Re: [asa] Cosmological Evolution?

From: Rich Blinne <rich.blinne@gmail.com>
Date: Thu Dec 28 2006 - 16:53:37 EST

On 12/28/06, Michael Roberts <michael.andrea.r@ukonline.co.uk> wrote:
>
>
> George
>
> It's Christmas, stop banging your head against a brick wall
>
> Michael
>
> ----- Original Message -----
> From: George L. Murphygmurphy@raex.com
> To: Janice Matchett ; George Murphy ; Gregory Arago ; asa@calvin.edu
> Sent: Thursday, December 28, 2006 7:12 PM
> Subject: Re: [asa] Cosmological Evolution?
>
>
>
> No, I didn't think you meant "everyone." I was simply pointing out that
> Teilhard himself can't be classified as a "biocentrist" in your sense. If
> that's simply a restatement of what you said, fine. I thought the point
> worth emphasizing because Teilhard often is criticized unjustly in
> conservative Christian circles, & while there are quite legitimate
> criticisms of his views, it's a mistake to reject everything he said.
>
> At this point I'm not particularly interested in getting into extended
> debate about the environment with someone whose views about such matters I
> would still characterize as "preposterous."
>
> ..............................
> George L. Murphy
>

In the interest of Christmas and George's head :-) I will take up the
debate. The thinking is that Christian evironmentalism is biocentric
but it does not need to be. For example, what about agricultural
yields? This clearly is anthropocentric (and Christian cf. Matthew
25:37). Earlier, Janice presented a Telegraph article where aerosol
sprays [sic] supposedly made the negative effects of GHG less
pronounced. But, we find the following from the cover of this week's
PNAS:

Integrated model shows that atmospheric brown clouds and greenhouse
gases have reduced rice harvests in India

http://www.pnas.org/cgi/content/full/103/52/19668

It seems that atmospheric brown clouds (ABCs) of black carbon caused
by burning biomass (a.k.a. wood fires) does not improve the rice
harvest in India that is negatively affected by anthropogenic
greenhouse gases (GHGs). From the abstract:

Previous studies have found that atmospheric brown clouds partially
offset the warming effects of greenhouse gases. This finding suggests
a tradeoff between the impacts of reducing emissions of aerosols and
greenhouse gases. Results from a statistical model of historical rice
harvests in India, coupled with regional climate scenarios from a
parallel climate model, indicate that joint reductions in brown clouds
and greenhouse gases would in fact have complementary, positive
impacts on harvests. The results also imply that adverse climate
changes due to brown clouds and greenhouse gases contributed to the
slowdown in harvest growth that occurred during the past two decades.

And the conclusion:

The evidence of a greater impact by ABCs and GHGs during the more
recent period is interesting in view of historical trends in Indian
rice harvests (Fig. 4). Thanks to the Green Revolution, rice harvests
grew dramatically after the mid-1960s. They have grown more slowly
since the 1980s; however, the annual growth rate peaked at nearly 3%
in 1984–1985 and leveled off by the early 2000s. This deceleration has
raised concerns that food shortages could recur (16, 17). Many
explanations for the deceleration have been offered, including falling
rice prices, deteriorating irrigation infrastructure, soil
degradation, stagnant technology on rain-fed farms, and the
technological frontier being reached on irrigated farms (16). Our
explanation, adverse regional climate change caused by the combined
effects of ABCs and GHGs, augments these explanations. Previous
statistical studies on the climate sensitivity of Indian agriculture
did not detect it for two reasons: they ignored ABCs, and their sample
periods ended in the 1980s, before the deceleration occurred (18, 19).

Our estimates of the impact of just ABCs on rice harvest, 3.94% during
1966–84 and 10.6% during 1985–1998 (Table 2), are within the range of
the previous estimates cited earlier. They differ, however, in several
important ways: they are derived from a statistical model based on
historical data instead of a crop-response simulation model, they
account for both area and yield effects instead of just the latter,
and they reflect the impacts of drying and cooling instead of dimming.
As already mentioned, the omission of the impact of dimming perhaps
causes our estimates to understate the amount by which rice harvest
would have increased if ABCs had been reduced. Our estimates are
conservative for two additional reasons: they ignore the possibility
that farmers might have achieved even greater rice harvests by
adjusting other inputs besides area harvested (20), and they ignore
direct damage to rice caused by air pollution (21). Some direct damage
from aerosols might be reflected in the June–September rainfall
variable: heavy rains reduce the concentrations of aerosols to which
rice plants are exposed, and this could contribute to the positive
impact of the rainfall variable in the regression equations. Because
the estimates in Table 2 ignore the fact that any incremental rice
area would have displaced other crops, they should not be taken as
indications of the net impact of ABCs on the overall Indian
agricultural sector.

The combustion processes that generate aerosols also generate GHGs.
Our finding that simultaneous reductions in ABCs and GHGs would
provide benefits to rice farmers is thus reassuring. For rice farming
at least, we do not find evidence of a tradeoff between the impacts of
reducing ABCs and GHGs. Reductions in ABCs would increase surface
warming, but the impact would be mainly on daytime temperatures, not
on the night-time temperatures that negatively effect rice, and it
would in any event be outweighed by a beneficial increase in rainfall.
To reduce night-time temperatures, reductions in GHGs are needed. We
cannot say, of course, whether this complementarity of impacts would
also occur for other crops in other countries. Understanding of the
regional climate impacts of ABCs remains limited, and the climate
sensitivity of crops varies, but at least we can say that a tradeoff
is not inevitable.

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Received on Thu Dec 28 16:54:07 2006

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