I have a question about the wiki graph that is often used in this forum?

Question

It is this one:

http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png

I have been bothered by this graph for a while now, for a number of reasons. So I began doing some research on the attribution of global warming due to a variety of forcings.

In the paper below, an 11 year smoothing shows that solar forcings are the major contibutor to warming of the last 100 years. A 9 year smoothing of the same data shows that greenhouse gases are the major contributor to warming. The paper then moves on to discuss how other small changes in parameters significantly changes the attribution results.

The wiki graph in question resembles the 9 year smoothing work shown in this paper.

Could it be that this graph is not as illustrative as it initially seems to be? Could it be that the models are not yet as refined as suggested, thus attribution is still unknowable?


REF:

Space Science Reviews (2006) 125: 199–211
DOI: 10.1007/s11214-006-9057-2

Keith P:

The author is using data from Jones and Moberg (2003) and smoothing that. I just found it interesting that the author could use the same data, treat it a little differently and get a different result. To me it indicates the fallibilty of simple regression techniques used far too often in a lot of papers.

Answer 1

What I've read in several places is that the solar correlation can be made to work well until recently, when it falls apart. That makes sense according to the cited graph, as solar is larger than greenhouse gases until about 1960.

EDIT - OK, got it from Dana's cite. He agrees that, in recent decades it's mostly man made. Here's a key sentence in the paper you cite:

"Uncertainties in the reconstruction of irradiance variation and in the full physics of the response would also hinder solar detection, as, in recent decades, would the larger anthropogenic signal."

Note that he's saying the exact same thing the oft cited graph and the scientific community does. In recent decades the solar contribution is less than the "larger anthropogenic signal".

We're not all of the problem. We are most of it. The IPCC says 90% with a range of 70-95%.

EDIT2: Ingram has published earlier papers about CO2. I'm sure a look at these would be illuminating.

Mitchell, J. F. B., C. A. Senior, and W. J. Ingram. 1989. CO2 and climate: A missing feedback? Nature 341:132–134.

Cess, R.D., M.-H. Zhang, G.L. Potter, H.W. Barker, R.A. Colman, D.A. Dazlich, A.D. Del Genio, M. Esch, J.R. Fraser, V. Galin, W.L. Gates, J.J. Hack, W.J. Ingram, J.T. Kiehl, A.A. Lacis, H. Le Treut, Z.-X. Li, X.-Z. Liang, J.-F. Mahfouf, B.J. McAvaney, V.P. Meleshko, J.-J. Morcrette, D.A. Randall, E. Roeckner, J.-F. Royer, A.P. Sokolov, P.V. Sporyshev, K.E. Taylor, W.-C. Wang, and R.T. Wetherald, 1993: Uncertainties in carbon dioxide radiative forcing in atmospheric general circulation models. Science, 262, 1252-1255.

ABSTRACT: Global warming, caused by an increase in the concentrations of greenhouse gases, is the direct result of greenhouse gas-induced radiative forcing. When a doubling of atmospheric carbon dioxide is considered, this forcing differed substantially among 15 atmospheric general circulation models. Although there are several potential causes, the largest contributor was the carbon dioxide radiation parameterizations of the models.

TETT, S.F.B., JONES, G.S., STOTT, P.A., Hill, D.C., MITCHELL, J.F.B., Allen, M.R., INGRAM, W.J., JOHNS, T.C., JOHNSON, C.E., JONES, A., ROBERTS, D.L., SEXTON, D.M.H. and WOODAGE, M.J., 2002: Estimation of natural and anthropogenic contributions to 20th century temperature change. J Geophys Res, 107 (D16), ACL 10-1 to ACL 10-24.

I think if you could talk to him, he'd certainly say global warming is mostly not natural.

EDIT 3DM - That interpretation of the words is not scientifically correct. He's using statistical jargon. By the "larger anthropological signal" he means exactly that the data shows the anthropological factors are greater. It's like a radio station. The larger signal is the more powerful one.

Solar forcing is a factor. But, since 1960 or so greenhouse gases are a bigger one. Starting 1990-2000, much bigger. Precisely as shown on this graph. That's exactly what Ingram's saying.

http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png

Marc G has acknowledged that. See his latest question.

Answer 2

Keith P (above) has provided an excellent answer and the graph he has produced clearly demonstrates that 9 year or 11 year 'smoothing' makes little difference. The only time there would be a significant change would be as a result of the inclusion or omission of a statistical anomoly.

