Context: Recently, United Nations’ Intergovernmental Panel on Climate Change (IPCC) has published the first part of its sixth assessment report (AR6), which will form the cornerstone of climate science for the years ahead.
Background

• Before this latest report, the IPCC had previously published five sets of “assessment reports” since its foundation in 1988. Each “comprehensively and consistently [lays] out the rapidly accumulating evidence of a changing climate system".
• The last set – the fifth assessment report (“AR5”) – was published in 2013-14. 

As usual, efforts of the IPCC for AR6 are divided into three “working groups”:

1. Working Group I (WG1): The physical science basis
2. Working Group II (WG2): Impacts, adaptation and vulnerability
3. Working Group III (WG3): Mitigation of climate change

WG1 report is the first of these to be published. Originally slated for April 2021, the publication date was pushed back due to the disruption caused by the Covid-19 pandemic. 

• The aim of the WG1 report is to “assesses the current evidence on the physical science of climate change, evaluating knowledge gained from observations, reanalyses, palaeoclimate archives and climate model simulations, as well as physical, chemical and biological climate processes.

The WG2 and WG3 reports are planned for publication in February and March next year, respectively. A “synthesis report” pulling together the findings of the three working groups will follow in September 2022.
Key Findings of the Sixth Report

• "Developed Countries have usurped far more than their fair share of the global carbon budget. 
• Reaching net zero alone is not enough, as it is the cumulative emissions up to net zero that determine the temperature that is reached. 
• The current global warming trends overall are likely to lead an increase in annual mean precipitation over India, with more severe rains expected over southern India in the coming decades.
• The planet was irrevocably headed towards warming by 1.5° Celsius over pre-industrial times in the next two decades, according to the most updated scientific consensus from the IPCC.

Keeping global warming below 2° Celsius of pre-industrial levels by the turn of century and endeavouring to limit it to 1.5°C was at the heart of the 2015 Paris Agreement. 

• Unless extremely deep emission cuts were undertaken by all countries immediately, these goals were unlikely to be met. 
• In line with this, the IPCC has recommended that countries strive to achieve net zero emissions — that is, no additional greenhouse gases were emitted — by 2050.
• In the most ambitious emissions pathway, the projection is that globe would reach the 1.5°C in the 2030s, overshoot to 1.6°C, with temperatures dropping back down to 1.4°C at the end of the century.

The report said warming is already accelerating sea level rise and worsening extremes such as heat waves, droughts, floods and storms. 

• Tropical cyclones are getting stronger and wetter, while Arctic sea ice is dwindling in the summer and permafrost is thawing and  all of these trends will get worse.

Impact on India
The report warns that with a 7,517 km coastline, India will face significant threats from rising seas. 

• Across six Indian port cities — Chennai, Kochi, Kolkata, Mumbai, Surat and Visakhapatnam — 28.6 million people will be exposed to coastal flooding if sea levels rise 50cm.

India is currently the world’s third largest greenhouse gas emitter, but per capita emissions are much lower. 

• The U.S. emitted nearly 9 times more greenhouse gases per capita than India in 2018. 

Based on existing commitments by countries to curb their emission, the world is on track for global temperature warming by at least 2.7°C by 2100, predicts the report, calling it ‘Code red for humanity’.

• There is intensification of the water cycle, which is going to affect the rainfall patterns... Change in the monsoon precipitation is also expected.
• While there isn’t much (scientific) model agreement on the changes in the heavy precipitation events, we can definitely say that hot extremes are projected to increase and cold extremes are projected to decrease in the 21st century.

Road Ahead

• The science is clear. The impacts of the climate crisis can be seen around the world and if we don’t act now, we will continue to see the worst effects impact lives, livelihoods and natural habitats.
• Our message to every country, government, business and part of society is simple. The next decade is decisive, follow the science and embrace your responsibility to keep the goal of 1.5C alive. 
• We can do this together, by coming forward with ambitious 2030 emission reduction targets and long-term strategies with a pathway to net zero.” This has been amply borne out in the IPCC report. It also vindicates India’s position that historical cumulative emissions are the source of the climate crisis that the World faces today.