Let’s be as generous as we can. The IPCC say feedbacks amplify CO2′s warming by a factor of about three.
Without the amplification from positive feedback there is no crisis
So being nice people, let’s assume it’s warmed since 1979 and assume that it was all due to CO2. If so, that means feedbacks are …. zero. There goes that prediction of 3.3ºC.
Feedbacks are the name of the game. If carbon dioxide doesn’t trigger off powerful positive feedbacks, there was and is no crisis. Even James Hansen would agree — inasmuch as he himself said that CO2 would directly cause about 1.2ºC of warming if it doubled, without any feedbacks (Hansen 1984).
Consider the warming from1979 to 2007, when we measured temperatures using satellites and not corrupted and adjusted land thermometers. Douglass and Christy (2008) point out that, given how much CO2 levels increased in that time, the warming only amounts to what the IPCC scientists predict we should get from CO2 alone, from the direct effect of CO2, and not from the effect of CO2 plus positive feedbacks.
The warming trend expected from CO2 without any feedbacks at all is 0.07 ºC/decade. The trends from the UAH satellites are 0.06±0.01ºC/decade. Since the two figures are almost the same, no one needs a super-computer to tell them that this implies that the sum of all feedbacks (and the sum of all fears) is zip, nada, nothing.
Furthermore, this study likely overestimates the effect of CO2. There is clearly a 60 year cycle of warming and cooling due to the Pacific Decadal Oscillation, and the 28 year study period was the steepest part of that 60 year cycle. Hence, trends over longer periods are likely to be smaller, which implies that feedbacks are negative.
Thus the upper bound on climate sensitivity (the temperature rise when CO2 doubles) from the last three decades of warming is about 1°C, and that’s assuming all the warming is due to CO2 increases and not due to other factors like solar magnetic effects, cosmic radiation, ocean current oscillations, or geomagnetic forces. Which is much less than the IPCC median estimate of 3.3°C.
The physical science of global climate change has been clouded by the political science of environmentalism
The IPCC relies on radiative feedback from CO2 for their models. There is an amount of feedback inserted in all the models even though it has never been measured. There is some re radiation, however the miniscule heat radiated from an atmospheric molecule of CO2 goes to a colder object like space. It always goes up, not down to a warmer object. It cannot go back to
the Earth against rising heat with no source of energy in the molecule. It
has to go to cold. Their theory violates the 2nd law of thermodynamics, but that won’t slow them down one bit.
Sorry scizzorbill but you are dead flat wrong.
Let me express this precisely as I had to do for someone else recently:
this is greenhouse effect and it is not in dispute.
If you still insist on believing there can be no electromagnetic feedback from atmosphere to earth I’ve got two words for you: “lightening strikes”.
Read your Clausius statement again: No process is possible whose sole result is the transfer of heat from a body of lower temperature to a body of higher temperature. This statement is always true because a body of higher temperature emits at a greater intensity than one of a lower temperature, hence the body of higher temperature will always lose energy at a greater rate than it gains it from a body of lower temperature, entropy is preserved despite the feedback from the body of lower temperature reducing the net rate of cooling of the body of higher temperature, all is right with the world and the misnamed greenhouse effect does not conflict with the 2nd Law in any way, shape or form.
Can you explain how much feedback is from water vapor and how much is from C02 vs Methane?
Thanks
Paul Angle
That’s a good question Paul. Because the greenhouse effect and its players vary with altitude and latitude there is often confusion over differing statements regarding the greenhouse potential of constituent gases.
Given the present composition of the atmosphere, the contribution to the total heating rate in the troposphere (the portion of the atmosphere of most interest — it is the region from the surface to basically the top of the active weather zone) is around 5% from carbon dioxide and around 95% from water vapor.
However, in the stratosphere, the contribution is about 80% from carbon dioxide and about 20% from water vapor, although this makes a relatively small contribution to total greenhouse effect.
Naturally, calculations for the total atmosphere yield different results yet again, as does consideration of latitude and season but the net effect in which we are interested is that which can realistically be expected to have significant effect on life at the surface, thus average tropospheric greenhouse at 95:5% water to carbon dioxide and other minor greenhouse gases.
The net total atmosphere greenhouse effect then is about 90% water (as vapor and cloud droplets) and 10% carbon dioxide and other minor greenhouse gases.
Remember that atmospheric properties in the Polar winter are tremendously different from the tropics, say during the monsoon rain season. Thus people may be correct citing widely varying greenhouse figures, always providing they are specific about the where and when.
If you have need to demonstrate to someone, say an AGW advocate that CO2 accounts for just 10% of the greenhouse effect you can use the IPCC’s CO2 forcing formula and Trenberth’s pretty graphic from Trenberth, K. E., J. T. Fasullo, and J. Kiehl, 2008: Earth’s global energy budget. Bull. Amer. Meteor. Soc., in press:
Point out Trenberth’s derived figure of 333 W/m2 net “back radiation” (downwelling longwave, in other words) and the IPCC’s formula for 2xCO2, 5.35*LN(2), which equals 3.7 W/m2. Since doublings are merely powers of 2 you point out 29 (or 9 doublings from 1) = 512, so the IPCC’s formula states that 512 ppm CO2 will deliver 9 * 3.7 W/m2 or, coincidentally, 33.3 W/m2, exactly 10% of Trenberth’s greenhouse effect in the figure above.
If you check CDIAC’s page for current GHG levels they calculate +0.5 W/m2 from methane (CH4) since 1750.
Hoping this answers your query.
Ed.
Thank you, Mr. Editor, that is a nice summary, I have looked at that diagram considerably, and I find that since the stated reflectances and absorbances are spectrally dependent and time variable and this puts the stated total hemispherical intensities within an error margin exceeding what has been calculated as a CO2 forcing by difference.
Indeed, differences in cloud percentage and altitude can make tremendous difference in albedo and a 5% change in that figure is more than the equivalent of the IPCC’s 2xCO2. The grain of truth is that CO2 is technically a greenhouse gas and can be involved in transfer of energy through the atmosphere. Unfortunately that grain lies on a beach of hysterical claims made by wannebe social engineers.
in 1967, I was 16 years old, a sophomore chemistry major in college, and was told by a physical chemist about a “lunatic” idea of Arrhenius that had been debunked around the turn of the 20th century on “overheating the atmosphere with CO2 from burning coal.”
That was the first time I heard about the idea, and I never anticipated hearing about it again.