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Many megacities to be hit annually by extreme weather in 2050, UN warns

Tropical storms will continue to amplify their destructive potential even if global warming is capped at two degrees Celsius, the UN warned.

Image: Shutterstock/Drew McArthur

THE UNITED NATIONS has warned that global warming is devastating oceans and Earth’s frozen spaces in ways that directly threaten a large slice of humanity.

Crumbling ice sheets, rising seas, melting glaciers, ocean dead zones, toxic algae blooms -  a raft of impacts on sea and ice are decimating fish stocks, destroying renewable sources of fresh water, and incubating superstorms that will ravage some megacities every year, according to a landmark assessment approved by the 195-nation Intergovernmental Panel on Climate Change (IPCC).

Some of these impacts it says are irreversible. 

“Even if we manage to limit global warming, we will continue to see major changes in the oceans,” said Valerie Masson-Delmotte, a researcher at the Laboratory for Climate and Environmental Sciences and an IPCC co-chair.

But it will at least buy us some time, both for future impacts and to adapt.  

The 900-page UN scientific report is the fourth such in less than a year, with others focused on a 1.5-Celsius cap on global warming, the decline of biodiversity, as well as land use and the global food system.

All four conclude that humanity must overhaul how it produces, distributes and consumes almost everything to avoid the worst ravages of global warming and environmental degradation.

By absorbing a quarter of manmade CO2 and soaking up more than 90% of the heat generated by greenhouse gases, oceans have kept the planet livable – but at a terrible cost, the report finds.

  • Seas have grown acidic, potentially undermining their capacity to draw down CO2
  • warmer surface water has expanded the force and range of deadly tropical storms
  • marine heatwaves are wiping out coral reefs, which are unlikely to survive the century

Most threatening of all, accelerating melt-off from glaciers and especially Earth’s ice sheets atop Greenland and Antarctica are driving sea level rise.

Smaller glaciers found for example in Europe, eastern Africa, the tropical Andes and Indonesia are projected to lose more than 80% of their current ice mass by 2100 under high emission scenarios.

PastedImage-71798 Source: IPCC

‘A world of higher seas’ 

Since 2005, the ocean has risen 2.5 times faster than during the 20th century. The rate at which the waterline rises will quadruple again by 2100 if carbon emissions continue unabated, the report found.

“Regardless of emissions scenarios, we face a world of higher sea levels,” said co-author Bruce Glavovic, a professor at Massey University, New Zealand, noting that humanity is concentrated on the world’s shorelines.

“It doesn’t take a big rise in sea level to lead to catastrophic problems,” he added. “Sea level rise is not a slow onset problem – it’s a crisis of extreme weather events.”

By 2050, many coastal megacities and small island nations will experience what were formerly once-a-century weather disasters every year – even with an aggressive drawdown of greenhouse gas emissions.

And by mid-century, more than a billion people will be living in low-lying areas vulnerable to cyclones, large-scale flooding and other extreme weather events amplified by rising seas.

“The open sea, the Arctic, the Antarctic and the high mountains may seem far away to many people,” said Hoesung Lee, Chair of the IPCC.

But we depend on them and are influenced by them directly and indirectly in many ways – for weather and climate, for food and water, for energy, trade, transport, recreation and tourism, for health and wellbeing, for culture and identity.

“If we reduce emissions sharply, consequences for people and their livelihoods will still be challenging, but potentially more manageable for those who are most vulnerable,” Lee said. 

Hefty price tag 

Some cities, such as New York, are planning to spend tens of billions of dollars – and probably far more – to shore up their defences.

Indeed, building dikes and levees along with other measures would reduce the risk of flooding caused by sea level rise and storm surges over the next 80 years 100- to 1,000-fold, according to the IPCC report’s 42-page summary for Policy Makers.

But with a hefty price tag: up to hundreds of billions of dollars a year. 

For many megacities and sprawling delta cities in the developing world, however, an engineered solution will be impractical or prohibitively expensive.

Under the IPCC’s consensus rules, all countries must sign off on the language of the report’s executive summary, designed to provide leaders with objective, science-based information.

The five-day meeting in Monaco went deep into overtime when Saudi Arabia objected what might have been a routine reference to the October 2018 IPCC report on the feasibility of capping global warming at 1.5 degrees Celsius.

Earth’s temperature has so far risen 1 C above pre-industrial levels.

Ahead of the publication of today’s report, Extinction Rebellion called on Irish Government to remember that unless our carbon emissions are greatly reduced, Ireland will be among those who will feel the brunt of climate disaster the most keenly.

Extinction Rebellion point out that long term, climate change, global overheating and rising sea levels will have far more disastrous impacts on Irish society and economy than Brexit, and as such should be prioritised in policymaking.

Additional reporting from AFP

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Adam Daly

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