Tuesday, January 22, 2013

Tuesday Links

  • The above shows a reputable estimate of the peak warming that will occur in a scenario where we start reducing global carbon emissions at a certain year on the x-axis and by a certain percentage rate post-peak (on the y-axis).  For comparison - we've got about 0.8 oC of warming since 1850 and that's proven enough to pretty much melt the North Pole and flood parts of Manhattan and New Orleans (once each so far).  Do we really want to see what 3 oC or 6 oC will do?
  • Interesting paper on the Fermi paradox in the presence of self-replicating machines.  The Fermi paradox is that, since the universe is very large, and life and civilization are possible in it (since we exist), we would expect other civilizations to have arisen elsewhere, probably many times, and if so it's very strange that we don't see obvious signs of them (eg their radio signals).  It's basically an observation that tuning the probability of life/civilization arising to give rise to exactly one civilization in such a very large universe seems hard to do.  Here "hard to do" is code for "it would seem like there must be many more possible universes with a lot of civilizations than possible universes with exactly one" - pointing out that the underlying metaphysical assumption is that the universe should have arisen out of some kind of random process.  This latest paper basically points out that the paradox gets that much harder if you believe computer intelligence will rise to the point of allowing a self-replicating space probe before too long.  Personally, given that we've yet to get out of our own solar system, I view it as considerably less obvious than the author that this is certain to be feasible.  You could see the Fermi paradox as an argument for God(s), who, after all, could presumably have tuned the relevant probabilities to create whatever effect they was trying for, so the whole problem goes away. Or is shifted to a question about why the gods felt it necessary to create such a large universe for a single planetary civilization - but who is in a position to question the aesthetic preferences of the gods?
  • Trying to figure out the maximum sea level during the Pliocene (when CO2 was 400ppm - which we will reach in a another few years)  Was it high enough that the main East Antarctic ice sheet was stable then?  Scientists don't know: old Pliocene beaches have been found from 33' to 295' above modern sea level, indicating the earth's crust has moved around a lot in the intervening few million years.
  • Oh - and the President made climate change the most prominent note in his inauguration speech.  Outstanding.

9 comments:

Luke Smith said...

To me, it seems that the confidence in the consensus (climate change models) is so high that climate change has now become undeniably moraly wrong, with no net human benefit. That to me, seems where the debate is heading.

Based on what we know: CO2 is a greenshouse gas emitted by fossil fuel consumption; there are uncertainties in climate models regarding possible cooling feedbacks like increased cloud formation and a shutdown in the thermohaline circulation, and cooling forced by solar irradiance changes.

Inevitably, because of this knowledge and uncertainty, I see the climate change debate evolving into two crowds of change=bad and stasis=good.

dr2chase said...

I would bet on closer to 80 feet of sea level rise. I grew up in the middle of an orange grove about 80 feet above sea level in Florida. Florida doesn't get many earthquakes, so it's probably been about 80 feet for a long time. Our yard, and the grove around us, was all fine sand. If you dig a post hole, the first foot or so is greyish, but then it turns a light yellow-tan, just like a lot of the existing beaches.

There are sinkholes (including a pond in the back yard) but those are obvious, and only reduce elevation in current times (i.e., going backwards in time, the elevation was higher).

Could be an old dune (those don't seem to grow very tall in Florida, don't know why) could also be something that was underwater, because the bottoms of the existing bays are generally sandy. Either way, about 80 feet.

Stuart Staniford said...

dr2chase: I don't think you can safely reason that way over the course of millions of years. Eg this link:

http://news.ufl.edu/2010/06/01/florida-rising/

says Florida is rising a millimeter in 20yrs. That's 150m in 3 million years. Of course it probably hasn't been uniform so I've no idea what the true rate is, but the point is that you can't apply the kind of everyday reasoning you use above over geological timeframes.

rjs said...

the idea that we would have seen signs of "other civilizations" elsewhere in the universe seems awful species chauvinistic...at a minimum, it assumes other life forms would approximate what we are...

Greg said...

Here's what looks like a technically and financially* workable carbon removal process:

http://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/

Produce the synfuel, pump it down disused oil and gas wells.

Now, we just need to work on the political, ideological, and social problems of changing from getting 82% of our primary energy from fossil fuels. (Easy! What do we do this afternoon? ;-)

------
* even at ten times the estimated cost.

dr2chase said...

Wow, who knew? I suppose you could assume it is so slow it remains in equilibrium, and you can look at the volume of rock missing under the various sinkholes that can be observed, and that (should?) give you the upward float (plus caves and/or sinkholes that are not yet formed).

The interesting thing is that it depends on the flow of acid rain and surface water (there's sulfur compounds involved; my nose assures me that H2S is present, too). Seawater's slightly alkaline -- that means that the dissolution is (?) mostly confined to the limestone under "dry" land. 20,000 years ago there was a lot more land exposed to rain.

Alexander Ac said...

Hi Stuart,

and another interesting thing from 155 leading (?) thinkers:

WHAT *SHOULD* WE BE WORRIED ABOUT?

Alas, no mention of peak oil at all, economic growth driven by population growth, and well, fear of declining birth rates...

I almost thought for a while we are intelligent creatures.

Unknown said...

I wouldn't discount the possibility that we simply are a very early bird AFA life and civilizations in the universe go. A sample size of one doesn't say much, after all.

BBD said...

Sorry for trailing in rather late with this, but you might be interested in Foster & Rohling (2013) Relationship between sea level and climate forcing by CO2 on geological timescales.

Discussion here with some links.

http://descentintotheicehouse.org.uk/new-study-documents-the-natural-relationship-between-co2-concentrations-and-sea-level/

Some previous discussion here:

http://descentintotheicehouse.org.uk/826/

Hope this helps; thanks for the always interesting blog.