For example, in this data set...

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 500

A nine point moving average (smoothing) about the number 20 provides a very different result from an 11 point moving average, the reason being the 11 point MA includes the 500 thus introducing an anomolous value into the range.

Provided that the results which are smoothed are reasonably consistent and there are no anomolies there will be very little difference in anything upwards of a few point moving average. The graphs use 5 point MA's and relatively consistent data, as such, any other graph constructed using MA's over different periods would be remarkably similar.

Perhaps a better illustration is to look at the more important total radiative forcing which is shown here comparing the forcings of 2000 to those of 1750 http://www.grida.no/climate/ipcc_tar/slides/large/06.01.jpg

Answer 3

Well, I don't see that.

I started with the historical solar irradiance data of Lean et. al. 2000 (which can be found at http://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/solar_variability/lean2000_irradiance.txt
) and plotted the yearly values, then took last 9-year and last 11-year averages to get smoothed values. The results can be found here on my Excel plot: http://www.columbusnavigation.com/images/solarforcing.png

All I can see is the expected greater bumpiness in the 9-year curve, because it's not accounting for the full 11-year Schwabe cycle like the 11-year curve is. Further, the two smoothed curves just aren't that different from each other, certainly not different enough for any statistical significance.

Answer 4

How folks like to use partial quotes. From the conclusion, the ENTIRE paragraph:

Anthropogenic signals in the late 20th century are very robustly detected. Reconstructed solar signals are repeatedly degenerate with others, particularly anthropogenic
ones for the 20th century and the volcanic one for previous centuries. Uncertainties in the reconstruction of irradiance variation and in the full physics of the response would also hinder solar detection, as, in recent decades, would the
larger anthropogenic signal. HadCM3 still gives evidence for a solar signal in the early 20th century, but not all GCMs agree, so D&A cannot currently refute the possibility that there is no long-term variation in solar irradiance (Lean et al., 2002).
“Solar amplification” remains an open issue.

Does this say that man-made emissions are the primary cause for global warming? No - it only says that signals are "robustly detected". Not the same thing, not even close.

Does it say that solar forcing is NOT a possibility? No - quite the opposite - it says that it cannot refute it, especially for an un-modeled long-term variation.

Bottom line conclusion that can be drawn from this is that there are still many variables that need to be accounted for - hardly the "scientific fact" or even the consensus that alarmists' trumpet.

So how much action is warranted by this CONCRETE evidence?

Do people still use the term "foolhardy" these days?

Answer 5

Okay, the plots you're talking about are just smoothed solar and greenhouse gas contributions as compared to the global temperature increase. Smoothing is kind of tricky as it's basically just averaging things out over a certain period, so if you choose the wrong period you end up flattening it all out, as illustrated in the 2 plots. I don't think they're terribly important.

What I think is important is Figure 5 on page 9 of the paper (which I've linked in my sources), and the explanation of it:

"The much-reproduced graphs in Figure 5 compare global-mean warming over the 20th century with the results of 3 HadCM3 ensembles. Plainly the ensemble with only natural forcings is deficient in the late-century warming, while the one with only anthropogenic forcings is deficient in the early-century warming – but the one with both natural and anthropogenic forcings looks just right!"

Natural forcings can't account for the recent acceleration in global warming, but when you add in anthropogenic forcings, it fits the data quite nicely. This is the sum of solar, volcanic, etc. and human greenhouse gas emissions, and it's the best fit. Solar contributions simply can't account for the recent increase in warming. If you examine the plots, most of the warming since 1960 has been due to anthropomorphic causes.

Answer 6

That is one estimate of attribution, which may be susceptible to smoothing variation. Higher confidence comes from multiple studies, such as the IPCC report.
http://en.wikipedia.org/wiki/Attribution_of_recent_climate_change

Unfortunately, only an estimate of the likelihood of human causes is possible. Solar variation is a popular skeptic argument since it is hard to quantify and is the source of all warming. Some people will point to a small uncertainty as proof that the theories are wrong.

Answer 7

I make it a point to ignore any response that uses wiki as a source of scientific data.

Answer 8

Create Your Own Animations : http://3dAnimationCartoons.com/?qFUm

Answer 9

Yes. Those that pretend to know are attributing far more knowledge than currently exists in the infant science.