as much ocean-front real estate is created by sea-level rise as is destroyed, approximately.
There isn’t a substantial change in the amount of ocean-front real estate, but there is a substantial change in the total amount of real estate. Super-crude model: you have a square island of side 1 unit; rising sea level reduces the side by 0.01 units of length, which by coincidence is also how near the sea something needs to be to be “ocean-front”. Before, the total amount of land is 1 unit and the total amount of sea-front land is 0.0396 units. After, the total amount of land is 0.9801 units and the total amount of sea-front land is 0.0392 units. So the total amount has gone down by ~2x as much relatively, and by ~50x as much in absolute terms.
From wikipedia we see that a 1% decrease in above sea level land area happens with about a 10 m sea level rise. In your example above you work with a 2% decrease in area, so you are developing numbers associated with a 20 m rise in sea level.
Predictions are for 0.2 to 0.6 m sea level rise in 100 years. This causes a 0.02% to 0.06% reduction in land area, associated with a 0.01% to 0.03% reduction in coastline.
So, pulling some numbers out of my rear end, let’s suppose that 5% of the world’s GDP comes from “land-based” activities in some sense, and let’s suppose that losing coastal land is 10% as bad as losing average land (e.g. because most farms aren’t right on the coast or near enough it to be badly affected by this change). Then losing 0.04% of the land would reduce “gross world product” by 0.05 x 0.1 x 0.0004 = 0.000002 = 2 x 10^-6 of its value, or about 2 x 10^-6 x $10^14 ~= $0.2B annually. That’s a lot of money but seems likely to be a lot smaller than, e.g., the impact on agriculture of temperature changes, or the cost of serious mitigation efforts.
(I’d guess that the costs would be relatively much greater for poorer countries, more of whose economic activity is agricultural.)
The economic impact depends mostly on the loss of homes and other buildings, not farmland. A good fraction of the world’s wealth is tied up in buildings, and those tend to be concentrated near coastlines. But levees can be built in many areas, and some buildings in other areas might be worth putting on stilts. So the costs of levees, stilts, and abandoned structures are what you most need to examine, I think, to assess the economic cost of sea-level rise.
What, that’s close to nothing! $0.03 per person per year.
And the effect is even smaller than that. Higher sea level pushes the atmosphere up as well, which means we are improving land at higher elevations by having more air on it. This will reduce the net loss of valuable land.
If the most effective charities can save a life for $2k, that’s enough to save 100k lives/year. But of course there are plenty of other things it’s small in comparison to; I mentioned a couple of relevant ones.
improving land at higher elevations
I think this is likely to be a much smaller effect. The great majority of land is no more than ~1000m above sea level.
If the most effective charities can save a life for $2k, that’s enough to save 100k lives/year.
The most effective charities can save a life for $2k today (where by “today” I mean ‘a couple years ago’) because there’s lots of low-hanging fruit, but I doubt this will continue to apply much longer.
Clever, yes. However, it also comes with the opening up of relatively low lands that were previously covered by ice. AND, I have read that a significant fraction of sea level rise is due to the ocean water expanding since slightly warmer water is not as dense as slightly cooler water, which would serve to push the atmosphere up.
I think if you totted it all up, you would see a small loss of value in the land area available, but much smaller loss in value than in land area lost. That is, the remaining land would have higher value per hectare on average for a few reasons.
I have read that a significant fraction of sea level rise is due to the ocean water expanding since slightly warmer water is not as dense as slightly cooler water, which would serve to push the atmosphere up.
The air is warming too, and the expansion of the air will make it less dense, which utterly swamps the effect from the expansion of the water.
That is, the remaining land would have higher value per hectare on average for a few reasons.
Really? I see that the other way around.
Beaches are valuable, and it will take a lot of time or money to make them at their new sites.
Estuaries provide a lot of ecological services and are basically flat. Having them be at the wrong depth will screw up those services.
Many cities (concentrated value) are right down on the water, and it will be muy expensive to save them and enough of their outlying areas that they remain convenient (which was a large part of why they were cities in the first place).
The link shows (just eyeballing the plot) about 80% of the earth’s land area being fairly uniformly distributed between 0 and 1000m above sea level. If we assume (a bit too simply, but it probably isn’t very far off) that a 10m rise in sea level will simply turn everything between 0 and 10m above sea level into no-longer-land, that suggests about (10m/1000m)*80% ~= 0.8% of the land would go away. Doesn’t seem too far out.
(How bad is the oversimplification mentioned above? It’s too pessimistic because some land below sea level might remain usable, as with the Netherlands. It’s too optimistic because some land still above sea level might become much less usable, e.g. by turning into little islands. My guess is that both these effects are quite small and they’re similar in size.)
but there is a substantial change in the total amount of real estate.
Substantial..?
Plug in the numbers for the size of the North American continent and for the expected sea level rise by 2100, for example, into your super-crude model.
I probably shouldn’t have said “substantial” since what I really meant was “not cancelled out in the way mwengler describes”.
I don’t think I can actually do the calculation without an estimate of the typical gradient of coastal land in the US (i.e., the conversion factor from sea level rise to shrinkage) but let’s make a crude guess and see what happens. So, North America has an area of about 25M km^2 so our square is about 5000km on a side. Expected sea level rise by 2100 is about 0.5m (I’ve seen wildly inconsistent figures for this, though). Let’s suppose that sea-level land has a typical gradient of 1 in 50, so that a 0.5m rise means a 25m shrinkage in the usable land. Then the total amount of land lost would be about 20000km x 25m = 20km x 25km = 500 km^2, roughly comparable to the area of San Francisco.
This is probably an underestimate: North America is wigglier than our square model (so more coast relative to its area) and I suspect that actually coastal land is flatter than 1 in 50.
