[Aqualist] 1. Free book 2. rapid climate change in Oz and USA

[Tim Barrows]

From: Barrie Pittock <Barrie.Pittock at csiro.au>

Dear Aqualist people,

As a longstanding quasi-amateur fan of paleoclimate studies, I thought you 
might be interested in my book written for the Australian Greenhouse 
Office, available free from them, and that you might be able to help with 
some material for my next book.

1. My book is a sort of update on the Intergovernmental Panel on Climate 
Change Third Assessment Report in 2001, entitled 'Climate Change: An 
Australian Guide to the Science and potential Impacts'. It covers the 
science of the enhanced greenhouse effect, globally and for Oz, and the 
potential impacts and adaptations. It is available free, all 239 pages in 
colour, with good index etc., in pdf form from 
http://greenhouse.gov.au/science/guide/pubs/science-guide.pdf. You can also 
request it free in hard back from the AGO via their webpage 
(<www.greenhouse.gov.au>) . There are some references to paleo-climate, 
mainly re rapid climate change, especially the Younger Dryas, and sea level 
change as affected by the stability/possible rapid melting of parts of the 
Greenland and Antarctic ice sheets. Some of you might find it useful, if 
only in writing grant proposals.

2. My next project is a 'semi popular' book in my own name, with no 
editorial limits, covering the whole of the enhanced greenhouse story, 
including global and with reference to mitigation (emissions reductions) 
and policy matters. Again, the subjects of rapid climate change and rapid 
sea level rise come up (see eg., the US National Research Council report 
'Abrupt Climate Change: Inevitable Surprises', 2002). This is of crucial 
importance for policy reasons as any risk assessment framework to determine 
what is a "dangerous level of interference in the climate system" (aim of 
the UN Framework Convention on Climate Change is to avoid same) must put 
weight on large/catastrophic impacts even if their probability is small but 
finite in the next century or more.

(i) As many of you will be aware, one of the risks is that global warming 
might bring on a slow-down or complete cessation of the North Atlantic 
Thermohaline Circulation due to rapid freshening of the high latitude North 
Atlantic from increased rainfall and river inflow and reduced sea ice 
cover. The same effect may occur in the Southern Ocean also, mainly from 
retreat of sea ice. There is some evidence for such effects beginning 
already from measurements of deep ocean temperatures and salinity, although 
attribution is difficult (refs. in AGO book, p.39).

There is growing concern that such an event will, like the Younger Dryas, 
lead to 5-6dC cooling of western Europe, relative to the rest of the world, 
and perhaps more widespread effects. See for example 'Abrupt Climate 
Change' by the Director of Woods Hole Oceanographic Institute, Robert 
Gagosian, available at 
www.whoi,edu/institutes/occi/currenttopics/climatechange_wef.html. and 
Project Rapid Climate Change (http://www.soc.soton.ac.uk/rapid/rapid.php). 
which is jointly funded by the US National Science Foundation and the UK 
NERC. Again, the YD is seen as a prime analogy, although there are 
important differences, but that did occur in some few decades and caused a 
change which persisted for 1200 years. It recovered then because 
Milankovitch forcing led to a recovery, but that may not be the case now. 
Also, the favoured cause of the YD event was in the North Atlantic only, 
whereas now it could be in the Southern Ocean as well.

Key policy-related questions which arise are how rapidly we could enter 
such an event, would we recover, and would it take western Europe seriously 
below present temperatures, and (from the view of whether the likelihood 
would draw the US into a change of policy) how seriously would such an 
event directly affect North America?

As to whether western Europe would get colder than now, that seems likely 
to depend on how rapid global warming occurs, and how soon and complete is 
the slow-down of the NATHC. Rapid warming, according to climate models, is 
more likely to lead to a complete breakdown, and if a breakdown occurs in 
the next century it would almost certainly take western Europe below 
present temperatures.

My question to Aqualist people is, can you comment in general, and provide 
references for impacts on, particularly, North America (USA) and Australia 
of the YD or similar rapid climate changes in the past (the Antarctic 
Reversal perhaps?).

(b) There are other rapid climate change concerns also arising from the 
paleo-record. One is rapid disintegration and melting of the Greenland ice 
sheet due to aspects of ice dynamics not yet modelled, viz., penetration of 
surface melt water into the ice cap leading to lubrication of the glacial 
movement. James Hansen is the most prominent advocate of this possibility, 
and his recent article in Scientific American, vol.290, 68-77 (2004) and 
longer writing on this at 
http://pubs.giss.nasa.gov/abstracts/2004/Hansen1.html documents the idea. 
The rapid break-up of the Larsen B ice shelf may be related (see my AGO 
book, p.35-36), as if this were to occur further south it could affect the 
West Antarctic Ice Sheet. This may be heretical stuff, but it is plausible 
and must be considered.

The other is rapid release of methane (a strong greenhouse gas) from that 
trapped in hydrates on the continental shelves. There is a lot of methane 
there, and some past evidence for its rapid release (see 'Methane Hydrates 
in Quaternary Climate Changes: The Clathrate Gun Hypothesis', by James 
Kennett et al., American Geophysical Union, 2003, 210+ pp., see 
www.agu.org). This source of methane is already being explored for 
potential exploitation by a US/Canada/Japan consortium, see 
http://gashydrate.nrcan.gc.ca/mallik2002, and a 2-page Fact Sheet is 
available from the US Geological Survey via the foregoing website. Warming 
and sea level rise may trigger instability in this store of methane.

So, any comments on these two possibilities from the paleo-perspective 
would also be welcome.

Best regards to all,

Barrie Pittock.



Dr. A. Barrie Pittock
Post-Retirement Fellow, Climate Impact Group
CSIRO Atmospheric Research, PMB 1, Aspendale 3195, Australia
Tel: +613 9239 4527, Fax: +61 3 9239 4688, email: <barrie.pittock at csiro.au>
WWW: http://www.dar.csiro.au/res/cm/impact.htm
Climate Change: An Australian Guide to the Science and Potential Impacts, 
ed. Barrie Pittock, 2003 (1.4Mb): 
http://greenhouse.gov.au/science/guide/pubs/science-guide.pdf

Note: The old <abp or barrie.pittock at dar.csiro.au> is no longer supported.

Currently I am working on a couple of books and other writing re science 
issues. Please refer any matters re the Climate Impact Group to Dr. Penny 
Whetton, Group Leader, at <penny.whetton at csiro.au>, tel.: +61 3 9239 4535. 
Normally I am in the lab Tuesdays and Thursdays.

"Far better an approximate answer to the right question which is often 
vague, than an exact answer to the wrong question which can always be made 
precise." J. W. Tukey