New Delhi: Emissions of carbon dioxide (CO2) caused by human activity must reach “net zero" by 2050 to keep the average rise in global temperatures at 1.5 °C above pre-industrial levels to reduce catastrophic climate-change risk on populations, the United Nations Inter-Governmental Panel on Climate Change (IPCC) said on Monday.

There is a need for urgent, unprecedented and collective action to limit global warming to 1.5°C instead of 2°C above pre-industrial levels, which otherwise will cause extreme weather events, rising sea levels, loss of biodiversity and challenging impact on water supply, food security, health and livelihood of several hundred millions of people, IPCC said in its report Global Warming of 1.5ºC, which was released at Incheon, South Korea on Monday.

The report warned that global warming is expected to surpass 1.5°C, under the current emission targets agreed to in the 2015 Paris Agreement, even if supplemented with very challenging increases of mitigation standards after 2030.

“Rise of average temperatures by 2°C is much more catastrophic than thought when the Paris Agreement was signed," warned the report prepared by scientists from 40 countries that is the result of a study instituted by the United Nations Framework Convention on Climate Change (UNFCCC).

More than 195 countries, including India, had pledged under the Paris Agreement signed at the UNFCCC meet in Paris in 2015 to limit the increase in global average temperatures to well below 2°C above pre-industrial levels and pursue efforts to limit the temperature rise further to 1.5°C .

Human-induced warming had in 2017 already reached 1°C above pre-industrial levels and is likely to reach 1.5°C between 2030 and 2052, if it continues to increase at the current rate, said the report.

This is significant for India, which could bear the brunt of the effect of global warming along with other developing nations.

“Even at a little over 1.0°C warming, India is being battered by the worst climate extremes. It is clear that the situation at 1.5°C is going to worsen. The report has served us a final warning that we must get our act together, now and quickly," said Sunita Narain, director general at Centre for Science and Environment.

The IPCC panel highlighted that it is not possible to limit global warming to 1.5°C even with the current ambition targets, unless rapid, far-reaching and unprecedented changes are made.

“Limiting warming to 1.5°C is possible within the laws of chemistry and physics, but doing so would require unprecedented changes," said Jim Skea, co-chairperson of IPCC working group III.

The global net human-caused CO2 would need to fall by about 45% from 2010 levels by 2030, reaching “net zero" around 2050 to limit warming at 1.5°C, the report noted.

Investments in low-carbon energy technologies and energy efficiency would need to approximately double in the next 20 years and investment in fossil-fuel extraction and conversion decrease by about a quarter.

India had committed to cutting its greenhouse gas emission intensity by 33-35% below 2005 levels and achieving 40% of its electricity generation from renewable sources by 2030.

Apart from its leading role in the launch of the International Solar Alliance to boost renewable energy, India has also announced that it will generate 175 gigawatts (GW) renewable energy by 2022, of which 100GW will be solar energy.

The report is the first in a series to be prepared by IPCC, the United Nations body for assessing the science related to climate change, and would be a key scientific input for the Katowice Climate Change Conference in Poland in December, when governments review the Paris Accord.

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