The main risk with sulphate dispersal is ozone loss, not acid rain.
Acid rain easily dealt with - anyone introducing high level sulphate
should reduce low level sulphate emissions by at least that amount,
producing a new benefit. For example by financing new and additional
reductions from shipping, power stations etc.
Oliver Tickell.
On 17/02/2011 11:11, John Nissen wrote:
>
> Hi Brian, Torsten,
>
> It's amazing how scared people are of geoengineering with stratospheric
> sulphate aerosol, when we've been putting so much sulphate aerosol into
> the troposphere. There is similar reflection of sunlight at either level
> in the atmosphere, but the aerosol in the troposphere typically gets
> washed out in a few weeks, whereas the aerosol in the stratosphere lasts
> for a few years, as we observed from Mt Pinatubo eruption in 1992 (which
> produced 0.5 C cooling over two years). So you need only a small
> fraction (a few per cent) of aerosol in stratosphere to produce the same
> dimming effect.
>
> Because of the relatively small quantities needed in the stratosphere,
> the danger from acid rain is negligible. This has even been agreed by
> Alan Robock, who is well known for his anti-geoengineering stance.
>
> Our human irrationality over "cleaning the atmosphere" was drawn to my
> attention by James Lovelock, in his book "Gaia's revenge". He points out
> how reducing pollution, and thus removing the sulphate aerosol from
> atmosphere, has unmasked global warming which is potentially
> catastrophic. One can see from the record of glacier ice mass loss [1],
> that there has been a sudden increase in rate around the late 80s, which
> cannot be explained by any sudden increase in CO2 level in the
> atmosphere. This could be explained by the reduction of sulphate
> aerosols around that time, or alternatively by some kind of positive
> feedback cutting in. Either way the scientific community has not reacted
> to this in a rational way - to seek some method _other than emissions
> reduction_ to counter global warming. Instead the scientific community
> has dug an even deeper hole for themselves, and put emissions reduction
> as the _only_ way to save the planet - rejecting geoengineering as a
> short term action. I even heard, with my own ears, Sir David King
> (former chief scientific adviser to the government) say, at a House of
> Commons event, that geoengineering wouldn't be needed for thirty or
> forty years, if ever [2]. How can one expect environmentalists to
> support geoengineering when the top scientists are saying things like
> that? It makes me really angry.
>
> The trouble is that climate scientists have dug such a big hole for
> themselves, that they cannot get out. It seems that any event which
> indicates the _immediate dangers_ of our situation on this planet causes
> them to dig harder, and downplay the danger. How often is the
> extraordinarily rapid retreat of Arctic sea ice mentioned, though the
> Arctic heating is like a burning fuse for the methane time bomb and
> Greenland ice sheet collapse. The fact that we have an emergency is
> ignored. It is criminal - no worse - genocidal. It is also incredibly
> stupid.
>
> John
>
> [1] http://raonline.ch/pages/edu/pdf/WorldGlaciersData0305.pdf
>
> [2] What is he doing here but to discredit geoengineering?
> http://www.oxfordgeoengineering.org/about.php
>
> ---
>
> On 16/02/2011 14:25, Brian Orr wrote:
>> Well that more or less wraps that up ........except "global dimming"
>> sounds a lot more user-friendly than
>> "Solar Radiation Management". Just adjust the blinds a little and the
>> room will soon get quite comfortable!"
>>
>> So all we have to do is to persuade our political leaders to swing our
>> industry and life-styles towards producing
>> enough dimming and cutting back on the stuff that's causing the
>> problem and over the course of the next 50 years
>> or so we'll get Mother Earth back on her feet again.
>>
>> Whose going to be first to explain the need to our political leaders?
>>
>> Brian Orr
>>
>> On 16 Feb 2011, at 12:12, Torsten Mark Kowal wrote:
>>
>>> Forumers:
>>>
>>> I agree with Jon Nissen's deep worry that key Earth Systems are
>>> already spiralling out of control. We can see NASA's images and
>>> diagnosis here -
>>> http://earthobservatory.nasa.gov/IOTD/view.php?id=49132 and that of
>>> NSIDC http://nsidc.org/arcticseaicenews These observations are
>>> extremely alarming.
>>>
>>> However, I am sorry to add to this bleak picture, but I think the
>>> arguments so far have neglected to account for the fact that humanity
>>> is, of course, already engaged in massive geo-engineering.
>>>
>>> Our species is already involved in immense negative forcing of global
>>> climate through /human-produced aerosols/ that are found in the Asian
>>> Brown Cloud, due to China/India/SE Asia etc. fossil-fuel burning;
>>> desertification; and other sources of tropospheric particles, such as
>>> African, Asian and Latin American forest burning.
>>>
>>> These are the drivers of the _global dimming phenomenon_. You can see
>>> this first covered by the media in the original Horizon 2005
>>> documentary on /Global Dimming /
>>> http://video.google.com/videoplay?docid=-4488155708142678419#docid=-5512125026951860045,
>>> which, while perhaps over-the-top in ringing alarm bells, does
>>> describe a phenomenon that is as yet little discussed.
