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  • “Business as usual” could lead to catastrophic global sea-level rise, says new study
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“Business as usual” could lead to catastrophic global sea-level rise, says new study

Source(s):  United Nations Environment Programme (UNEP)

As hurricane season bears down on many people and communities this month, one of the key factors linked to increasing severity of a storm’s impacts—sea level rise—sees new predictions emerge for “worst-case scenarios”.

Mathematicians and scientists calculate likely and possible outcomes based on probabilities, with computers able to crunch ever larger volumes of data to come up with more accurate predictions.

Climate modelling has improved enormously in the past 20 years, and where predictions of catastrophe are distinct—as opposed to remote—we should take note.

In Ice sheet contributions to future sea-level rise from structured expert judgment, published in the Proceedings of the National Academy of Sciences of the United States of America in May 2019, scientists conclude that if global temperatures reach 5°C above pre-industrial era levels, there is a one in 20 chance that global mean sea level rise could exceed two metres.

A 5°C temperature rise is consistent with unchecked emissions growth.

“This is more than twice the upper value put forward by the Intergovernmental Panel on Climate Change in the Fifth Assessment Report [2013],” notes the study.

Such a rise over the next 80 years could trigger the gradual displacement of millions of people around the world and swallow up an area of land three times the size of Texas.

Much of the land losses would be in important food-growing areas such as the Nile delta. Coastal communities, ports and low-lying countries like Bangladesh would be hard hit. Large numbers of small islands would disappear. Major global cities, including London, New York and Shanghai would end up, at least partially, underwater.

Under a “business as usual” scenario where temperatures rise by 5°C, the picture is even grimmer beyond 2100, with a projected increase by 7.5 metres.

A New Climate for Peace: Taking Action on Climate and Fragility Risks, commissioned by members of the G7 group of nations, outlines seven “climate-fragility” risks that pose serious threats to global stability in the next decades.

One of the risks identified is rising sea levels: “Rising sea levels are threats to the economic and physical viability of low-lying areas, as land and coastal resources are gradually lost. This can lead to social disruption, displacement and migration, as well as disagreements over maritime boundaries and ocean resources.”

UN Secretary-General António Guterres recently warned: “The loss of ice in Greenland and Antarctica is accelerating, meaning that sea levels will rise a full metre by 2100 if nothing is done to avoid it.”

Important warning

“Climate change is the ultimate threat multiplier,” says UN Environment Programme (UNEP) climate change specialist Niklas Hagelberg. “Hurricanes aren’t new, but the increasing likelihood of dangerous storm surges linked to sea level rise, is. This new study is a further warning for policymakers engaged in contingency planning for a significant rise in sea levels. It underscores the need for urgent action to reduce global heating.”

Through its Joint Unit with the UN Office for the Coordination of Humanitarian Affairs, UNEP at the request of governments, seconds disaster assessment experts to areas affected by climate-related emergencies. This was the case in 2017, after Hurricane Maria struck Dominica and Puerto Rico, as well as in April 2019 after cyclones Idai and Kenneth hit Mozambique.

In collaboration with United Nations Office for Project Services (UNOPS), and with funding from the Global Environment Facility, UNEP supported the Government of Tanzania to build extensive seawalls along the country’s coast, including over 2,400m of defence structures. The project, which was completed in June 2018, was part of a broader UNEP initiative to build climate resilience by improving natural ecosystems.

UNEP also works with partners to highlight scientific issues of emerging concern, for example, in its annual Frontiers Report.

The climate crisis is gaining the attention of the world’s media and politicians. Several countrieshave declared climate emergencies, and climate emergency declarations have reportedly been made in several hundred jurisdictions and local governments covering over 100 million citizens.  

Nineteen countries and 32 cities have joined the Carbon Neutrality Coalition, committing to take concrete and ambitious action to achieve the aims of the Paris Climate Agreement. This means they aim to be carbon neutral by 2050. The world’s largest container shipping company as well as dozens of big-name fashion brands have made similar commitments.

“With around 40 per cent of the world’s population living within 100 km of a coast, we need to do everything possible to make this scenario less likely and prevent us from reaching tipping points beyond which it will not be possible to prevent runaway climate change,” Hagelberg adds.

Over 6 million people currently live in coastal areas vulnerable to sea level rise today. Even in a 2°C global heating scenario, 10 million more would be affected, according to the Intergovernmental Panel on Climate Change. 

“Ocean science plays a crucial role in achieving sustainable development and UN-Oceansremains committed to playing its part in enhancing science to achieve this objective,” said Miguel de Serpa Soares, Under-Secretary-General for Legal Affairs and United Nations Legal Counsel, and UN-Oceans Focal Point, in a statement on 13 June 2019 in New York.

The UN Climate Action Summit will take place in New York City on 23 September 2019 to increase ambition and accelerate action on the global climate emergency and support the rapid implementation of the Paris Climate Change Agreement. The 2019 UN Climate Action Summit is hosted by UN Secretary-General António Guterres.



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  • Publication date 11 Sep 2019

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