Hot Earth Dreams--The Future In A Hot World

[wili]

https://heteromeles.files.wordpress.com/2015/11/hot-earth-dreams-sample1.pdf

The introduction and first five chapters of this book are provided here for free. The book is an attempt to lay out what the world will look like in a century, in a couple millennia, and in a few hundreds of thousands of years, under worst case GW scenarios.

I would be interested in what others think about some of his prognoses. WRT topics most relevant to this site, he seems to be, to my mind, a bit optimistic or understated (uninformed?) about the potential consequences of methane releases from both sea beds and from permafrost (the latter of which he doesn't seem to even mention). But he has rather...advanced...ideas about aslr (ASLR, please take note!).

I would be most interested in peoples thoughts and critiques. I'd rather hear others' points first before sharing many of my own. Is anyone else planning on working on a book like this. It seems to me that some of us here could do a somewhat better job of some parts of this, at least.

[crandles]

"with 3.3 meters (11 feet) of rise happening in spurts in the weeks and months after catastrophic ice sheet failures"

seemed to follow

"they [ice sheets] can fall apart very quickly in ways that climate modelers have trouble duplicating in their models. This happened to the Larsen B Ice Shelf in 2002 and Arctic sea ice subsequently"

Hmm. Ice sheets are not ice shelves nor sea ice. An ice shelf is floating and doesn't have much direct effect on sea level - the effect it has is from un-buttressing glaciers allowing them to speed up so has effect over several years rather than week or months.

I can't imagine Greenland melting away so much in spurts the exits are too narrow. West Antarctica could do so, A possible/probable? mode could be: high cliffs of ice failing and ocean washing away the debris rapidly to set the scene for more cliff failure. I would expect it would not be entirely steady growth in the rate of rise. Is too much emphasis being put on the spurts?

4.8m over 200 to 300 years seems a sensible amount of slr to imagine over that timeframe.

He seems to think this will cause really important problems perhaps as far as civilisation collapse. Is it all that great a problem?

He sensibly suggests "Since harbors have to be rebuilt every century or so anyway, just to accommodate wear, tear, siltation and changes in shipping". However has sufficient thought been given to adapting ports which may well take considerably less than  "decades to rebuild harbors"?
Ports cope with quite a tidal range and I suggest can be adapted as steady rise proceeds. Add 0.5m in some spurt over a shortish period, some would cope, some would be flooded at high tide and during storms. I would expect that within a few months, except for a few worst affected, most would be back to being operational for at least 75% of the time. Not trying to say this wouldn't cause a lot of problems, it would. I am thinking the major problems are from too many refugees to be easily accommodated. It isn't as if ships are our only means of transport. Even if other transport using ff are severely reduced or even completely stopped, by that time I expect renewable electric self driving lorries would have become viable. Cutting all trade or even 75% of trade doesn't look like the easiest or most obvious way to break civilisation. A 25% cut in trade would result in prioritising what is important. We might not like the consequences of such a cut but would it collapse civilisation? A huge influx of refugees and unrest at the same time, then possibly. A 25% cut in trade alone when people understand the cause, I am doubtful. OK, small islands that don't have large height range so all their ports severely adversely affected would face much more severe problems than mainland continents away from areas like Bangladesh, Florida, Holland.

In short, I think he overplays SLR and cutting trade as route to collapsing civilisation, it needs more floods of refugees, unrest and so on to make the case.

[wili]

Thanks, crandles.

That's pretty much what I thought about that section, but I wasn't sure if I had missed some significant science. Is he just making up the claims about these 'spurts'? Or is there some published science behind it?

Particularly disappointing is fusing/confusing of gigatons CO2 with gigatons C early on, even though later he points out the differences specifically.

