Environment

New IPCC report warns of dire threat to oceans

Chair of IPCC Hoesung Lee poses with the special report on the Ocean and Cryosphere in a Changing Climate Context as part of the 51st Session of the Intergovernmental Panel on Climate Change (IPCC) in Monaco, September 25, 2019.

Chair of IPCC Hoesung Lee poses with the special report on the Ocean and Cryosphere in a Changing Climate Context as part of the 51st Session of the Intergovernmental Panel on Climate Change (IPCC) in Monaco, September 25, 2019.   | Photo Credit: Reuters

With representatives from nearly 200 countries at the United Nations Climate Summit underway in the United States, the Intergovernmental Panel on Climate Change (IPCC) — the apex referee for scientific evidence on the impact of global warming — made public a special report on Wednesday that underlined the dire changes taking place in oceans, glaciers and ice-deposits on land and sea.

‘Unprecedented’

“Over the 21st 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,” according to a summary of the report made available to policymakers.

The report updates scientific literature available since 2015 — when the IPCC released its comprehensive 5th Assessment Report — and summarises the disastrous impacts of warming based on current projections of global greenhouse gas emissions.

“It is virtually certain that the global ocean has warmed unabated since 1970 and has taken up more than 90% of the excess heat in the climate system (high confidence). Since 1993, the rate of ocean warming has more than doubled. Marine heatwaves have very likely doubled in frequency since 1982 and are increasing in intensity,” the report notes.

The Southern Ocean accounted for 35%–43% of the total heat gain in the upper 2,000 m global ocean between 1970 and 2017, and its share increased to 45%–62% between 2005 and 2017.

The ‘Special Report on the Ocean and Cryosphere in a Changing Climate’ was prepared following an IPCC Panel decision in 2016 to prepare three Special Reports and follows the Special Reports on Global Warming of 1.5°C (SR1.5), and on Climate Change and Land (SRCCL).

Countries’ commitment

The 1.5°C report was a key input used in negotiations at Katowice, Poland last year for countries to commit themselves to capping global temperature rise to 1.5°C by the end of the century.

“A major impact is in the Hindu Kush Himalayan Regions,” said Anjal Prakash, a researcher at The Energy Resources Institute (TERI) School of Advanced Studies, and among those involved with the report, adding, “Floods will become more frequent and severe in the mountainous and downstream areas of the Indus, Ganges and Brahmaputra river basins, because of an increase in extreme precipitation events... the severity of flood events is expected to more than double towards the end of the century.”

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Printable version | Sep 23, 2020 2:14:53 AM | https://www.thehindu.com/sci-tech/energy-and-environment/new-ipcc-report-warns-of-dire-threat-to-oceans/article29511292.ece

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