More Thoughts on Otto

More thoughts on the Otto et al paper that finds a lower transient climate response:

• they find a lower transient climate response -- the warming expected at the point where atmospheric CO2 has doubled -- but not a statistically signifcantly lower equilibrium climate response -- the ultimate amount of warming that will happen over a few centuries time.
• The target of 2°C is still a lot of warming. That's the average global change for the surface. It will be more over land, more over the northern hemisphere, and more in the interior of continents.... Based on the observed ratios in the UAH lower troposphere data for the last 34 years, and converting to the unit that is more recognizable for U.S. readers, it means a total warming of (from pre-industrial temperatures):

  globe: 3.6°F
  global land: 4.5°F
  northern hemisphere land: 5.9°F
  continental US: 6.0°F
  north pole: 12°F

• These are obviously nothing to dismiss lightly.
• A lower transient climate response doesn't change anything about the level of ocean acidification, the other global warming problem.
• if aerosols -- air pollution -- are holding down temperatures (I'm dubious), then we will see higher temperatures if the Chinese clean up their skies (and the rest of us keep doing so). On the other hand, changes in the Sun may help a little.
• The Otto et al analysis ends in 2010, but that year's La Nina didn't influence tempertures until months later, so that factor shouldn't matter as much of an end point effect. (Globally, HadCRUT4 found 2011 to be 0.14 C cooler than 2010.)
• Atmospheric methane levels didn't increase from about 1998 to 2008, but have begun trending back up. In the last few years the annual change in CH4 forcing has been about 10% of the annual change in CO2 forcing.
• The IPCC 5th Assessment Report is going to be awkward, and maybe immediately dismissed by some, which would be very unfortunate. It doesn't include this work, but some of its authors are authors (and lead authors) on the AR5, so this work might influence their writings.
• Why didn't the "team" suppress this paper via pal review? Hmm....? Why didn't the communists at Nature keep it out of their journal? The worldwide consipracy to enslave you must have slipped up on this one....