Climate Sensitivity is High; Burning All FF Will Render Most Areas Uninhabitable

[wili]

Hansen Study: Climate Sensitivity Is High, Burning All Fossil Fuels Would Make Most Of Planet ‘Uninhabitable’

   

James Hansen, the country’s most prescient climatologist, is out with another must-read paper, “Climate sensitivity, sea level and atmospheric carbon dioxide.” The paper, co-authored by a number of Hansen’s former colleagues at NASA, is an antidote to the rosy scenarios the mainstream media have recently been pushing.

    The key findings are

    The Earth’s actual sensitivity to a doubling of CO2 levels from preindustrial levels (to 550 ppm) — including slow feedbacks — is likely to be larger than 3–4°C (5.4-7.2°F).
    Given that we are headed towards a tripling (820 ppm) or quadrupling (1100 ppm) of atmospheric CO2 levels, inaction is untenable.
    “Burning all fossil fuels” would warm land areas on average about 20°C (36°F) and warm the poles a stunning 30°C (54°F). This “would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.”

    Burning all or even most fossil fuels would be a true scorched Earth policy.

    Given that James Hansen has been right about global warming for more than 3 decades, his climate warnings need to be taken seriously...

    if we ultimately burn all of fossil fuels, Hansen et al find almost unimaginable consequences:

    Our calculated global warming in this case is 16°C, with warming at the poles approximately 30°C. Calculated warming over land areas averages approximately 20°C. Such temperatures would eliminate grain production in almost all agricultural regions in the world. Increased stratospheric water vapour would diminish the stratospheric ozone layer.

    More ominously, global warming of that magnitude would make most of the planet uninhabitable by humans. The human body generates about 100 W of metabolic heat that must be carried away to maintain a core body temperature near 37°C, which implies that sustained wet bulb temperatures above 35°C can result in lethal hyperthermia...

    A warming of 10–12°C would put most of today’s world population in regions with wet a bulb temperature above 35°C….

    ...we are headed towards CO2 levels in 2100 last seen when the Earth was 29°F (16°C) hotter.

[domen_]

Here's link: http://m.rsta.royalsocietypublishing.org/content/371/2001/20120294.full

They used paleoclimate data to determine climate sensitivity. Haven't read it through, but some scary stuff written there.

[Bruce Steele]

In the last couple paragraphs of the Hansen paper the 5000gt of proven carbon reserves are the same as the 5000gt that Caldeira used in his acidification projections (2003 ). See my comments in the
Consequences " oceans " page. The Hansen paper has 5000-15,000gt in carbon if  unconventional sources are included. If the 5000gt carbon Caldeira modeled would drive down average ocean pH by .7 from preindustrial levels then the extra 5000-10,000gt in unconventional carbon would produce some very unprecedented ocean pH levels. Unprecedented in the fossil record over the last 300 million years. Hard to imagine how the ocean would react to pH levels at 7.5 ( the result of burning conventional reserves). Crazy   

[wili]

Thanks, domen and Bruce.

Here's the link to the Climate Progress article that the above headline and quote were taken from:

http://thinkprogress.org/climate/2013/09/17/1892241/hansen-climate-sensitivity-uninhabitable/

Bruce, could you give the gist of your argument about proven carbon reserves here (the one you say you lay out in the consequences "oceans" page) or provide a link to it?

[Lennart van der Linde]

Two quotes from Hansen et al 2013 that are particularly noteworthy, at least to me, living in Holland:

“The empirical data support a high sensitivity of the sea level to global temperature change, and they provide strong evidence against the seeming lethargy and large hysteresis effects that occur in at least some ice sheet models [p.22].”

“The amount of CO2 required to melt most of Antarctica in the MMCO [Middle Miocene Climatic Optimum, about 16 million years ago] was only approximately 450–500 ppm, conceivably only about 400 ppm. These CO2 amounts are smaller than suggested by ice sheet/climate models, providing further indication that the ice sheet models are excessively lethargic, i.e. resistant to climate change [p.23].”

