Friday, December 9, 2016

Hansen's 1988 scenarios and outcome

While arguing at WUWT, eg here, about Hansen's projections, I've been encountering arguments about which scenario should be applied. I did discuss that in last month's post on the projections. But I have since looked up more information on what they were, and how they panned out. In this post, I'll review the files, numbers, compare with current, and post what data we have. I'll also review a discussion by Stephen McIntyre at Climate Audit in 2008, and show some of his graphs. The conclusion is that based on input and outcome, the temperatures should lie between scenarios B and C.

Thursday, December 8, 2016

Global TempLS unchanged in November; sea ice is low.

The November TempLS mesh index was virtually unchanged, at 0.687°C in November from 0.692°C in October. The TempLS grid index declined, from 0.626°C to 0.56°C. The disparity between mesh and grid is unusually large, and is caused by the polar warmth, which LS mesh is more sensitive to. Other indices generally rose in November; NCEP/NCAR index by 0.06°C, and also UAH lower troposphere (0.04°C).

The main map features are a cool band across Siberia, and big warmth in North America. Antarctic was warm, also Arctic.



I mention sea ice again, because it is starting to get more general attention. Arctic ice remains at record low, although it didn't really get worse during the month, despite an actual melting episode mid-month. But Antarctic ice has been exceptionally low since mid October, and is now entering the fast melt times.. Here is a section of the radial plot:





Sunday, December 4, 2016

Where do GHCN monthly numbers come from? A demo.

I've been arguing at WUWT, eg here. More and more I find people saying that all surface measures are totally corrupt. Of course, they give no evidence or rational argument. And when sceptics do mount an effort to actually investigate, eg here, it falls in a heap. BEST was actually one such effort that was followed through, but ended up confirming the main indices. So of course that is corrupt too.

As linked, I do sometimes point out that I have been tracking for six years with an index, TempLS, which uses unadjusted GHCN and gets very similar results to GISS and others. I have posted the code, which is only about 200 lines, and I have posted monthly predictions (ahead of GISS and all) for about six years. But no, they say, GHCN unadjusted is corrupted too. All rigged by Hansen or someone before you see it.

The proper way to deal with this is for some such sceptic to actually follow through the quite transparent recording process, and try to find some error. But I see no inclination there to do that. Just shout louder.

So here I'll track through the process whereby readings in my country, from BoM, go through the WMO collection in CLIMAT forms, and so into the GHCN repository. That's partly to show how it can be done, if a sceptic ever was inclined to stop ranting and start investigating.

Saturday, December 3, 2016

NCEP/NCAR November up 0.06°C - warmest since April.

The Moyhu NCEP/NCAR index rose from 0.419°C in October to 0.48°C. Not huge, but it makes it the warmest (just) since April, an ENSO peak month. The change mirrors a rise to November of 0.04°C in UAH V5.6.

The month started with a big peak, then a dip, then a smaller peak, still current. The big feature was a cold band across Siberia, extending into N Pacific. But it was balanced by warmth in Arctic, Antarctic and N America.

Sea ice at both poles was unusually low, with even some days of melting in the Arctic. Arctic is still record low, but will probably become more normal. Antarctic is very low indeed, and seems to be getting more so, heading into peak melting season. Here is the recent part of the radial plot, where black is 2016, and colors are other recent years:







Monday, November 28, 2016

Spectral methods in GCMs - and some thoughts on CFD.

There has been a lot of discussion recently on the maths of GCMs. I have summarised some in a series on chaos and the Lorenz equations (here, here, and here). David Young has commented substiantally on this thread, and raised the issue of the use of spectral methods in GCMs. These are used in the dynamical core, which relates pressure and velocity via the Navier-Stokes equations. They are time critical, because they require resolving sound waves, and so the speed performance here fixes that of the code as a whole. Spectral methods are used because they are fast. But some mystery is made of them, which I would like to try to dispel. But I'd like to do this in the context of some simplifying observations about CFD.

