Guest post by J Storrs Hall
There are several ways to predict what the temperature trends of the next century will be like. The standard method of prediction in science is to create a theory which embodies a model, test the model experimentally, and then run it into the future for the prediction. There is another way, however, which is simpler in some ways although more complex in others. That’s simply to remember what’s happened before, and assume it will happen again.
Here’s a record of what’s happened before, which most WUWT readers will be familiar with. It’s the GISP2 Greenland ice core record, shown for the Holocene:
I have shamelessly spliced on the instrumental record in red (by setting the temps in 1850 equal); it is the HadSST record.
When I first started looking at GISP2 it seemed to me that there were several places in the record that looked very much like the sharp spike in temperature we’re experiencing now. The obvious thing thing to do seems to be to overlay them for an easy comparison:
Here I’ve plotted the 400 years following each minimum in the record that leads to a sustained sharp rise. There were 10 of them; the first five are plotted in cyan and the more recent 5 in blue. You can see that in the latter part of the Holocene the traces settle down from the wilder swings of the earlier period. Even so, every curve, even the early ones, seems to have an inflection — at least a change in slope — somewhere between 200 and 250 years after the minimum.
The hatched black line is the average of the 5 recent (blue) spikes. The red dots are the uptick at the end of GISP2 and HadSST, spliced at 1850. Note that ALL the minima dates are from GISP2.
Prediction of the 21st century is left to the reader as an exercise.
Read ’em and weep.
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Every time I look at the GISP2 ice core record, I want to get it printed on a t-shirt or something. To me, it sure as heck looks like we’re in another uptick of a fairly regular ~1000 year cycle, using my trusty Mark-I eyeball. Of course, you don’t get fancy research grants for eyeballs…
That’s a frightening long term trend. Is the Holocene almost out of gas?
JSH:
I think others have already asked this, but is it possible to have you number or letter the curves on the second graph, and key them to the corresponding peaks on the first graph?
Thanks,
Mark H.
Henry@DaveSpringer
It seems my previous answer got lost in the air somewhere.
My own observations tell me that maximum temps. during the past 4 decades have been rising pretty much everywhere I look:
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
However, unlike the NH, which is warming, it seems the SH is cooling.
(look at the tables for the average and minima)
Humidity (RH%) and precipitation (mm/mnth/yr) at Tandil show slight increases over the past 4 decades.
Is that a sign of desert-ification?
Way after the fact, but what the heck, it’s still July, I came to this post (again) from Anna V’s comment on Lubos Motl’s blog. My two cents: Any “scientist” who pays no attention to history, Earth’s history — and this is what is being charted — is a fool. Yes, how accurate are ice cores? And, yes, the Southern Hemisphere (Antarctica ice cores) goes about cooling somewhat differently from the Northern; nevertheless it gets just as cold there, too. But history is about collecting the data from as many sources as possible, considering them skeptically, for the greatest truths they can tell about the past according, and making hypotheses. Ain’t this very close to the scientific method? Science adds the physical mechanisms so we can test our historical hypotheses. Ignore Earth’s history at your peril. I personally hope that CO2 does add some anthropogenically caused warming ’cause this history says we’re gonna need it. Unfortunately I have not seen much evidence such that I can say with absolute scientific certainty that our — human generated — CO2 is going to make much of a difference, except perhaps make the biosphere green and happy and protect plants from drought conditions.