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Quote from Nelson Polsby

Nelson Polsby, a political scientist widely respected for his pioneering studies of Congress and political parties, died earlier this week. This interesting quote is from an interview with Prof. Polsby in his obituary in

"There are often too many facts and not infrequently too many different versions of the facts. Rather than speaking for themselves, various facts have what we have come to refer to as spokespersons." Posted on February 9, 2007 02:08 PM

Comments

I may be in over my head in this forum, but I would like some help. I am trying to get a better understanding of the science behind the focus on AGW and seemingly impossible policy recommendations I see in the IPCC summary and the press interpretation.

I had followed some of the debate between climateaudit.org and realclimate.org during 2005 and 2006. I also watched the Jul 19, 2006 Barton hearings that aired this debate (video is now unavailable at http://energycommerce.house.gov/108/Hearings/07192006hearing1987/hearing.htm – though I have contacted the web admin and asked for a forwarding URL). Also, I read quite a bit of Dr Wegman’s report.

What I took away from all of this was that Mann, et al., had made significant errors in modeling the ‘hockey stick’, but that CO2 had risen significantly and the climate was indeed warming. So, looking at 1000AD to 2000AD, instead of a flat line with a spike upwards, it was more like a roller coaster with a slightly(?) larger second hill.

I have three questions:

1. Is my understanding that the warming we see in the 20th century roughly 66% due to other natural cyclic forcing and 33% due to AGW, i.e., CO2, anywhere near correct?

2. From this link http://www.cgfi.org/cgficommentary/global-warming-famine-or-feast , which is focused on food production, I infer that increased CO2 and warming will be responded to by increased vegetation. Will this vegetation remove significant CO2 and establish a new equilibrium? Would it prevent a runaway GHG effect?

3. I searched the IPCC 2007 Policy Summary for any mention of CRF, cosmic rays, or flux and found none. They mention it briefly in the 2001 TAR http://www.grida.no/climate/ipcc_tar/wg1/246.htm as inconclusive. Yet, Nir Shaviv wrote in GSA Volume 13, Issue 7 (July 2003) that it showed great promise, and in 2007 responds with a link to http://www.sciencebits.com/CO2orSolar that indicates a stronger position on the impact of CRF on climate.

My rudimentary bachelors’ science education left me with understanding that the four big factors in climate forcing were:

> Variations in the Earth's orbital characteristics.
> Atmospheric carbon dioxide variations.
> Volcanic eruptions
> Variations in solar output.

Is CRF such a new theory that it has received no attention?

Thanks for any help that you folks can provide.

James Williams

Posted by: jdwill at February 10, 2007 09:36 AM

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Hi James,

You write, "1. Is my understanding that the warming we see in the 20th century roughly 66% due to other natural cyclic forcing and 33% due to AGW, i.e., CO2, anywhere near correct?"

Let's start with a minor but important point. You wrote "i.e., CO2" ("that is, CO2"). But it really should have been, "e.g., CO2" ("for example, CO2").

CO2 is a positive forcing, but so is methane, and so is black carbon (soot).

Humans can also cause albedo (reflectivity) changes. For example, smoke/dirt that makes snow dirty lowers the reflectivity of snow. If the Sahara desert was turned from a desert to an irrigated farming area (just to take a totally hypothetical future possiblity) that would really lower the albedo (reflectivity) of that area of the world, and would therefore potentially increase temperature.

Now considering all that...my own personal estimate is that, of the warming from the average of the 1880s to the present, somewhere between 30 and 90 percent is caused by humans. That's just my own estimate. I think the likely answer is towards the middle, rather than the edges of the range. So my personal estimate includes your value of 33 percent, but my personal estimate would be higher.

"...is focused on food production, I infer that increased CO2 and warming will be responded to by increased vegetation. Will this vegetation remove significant CO2 and establish a new equilibrium?"

Over the last ~40 years, the amount of human CO2 emissions absorbed by plants has stayed pretty constant, ***on average***, at 55%. (I say, "on average" because the year-to-year variations are very large.)

