Monday, February 15, 2010

Another IPCC mistake--Bias with residence time

Table 1 of the IPCC TAR WG1 report says that the time CO2 stays in the atmosphere before being removed is somewhere between 5 and 200 years. They give NO scientific reference for that 200 year residence time. source. But first, a definition of residence time.

When one puts a gas or dust or anything into the atmosphere or ocean natural chemical processes will tend to remove individual atoms and molecules and lock them away in another form. In the case of CO2, trees, algae and chemical weathering remove CO2 from the atmosphere. The residence time, is the time it takes for half of the molecules to be removed from the atmosphere. In the case of CO2 the residence time can be calculated from the nuclear bomb C14.

In the 1950s and 1960s many nuclear bombs were tested in the atmosphere. That caused a spike in atmospheric C14 all of which ended up eventually in carbon dioxide. In 1963 the atmospheric test ban went into effect and the carbon dioxide containing Carbon 14 was at a maximum. Since that time the bomb created carbon dioxide has been continuously removed from the atmosphere and the half-life is less than 12 years.



This has huge implications for claims by global warming hysteriacs. The atmosphere contains 750 billion tonnes of CO2.

"Anthropogenic CO2 emissions are
only about 3% of the natural carbon cycle and less than 1% of
the atmospheric reservoir of carbon of 750 Gt. The vast majority
of CO2 fluxes are natural.
Source: C. R. DE FREITAS
Are observed changes in the concentration of carbon dioxide
in the atmosphere really dangerous? BULLETIN OF CANADIAN PETROLEUM GEOLOGY
VOL. 50, NO. 2 (JUNE, 2002), P. 297-327, p. 301

Given the half-life (residence time) for CO2, it means that each year 750/12 or 62.5 Gigatonnes of CO2 are removed from the atmosphere each year. Most estimates say that the residence time is 5-7 years, so this bomb related argument is not the most stringent one could use.

So, how much CO2 do humans emit each year? The answer is an amazing 1/10th of the amount removed each year.





"Each year, human activity — primarily the use of coal, oil,
natural gas and production of cement — emits about 6.5 Gt of
carbon into the atmosphere. Despite this, the annual rate of
increase of CO2 in the atmosphere is highly variable, falling
close to zero in some years (for example, in 1992) and declining
in others (for example, in 1998). In general, data show that
human-caused CO2 is levelling off, despite increased emissions
(Figs. 2, 3). This is believed to be the result of natural stabilizing
feedbacks. Carbon dioxide is food for plants. The more
there is, the more they use."


Source: C. R. DE FREITAS Are observed changes in the concentration of carbon dioxide
in the atmosphere really dangerous? BULLETIN OF CANADIAN PETROLEUM GEOLOGY
VOL. 50, NO. 2 (JUNE, 2002), P. 297-327, p. 300


We put out 6.5 gigatonnes of carbon and the natural systems put out 9 times+ what we do. Given this, it is very unlikely that humans are the main cause of the rise in CO2, natural processes are responsible in large measure. Segalstad writes:


"Both radioactive and stable carbon isotopes show that the real atmospheric CO2
residence time (lifetime) is only about 5 years, and that the amount of fossil-fuel CO2 in the atmosphere is maximum 4%. Any CO2 level rise beyond this can only come from a much larger, but natural, carbon reservoir with much higher 13-C/12-C isotope ratio than that of the fossil fuel pool, namely from the ocean, and/or the lithosphere, and/or the Earth's interior."
Source: Tom V. Segalstad, "Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO2:
on the construction of the "Greenhouse Effect Global Warming" dogma." source

The data doesn't support the IPCC contention that carbon dioxide has a residence time of 200 years. If that were true, we should have far more C14-based carbon dioxide in the atmosphere than we do. Its short residence time shows that the IPCC is simply making this up as they go along.

2 comments:

  1. I feel really scared with these statistics because global warming is a serous problem and we don't do anything to revert the results, people only think in money and power.m10m

    ReplyDelete
  2. Interesting, I don't really now to much about this stuff, i just have superficial studies because i couldn't pay the career, anyway thanks

    ReplyDelete