https://ocean.si.edu/through-time/ancient-seas/sea-level-rise
The rate of sea level rise has also increased over time. Between 1900 and 1990 studies show that sea level rose between 1.2 millimeters and 1.7 millimeters per year on average. By 2000, that rate had increased to about 3.2 millimeters per year and the rate in 2016 is estimated at 3.4 millimeters per year . Sea level is expected to rise even more quickly by the end of the century.
Not 200 feet. Look up the volume of ice in Greenland. Then look up the surface area of the oceans. Divide the latter into the former and you get 21 feet if memory serves me. Definitely not 200 feet. This is exactly what bothers me. Exaggeration and scaremongering. It’s a disservice to science. Stick to the facts and there will be a lot less skepticism.
“only 21 feet”
So, absolutely catastrophic sea-level rise.
If you look at it from and energy viewpoint it is quite simple. Energy available per year per the greenhouse forcing effect formula divided by the energy needed equals years. Calculated SLR divided by the resulting years equals mm/yr. The energy influx from the sun is constant. The energy retained by earth and available is increasing at a rate dictated by the greenhouse gas forcing effect. So you are right that the available energy is increasing but the needed energy must also increase to achieve the rates quoted so the rate of SLR should be relatively constant. By my estimate it is less than 3.5mm/yr. I don’t think it is possible that it could be 25mm/yr as the paper states. Exaggeration breeds skepticism. Skepticism is the enemy of the changes we need to keep our world livable.
But it will take ~700 years
I haven’t followed the whole discussion here about SLR, but isn’t part of it that ice cubes not currently in the drink will later slide into the drink? In other words, glaciers don’t have to melt, they just have to be in the ocean rather than sitting on land?
You can tell me if I’m wrong.
True. But the “ice cubes” can’t move much faster into the ocean than they have historically without a lot of warming. Then once released from grounding they will have to melt and be heated to the average ocean temp in order for thermal expansion effects to not to nullify some of the SLR. It’s possible that a sudden collapse of very large ice shelves could cause a quick increase in SLR but it is complicated and I just don’t have a full understanding of the range of possibilities.
That’s correct. Also thermal expansion is a big factor. Additionally the methane gun is a very concerning prospect.
Methane is a much stronger ghg than co2, and there’s a lot of it on the bottom of the arctic ocean. And once enough sea ice is cleared and the water warms the methane clathrates will boil into the atmosphere and rapidly accelerate warming.
From what I’ve read, the West Antarctic Ice Sheet is the one we’re most worried about collapsing, and while it’s not likely in our lifetimes, that’s a big part of how we’d get to 200 feet.
That’s my understanding too: stronger by a factor of something like 84 in the short term or 28 over the longer term. Also that CO2 will linger for several hundred or thousands of years, while methane will be broken down or reabsorbed on the order of decades.
you’re also not taking into account how much more energy open sea and bare ground absorb compared to ice.
Your estimate was that it wouldn’t exceed 3mm per year – I cited peer-reviewed figures to the contrary. Moving goalposts and indulging in a lack of precision (in this context a tenth of a mm is a significant amount) isn’t helpful in this discussion.
The peer-reviewed paper in this case is specifically pointing out a worst-case scenario in which very little is done to mitigate anthropogenic climate change, resulting in multiple feedback loops causing accelerated rates of sea level rise. It is re-evaluating the upper limit in that case.
Since there are still all too many denialists and (when denial is impossible) irresponsible and greedy people out there in positions of power, that scenario has to be presented despite your concern.
But the administration did not offer this dire forecast, premised on the idea that the world will fail to cut its greenhouse gas emissions, as part of an argument to combat climate change. Just the opposite: The analysis assumes the planet’s fate is already sealed.
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