The Conversation is fact-checking claims made on Q&A, broadcast Mondays on the ABC at 9.35pm. Thank you to everyone who sent us quotes for checking via Twitter using hashtags #FactCheck and #QandA, on Facebook or by email.
PETER SINGER: That is going to basically inundate every coastal city around the world, including, of course, all Australian major cities are coastal. It is going - estimated to cause something like 750 million refugees just moving away from that flooding. Never mind those who also because refugees because (indistinct)…
VIRGINIA TRIOLI: Some of those claims are contested, of course?
PETER SINGER: Well, they are contested but do you want to take the chance, right? – Peter Singer, Ira W. DeCamp Professor of Bioethics, Princeton University, speaking on Q&A with host Virginia Trioli, August 2, 2016.
Ethicist Peter Singer told Q&A that climate change-related sea level rises are “estimated to cause something like 750 million refugees just moving away from that flooding”.
It is beyond the scope of a FactCheck to say with any certainty what will happen in the future. And there is no single official data source on the numbers of people who migrate because of the impacts of climate change, partly because there is no legal definition of a “climate change refugee”. Furthermore, most such displacement occurs within countries, not across international borders, and is always due to a number of different factors. Finally, there is no systematic monitoring of such movement.
That said, we can check how Singer’s figure of 750 million fits within the range of estimates that exist on this question.
Checking the source
When asked by The Conversation for sources to support his statement, Peter Singer said:
The figure I gave is near the top end of the Climate Central range, but remember that I agreed with Virginia Trioli that this is contested. I argued that if it is even a small chance, the stakes are too high to be worth taking the risk.
Carbon emissions causing 4°C of warming — what business-as-usual points toward today — could lock in enough sea level rise to submerge land currently home to 470 to 760 million people, with unstoppable rise unfolding over centuries.
Predictions vary and uncertainties abound, but climate scientists say it is possible we may reach 4°C of warming by 2100 if insufficient effort is made to reign in emissions.
As Singer acknowledges, his figure of 750 million is at the upper end of estimates – and he readily agreed that estimates are contested.
Without detracting from Singer’s broader point about the human consequences of climate change, it is worth taking a closer look at the context, assumptions and methodologies behind some of these alarming-sounding figures.
What does Singer’s source say about climate refugees?
When Climate Central released its Mapping Choices report in 2015, the headline it used on its website was “New Report and Maps: Rising Seas Threaten Land Home to Half a Billion”.
But to be clear, Climate Central’s full report did not say that 750 million people would need to move away due to rising sea levels – in fact, unlike Singer, it didn’t use the term “refugees” at all.
Instead, it said only that under a 4°C warming scenario, there could be “enough sea level rise to submerge land currently home to 470 to 760 million people” (emphasis added).
The Climate Central report acknowledges that its estimates do not take adaptation strategies into account, noting:
Results do not account for present or future shoreline defences, such as levees, that might be built, nor for future population growth, decline or relocation.
A vast range of estimates – and plenty of guesswork
Some of the numerical estimates on climate-related displacement are based on crude methodologies, as explained in my 2012 book, Climate Change, Forced Migration, and International Law.
For example, in 1993 social scientist Norman Myers wrote a paper suggesting that 150 million people could be displaced by climate change by the the mid-21st century. He had identified areas expected to be affected by sea-level rise, and then calculated the anticipated population of those areas in 2050. In subsequent work and interviews, he said the figure could be closer to 200 million or 250 million. Estimates ranging from 50 million to 600 million to even a billion have been cited by some.
The Observer published an article in 2010 headlined “Climate change will cost a billion people their homes, says report”.
However, that report misconstrued a paper by Dr François Gemenne – whose work is empirically based and well-reasoned – that referred to the Intergovernmental Panel on Climate Change’s (IPCC) comment that freshwater availability in a changing climate may adversely affect more than a billion people by the 2050s. That’s a different story from the one told in The Observer’s headline.
Many of these upper end estimates – and the methodologies used to calculate them – have been criticised by other researchers, who note that very big estimates often fail to account for adaptation.
The IPCC itself has said that:
Estimates of the number of people who may become environmental migrants are, at best, guesswork.
How much weather-related displacement of people have we seen so far?
Peter Singer’s comment was about future impacts of climate change. But what do we know about current and past climate-related movement?
The best statistics on this are published by the Internal Displacement Monitoring Centre (IDMC), the leading source of information on internal displacement whose role has been endorsed by the UN. It said in its Global Estimates 2015: People displaced by disasters report that:
Since 2008, an average of 22.5 million people have been displaced by climate- or weather-related disasters [each year].
Authors: Jane McAdam, Scientia Professor and Director of the Andrew & Renata Kaldor Centre for International Refugee Law, UNSW Australia