Does anyone have a quantitative alternative explanation for the current global warming?

Question

Ignoring other problems with Svensmark's galactic cosmic ray (GCR) theory discussed here:

http://answers.yahoo.com/question/index;_ylt=As6MMc8lLk5ZrMSOAhywS77sy6IX;_ylv=3?qid=20071030112550AA7AXSu

The main problem with the theory is that the GCR flux has had no long-term trends while global warming has accelerated rapidly:

http://www.realclimate.org/images/TheChillingStars.jpg

A more plausible attribution is total solar irradiance, but it cannot account for much of the warming either.

"...this would lead to a net warming not more than 0.062 deg.C. And that is the most generous estimate possible, using the ACRIM composite, the 2-sigma upper bound on the trend rate, and allowing for all the warming to be already in effect with no delay due to thermal inertia. The actual global warming over the time interval in question is, in fact, in excess of 0.5 deg.C.

http://tamino.wordpress.com/2007/07/24/pmod-vs-acrim/

Can anyone provide an alternative scientific explanation?

Yes if you accept the furthest outlying model which contains questionable assumptions, the TSI might be responsible for as much as 35% of the current warming.

If you accept any of the more realistic studies which attribute more like 10% of the current warming to the TSI, your argument falls apart.

An argument which relies on extreme outlying data is not a strong one.

Yes Tomcat, the fact that Scafetta and West have 20-30% uncertainty makes their argument even more convincing.

That sounds like a pretty standard denier argument.

Answer 1

Not a valid one.

Scafetta and West have hardly taken the world by storm. Their statistical analysis is questionable. Few scientists, if any, have supported them. They are taken apart here:

http://www.realclimate.org/index.php/archives/2006/10/how-not-to-attribute-climate-change/

Key quote:

"one should stay away from analyses based on the difference between two large but almost equal numbers, especially when their accuracy is not exceptional. And using differences of two large and similar figures in a denominator is asking for trouble."

Bottom line:

"There's a better scientific consensus on this [climate change] than on any issue I know... Global warming is almost a no-brainer at this point. You really can't find intelligent, quantitative arguments to make it go away."

Dr. Jerry Mahlman, NOAA

Answer 2

Dana, your statement that GCR flux has no long term trends is not established. I have seen research that did show a long term trend up until the late 90s when the measurements stopped being taken. Real Climate is not a reliable source. It is owned by a public relations company. Ask a question about the science from a skeptical perspective and they will censor your question. Michael Mann is the one who got caught hiding results contrary to his conclusions in a peer-reviewed paper, so the credibility of this site is no better than junkscience.com

The best alternative explanation is internal climate variability from the ocean-atmosphere interface. This is an issue the climate models do not model well and they do not weight strongly enough. The oceans have different oscillations switching back and forth from a warm phase to a cool phase. The most significant of these on a long term trend is the Pacific Decadal Oscillation. Each phase lasts 30-40 years. It was in a warm phase in 1905 to 1945, a cool phase from 1945-1975 and a warm phase from 1975 until just recently. Take those years and then look at a chart of the global surface temperature. The correlation is quite strong. Is it a coincidence? If that was the only evidence we had, you might think so. But other oscillations exist, including the North Atlantic Oscillation (NAO) and the El Nino Southern Oscillation (ENSO). The NAO has about 15-20 cycle and ENSO is much shorter. The El Nino is warm and La Nina is cool. When all three are in a warm phase (as in 1998 and 2006), it can be quite warm indeed.

These combination of factors and the resulting increase and decrease in global temperatures indicate temperature responds more to internal variability than to anything else.

http://www.uwm.edu/~kravtsov/downloads/GRL-Tsonis.pdf
http://en.wikipedia.org/wiki/Pacific_decadal_oscillation

Answer 3

Sure Dana, let me help you out there. The ACRIM composite contributes 35% (or 0.175 deg. C) of the current global warming (N. Scafetta1 and B. J. West1,2), just from the perspective of solar forcing. For whatever reason you choose to believe, at solar max low level cloud cover is lower than average, and at solar minimum, low level cloud cover is higher than normal. Since an increase in low level clouds results in a net cooling effect, this phenomena essentially amplifies the solar forcing parameters, and the IPCC report essentially has Earths energy budget wrong.

It is generally assumed that an increase in Solar output lead to our climb from the little ice age, so the sun is outputting more energy currently than it was one hundred years ago ( as much as 2 watts or more). If that is true the world has to be warmer than it was one hundred years ago, it is physically not possible for it to remain the same temperature. Naturally the world will support more water vapor in the atmosphere than 100 years ago, and naturally the world will support less ice on the surface than it would 100 years ago, those two simple positive feedback mechanisms also to my knowledge have not been accounted for.

EDIT:

Extreme outliers?

Oh now come on Dana, if I were going to use extreme outlying data, I would say that the Scafetta West paper indicated that the Sun contributed to as much as 60% of the warming in the twentieth Century, without any help from solar magnetic field, UV radiation, solar flares and cosmic ray intensity modulations, according to CO2 science. But I am a very open minded kind of guy, so I am still trying to believe in your trace gas theory, as a dominant climatic change factor, but it's just so silly, and I do not understand why you can't see that.

http://www.co2science.org/scripts/CO2ScienceB2C/articles/V9/N24/C1.jsp

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Answer 4

Well it is a no brainer that increasing the amount of CO2 in the air by 30%, which is in fact how much it has increased in the last 200 years, should have some effect on the termperature balance of the world. 0.5 degrees seems a plausible amount of temperature rise from a 30% increase in CO2. The argument starts when you talk about the secondary effects. Will the small CO2 effect trigger positive feedbacks that increase the temperature even faster or will it trigger negative feedback effects that counteract the warming? The jury is still out on that, IMO.