By Steve Goddard
My friend Tamino says that “the modern global warming era starts in 1975.”
He goes on : “It’s an estimate of the time at which the trend in global temperature took its modern value.”
As you can see in Phil Jones’ HadCRUT graph above, the 25 year period from about 1975 to 2000 did warm about half a degree C.
You can also see that the 30 year period from 1910 to 1940 similarly warmed about half a degree C. At that time, atmospheric CO2 averaged about 305 ppm, well below Dr. Hansen’s suggested “safe level” of 350 ppm. See the graph below for that period:
Here’s an annotated HadCRUT graph to help you see the relevant periods and the changes of temperature versus changes in global CO2 concentration during the same period:
The video below superimposes the 1975 warming (blue line) on the 1910 warming (black line.) Note the similarity in slope, duration and patterns. It would be difficult to explain the 1910 warming as being due to CO2, because CO2 was barely above pre-industrial levels and rose only 10 ppm during that period.
Given the similarity between the 1975 warming and the 1910 warming, it is irrational to blame the 1975 warming entirely on CO2. The practice of good science tells us to look for a hypothesis which can explain both similar warming periods.
If there is an influence of CO2 in the recent warming, it appears small. And the warming stopped ten years ago, as shown in the HadCRUT graph, despite rapid increases in CO2.
Or perhaps one might conclude that climate sensitivity has decreased as CO2 levels have risen. In 1910, with CO2 at 300 ppm, it only took ten additional ppm to raise temperatures by 0.5°C. By contrast, in 1975 it took about fifty ppm more to produce the same 0.5°C warming by the year 2000.
There were also periods of time with rising CO2, and little or no rise in temperature. From 1940 to 1980, there was no net warming while CO2 rose by 30 ppm. Since 1998, there has been no warming – as CO2 levels have risen 30 ppm.
I feel a chill of La Niña coming on.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
“””” ShrNfr says:
August 23, 2010 at 7:32 am
@GeoFlynx I doubt that any serious scientists on this site will disagree that an increase in carbon dioxide does give you a net increase in temperature. “”””
Well I don’t know who is saying what here; but I certainly consider myself a serious scientist; and I certainly “disagree that an increase in carbon dioxide does give you a net increase in temperature”.
And the basis for my disagreement is the complete lack of any data showing such a relationship. CO2 certainly continues to go up; and at least the current trend is monotonically up. But the Temperature or its trend is certainly NOT monotonically up; it goes up, and it goes down; and itdoesn’t show any net relationship to CO2; nor does it show any logarithmic connection to CO2.
Take the Phil Jones Temperatures above that Steve gives; and take the well documented Mauna Loa CO2 data; and please somebody plot for us the straight line logarithmic relationship between those two.
Or else please quit talking about such a non existent relationship; nor is there a linear relationship.
Oh, and also please do look up that word “net” in a dictionary. There’s lots of “holes” in that net, including the effect of WATER.
Yes I most certainly do believe that it is true that CO2 does intercept some LWIR radiation emitted from the earth surface with (evidently) an apparent global average source Temperature of about 288 K. (about 390 W/m^2) Their numbers; not mine.
And I even suspect that the fundamental “forcing” that starts that CO2 “net” Temperature increasing trapping mechanism does itself vary with the fourth power of the Surface Temperature; so which is the cause, and which is the effect ?
I could also record that at the end of a quite unremarkable work week that started out with two days of local all time record high temperatures (for those dates); record highs incidently that were themselves quite unremarkable ordinary record highs; that won’t make the record books for any record record highs, we had two midweek days of unremarkable non record highs but still with quite noticeable early morning radiant warmth from the sun; due to the low atmospheric humidity, and relative lack of the solar spectrum “heat” absorbing H2O vapor; we finally got up (this morning) to an early morning dew; and the beginning of some high altitude cloudiness; and a noticeable deficiency in that solar heat spectrum intensity at sunrise; clearly an indication that the H2O vapor was doing its thing in taking out parts of the solar spectrum that human skin senses as “heat”.
The LWIR radiation that interracts with the CO2 (and the H2O) is quite beyond any human sensing mechanism; and is NOT recorded as “heat” by us, although its effect on the atmosphere because of the GHGs is an increase in molecular kinetic energy which is what we denote as heat in the Temperature sense.
So any 4-H club or 8th grade science student (maybe 5th) could have used this week in San Jose, to write a learned dissertation on global warming. The effect of CO2 was noticeably absent this week. IT’S THE WATER !!
“So any 4-H club or 8th grade science student (maybe 5th) could have used this week in San Jose, to write a learned dissertation on global warming. The effect of CO2 was noticeably absent this week. IT’S THE WATER !!”
Perhaps a grade-schooler could write a term paper about it and get a passing grade. But no doctoral student could write a dissertation about climate -based solely on local, short term weather- and expect to achieve their degree.
Even at UAH.
How DO the regulars here know when they are being poe’d?