RE: Rain

[Les Schaffer <godzilla@xxxxxxxxxxxxxx>]

Paddy said:

> It IS nonsense to talk about CO2 as a danger.  It is a proven fact
> that plants can only grow and photosynthesise with adequate supplies
> of CO2 - and that increasing CO2 results in more rapid growth and
> photosynthesis (given a sufficient reply of light, water, nitrate,
> phosphate and potash + a variety of other trace materials).  It has
> for long been recognised by greenhouse growers that a raised CO2 is
> beneficial and many an installation provides for this.


unbelievable.... absolutely amazingly incredible that you talk to
marxist comrades worlwide spreading this nonsense instead of using
your long experience and technical background to help non-technical
people get a grip on what the latest scientific findings are
indicating (or not indicating).

its painful to listen to you go on like this.

here's some stuff by colleagues over your way. i invite you to join me
in an email dialgue with these scientists, and others i am in touch
with world-wide, making modern scientific results available to people
here in such a way that they can attempt to get some kind of handle on
these difficult issues for themselves.

les schaffer

-----------------------------

Nature 408, 184 - 187 (2000) © Macmillan Publishers Ltd.


Acceleration of global warming due to carbon-cycle feedbacks in a
coupled climate model

PETER M. COX*, RICHARD A. BETTS*, CHRIS D. JONES*, STEVEN A. SPALL* &
IAN J. TOTTERDELL?

* Hadley Centre, The Met Office, Bracknell, Berkshire RG12 2SY, UK
? Southampton Oceanography Centre, European Way, Southampton SO14 3ZH, UK

Correspondence and requests for materials should be addressed to
P.M.C. (e-mail: pmcox@xxxxxxxxxxx).


The continued increase in the atmospheric concentration of carbon
dioxide due to anthropogenic emissions is predicted to lead to
significant changes in climate[1]. About half of the current emissions
are being absorbed by the ocean and by land ecosystems[2], but this
absorption is sensitive to climate[3, 4] as well as to atmospheric
carbon dioxide concentrations[5], creating a feedback loop. General
circulation models have generally excluded the feedback between
climate and the biosphere, using static vegetation distributions and
CO2 concentrations from simple carbon-cycle models that do not include
climate change[6]. Here we present results from a fully coupled,
three-dimensional carbon-climate model, indicating that carbon-cycle
feedbacks could significantly accelerate climate change over the
twenty-first century. We find that under a 'business as usual'
scenario, the terrestrial biosphere acts as an overall carbon sink
until about 2050, but turns into a source thereafter. By 2100, the
ocean uptake rate of 5 Gt C yr-1 is balanced by the terrestrial carbon
source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in
our fully coupled simulation than in uncoupled carbon models[2],
resulting in a global-mean warming of 5.5 K, as compared to 4 K
without the carbon-cycle feedback.

[snip]

[snip many caveats at end]


============

Nature 408, 187 - 190 (2000) © Macmillan Publishers Ltd.


Offset of the potential carbon sink from boreal forestation by
decreases in surface albedo

RICHARD A. BETTS

Hadley Centre for Climate Prediction and Research, The Met Office ,
Bracknell, Berkshire RG12 2SY, UK

Correspondence should be addressed to the author (e-mail: rabetts@xxxxxxxxxxx).


Carbon uptake by forestation is one method proposed[1] to reduce net
carbon dioxide emissions to the atmosphere and so limit the radiative
forcing of climate change[2]. But the overall impact of forestation on
climate will also depend on other effects associated with the creation
of new forests. In particular, the albedo of a forested landscape is
generally lower than that of cultivated land, especially when snow is
lying[3-9], and decreasing albedo exerts a positive radiative forcing o
climate. Here I simulate the radiative forcings associated with
changes in surface albedo as a result of forestation in temperate and
boreal forest areas, and translate these forcings into equivalent
changes in local carbon stock for comparison with estimated carbon
sequestration potentials[10-12]. I suggest that in many boreal forest
areas, the positive forcing induced by decreases in albedo can offset
the negative forcing that is expected from carbon sequestration. Some
high-latitude forestation activities may therefore increase climate
change, rather than mitigating it as intended.

[snip]

The work I report here has focused on perturbations to the Earth's
radiation budget, which is the fundamental driver of the climate
system. Forestation may also influence the climate by modifying the
fluxes of heat, moisture and momentum between the land surface and
atmosphere. Whereas boreal forests warm their local climate through
reduced albedo, tropical forests tend to cool and moisten their local
climates by greatly enhancing evaporation. Both may also influence
distant regional climates via the atmospheric circulation[9,
27]. Assessment of the effect of forestation on climate at a given
time in the future will require simulations with a climate model that
incorporates vegetation dynamics[25, 28] and other atmospheric,
terrestrial and oceanic components of the carbon cycle[28], in which
forest growth occurs at appropriate rates in relation to changes in
atmospheric CO2 and snow cover. Nevertheless, my results suggest that
high-latitude forestation would exert a positive radiative forcing
through reduced albedo that in many places could outweigh the negative
forcing through carbon sequestration. If afforestation and
reforestation are required to decrease radiative forcing rather than
simply to reduce net CO2 emissions, then changes in surface albedo
must also be considered.