>>>
>>> I don't know how many on this list are aware of the issue, but
>>> science clearly finds that these mixtures of aerosol particles
>>> suspended in the atmosphere (coming from deserts and the burning of
>>> fossil fuels and forests) is - for the time being - "holding in
>>> check" part of the GHG-induced warming our species has already
>>> committed the planet to.
>>>
>>> While the effects of aerosols are very complex, NASA's James Hansen
>>> has stated that today's evidence shows that the aerosol load could be
>>> causing from -1 to -2 w/m2 of radiative forcing reduction, due to
>>> increased reflectivity of clouds and atmosphere that these aerosols
>>> cause, thus offsetting global warming.
>>>
>>> This could be a lot more than shown in AR4's "SPM2" Figure from 2007.
>>>
>>> Once humankind begins to clean these up (to reduce carbon emissions
>>> from dirty sources, so as to achieve cleaner air locally), then the
>>> reductions in total global radiative forcing will lead to the release
>>> of significant further global climate change, in the decades that
>>> follow the clean-up.
>>>
>>> The further hidden commitment to warming will come into play would be
>>> in addition to the approximate 0.8 degree centigrade 'global warming
>>> commitment' that is coming our way over the next three decades -
>>> whatever humanity does about our GHG emissions - due to the delay in
>>> the responses of the Earth's systems to the planet's energy imbalance
>>> from current radiative forcing. [See Global and Regional Climate
>>> Change: Underlying Science and Emerging Riddles
>>> http://mitworld.mit.edu/video/589 ]
>>>
>>> This is a very significant trap that humankind faces - we clean up
>>> China, India, eastern Europe etc; we reduce desertification and
>>> deforestation - but then we also immediately stop benefiting from the
>>> geo-engineering we have already caused, via these vast emissions of
>>> reflective aerosol particles.
>>>
>>> In effect our species has made a pact with our climate - the
>>> longer-term, diffuse impacts of our continued carbon pollution are
>>> for now offset by that same pollution - due to the regional dimming
>>> resulting from the aerosols that this carbon burning also liberates.
>>>
>>> This is explained in the attached paper, just published in
>>> Geophysical Research Letters - */Climate commitment in an uncertain
>>> world/* by K. C. Armour and G. H. Roe; reported in "Nature" here -
>>> http://www.nature.com/nclimate/2011/110215/full/nclimate1044.html?WT.ec_id=NCLIMATE-20110215
>>>
>>>
>>> /Climate commitment|the warming that would still occur given no
>>> further human inuence|is a fundamental metric for both science and
>>> policy. It informs us of the minimum climate change we face and,
>>> moreover, depends only on our knowledge of the natural climate
>>> system. Studies of the climate commitment due to CO2 show that global
>>> temperature would remain near current levels, or even decrease
>>> slightly, in the millennium following the cessation of emissions.
>>> However, this result overlooks the important role of the non-CO2
>>> greenhouse gases and aerosols.
>>>
>>> This paper shows that global energetics require an immediate and
>>> significant warming following the cessation of emissions as aerosols
>>> are quickly washed from the atmosphere, and the large uncertainty in
>>> current aerosol radiative forcing implies a large uncertainty in the
>>> climate commitment.
>>>
>>> Fundamental constraints preclude Earth returning to pre-industrial
>>> temperatures for the indefinite future. These same constraints mean
>>> that observations are currently unable to eliminate the possibility
>>> that we are already beyond the point where the ultimate warming will
>>> exceed dangerous levels.
>>>
>>> /Just like the courtier Damocles asking to try out King Dionysius's
>>> magnificent lifestyle, the human species is fortunate only for a
>>> short time. We know that while Damocles sat down in the king's throne
>>> surrounded by every luxury, Dionysius had arranged that a huge sword
>>> should hang above the throne, held by the handle only by a single
>>> hair of a horse's tail. Damocles begged the tyrant that he be allowed
>>> to depart, because he no longer wanted to be so "fortunate". So,
>>> prophetically, "The value of the sword is not that it falls, but
>>> rather, that it hangs." It may appear to be enviable to wear a crown
>>> of power and to have access to all resources, but there are threats
>>> at all times to the one who wears the crown.
>>>
>>> I have a strong sense of foreboding engendered by this terribly
>>> precarious situation, of visible and close peril. The onset of this
>>> long-playing tragedy is for now delayed, but only by the delicate
>>> trigger of humanity's procrastination in reducing the dirty load of
>>> carbon-related aerosols.
>>>
>>> Mark Kowal
>>>
>>> <ArmourRoe_committed_draft.pdf>
>>
--
--
Oliver Tickell
e: [log in to unmask]
p: +44 1865 728118
a: 379 Meadow Lane, Oxford OX4 4BL, UK.
|