So we could be very close to melting all of the ice on Earth, resulting in about 70m of SLR. Maybe that would take as little as a few millennia and could be very hard to stop, if we don't succeed in decarbonizing our economy very fast and/or in geoengineering our way out of this prospect. About 10m of SLR could be possible in the coming three centuries, which may be inevitable in the longer term anyhow, but could still be slowed down substantially by fast decarbonization.

How Holland and the world could or would adapt to 10m of SLR over the coming centuries is an interesting question, but it looks like it would be a lot more expensive than rapidly decarbonizing. Which of course would also mitigate the need for adaptation to earlier and maybe even more urgent pressures, like food and water shortages, heat waves, droughts, fires, storms, floods, diseases, migration and conflicts over all kinds of resources.

[Richard Rathbone]

I've seen something very similar to this paper before. Maybe it was on open review?

Well worth the read. Hansen is the best around for this sort of analysis. Uninhabitable in 2100 isn't certainty, but it can't be ruled out as a possibility under BAU.

Still a little time for an Augustinian "Grant me chastity and continence, but not yet." but best keep a careful eye on developments or it may get too late.

[Shared Humanity]

"How Holland and the world could or would adapt to 10m of SLR over the coming centuries is an interesting question....."

In the most recent National Geographic, there is a nice article on the impact of sea level rise.

http://ngm.nationalgeographic.com/2013/09/rising-seas/folger-text

The author spent quite a bit of time in Holland to get a sense of how the most skilled nation in the world is currently battling this rise. If you read the article, "a recent Dutch study predicted that the Netherlands could engineer solutions at a manageable cost to a rise of as much as five meters, or 16 feet." Keep in mind this is a wealthy country with a great deal of expertise in dealing with the sea. Most other nations will not be able to deal with such a rise and for some areas (Florida) there are simply no solutions that will prevent the complete evacuation of the southern 1/3 of the state, including Miami.

[Bruce Steele]

https://pangea.stanford.edu/research/Oceans/GES205/Caldeira_Science_Anthropogenic%20Carbon%20and%20ocean%20pH.pdf
 Wili, I suppose most members of this forum can track emissions trajectories. How far we proceed from  ~ 356 gt total carbon  emissions ( 1750 to 2010)  towards the potential + 5000gt of carbon emissions from fossil fuel reserves will determine future terrestrial and ocean temperatures. It will also determine the extent to which ocean acidification proceeds. We are currently adding 10gt C annually and that rate will increase to 15gt C annually around 2045. Adding in potential unconventional sources of fossil fuel jacks these numbers up .  The 5000 gt C from conventional sources is plenty enough to really make a mess of this planet.         

[Lennart van der Linde]

I've seen something very similar to this paper before. Maybe it was on open review?

Yes, the draft was public since the end of 2012.

[prokaryotes]

This page needs updates


https://en.wikipedia.org/wiki/Climate_sensitivity

Here is the 2011 report "Climate sensitivity in the Anthropocene" (CC-BY) http://www.earth-syst-dynam-discuss.net/2/531/2011/esdd-2-531-2011-discussion.html

[werther]

Hi all,
I'm four days late in the thread, after being alarmed by Wayne Kernochan on the Blog.
But I find even the abstract sobering enough:
“…we show that the slow response and hysteresis in prevailing ice sheet models are exaggerated…”
“…and increased water vapour elevates the tropopause…”
“…calling into question strategies that emphasize adaptation to climate change…”
Three initial comments:
- while this year wasn't exceptional on the GIS, 2012 showed what is possible now. Pretty soon mass loss will exceed 1000Gt per year, corresponding with a trend to complete melt of the Southern tip of the GIS by +/- 2050 and 50 cm SLR
- even an amateur survey of NCEP/NCAR data shows sign of this for last year; it isn't way out to check whether the Ferrell Cell is fading
- adaptation could be acceptable in an appeasing, non-violent state of dealing with what's to come. The question rises whether the protection we ought to offer to what's weak legitimates a more agressive approach?
Maybe even the Greenpeace approach just isn't responding to reality...