[Bruce Steele]

Wili, In the chapter " the fart that broke civilization " p.35 the author describes his view  of weathering( earth breathing ) and it describes the long cycle of how rain + Co2 reduce in physical processes Ca( OH)2 ,Si2 and other minerals and deposits them terrestrially( and presumably in the oceans.). I think he is missing some important points as to how Co2 is largely moved from the ocean surface and into sediments by ORGANIC processes.
 Weathering is very important in the 100,000 year timeframe because as the earth heats the atmosphere also can carry more water and thus rain to increase weathering processes. The resultant riverine flow carries alkalinity from terrestrial silicates and calcium minerals into the ocean and thus buffers the H- ions released as carbonic acid forms. The problem is the disconnect between the rate of how fast we are adding Co2 and the delay of the earth system , additional weathering from heating and how long it takes to weather out enough minerals to rebalance the system.
 In the intervening 100,000 years some sensitive animals like pteropods will fail in a large part of their habitat . When they are removed a part of the biological carbon sink is reduced. Later as more CO2 builds because the biological process is not working as well other calcifies like coccoliths also begin to fail and the biological pump is weaker still. Ultimately this cascade of biological failures reduces the ability of calcifiers to remove surface water CO2 and as it builds the partial pressure between the surface oceans and the atmosphere is reduced. Co2 then builds further in the atmosphere as the ocean sink fails.
 I am trying to stress the importance of biological processes which in my first read the author seems not to understand. We cannot quantify the degree to which the processes I am describing will play out but if we push certain populations to the point of extinction ( like pteropods ) evolution will struggle for much longer periods than the 400,000 years suggested to return the atmosphere to current levels.
It we were strictly dependent on physical processes the 400,000 year timeframe might be correct but we are on a extremely fast trajectory that will test biological processes in ways we simply cannot fathom. If we trigger positive feedbacks that raise Co2 far enough to trigger extinctions of important species in the biological carbon pump then in my opinion our extinction is also assured. 

[wili]

Wow, Bruce. Great insights. Thanks.

[Bruce Steele]

 
            The carbonate-silicate cycle, which plays a key role in stabilizing Earth's climate over long time scales, is shown in Fig. 2. The cycle begins when atmospheric CO2 dissolves in rainwater, forming carbonic acid, H2CO3. Through a process termed "weathering", this weak acid dissolves silicate rocks on the continents, releasing Ca++, Mg++, HCO3- (bicarbonate), and SiO2 (dissolved silica) into solution. The products of weathering make their way down to the oceans in streams and rivers. There, organisms such as the planktonic foraminifera that live in the surface ocean use them to make shells out of calcium carbonate (CaCO3). When the organisms die, they fall down into the deep ocean, where most of the shells redissolve. Some of the calcium carbonate survives, however, and is buried in sediments on the seafloor. The seafloor spreads from the midocean ridges and, at some plate margins, is carried down subduction zones. The carbonate minerals recombine with SiO2, which by this time is the mineral quartz, to reform calcium and magnesium silicates and release gaseous CO2. This CO2 is vented into the atmosphere through volcanoes, thereby completing the cycle.


 
Fig. 2 Diagram illustrating the carbonate-silicate cycle. The term "metamorphosis" should read "metamorphism." (From J. F. Kasting, Science Spectra, 1995, Issue 2, p. 32-36. Adapted from J. F Kasting, 1993.)
 
            The stabilizing negative feedback in the carbonate-silicate cycle is produced by the dependence of the silicate weathering rate on temperature. When surface temperatures drop, the weathering rate slows down, and CO2 accumulates in the planet's atmosphere. Thus, an Earth-sized planet that had such a cycle would be expected to build up a dense CO2 and a large greenhouse effect if its surface temperature became too low. This suggests that the outer edge of the HZ is relatively far out, perhaps beyond the orbit of Mars (Mischna and Kasting, 2000). It also explains how our own planet escaped from Snowball Earth episodes in the past (Caldeira and Kasting, 1992).


From the link
http://www3.geosc.psu.edu/~jfk4/PersonalPage/ResInt2.htm

I would like to stress the importance of the shelf / relativily shallow organically derived carbonates and silicates in ocean sediments. These deposits rather than the deeper dissolved inorganic carbon represent the very long lived carbon sink. The deeper dissolved inorganic carbon can move back into the atmosphere in 1000-1500 timeframes whereas the shallower sediments are moved by tectonic processes and on geological timeframes. Even Rob Painting's piece in Skeptical seemed to miss this point.