Posts Tagged ‘Airborne fraction’

Are global warmists preparing exit strategies?

March 28, 2013

Are global warmists preparing their arguments so that they can have exit strategies ready for when they have to abandon the global warming religion?

The purpose of an exit strategy is – as a minimum – to save face and minimise losses. In the best case it ends an engagement while realising potential benefits and protecting past gains. This is common enough in – and a necessary part of  – business and military planning. Politicians – at least the skilled ones – always have exit strategies in place when they choose to follow a particular “path of principle”. It is less likely that ideologues or religious leaders have prepared exits from dogmatic positions. However even they do have to change their colours from time to time. (Fanatics of course are not permitted exit strategies. They are expected to fall on their swords and die for their cause).

To escape from a discredited or outdated or bankrupt “faith-based” dogma usually requires some strong, visible reason for leaving a dogmatic position. A divine “revelation” is best though “new data” or  just “seeing the light” are also acceptable. This provides both a new faith as a destination and a reason for leaving the current position. A good exit strategy will also include a high profile “conversion” from one faith to another such that much credit can accrue, first for an”honourable” mea culpa for having followed the wrong path and then for the “principled and difficult” shift to the new path! Damage control may also require that the new converts repudiate their former “brothers of the faith”. In fact it is often “converts” who become the most fanatical about their new “religion”. The success of an exit strategy can be judged by how much baggage or stigma the ideologue or politician can avoid after the conversion.

James Hansen has been one of the most vocal and active proponents of the global warming hypothesis that it is caused by man-made emissions of carbon dioxide. He has been seen as one of the high priests of the global warming religion and qualifies as an ideologue:

Hansen is best known for his research in the field of climatology, his testimony on climate change to congressional committees in 1988 that helped raise broad awareness of global warming, and his advocacy of action to avoid dangerous climate change. In recent years, Hansen has become an activist for action to mitigate the effects of climate change, which on a few occasions has led to his arrest.

But he has a new (open access)  paper which makes me wonder whether he is preparing a position for the execution of an exit strategy when it becomes necessary.  He now admits that less of human made CO2 is entering the atmosphere than it should but that it is due to the increased use of coal which has increased aerosol particulates. He argues that this short term masking by aerosols of global warming will eventually have to appear and his doomsday messages have not changed. But he is adjusting his arguments quite fundamentally to account for the real life observations which he can no longer ignore. The “fertlisation of the biosphere” to account for man-made carbon dioxide not entering the atmosphere sounds a lot like back-pedalling to me. That the biosphere feeds on and relishes carbon dioxide is obvious. It does not much care  where it comes from.

James Hansen et al 2013 Environ. Res. Lett. 8 011006 doi:10.1088/1748-9326/8/1/011006

Climate forcing growth rates: doubling down on our Faustian bargain

As The Hockey Schtick reports some of the contents are startling – coming from Hansen:

  • the effect [forcing] of man-made greenhouse gas emissions has fallen below IPCC projections, despite an increase in man-made CO2 emissions exceeding IPCC projections
  • the growth rate of the greenhouse gas forcing has “remained below the peak values reached in the 1970s and early 1980s, has been relatively stable for about 20 years, and is falling below IPCC (2001) scenarios (figure 5).”
  • the airborne fraction of CO2 [the ratio of observed atmospheric CO2 increase to fossil fuel CO2 emissions] has decreased over the past 50 years [figure 3], especially after the year 2000
  • Hansen believes the explanation for this conundrum is CO2 fertilization of the biosphere from “the surge of fossil fuel use, mainly coal.”
  • “the surge of fossil fuel emissions, especially from coal burning, along with the increasing atmospheric CO2 level is ‘fertilizing’ the biosphere, and thus limiting the growth of atmospheric CO2.”
  • “the rate of global warming seems to be less this decade than it has been during the prior quarter century”

From the paper:

The simple Keeling airborne fraction, clearly, is not increasing (figure 3). Thus the net ocean plus terrestrial sink for carbon emissions has increased by a factor of 3–4 since 1958, accommodating the emissions increase by that factor.

Figure 3.

Figure 3. Fossil fuel CO2 emissions (left scale) and airborne fraction, i.e., the ratio of observed atmospheric CO2 increase to fossil fuel CO2 emissions. Final three points are 5-, 3- and 1-year means.

Remarkably, and we will argue importantly, the airborne fraction has declined since 2000 (figure 3) during a period without any large volcanic eruptions. The 7-year running mean of the airborne fraction had remained close to 60% up to 2000, except for the period affected by Pinatubo. The airborne fraction is affected by factors other than the efficiency of carbon sinks, most notably by changes in the rate of fossil fuel emissions (Gloor et al 2010). However, it is the dependence of the airborne fraction on fossil fuel emission rate that makes the post-2000 downturn of the airborne fraction particularly striking. The change of emission rate in 2000 from 1.5% yr-1 to 3.1% yr-1 (figure 1), other things being equal, would have caused a sharp increase of the airborne fraction (the simple reason being that a rapid source increase provides less time for carbon to be moved downward out of the ocean’s upper layers). ……

…… We suggest that the surge of fossil fuel use, mainly coal, since 2000 is a basic cause of the large increase of carbon uptake by the combined terrestrial and ocean carbon sinks. One mechanism by which fossil fuel emissions increase carbon uptake is by fertilizing the biosphere via provision of nutrients essential for tissue building, especially nitrogen, which plays a critical role in controlling net primary productivity and is limited in many ecosystems (Gruber and Galloway 2008). Modeling (e.g., Thornton et al 2009) and field studies (Magnani et al 2007) confirm a major role of nitrogen deposition, working in concert with CO2 fertilization, in causing a large increase in net primary productivity of temperate and boreal forests. Sulfate aerosols from coal burning also might increase carbon uptake by increasing the proportion of diffuse insolation, as noted above for Pinatubo aerosols, even though the total solar radiation reaching the surface is reduced.

The paper concludes

The principal implication of our present analysis probably relates to the Faustian bargain. Increased short-term masking of greenhouse gas warming by fossil fuel particulate and nitrogen pollution represents a ‘doubling down’ of the Faustian bargain, an increase in the stakes. The more we allow the Faustian debt to build, the more unmanageable the eventual consequences will be. Yet globally there are plans to build more than 1000 coal-fired power plants (Yang and Cui 2012) and plans to develop some of the dirtiest oil sources on the planet (EIA 2011). These plans should be vigorously resisted. We are already in a deep hole—it is time to stop digging.

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