June 30, 2017, by Tim Radford
A refugee camp in Chad: Finding shelter will be harder as climate refugee numbers mount.
Image: By Mark Knobll, via Wikimedia Commons
Where can the climate refugees go, if 2 billion are driven away by rising tides, and the interior available becomes ever more inhospitable?
LONDON, 29 June, 2017 – By 2060, around 1.4 bn people could be climate refugees, driven from low-lying coastal cities by sea level rise. By 2100, as the global population may have reached 11bn, there could be 2bn climate refugees.
To feed those 9 to 11 bn people expected in the second half of the century, farmers will have to grow as much food in 40 years as they have grown in the last 8,000 or so.
And in a world of accelerating sea level rise and climate change, in which farmland is being degraded and turned to desert, in which ever more land is set aside for carbon storage in the form of forest, and in which the strains of survival increase social divisions and social conflict, there is a new challenge: where will the 2bn climate refugees find new homes?
“The colliding forces of human fertility, submerging coastal zones, residential retreat, and impediments to inland resettlement are a huge problem,” said Charles Geisler, professor emeritus of development sociology at Cornell University, in New York state.
“We offer preliminary estimates of the lands unlikely to support new waves of climate refugees due to the residues of war, exhausted natural resources, declining net primary productivity, desertification, urban sprawl, land concentration, ‘paving the planet’ with roads, and greenhouse gas storage zones offsetting permafrost melt.”
“Although reclaiming land from oceans has been an important human project for millennia, it seems that oceans are now ‘reclaiming’ the land”
In any concerted attempts to contain climate change and limit global warming, climate scientists have to consider two big things. One is: how to drastically reduce fossil fuel use. The other is: how to use the land surface so that it takes up atmospheric carbon dioxide most efficiently.
Professor Geisler and his co-author Ben Currens, an earth and environmental scientist at the University of Kentucky, look at the big picture of land use in the long term.
They report in the journal Land Use Policy that they considered the implications of an ever faster rate of global sea level rise, as atmospheric temperatures warm and glaciers melt.
A study in Nature Climate Change has just confirmed that the seas that in the last century were rising by on average 2.2mm a year are now rising by 3.3mm a year. “Although reclaiming land from oceans has been an important human project for millennia,” write Geisler and Currens in their study, “it seems that oceans are now ‘reclaiming’ the land.”
They start from the premise that global mean sea level rise will continue beyond 2100, and from the prediction that for every 1°C of climate warming, humans should expect an eventual 2.3 metre rise in sea levels.
In 2000, around 630 million people lived in low-lying coastal zones. By 2060, this number could have risen to 1.4bn. In the worst case scenario, the two scientists reason, almost all who dwell on the low-lying coasts will become climate refugees.
But the land that could be used to resettle those refugees is dwindling: between 1981 and 2003, around 35 million square kilometres of the planet became “degraded” and now make up almost one fourth of the world’s drylands.
Permafrost, described in the study as “a vast and cost-free warehouse” for greenhouse gases, is thawing: as it melts, it could double the current levels of atmospheric carbon and feed back into ever-faster climate change.
Were global forests to be planted in a bid to absorb this extra carbon, they would take up more than 42 million sq km or 28% of the planet’s land surface.
The two scientists then considered the barriers that climate refugees could face as they moved from the coasts. They defined what they called depletion zones – drylands, thawing permafrost and degraded land – that would be unlikely to support human existence. They identified what they call “win-lose” zones that because of urban sprawl, landfill needs and mushrooming roadways could help in some ways but not in others.
And they listed a set of what they call “no trespass zones”, from which refugees would be excluded either legally, or by violence, or by the risk of landmines or radioactive pollution.
They considered case studies, in China and in Florida in the US, where state officials have begun to plan for weather-induced population shifts.
And, although President Trump has declared climate change a hoax and is to take the US out of the Paris Agreement of 2015 in which the world’s nations undertook to reduce fossil fuel use and contain global warming to less than 2°C, the two authors think there is no other answer.
“The pressure is on us to contain greenhouse gas emissions at present levels. It’s the best ‘future proofing’ against climate change, sea level rise and the catastrophic consequences likely to play out on coasts, as well as inland, in the future,” said Professor Geisler. – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.