Tuesday, April 12, 2016

A Simple Sea Level Rise Model

... because curve-fitting is so much fun.


Mark Bofill raises an interesting question over at Lucia's:
SLR is evidence warming is occurring. It doesn’t put the A in AGW though, FWIW. It’s always seemed to me that sea level rise started a trifle early for CO2 increase to be the original cause.
There being a number of SLR reconstructions floating about, I asked which one(s) he's been looking at.  He proposed I we have a look at Jevrejeva et al. (2008), Recent global sea level acceleration started over 200 years ago?
Abstract: We present a reconstruction of global sea level (GSL) since 1700 calculated from tide gauge records and analyse the evolution of global sea level acceleration during the past 300 years.  We provide observational evidence that sea level acceleration up to the present has been about 0.01 mm/yr 2 and appears to have started at the end of the 18th century.  Sea level rose by 6 cm during the 19th century and 19 cm in the 20th century.  Superimposed on the long-term acceleration are quasi-periodic fluctuations with a period of about 60 years.  If the conditions that established the acceleration continue, then sea level will rise 34 cm over the 21st century.  Long time constants in oceanic heat content and increased ice sheet melting imply that the latest Intergovernmental Panel on Climate Change (IPCC) estimates of sea level are probably too low.

Monday, April 11, 2016

Red Team Blue Team

... old team new team.  Or: why I would support publicly funding research into "legitimate, alternative hypotheses" to explain observation.


Back in February of this year, Dr. John Christy of UAH -- and guru of retrieval algorithms for estimating bulk upper atmosphere temperatures from orbit -- went to Washington.  In his prepared testimony, tucked away near the end of his standard fare, he wrote something not so novel in terms of concept, but in the fact that he actually put some numbers to it:
We know from Climategate emails and many other sources that the IPCC has had problems with those who take different positions on climate change than what the IPCC promotes. There is another way to deal with this however. Since the IPCC activity and climate research in general is funded by U.S.taxpayers, then I propose that five to ten percent of the funds be allocated to a group of well-credentialed scientists to produce an assessment that expresses legitimate, alternative hypotheses that have been (in their view) marginalized, misrepresented or ignored in previous IPCC reports (and thus the EPA Endangerment Finding and National Climate Assessments).

Such activities are often called “Red Team” reports and are widely used in government and industry. Decisions regarding funding for “Red Teams” should not be placed in the hands of the current “establishment” but in panels populated by credentialed scientists who have experience in examining these issues. Some efforts along this line have arisen from the private sector (i.e. The Non-governmental International Panel on Climate Change at http://nipccreport.org/ and Michaels (2012) ADDENDUM:Global Climate Change Impacts in the United States). I believe policymakers, with the public’s purse, should actively support the assembling all of the information that is vital to addressing this murky and wicked science, since the public will ultimately pay the cost of any legislation alleged to deal with climate.
Setting aside the editorializing (which is NOT easy for me to do -- "wicked and murky science" -- really?) and extracting the the essence of his proposal from his polemic, I'm very much open to putting my tax monies where his mouth is.

Saturday, April 9, 2016

Poor Air Quality is Almost Certainly Unhealthy

... the question is one of quantity.


This post comes out of one point I raised in the Partisan Snark blurb, which further evolved in discussion over at Lucia's in the current open thread.  My leading argument was my usual: nuclear fission has been historically less hazardous than coal-fired electricity generation.  Using statistics I've bookmarked at the ready, the worldwide mortality rate is fully two orders of magnitude different.  That's using the worst-case mortality estimate from nuclear against the best-case coal statistic.

Side note: Brandon Shollenberger finds that the Forbes article I so often cite has been silently changing the stats over time.  Not kewl.

My arguments have long rested on noting that while there's certainly slop in both estimates, a two-order of magnitude of difference leaves a room for a lot of slop.  A 95% confidence interval is 1.96 standard deviations under a Gaussian normal distribution.  Must I really do a significance test when the lower bound of the higher risk factor is 100 times larger than the upper bound of the smaller risk factor?

Maybe I do.