Wednesday, November 23, 2016

Update check on Hansen's 1988 projections

Hansen's famous 1988 paper used runs of an early GISS GCM to forecast temperatures for the next thirty years. These forecasts are now often checked against observations. I wrote about them here. That post had an active plotter which allowed you to superimpose various observation data on Hansen's original model results.

I did an update in 2015 here, and a lot of text from there is repeated here.. I think Hansen's projections had stood up well, but they ran ahead of warming during the "pause" of around 2006-13. That pause is now over, so the interest is in whether Hansen's projection is still running warm.

I've updated to Oct 2016, or latest available. Hansen's original plot matched to GISS Ts (met stations only), and used a baseline of 1951-80. I have used that base where possible, but for the satellite measures UAH and RSS I have matched to GISS Ts (Hansen's original index) in the 1981-2010 mean. But there is also a text window where you can enter your own offset if you have some other idea.

A reminder that Hansen did his calculations subject to three scenarios, A,B,C. GCM models do not predict the future of GHG gas levels, etc - that must be supplied as input. People like to argue about what these scenarios meant, and which is to be preferred. The only test that matters is what actually occurred. And the test of that are the actual GHG concentrations that he used, relative to what we now measure. The actual numbers are in files here. Scenario A, highest emissions, has 410 ppm in 2015. Scen B has 406, and Scen C has 369.5. The differences between A and B mainly lie elsewhere - B allowed for a volcano (much like Pinatubo), and of course there are other gases, including CFC's, which were still being emitted in 1988, but not much now. Measured CO2 fell a little short of Scenarios A and B, and methane fell quite a lot short, as did CFCs. So overall, the actual scenario that unfolded was between B and C.

Remember, Hansen was not just predicting for the 2010-16 period. In fact, his GISS Ts index tracked Scenario B quite well untill 2010, then his model warmed while the Earth didn't. But then the model stabilised while lately the Earth has warmed, so once again the Scenario B projections are close. Since the projections actually cool now to 2017, surface air observation series for now are warmer than Scen B (Giss). GISS Ts corresponds to the actual air measure that his model provided. Land/ocean indices include SST, which was not the practice in 1988. Hansen himself has expressed the view that the right measure of his projection now lies between Ts and Ts+SST.

So in the graphic below, you can choose with radio buttons which indices to plot. You can enter a prior offset if you wish. It's hard to erase on a HTML canvas, so there is a clear all button to let you start again. The data is annual average; 2016 is average to date. You can check the earlier post for more detail.




Monday, November 21, 2016

Chemistry of sequestration and carbon cycles.

There has been some recent discussion of carbon cycles. ATTP had a good series on ocean CO₂ uptake here. And in the context of sequestration, WUWT reported on some recent experiments with sequestering CO₂ in basic basalt rocks. The discussion showed that there is a lot people don't understand about the basic chemistry driving the carbon cycle, which this chemical sequestration tries to exploit.

Long term cycles and disruption

There is a finite amount of carbon in short term exchange with the atmosphere; it passes through forms where it is reduced by photosynthesis, and re-oxidised quite quickly, as it must be by the ubiquity of oxygen. And there is constant exchange with the upper layers of the ocean. Over millions of years, the amount of such carbon varied, reflected in atmospheric ppm. Carbonate rocks are unstable to heat; CO₂ is emitted by molten rock, most obviously appearing in volcanic eruptions. This would lead to indefinite accumulation, were it not for a process where basic rocks are weathered, exposing surfaces which can convert the CO₂ back to carbonate. This leads to a kind of balance.

Humans are disrupting this by digging and oxidising many gigatons of reduced carbon. The energy that enabled this reduction came from millions of years of photosynthesis and deposition, which prevented re-oxidation. Our burning is running far ahead of the long cycle, so the idea of the basalt absorption is accelerated weathering, probably through fracking etc. I have no strong views on whether this is feasible, but I'd like to talk about the driving chemiatry.