World could cross critical 1.5 deg C threshold by 2024, says UN

SINGAPORE – Global warming could exceed the key threshold of 1.5 degrees Celsius by 2024 – far sooner than scientists had predicted, a major United Nations (UN) update on climate change indicators said on Wednesday (Sept 9), adding further pressure on nations to rapidly cut fossil fuel emissions that are heating up the planet.

The update, released by UN agency World Meteorological Organisation (WMO), said even the temporary drop in global greenhouse gas emissions due to Covid-19 lockdowns will have minimal impact on the pace of global warming, with 2016-2020 on track to be the warmest five-year period on record.

The 1.5 deg C level is central to global efforts to fight climate change. Under the 2015 Paris Climate Agreement, nearly 200 nations agreed to limit global warming to well below 2 deg C and ideally 1.5 deg C, deeming anything above these levels would put people and livelihoods at tremendous risk.

Yet, since the pact was agreed, global greenhouse gas emissions have continued to grow quickly and most nations are far from achieving these Paris targets.

“While emissions fell during the peak of the pandemic confinement measures, they have already mostly recovered to within 5 per cent of the same period in 2019 and are likely to increase further,” said UN Secretary-General Antonio Guterres, in a note accompanying the report.

The report, titled United in Science 2020, said there is a one-in-five chance global annual average temperatures will exceed 1.5 deg C above pre-industrial levels for at least one year over the next five years. And there is roughly a 70 per cent chance one or more months during the next five years will be at least 1.5 deg C warmer.

“This first overshoot beyond 1.5 deg C would be temporary, likely aided by a major climate anomaly such as an El Niño weather pattern. However, it casts new doubt on whether Earth’s climate can be permanently stabilised at 1.5 deg C warming,” said Dr Pep Canadell, executive director of the Global Carbon Project (GCP), and his colleague Dr Rob Jackson, chair of the GCP, in a commentary for The Conversation website on Wednesday.

El Niños are natural events that bring warmer global temperatures and usually cause droughts in South-east Asia and parts of Australia.

The key point is unless global CO2 emissions drop sharply this decade, said the UN, there will be no chance of limiting warming to relatively safe levels.

The WMO said the world has already warmed 1.1 deg C on average since the start of industrial times and that further heating will be fuelled by the steady rise in greenhouse gas emissions, chiefly carbon dioxide (CO2), methane and nitrous oxide from industry, transport and agriculture.

Burning fossil fuels such as coal, oil and gas are the main sources, and total fossil CO2 emissions are now 62 per cent higher than emissions at the time international climate negotiations began in 1990, the WMO says.

Even with warming of 1.1 deg C, the world is suffering more extreme and deadly weather, such as droughts and wildfires and more intense floods and storms. Turning up the global thermostat even more, and so quickly, will likely worsen those extremes.

The UN’s top climate science body, the Intergovernmental Panel on Climate Change, said keeping warming to 1.5 deg C would limit the threat from climate change. Every half a degree increase matters, the IPCC said.

At 2 deg C, the risks to crop production increase, sea level rise speeds up and most coral reefs are badly damaged or destroyed.

The United in Science report, prepared by six leading science agencies including the GCP, also said for the five-year period ending in 2024 there was a high risk of “unusual regional rainfall over the period, with some regions experiencing increasing drought-related risks and others increased risks associated with heavy rainfall”.

The Arctic was also predicted to continue to warm at more than twice the overall global rate.

“The findings of the report are yet again another reminder that while we are busy finding ways out of the Covid-19 crisis, climate change continues to build the foundation of what will be the biggest ever global crisis if we don’t do more to mitigate it, and quickly,” said Dr Canadell, who was also one of the report’s authors.

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