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.