[Global Change: 3869] The Pacific Ocean drives climate much more dramatically than the reverse
Robert I Ellison <robert <at> robertellison.com.au>
2011-01-16 01:10:15 GMT
Greetings from the flood zone. I am fine - thank you - but
traumatised by the deaths and angered and saddened by idiots who seek
to make a political point out of tragedy. Both sides of this argument
are full of shit - intellectual featherweights who are instant
internet experts on everything and are utterly convinced of their own
logical infallibility. Both sides angling to blame the deaths and
destruction on the other. I wish they would pull their f....... heads
in.
Rant over - I thought I would see if I could put a ruler under 20
years of work. Neither the floods or the current La Nina are notably
unusual over the longer term - it is part of a Pacific decadal pattern
that is likely to lead to decades more intense and frequent La Nina.
see - http://www.earthandocean.robertellison.com.au/index.html
As an Australian hydrologist, I was introduced to the concept of
drought dominated and flood dominated regimes (DDR and FDR) in the
late 1980’s. These are 20 to 40 year periods dominated by droughts
followed by a 20 to 40 year period dominated by floods. The original
result was replicated dozens of times across Australia in the
following decade. In 1997 the Pacific Decadal Oscillation was
described defining a link between sea surface temperatures and
fisheries biology. The periods of the PDO modes were exactly the same
as the periods of DDR and FDR. An apparent but astonishingly odd link
between North American fisheries and Australian rainfall. Over the
following decade it emerged that the PDO is part of a pattern of
decadal and longer changes in sea surface temperature in the Pacific
Basin with teleconnections to Asian, Australian, African and American
rainfall - and seemingly to the formation of cyclones in the
Atlantic.
In 2003 I made the mistake of looking closely at the Climatic Research
Unit surface temperature record - and saw that the inflection points
are at exactly the same periods as the transitions between DDR and FDR
and between PDO modes. Still looking for the causes of DDR and FDR I
read nearly everything that emerged on the PDO and the El Niño
Southern Oscillation (ENSO). However, without much of an idea
anywhere of causative mechanisms, there was not much more than an
intriguing similarity in the timing of changes.
More recent work has identified the Pacific Ocean climate system as
chaotic. As I eventually realised, chaos is not just a word but a
property of complex and dynamic systems in chaos theory. It explains
abruptness in the changes observed in ocean states and therefore in
global temperature and in the transitions of Australian rainfall
regimes. It changes the way in which climate risk is viewed. Where
before, climate evolved slowly with cycles of minor warming and
cooling in a system that is far from driven solely by greenhouse gas
forcing. After chaos theory, climate change is abrupt and predictable
only as a probability density function. There is objectively a small
risk of catastrophic climate change (warming or cooling) that could
happen within months as a result of anthropogenic greenhouse gas
emissions.
Currently, revisions to existing satellite records, new data sources
for radiative flux and ocean heat content, new theoretical work and
computer modeling and new compilations of surface cloud observations
are providing new ways of confirming a Pacific Ocean influence on
global climate. The picture that emerges is of the Pacific Ocean as
far and away the major driver of global climate. It does this
primarily by changing cloud formation dynamics. More cloud forms
above cold water - and the biggest change to sea surface temperature
on interannual, decadal and millennial scales occurs as a result of
upwelling of cold and nutrient rich (and also acidic) sub-surface
water in the eastern Pacific. These changes in cloud cover are seen
in surface observations of cloud over the Pacific, in satellite
measurements of reflected shortwave and outgoing long wave radiation
and in modeling studies. Most recent climate change has been as a
result of changing cloud cover.
And the cause of these changes? A small change in the initial
conditions of a complex and dynamic system that most probably involves
top down forcing by solar UV heating of ozone in the upper
atmosphere. As Judith Lean says - ‘ongoing studies are beginning to
decipher the empirical Sun-climate connections as a combination of
responses to direct solar heating of the surface and lower atmosphere,
and indirect heating via solar UV irradiance impacts on the ozone
layer and middle atmospheric, with subsequent communication to the
surface and climate. The associated physical pathways appear to
involve the modulation of existing dynamical and circulation
atmosphere-ocean couplings, including the ENSO and the Quasi-Biennial
Oscillation.'
Cheers
Robert
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