Some years ago, Norman Myers suggested that there would be 150 million "environmental refugees" caused by climate change in the 21st Century. Then he changed his mind: they would be 200 million. Then he changed his mind again: they could be up to 250 million. Christian Aid soon won the bid with the "b" number- announcing 1 billion "climate refugees" by 2100.
The only difficulty is that none of these figures was supported by any solid analysis of what a "climate" or "environmental refugee" is. Is it someone seeking refuge abroad (like current refugees), or in another part of the same country? Does it encompass individuals who are temporarily displaced, perhaps just evacuated for a few days during, say, a violent typhoon? Do all of these "climate refugees" share the same protection needs? Do they share anything at all?
Often, climate change does not directly cause displacement. The frequency of natural disasters may be related to climate change, but these are matters of probability: a natural disaster cannot, usually, be said to be "caused" by climate change. Likewise, a natural disaster does not displace people in a vacuum: a lot depends on the particular circumstances taken, for instance to prepare a society to a particular weather hazard. Displacement may be a measure to protect individuals in the midst of a cyclone, just as much as it can be a sign of a lack of preparedness when people literally run for their life. What is gained by putting people in a bag called "climate refugees"?
The scientific literature has progressively denounced these figures as based on little conceptual and analytical bases. Yet, numbers continue to attract the media. Numbers have gone down in the latest report, which speaks about 140 million of "climate refugees" – but with this specific number comes, implicitly, the claim of a more accurate scientific method for determining and predicting the number of "climate refugees" a little like climate scientists predict the impact of greenhouse gas emissions on a thermometer.
"Experts warn of 'looming human crisis' as millions are driven to migrate within national borders due to water scarcity, sea-level rise and storm surges"https://www.independent.co.uk/environment/climate-change-force-140-million-people-from-homes-2050-developing-countries-global-warming-report-a8263741.html