So it's very unlikely that a "new equilibrium" will be established if CO2 emissions continue to increase...or even remain the same.

"Is CRF such a new theory that it has received no attention?"

My personal opinion is that there is a bias within the IPCC against the idea of solar-related changes in earth's average temperature. (To large an effect would essentially put them out of business.)

Here's an article from Real Climate that discusses *recent* warming versus CRF:

http://www.realclimate.org/index.php?p=42

It seems to me that a key issue is exactly what the earth's temperature was during periods such as the Medieval Warming Period (MWP) and Little Ice Age (LIA), and what the CRF was during those periods.

If the MWP was substantially warmer than present (say 1-2 deg C) and the LIA was at its low point much colder than at present (say 1-2 deg C), and we know that those changes tracked very well with changes in the CRF, then we've got a potential important phenomenon.

Best wishes,
Mark Bahner

Posted by: Mark Bahner at February 10, 2007 11:05 AM

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Hi James,

A couple extra thoughts/corrections, then I need to get out into this chilly NC day ;-):

1) Let's say humans have been responsible for 70 percent of warming since the 1880s, but CO2 has been responsible for 2/3rds of that 70 percent...that would be 0.7 x 0.66 = 46 percent caused by CO2 alone. So if you really wanted to get an opinion on CO2 alone, my answer would be closer to your 33 percent (though probably still not that low).

2) I said that the "amount" of CO2 absorbed by plants had been constant at 55 percent. But a better word would have been the PERCENTAGE of CO2 absorbed by plants has been, on average, constant at 55 percent.

Mark

Posted by: Mark Bahner at February 10, 2007 11:23 AM

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Mark,

Comparing warming from ghg's and black carbon is comparing apples and oranges. The mechanism is different.

Black carbon decreases albedo.

Ghg's decrease the rate at which heat leaves the proximaty to the surface, and radiation is only one way that is done. There is also convection. With an increased lapse rate due to ghg's, convection increases to compensate. While there is a second order effect from ghg's of increasing water vapor, it's not a first order effect like black carbon decreasing albedo.

The first order effect of increasing ghg's is to increase convection, which moves more water vapor up faster, increasing cloudiness.

Posted by: Steve Hemphill at February 10, 2007 12:07 PM

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Hi Mark,

Thank you very much for your response. You are right, I should have said e.g., instead of i.e.

I am taking your 55% CO2 absorption by vegetation as a constant ratio, but a net linear increase in absorption. Not enough to prevent a higher percentage of CO2 in the atmosphere over time.

From the CFGI article linked above, “Worldwide, vegetative activity generally increased by 6.17 percent between 1982 and 1999”. I believe this is arrived at by satellite imagery surveys. This percentage does not keep pace with our current increase in CO2 emission, yet the 55% constant absorption ratio would seem to indicate that plants are absorbing more CO2 per plant. Is this right?

I am wondering if aggressive reforestation might be a cost effective tool in the kit for dealing with increased atmospheric CO2.

I work in the US automotive industry. While I agree that we need to reduce and eventually eliminate using fossil fuels for energy production (and not just because of AGW), I don’t currently see how the world economy can react rapidly enough, purely by reduction of emissions, if the IPCC predictions are realized.

James Williams

Posted by: jdwill at February 10, 2007 12:19 PM

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James

How do you integrate these two problems?

People want reforestation while going back to biologic farms that requires more deforested land than the more technological farms.

Posted by: Sylvain at February 11, 2007 02:27 PM

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Sylvain,

I'm not sure that we would need to integrate them. My sense is that the demand for 'organically' grown food is not that high a percentage. Also not my field, but there is a lot of land where the soil is not optimal for farming, that could support trees (perhaps genetically modified) that would use less from or even add to the soil while providing a carbon sink. We also might see a solution that integrates more planting with our suburban sprawl.

Posted by: jdwill at February 11, 2007 05:55 PM

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I wonder if identifying terrestrial C02 generators
is as important as studying ocean C02 output of which 70% of the earth is covered. So then "how we affect the oceans" should be primary.

Posted by: Nick at August 1, 2007 12:07 PM

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