Abstract Most estimates of global mean sea-level rise this century fall below 2 m. This quantity is comparable to the positive vertical bias of the principle digital elevation model (DEM) used to assess global and national population exposures to extreme coastal water levels, NASA’s SRTM. CoastalDEM is a new DEM utilizing neural networks to reduce SRTM error. Here we show – employing CoastalDEM—that 190 M people (150–250 M, 90% CI) currently occupy global land below projected high tide lines for 2100 under low carbon emissions, up from 110 M today, for a median increase of 80 M. These figures triple SRTM-based values. Under high emissions, CoastalDEM indicates up to 630 M people live on land below projected annual flood levels for 2100, and up to 340 M for mid-century, versus roughly 250 M at present. We estimate one billion people now occupy land less than 10 m above current high tide lines, including 230 M below 1 m.
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It all depends ob your assumptions, i.e. the actual effects of climate change on extreme weather events, the capacity of various polities to adapt to these effects and how you would define "climate change related deaths" and the timeframe you are looking at.
Direct fatalities from weather related natural disasters (droughts, floods, storms, etc) between 2005 and 2024 worldwide are estimated somewhere around 200.000 people, so about 10.000 deaths per year [0].
If you assume (just for the sake of the argument) that climate change will increase this death toll by 10% every year for 100 years, direct deaths from natural disasters caused by climate change alone will amount to…
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close to 140.000.000 deaths over that time period.
Add to this indirect deaths, i.e. premature deaths due to insufficient nutrition during childhood caused by drought, disease spread by floods, etc. etc.
And because the effects of climate change are mostly political in nature, you'll have to make some assumptions about that, too. Sea level rise will affect (as in inundate their current homes at least once a year) more than 600 million people by the year 2100 [1]. Many of these peoples will be displaced and depending on the political and economic capacity of their societies to cope with this displacement, this alone could result in millions of deaths.
Climate change is also a contributor to general political instability and the risk of both civil and nation state war. How do you account for those deaths?
In summary, the death toll of climate change can inherently not be known. But if you look at the next hundred years, I doubt you can assume a number of less than in the hundreds of millions, if we assume climate change effects based on current estimates of "status quo" emissions. Which makes emission reductions essential, because there is a literal connection between an additional ton of CO2 in the atmosphere and an increase in the number of deaths.
[0] https://ourworldindata.org/grapher/number-of-deaths-from-nat... [1] https://www.nature.com/articles/s41467-019-12808-z
It's nice that more crops are available, because salinisation is a real problem. It's not clear if it's a new problem in the area, or that are used to haves less people there.
Anyway, this claim is weird
> By 2050, [...]. The sea level is projected to rise by 50cm over the same period, leading to a loss of about 11% of Bangladesh’s land.
But there is a recent article in Nature that has a much lower prediction https://www.nature.com/articles/s41467-019-12808-z
> Central estimates in the recent literature broadly agree that global mean sea level is likely to rise 20–30 cm by 20503.
The flooding is hardly "water world": https://www.nature.com/articles/s41467-019-12808-z
"Central estimates in the recent literature broadly agree that global mean sea level is likely to rise 20–30 cm by 20503,4,5,6,7,8,9,10. End-of-century projections diverge more, with typical central estimates ranging from 50–70 cm under representative concentration pathway (RCP) 4.5 and 70–100 cm under RCP 8.53,9,10,12, though more recent projections incorporating Antarctic ice sheet dynamics indicate that sea levels may rise 70–100 cm under RCP 4.5 and 100–180 cm under RCP 8.5, and could even exceed 2 m or more in far-tail scenarios4,7,8,11. Via a structured elicitation of opinion, experts now estimate there is a 5 percent chance 21st century sea-level rise will exceed 2 m"
Bad news for East Anglia and the Somerset Levels, and many estuary cities including London will need mitigation work.
>Our best hope it to adapt to the new norm rather than fight a losing battle.
The next stage in climate denialism is climate nihilism: thinking that it's too late now to do anything to directly confront the problem so why bother. All it does is protect and entrench existing extractive interests. We can accomplish amazing things (landing on the moon, overthrowing the nazis and winning WW2) when we align our society and focus the right incentives.
Anything we do to adapt along the margins won't mitigate the next great mass of people opening the spigot on high carbon lifestyles. Political systems will buckle under the weight of human migration away from the vulnerable…
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coasts[1] and once-fertile land now too chaotic to farm[2]. We need to fund and develop the next wave of low-carbon tech to make it good enough and cheap enough to satisfy people's needs now, not piddle around looking for ways to monetize the fall.
1. https://www.nature.com/articles/s41467-019-12808-z
2. https://www.bloomberg.com/news/articles/2019-08-28/crazy-mid...
In my work with climate data, scientists in my cohort are instructing caution that many (linear) models are incorrect, and those are the figures you quote (1cm/year sea-level rise). However, not only have past sea-level rise projections been incorrectly low(1), but tropical storms/hurricanes have become measurably more frequent, more powerful, and slower(2), which also causes increased flooding. So, even if your beachfront property is not at increased risk from sea level rise, there is an increased risk of flooding and storm-surge exposure (in some places).
When I was attempting to establish historical storm trends for the Florida Keys in the early 18th century (for an…
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archaeological study), one colleague suggested I not use post-2004 data, because the warming of the oceans was skewing everything from mean wind directions to the number of hurricanes to the current patterns. The costs associated with beachfront property are also rising, due to the insurance industry's discomfort with the risks and the additional maintenance costs(3). Even the US's National Flood Insurance Program is increasing the charges of its subsidized coastal insurance products(4), because private industry deems many coastal properties uninsurable.
So, I gotta ask: On what data are you basing your opinions?
1) https://www.nature.com/articles/s41467-019-12808-z
2) https://www.theguardian.com/weather/ng-interactive/2018/sep/...
3) https://www.allpropertymanagement.com/blog/post/what-climate...
4) https://www.gulfshoreinsurance.com/summary-of-nfip-program-c...
I believe the paper is https://www.nature.com/articles/s41467-019-12808-z.
If I'm reading the paper correctly, the authors don't argue that sea levels will rise more than previously predicted. Rather, they argue that the classical technique for estimating impact by using elevation (SRTM) is overestimating elevation and therefore underestimating the impact of rising sea levels. The authors claim that their technique (CoastalDEM) also underestimates the impact of rising sea levels, but reduces the systemic bias present in previous estimates.
It would have been nice to link to the actual paper instead of a third-party commentary piece.
https://www.nature.com/articles/s41467-019-12808-z
Just the title of the paper is dubious. "New elevation data" should be "the output of a neural network trained on data from the US coastline, extrapolated into wildly different climates and regions".
The first paragraph says "Even with sharp, immediate cuts to carbon emissions, it could rise another 0.5 m this century."
Then later in the paper share this wildly broad range of predictions: "Central estimates in the recent literature broadly agree that global mean sea level is likely to rise 20–30 cm by 20503,4,5,6,7,8,9,10.…
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End-of-century projections diverge more, with typical central estimates ranging from 50–70 cm under representative concentration pathway (RCP) 4.5 and 70–100 cm under RCP 8.53,9,10,12, though more recent projections incorporating Antarctic ice sheet dynamics indicate that sea levels may rise 70–100 cm under RCP 4.5 and 100–180 cm under RCP 8.5, and could even exceed 2 m or more in far-tail scenarios"
Summary: neural network using the highest levels predicted in the most recent models, trained on data from areas with climates and landscapes wildly different than where the model is applied produces maps that freak people out and fuel political agendas.
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