Mike
Do you think that the higher levels of SO2 from Chinese coal burning
could account for some of the increase in Arctic temperatures?
Another thought for your list might be to increase the drag of water
flowing in through the Bering Strait. In summer kelp grows at an amazing
rate but not below about 30 metre water depth because of the shortage of
light. The net flow is 800,000 m3 a second and it will be warmer than
polar water so a small velocity reduction makes a big difference. What
if we put strong ropes moored at 30 metres to give them kelp a foot
hold? If kelp gets scraped off by floating ice it will can grow again.
Does ice reach down to 30 metres?
Stephen
On 11/09/2012 18:05, Mike MacCracken wrote:
Re: [geo] Coupled Model Intercomparison Project 5 (CMIP5) simulations
of climate following volcanic eruptions In my view, this is just why
geoengineering efforts to cool the Arctic should consider as
approaches: (a) spring-summer only injection of the appropriate sulfur
compound (whatever will lead to sulfates) into the LOWER stratosphere
or free troposphere, (b) cloud brightening in region or over currents
carrying heat into the region, (c) approaches to brighten the surface
albedo (e.g., microbubbles) in or near the region, and, perhaps, (d)
approaches to reduce cirrus that are reducing IR loss.
Parallel to these efforts, we should also be working to limit
emissions of substances that amplify Arctic warming above and beyond
the amplification that happens due to natural processes, so black
carbon from sources in and near the region, etc.
Mike
On 9/11/12 5:03 AM, "Stephen Salter" <[email protected]> wrote:
Hi All
Six out of the eight models in the Driscoll et al paper show near
surface-warming in Arctic winters following volcanic eruptions.
This is in line with figure 2a the Jones Hayward Boucher Robock
2010 paper in Atmospheric Chemistry and Physics. The obvious
mechanisms are blanketing of outgoing radiation and side-scatter
of high solar rays that might have missed the polar regions.
Given the concerns about the loss of Arctic ice and increased
methane release we will have to be very careful not to let any
geo-engineering sulphur that we inject at low latitudes reach the
Arctic in winter.
Stephen
On 10/09/2012 16:52, Simon Driscoll wrote:
Dear all,
the published version (no longer PiP) is now available here:
http://www.agu.org/pubs/crossref/2012/2012JD017607.shtml
Warm regards,
Simon
________________________________________________
Simon Driscoll
Atmospheric, Oceanic and Planetary Physics
Department of Physics
University of Oxford
Office: 01865 272930
Mobile: 07935314940
http://www2.physics.ox.ac.uk/contacts/people/driscoll
http://www.geoengineering.ox.ac.uk/people/who-are-we/simon-driscoll/
------------------------------------------------------------------------
*From:*[email protected]
[[email protected]] on behalf of Andrew Lockley
[[email protected]]
*Sent:* 14 August 2012 02:06
*To:* geoengineering
*Subject:* [geo] Coupled Model Intercomparison Project 5
(CMIP5) simulations of climate following volcanic eruptions
http://www.agu.org/pubs/crossref/pip/2012JD017607.shtml
The ability of the climate models submitted to the Coupled
Model Intercomparison Project 5 (CMIP5) database to simulate
the Northern Hemisphere winter climate following a large
tropical volcanic eruption is assessed. When sulfate aerosols
are produced by volcanic injections into the tropical
stratosphere and spread by the stratospheric circulation, it
not only causes globally averaged tropospheric cooling but
also a localized heating in the lower stratosphere, which can
cause major dynamical feedbacks. Observations show a lower
stratospheric and surface response during the following one or
two Northern Hemisphere (NH) winters, that resembles the
positive phase of the North Atlantic Oscillation (NAO).
Simulations from 13 CMIP5 models that represent tropical
eruptions in the 19th and 20th century are examined, focusing
on the large-scale regional impacts associated with the
large-scale circulation during the NH winter season. The
models generally fail to capture the NH dynamical response
following eruptions. They do not sufficiently simulate the
observed post-volcanic strengthened NH polar vortex, positive
NAO, or NH Eurasian warming pattern, and they tend to
overestimate the cooling in the tropical troposphere. The
findings are confirmed by a superposed epoch analysis of the
NAO index for each model. The study confirms previous similar
evaluations and raises concern for the ability of current
climate models to simulate the response of a major mode of
global circulation variability to external forcings. This is
also of concern for the accuracy of geoengineering modeling
studies that assess the atmospheric response to
stratosphere-injected particles.Received 13 February 2012;
accepted 24 July 2012.
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