Friday, 13 March 2015

Review of BBC4's 'Climate Change by Numbers', March 2015

Presented by three mathematicians - Dr Hannah Fry, Prof Norman Fenton (Statstiician) and Prof David Spiegelhalter - it hones in on just three key numbers that clarify all the important questions around climate change:-
·         0.85 degrees (the amount of warming the planet has undergone since 1880)
·         95 per cent (the degree of certainty climate scientists have that at least half the recent warming is man-made)
·         1 trillion tonnes (the total amount of carbon we can afford to burn - ever - in order to stay below 'dangerous levels' of climate change)

I studied Mathematical Physics very many years ago and had a career in computer engineering. I'm well aware that statistics and numerical computational solutions can give misleading answers, therefore require testing in the real world (which we can't do with climate) so was very interested to view this programme. 

It covered lots of uncertainties and issues that need working around. The history of how the differing techniques were developed illuminated the problems well.  This is good because far too often we get told simplified analogies about the science which numerate and educated people can be deeply suspicious of – like I am.

My review covers a few issues about the presentation for each number, and follows with a few more numbers that I would like investigated.
·         200-300% Amplification by water vapour of the carbon-dioxide heating
·         0.2% of the total Carbon Flux in the atmosphere
·         the average ammount that Minimum & Maximum Temperatures have increased

The First Number:- 0.85 degrees Centigrade Warming Since 1880
Question:-       Is 0.85 deg. Centigrade unusual?
Answer:-         No. The previous 170 years also warmed at about the same rate. (I applaud the presentation in explaining that, as we go back in time, the accuracy of known temperatures declines so that we have talk in approximations.) Unfortunately, noone knows why the warming of 300 years ago started, and continued in fits and starts. Thus there's no way to show that the same natural warming isn't happening now.

The Second Number – 95% Certainty that Human Carbon-Dioxide Emissions Contribute at least Half of Recent Warming
As a statistician, Prof. Fenton should have explained that just because 2 things happen at more or less the same time, (i.e. in his example, winning and football club wage bill; for climatology, carbon dioxide and temperature) doesn't mean one causes the other or even that they have the same cause.  In fact, in the case of carbon dioxide, it's a 'confounding' variable which is expected to increase due to warmth. As the oceans get hotter, carbon-dioxide is transferred to the atmosphere (and the sea holds correspondingly less carbon-dioxide, becoming more acidic).  Another number that would be really interesting to look at is the % of the carbon flux that is due to humans.  I understand it's tiny, ~0.04%
Prof Fenton's presentation used a Bayesian Statistics approach which showed that the computer models depended on human carbon dioxide emissions creating more than half of the recent warming. The impression given was that observational data from the real world supports this conclusion.  There was no investigations into how good the models were at modelling past temperatures, nor of the methods of model 'tuning' that take place.
A Computer Model output of the troposphere was shown indicating additional heat over the tropics is expected from human carbon dioxide warming but not from natural variability.  If observed for real, it would be decisive. However, it's not present in the real atmosphere!
… I'm really disappointed that it was unclear that the model results hadn't been checked against reality.

The Third Number – Total Amount of Carbon we can burn to stay below 'dangerous levels' of climate change

First, you have to show that it could be dangerous.  A really important number was omitted – an expected 200-300% amplification by water vapour of the basic carbon-dioxide heating.  This is unproven and is probably the most contentious thing in climate science because, without it there's no catastrophe.

Thursday, 12 March 2015

Science Moves On. Even Climate Science

Science moves on.  Thus Al Gore's 2006 "Inconvenient Truth" is full of unmet expectations e.g.
·         Polar Bears are not dying out – their numbers have been increasing since the hunting ban
·         Both poles are not melting – the Antarctic ice is much the same as previously. (Ice-shelves  and sea-ice are always breaking up due to wind activity.  Depth and Extent of ice, particularly land-ice, is the important metric.)
·         1975 to 1998 warming is not the fastest ever, …
·         Temperatures are not the highest ever during human civilisation – Mediaeval Warm Period (~11---1250 AD), Roman Warm Period  and Minoan Warm Period were all at least as warm (within the error margins of times when people didn't have thermometers).
·    Extreme weather – IPCC says no connection found with Climate Change
And, whatever they say now, the vocal scientist supporters of the Dangerous Global Warming hypothesis were surprised by the 'pause' or 'hiatus' in warming (Quotes here)

Those scientists who'd kept their heads down and continued researching ocean currents, cloud formations, atmospheric circulation and ice formation /melting were now finding their research results more popular.

IPCC's AR5 report in 2013 accepted for the first time that the 1975-1998 warming could have been 50% natural due to a series of warm El Nino currents in the Pacific.

Supporters of the 'Climate Change – Earth's Energy Budget is being wrecked by human emissions of carbon-dioxide' theory (e.g. Michael Mann, Kenneth Trenberth, Naomi Oreskes) are 'finding' all the extra heat hidden in the deep oceans where it can't be measured reliably; & prophesying that there'll be a sudden huge release of heat in the future.

While some recent developments include:-
     (i)            Arctic warming happens from time to time without any help from human carbon-dioxide emissions
   (ii)            Atmospheric water vapour does not behave as simply as depicted in NASA's Runaway Warming hypothesis:-
a.       IPCC says cloud formation is very uncertain
b.      March 2015 Paper discussing a stabilizing feedback between atmosphere & ocean circulations, clouds and radiation . From the summary: "The major source of albedo variability and the principal mode of regulation are associated with the interannual variations of cloudiness. The small variability observed suggests a high degree of buffering by the albedo of clouds"

d.      Clouds have the biggest effect at the equator – January 2015 paper: Current Hiatus of Global Warming Tied to Equatorial Pacific Surface Cooling, Yu Kosaka, University of Tokyo, Tokyo, Japan; and S. P. Xie.

See images below

Cloud Cover vs Surface Temperature

Carbon-dioxide Global Distribution

Reflected Sunlight Global Distribution

As with all science, Time Will Tell.  Eventually.