It seems like we’ve identified a crux here: what will be the total number of people living in Greenland in 2100 / world with 4 degrees warming?
I have disagreements with some of your estimates.
The total drylands population is 35% of the world population
Large populations currently reside in places like India, China and Brazil. These currently non-drylands could be converted to drylands in the future (and also possibly desertified). Thus, the 35% figure could increase in the future.
So less than 10% of those from drylands have left.
Drylands are categorised into {desert, arid, semi-arid, dry sub-humid}. It’s only when a place is in the desert category, that people seriously consider moving out (for reference all of California comes under arid or semi-arid category). In the future, deserts could form a larger share of drylands, and less arid regions could form a smaller share. So, you could have more than 10% of people from places called “drylands” leaving in the future.
The total number of migrants, however, is 3.5% of world population.
Yes, that is correct. But that is also a figure from 2019. A more relevant question would be how many migrants would there be in 2100? I think it’s quite obvious that as the Earth warms, the number of climate migrants will increase.
So suppose a billion people newly found themselves in drylands or desert, and that 5% migrated, making 50M migrants.
I don’t really agree with the 5% estimate. Specifically for desertified lands, I would guess the %age of people migrating to be significantly higher.
Of the world’s 300M migrants, Greenland currently has only ~10k.
This is a figure from 2020 and I don’t think you can simply extrapolate this.
After revising my estimates to something more sensible, I’m coming with ~50M people in Greenland. So, Greenland would be far from being a superpower. I’m hesitant to share my calculations because my confidence level for my calculations is low—I wouldn’t be surprised if the actual number was upto 2 orders of magnitude smaller or greater.
A key uncertainity: Does desertification of large regions imply that in-country / local migration is useless?
The world, 4 degrees warmer. A map from Parag Khanna’s book Connectography
I’m not sure you’ve understood how I’m calculating my figures, so let me show how we can set a really conservative upper bound for the number of people who would move to Greenland.
Based on current numbers, 3.5% of world population are migrants, and 6% are in deserts. So that means less than 3.5/9.5=37% of desert populations have migrated. Even if half of those had migrated because of the weather, that would be less than 20% of all desert populations. Moreover, even if people migrated uniformly according to land area, only 1.4% of migrants would move to Greenland (that’s the fraction of land area occupied by Greenland). So an ultra-conservative upper bound for the number of people migrating to Greenland would be 1B*.37*.2*.014=1M.
So my initial status-quo estimate was 1e3, and my ultra-conservative estimate was 1e6. It seems pretty likely to me that the true figure will be 1e3-1e6, whereas 5e7 is certainly not a realistic estimate.
Hmm this is interesting. I think I broadly agree with you. I think a key consideration is that humans have a good-ish track record of living/surviving in deserts, and I would expect this to continue.
Thanks Ryan for your comment!
It seems like we’ve identified a crux here: what will be the total number of people living in Greenland in 2100 / world with 4 degrees warming?
I have disagreements with some of your estimates.
Large populations currently reside in places like India, China and Brazil. These currently non-drylands could be converted to drylands in the future (and also possibly desertified). Thus, the 35% figure could increase in the future.
Drylands are categorised into {desert, arid, semi-arid, dry sub-humid}. It’s only when a place is in the desert category, that people seriously consider moving out (for reference all of California comes under arid or semi-arid category). In the future, deserts could form a larger share of drylands, and less arid regions could form a smaller share. So, you could have more than 10% of people from places called “drylands” leaving in the future.
Yes, that is correct. But that is also a figure from 2019. A more relevant question would be how many migrants would there be in 2100? I think it’s quite obvious that as the Earth warms, the number of climate migrants will increase.
I don’t really agree with the 5% estimate. Specifically for desertified lands, I would guess the %age of people migrating to be significantly higher.
This is a figure from 2020 and I don’t think you can simply extrapolate this.
After revising my estimates to something more sensible, I’m coming with ~50M people in Greenland. So, Greenland would be far from being a superpower. I’m hesitant to share my calculations because my confidence level for my calculations is low—I wouldn’t be surprised if the actual number was upto 2 orders of magnitude smaller or greater.
A key uncertainity: Does desertification of large regions imply that in-country / local migration is useless?
I’m not sure you’ve understood how I’m calculating my figures, so let me show how we can set a really conservative upper bound for the number of people who would move to Greenland.
Based on current numbers, 3.5% of world population are migrants, and 6% are in deserts. So that means less than 3.5/9.5=37% of desert populations have migrated. Even if half of those had migrated because of the weather, that would be less than 20% of all desert populations. Moreover, even if people migrated uniformly according to land area, only 1.4% of migrants would move to Greenland (that’s the fraction of land area occupied by Greenland). So an ultra-conservative upper bound for the number of people migrating to Greenland would be 1B*.37*.2*.014=1M.
So my initial status-quo estimate was 1e3, and my ultra-conservative estimate was 1e6. It seems pretty likely to me that the true figure will be 1e3-1e6, whereas 5e7 is certainly not a realistic estimate.
Hmm this is interesting. I think I broadly agree with you. I think a key consideration is that humans have a good-ish track record of living/surviving in deserts, and I would expect this to continue.