As world warms, 'half a degree' will worsen suffering, scientists say

LONDON - Many more people - besides the world's poorest - will face sweltering heatwaves, more extreme rainfall, shrinking harvests and worsening water shortages unless unprecedented efforts to slow climate change start now, scientists warned on Monday.

Without stepped-up action, efforts to adapt to the coming changes - from farmers switching crops to cities building sea-walls - are likely to run up against limits that could end in growing disaster losses, poverty and migration, they said.

"The world we know today is not the world we will see in 50 years" if global warming exceeds 1.5 degrees Celsius (2.7 degrees Fahrenheit), warned Debora Ley, one of 91 authors of a report looking at the feasibility of holding temperature rise to the most ambitious target set in the 2015 Paris Agreement.

From accelerating species extinctions to escalating forest fires, "it will be considerably worse", she told the Thomson Reuters Foundation.

The Intergovernmental Panel on Climate Change (IPCC) report, requested by governments, was issued ahead of a U.N. conference in December in Poland that will consider how to increase country ambitions to cut emissions and manage climate risks better.

Current government commitments to curb climate change under the Paris pact, even if fully met, would still leave the world on track for about 3 degrees of warming, scientists said.

The IPCC report noted that while risks are highest for the world's poorest and most vulnerable, no part of the world will be immune from rising threats if temperatures push past 1.5 degrees Celsius above pre-industrial levels.

"We have this idea that those who suffer the most impacts (from global warming) are marginalised or live in remote areas," said Patricia Pinho, a Brazilian sustainability expert and one of the report authors.

But Sao Paulo, a Brazilian city of 12 million, nearly ran out of water in 2015 as a result of extreme drought, she said - and Cape Town in South Africa faced a similar threat this year.

"We are not talking about something that is going to happen. It is happening," she said - even with warming of about 1 degree Celsius so far.

Limiting global warming to 1.5 degree Celsius compared to 2 degrees - the higher target in the Paris pact - could reduce the proportion of the world's population exposed to increasing water stress by up to half, the report noted.

And the lower target would mean up to 10 million fewer people would face risks from sea level rise, such as flooding or displacement, the report said.

"It's clear half a degree matters," Valerie Masson-Delmotte, a French scientist and IPCC report co-chair, told journalists.

MORE HEAT, MORE POVERTY?

The report examined how meeting - or missing - the 1.5 degree goal would affect efforts to achieve global sustainable development goals aimed at everything from slashing poverty and hunger to providing clean, affordable energy to all.

It found that warming of 2 degrees Celsius, compared to 1.5 degrees, would likely make it harder to reduce poverty, as extreme weather, crop failures and other problems made life harder for the world's most vulnerable.

In India, for instance, late monsoons and rain falling in the harvest season in states such as Punjab and Madhya Pradesh, have led to crop losses as high as 50 percent, said Joyashree Roy, a report author and economics professor at India's Jadavpur University.

Farmers could once recover from losses - but as they become more frequent, that is getting harder to do, she said.

"If it happens within three years again, then they are unable to cope, so they are in a series of indebtedness," she said.

Such problems suggest "hundreds of millions of people will benefit" in terms of poverty eradication if warming is limited to 1.5 degrees, said Hans-Otto Portner, a German author of the report.

Worsening climate impacts at higher levels of warming also may require a rethink of how to adapt to climate change, said Ley, who works on adaptation and renewable energy in Guatemala.

For example, helping farmers in coastal areas shift to crops that are more tolerant of drought or salty floodwater might not work longer term if their land is submerged entirely, she said.

Instead, they might need to change their trade or move to new areas, she said.

"It's a step further from the adaptation we're used to seeing," Ley said.

Nor is it just the poor who will need to adapt, experts said.

Stronger heatwaves in Europe and more powerful hurricanes in the United States suggest that even richer countries will need to prepare for rising disaster risks, said Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre.

"We're concerned about places like Somalia where we see people dying. But we also see people dying in heatwaves in Europe - and the flood risk in Houston is about three times more likely than it was before climate change," he said.

"The most vulnerable are everywhere," he said. "We need to step up adaptation on a much more dramatic scale."