in India were biomass and coal fuel-based cooking and heating, with secondary contributions from energy and industry.
• The only SLCF that India showed a decrease in was black carbon.

IPCC climate report: Profound changes are underway in Earth’s oceans and ice

• One example of a system that might undergo abrupt changes is the large-scale pattern of ocean circulation known as the Atlantic Meridional Overturning Circulation, or AMOC, of which the Gulf Stream is part.
• Paleoclimate evidence tells us that AMOC has changed rapidly in the past, and we expect that AMOC will weaken over this century.
• If AMOC were to collapse, it would make Europe warm more slowly, increase sea level rise along the US Atlantic coast, and shift storm tracks and monsoons. However, most evidence indicates that such a collapse will not happen in this century.

IPCC on 1.5 Degree Warming:

• This is the first time that the IPCC has said that the 1.5 degree warming was inevitable even in the best case scenario.
• Even if emissions are brought to net-zero by 2050, there will be an ‘overshoot’ of the 1.5°C limit by 0.1°C
• The average surface temperature of the Earth will cross 1.5 degrees Celsius in the next 20 years, and 2°C by the middle of the century without sharp reduction of emissions, warned the latest report by IPCC
• The threshold of2°C will be “exceeded during the 21st century.
• The IPCC said that a global net-zero by 2050 was the minimum required to keep the temperature rise to 1.5 degree Celsius. Without India, this would not be possible. Even China, the world’s biggest emitter, has a net-zero goal for 2060.

Previous Assessment Reports:

• The five previous assessment reports that have come out since the IPCC was established in 1988 have formed the basis of international climate change negotiations   and the actions that governments across the world have been taking in the last three decades to restrict the rise of global temperatures.
• The First Assessment Report led to the setting up of the UN Framework Convention on Climate Change (UNFCCC).
• The Second Assessment Report was the basis for the 1997 Kyoto Protocol.
• The second and third parts of the report, dealing with the expected impacts of climate change, and the actions required to prevent the worst impacts, are slated to come out next year.
• The fourth assessment report, which came out in 2007, won the IPCC the Nobel Peace Prize.
•  The Fifth Assessment Report, which came out in 2014, guided the Paris Agreement.
• In the immediate future, the IPCC report could serve as the most important warning towards the rapidly closing window of opportunity to halt the rise in temperatures to unacceptable levels, and propel the governments to take more urgent actions.

About Intergovernmental Panel on Climate Change (IPCC):

• The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change.
• It was set up in 1988 by the World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to provide policymakers with regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation.
• The IPCC does not conduct its own research.
• IPCC reports are neutral, policy-relevant but not policy-prescriptive.