Why do you say that a 1.5 to 2C change over 100 years is tiny,
Martin? I would have thought a temperature change of that magnitude
is quite significant.
Anyhow, the article in question is available at
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1353.html
The abstract is as follows:
"Enhanced warming over the global subtropical western boundary currents
• Lixin Wu, • Wenju Cai, • Liping Zhang, • Hisashi Nakamura, • Axel
Timmermann, • Terry Joyce,• Michael J. McPhaden, • Michael Alexander,
• Bo Qiu, • Martin Visbeck, • Ping Chang • & Benjamin Giese
Nature Climate Change (2012) doi:10.1038/nclimate1353Received 06 May
2011 Accepted 30 November 2011 Published online 29 January 2012
Subtropical western boundary currents are warm, fast-flowing currents
that form on the western side of ocean basins. They carry warm
tropical water to the mid-latitudes and vent large amounts of heat and
moisture to the atmosphere along their paths, affecting atmospheric
jet streams and mid-latitude storms, as well as ocean carbon uptake1,
2, 3, 4. The possibility that these highly energetic currents might
change under greenhouse-gas forcing has raised significant concerns5,
6, 7, but detecting such changes is challenging owing to limited
observations. Here, using reconstructed sea surface temperature
datasets and century-long ocean and atmosphere reanalysis products, we
find that the post-1900 surface ocean warming rate over the path of
these currents is two to three times faster than the global mean
surface ocean warming rate. The accelerated warming is associated with
a synchronous poleward shift and/or intensification of global
subtropical western boundary currents in conjunction with a systematic
change in winds over both hemispheres. This enhanced warming may
reduce the ability of the oceans to absorb anthropogenic carbon
dioxide over these regions. However, uncertainties in detection and
attribution of these warming trends remain, pointing to a need for a
long-term monitoring network of the global western boundary currents
and their extensions."
The point remains that a lot of pelagic birding occurs along the East
Australian Current and a 2C warming may have a significant impact on
marine activity off SE Australia.
Regards, Laurie.
On 31/01/2012, at 8:52 PM, Martin Wigginton wrote:
Yes, I agree with Laurie that we should welcome any study that seeks
to obtain REAL data. With such tiny differences in ocean
temperatures, it might be difficult to detect impacts on bird
distributions. Nevertheless, real data is the stuff that counts.
But flawed studies such as Wenju Cai's ocean 'hot-spots' give the
game away when they state:
“Detecting these changes has been hindered by limited observations
but with a combination of multi-national ocean watch systems and
computer simulations we have been able to reconstruct an ocean
history…”
We should view with considerable scepticism studies such as these
which rely so heavily on computer modelling to reach what is clearly
a pre-determined conclusion.
See also
http://wattsupwiththat.com/2012/01/30/oh-noes-wind-driven-global-warming-hot-spots/
------------
Martin
*All outgoing mails scanned by Norton Anti-Virus 2011
-----Original Message----- From: Laurie Knight
Sent: Tuesday, January 31, 2012 7:58 AM
To: Birding Aus
Subject: [Birding-Aus] Impact of climate change on pelagic birding
There are some interesting articles reporting rapidly rising
temperatures in key ocean currents - scientists compared "five ocean
currents that run along the east coasts of Africa, Japan, the USA,
Brazil and Australia" and "that over the past century the water in the
currents has warmed two to three times faster than the rest of the
world's oceans." <http://www.abc.net.au/worldtoday/content/2012/s3418386.htm
These temperature changes will affect the distribution of marine life
and I suspect are likely to impinge on the distributions of pelagic
bird species. It would be an interesting exercise to overlay species
sightings with sea temperatures and to see how bird distributions
change over time.
Perhaps a thesis topic for someone ...
Regards, Laurie.
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