So it’s a small fraction of the total area (as of course was obvious from the outset) but personally I’d consider it a substantial loss if an area the size of San Francisco fell into the sea.
There isn’t a substantial change in the amount of ocean-front real estate, but there is a substantial change in the total amount of real estate. Super-crude model: you have a square island of side 1 unit; rising sea level reduces the side by 0.01 units of length, which by coincidence is also how near the sea something needs to be to be “ocean-front”. Before, the total amount of land is 1 unit and the total amount of sea-front land is 0.0396 units. After, the total amount of land is 0.9801 units and the total amount of sea-front land is 0.0392 units. So the total amount has gone down by ~2x as much relatively, and by ~50x as much in absolute terms.
Cool idea using numbers!
From wikipedia we see that a 1% decrease in above sea level land area happens with about a 10 m sea level rise. In your example above you work with a 2% decrease in area, so you are developing numbers associated with a 20 m rise in sea level.
Predictions are for 0.2 to 0.6 m sea level rise in 100 years. This causes a 0.02% to 0.06% reduction in land area, associated with a 0.01% to 0.03% reduction in coastline.
So, pulling some numbers out of my rear end, let’s suppose that 5% of the world’s GDP comes from “land-based” activities in some sense, and let’s suppose that losing coastal land is 10% as bad as losing average land (e.g. because most farms aren’t right on the coast or near enough it to be badly affected by this change). Then losing 0.04% of the land would reduce “gross world product” by 0.05 x 0.1 x 0.0004 = 0.000002 = 2 x 10^-6 of its value, or about 2 x 10^-6 x $10^14 ~= $0.2B annually. That’s a lot of money but seems likely to be a lot smaller than, e.g., the impact on agriculture of temperature changes, or the cost of serious mitigation efforts.
(I’d guess that the costs would be relatively much greater for poorer countries, more of whose economic activity is agricultural.)
The economic impact depends mostly on the loss of homes and other buildings, not farmland. A good fraction of the world’s wealth is tied up in buildings, and those tend to be concentrated near coastlines. But levees can be built in many areas, and some buildings in other areas might be worth putting on stilts. So the costs of levees, stilts, and abandoned structures are what you most need to examine, I think, to assess the economic cost of sea-level rise.
What, that’s close to nothing! $0.03 per person per year.
And the effect is even smaller than that. Higher sea level pushes the atmosphere up as well, which means we are improving land at higher elevations by having more air on it. This will reduce the net loss of valuable land.
If the most effective charities can save a life for $2k, that’s enough to save 100k lives/year. But of course there are plenty of other things it’s small in comparison to; I mentioned a couple of relevant ones.
I think this is likely to be a much smaller effect. The great majority of land is no more than ~1000m above sea level.
The most effective charities can save a life for $2k today (where by “today” I mean ‘a couple years ago’) because there’s lots of low-hanging fruit, but I doubt this will continue to apply much longer.
Higher sea level from ice falling into the water results in the air being lowered since the ice became denser in the process.
Clever, yes. However, it also comes with the opening up of relatively low lands that were previously covered by ice. AND, I have read that a significant fraction of sea level rise is due to the ocean water expanding since slightly warmer water is not as dense as slightly cooler water, which would serve to push the atmosphere up.
I think if you totted it all up, you would see a small loss of value in the land area available, but much smaller loss in value than in land area lost. That is, the remaining land would have higher value per hectare on average for a few reasons.
The air is warming too, and the expansion of the air will make it less dense, which utterly swamps the effect from the expansion of the water.
Really? I see that the other way around.
Beaches are valuable, and it will take a lot of time or money to make them at their new sites.
Estuaries provide a lot of ecological services and are basically flat. Having them be at the wrong depth will screw up those services.
Many cities (concentrated value) are right down on the water, and it will be muy expensive to save them and enough of their outlying areas that they remain convenient (which was a large part of why they were cities in the first place).
I am sorry, I don’t see anything like these numbers in your link.
I digitized the elevation distribution figure and took the slope right around sea level.
The link shows (just eyeballing the plot) about 80% of the earth’s land area being fairly uniformly distributed between 0 and 1000m above sea level. If we assume (a bit too simply, but it probably isn’t very far off) that a 10m rise in sea level will simply turn everything between 0 and 10m above sea level into no-longer-land, that suggests about (10m/1000m)*80% ~= 0.8% of the land would go away. Doesn’t seem too far out.
(How bad is the oversimplification mentioned above? It’s too pessimistic because some land below sea level might remain usable, as with the Netherlands. It’s too optimistic because some land still above sea level might become much less usable, e.g. by turning into little islands. My guess is that both these effects are quite small and they’re similar in size.)
Substantial..?
Plug in the numbers for the size of the North American continent and for the expected sea level rise by 2100, for example, into your super-crude model.
I probably shouldn’t have said “substantial” since what I really meant was “not cancelled out in the way mwengler describes”.
I don’t think I can actually do the calculation without an estimate of the typical gradient of coastal land in the US (i.e., the conversion factor from sea level rise to shrinkage) but let’s make a crude guess and see what happens. So, North America has an area of about 25M km^2 so our square is about 5000km on a side. Expected sea level rise by 2100 is about 0.5m (I’ve seen wildly inconsistent figures for this, though). Let’s suppose that sea-level land has a typical gradient of 1 in 50, so that a 0.5m rise means a 25m shrinkage in the usable land. Then the total amount of land lost would be about 20000km x 25m = 20km x 25km = 500 km^2, roughly comparable to the area of San Francisco.
This is probably an underestimate: North America is wigglier than our square model (so more coast relative to its area) and I suspect that actually coastal land is flatter than 1 in 50.
So it’s a small fraction of the total area (as of course was obvious from the outset) but personally I’d consider it a substantial loss if an area the size of San Francisco fell into the sea.