A discussion of Hansen's new paper on rapid sea level rise

[GliderGuider]

Warning From Scientists — Halt Fossil Fuel Burning Fast or Age of Superstorms, 3-20 Foot Sea Level Rise is Coming Soon

First the good news. James Hansen, one of the world’s most recognized climate scientists, along with 13 of his well-decorated fellows believe that there’s a way out of this hothouse mess we’re brewing for ourselves. It’s a point that’s often missed in media reports on their most recent paper — Ice Melt, Sea Level Rise, and Superstorms. A paper that focuses on just two of the very serious troubles we’ll be visiting on ourselves in short order if we don’t heed their advice.

The way out? Reduce global carbon emissions by 6% each year and manage the biosphere such that it draws carbon down to 350 ppm levels or below through the early 22nd Century. The bad news? According to Hansen and colleagues, even if we just continue to burn fossil fuels and dump carbon into the atmosphere at a ‘moderate’ pace some of the terrifically catastrophic impacts of human caused climate change are not too far off.

Turning to the current day, there’s a growing number of reasons why we should be concerned that rapid land ice melt, large fresh water outflow to oceans, and resulting superstorms could be in our future. First, we’ve learned that the topography of Greenland and Antarctica include numerous channels that tunnel deep into its great glaciers at depths well below sea level. When oceans warm, and they’re warming as you read this, the submerged, sea-facing slopes of glaciers are confronted with more and more heat gnawing away at their under-bellies. Just a 0.1 C increase in water temperature can melt away a meter of ice over the course of a year. Multiply that by glaciers with faces that are submerged hundreds of feet deep whose sea fronting cliffs extend for many miles and you can end up with quite a lot of melt due to very little warming. As more of the undersides of glaciers melt, more of the water tunnels inland and large masses of ice are rafted away from the central ice exposing still more of the land anchored ice to a warming ocean flood.

As bad as this dynamic may sound, the process includes one more wrinkle that makes it even worse. As the undersides of ice shelves erode and more fresh water laden ice bergs are pulled out into the ocean, these ice bergs begin to melt en mass. This massive ice melt develops into an enormous and expanding pool of fresh water at the surface. And its this troublesome demon that traps heat in the deeper ocean levels. So, in other words, as the ice from the land glaciers floats away and melts it traps and focuses more heat at the base of these great glaciers. It’s an amplifying feedback. A very serious kind that doesn’t even require the human forced kick to create severe trouble. One that during the Eemian really wrecked the weather and caused massive surges in ocean height.

So what does all this mean? In the worst case (5-10 year melt rate doubling times), it’s possibly 3 meters of sea level rise by mid Century, perhaps 7 meters by end Century under business as usual fossil fuel emissions. Even in the more moderate cases (10-20 year melt rate doubling times), 1 meter of sea level rise by mid Century and 3 meters or more of sea level rise by end Century is not entirely out of the question, according to Hansen’s new research. These potentials are markedly different than the more conservative rates outlined by IPCC which is still calling for a less than 1 meter sea level rise under even the worst case human carbon emissions scenarios (1000 parts per million CO2, in the range of 1200 ppm CO2e).

Here is what a 6% annual reduction in CO2 emissions looks like, compared to two likely trends - one linear, one exponential.



In Hansen's judgement, by 2045 we need to be down around 5,000 Mt of emissions compared to 35,000 Mt today. The two BAU scenarios show us emitting 10 to 13 times that amount.

Not to mention that we simultaneously have to figure out some way to being down CO2 to 350 by the end of the century, and actually do it.

If averting the crisis means we must do both of these likely impossible things, we're hooped. Economics will win out over the biosphere once and for all.

Hansen isn't doing himself (or the world) any favours by being such a Pollyanna.

[Gregorian]

1. On an individual level I see concern, but no action.

So what has to change is behavior. We can engineer only fractions, unless there's some quantum increase in ideas to get carbon out of the atmosphere, which is really only one part of a bigger problem we have. But the moment anyone even dare to discuss changing behavior, and my prediction is it would be treated with outrage. After all, Cuba's going to be open for Americans now. What's that carbon footprint going to be? And how dare I even ask. What a cultural downer.

[kristopher]

2. It is a good thing renewables have fallen so much in price and are rapidly scalable.

Now all we have to do is give the coal/gas/petroleum and nuclear industries a GI style financial haircut. I believe we are at the point where the winners from inexpensive, low-carbon renewable deployment are better positioned going forward than the entrenched system.
In the past 24 months a frontline battle has been waging on the policy front and the trend is not going the way the utilities would like to see. And it's only going to get worse as the impact of the new "lowest priced generation" status of wind and solar sow more manufacturing demand seeds in the developing world.

The economic blowback on the advanced industrialized economies will be overwhelming easily within 10 years and all of the battles being waged by ALEC to preserve the carbonized status quo will completely crumble. All IMHnsO, of course.

[Ghost Dog]

3. To make the necessary changes would require an 'enlightened' dictatorship

with extensive powers ('inquisitions') & preferably widespread public aquiescence (through some kind of religion?)... Otherwise the observed processes will continue their course. So either way what we call today 'civilisation' will for most survivors revert back to something like the darkest of European feudal times, or worse...

[GliderGuider]

4. And not just an enlightened national dictatorship, but a global one. Ain't happening.

We would rather die than submit, so we will.

[Ghost Dog]

5. Global, yeah.

No.

[NickB79]

6. And after civilization falls to feudal status, we still get the dictators anyway

Only they won't be enlightened, they'll be warlords ruling with iron fists.

Fuck.

[Ghost Dog]

7. Exactly.

Unless... something like the Chinese Communist dictatorship could do better?