Dear James,
There are decadal changes that are 'captured' by indices. These are
not cycles - but are emergent behaviour of a dynamic complex system
that are inherently unpredicatable.
The proximate cause of the lack of warming in the past decade is the
Earth albedo changes captured by both Project Earthshine and the
ISCCP. About a 2.7 W/m2 decrease in short wave radiation hitting the
surface since 1999 - with especial implications for the thermal
evolution of ENSO. Will this change again - yes. But when can't be
known. As I said - we are looking at greenhouse gases increasing
climate instability and the potential (evidenced in reality) for
abrupt climate change on decadal timescales. It could get cooler
again - we could get back to the cloud cover - and therefore albedo -
of 1984. We have been treating clouds as a global warming feedback -
but essentially the reasons for observed cloud dynamics are obscure.
The risk is in not acting to reduce carbon emissions - but people (the
majority everywhere) are only seeing that the planet is not warming as
predicted (I know some people are insisting that it is - but I cant
stop insanity). Making a bet with me will not change that.
Cheers
Robert
Arctic Oscillation
‘The oscillation exhibits a ‘negative phase’ with relatively high
pressure over the polar region and low pressure at mid latitudes
(about 45 degrees North), and a "positive phase" in which the pattern
is reversed. In the positive phase, higher pressure at mid latitudes
drives ocean storms farther north, and changes in the circulation
pattern bring wetter weather to Alaska, Scotland and Scandinavia, as
well as drier conditions to the western United States and the
Mediterranean. In the positive phase, frigid winter air does not
extend as far into the middle of North America as it would during the
negative phase of the oscillation. This keeps much of the United
States east of the Rocky Mountains warmer than normal, but leaves
Greenland and Newfoundland colder than usual.’
Weather patterns in the negative phase are in general "opposite" to
those of the positive phase. The AO is trending negative.
Atlantic Multidecadal Oscillation
‘Recent research suggests that the AMO is related to the past
occurrence of major droughts in the Midwest and the Southwest. When
the AMO is in its warm phase, these droughts tend to be more frequent
and/or severe (prolonged?). Vice-versa for negative AMO. Two of the
most severe droughts of the 20th century occurred during the positive
AMO between 1925 and 1965: The Dustbowl of the 1930s and the 1950s
drought.’
With a cool Pacific mode happening at the same time - a positive AMO
suggests widespread drier US conditions over a decade or more.
NAO Index
The negative NAO index phase shows a weak subtropical high and a weak
Icelandic low. The reduced pressure gradient results in fewer and
weaker winter storms crossing on a more west-east pathway.
They bring moist air into the Mediterranean and cold air to northern
Europe
The US east coast experiences more cold air outbreaks and hence snowy
weather conditions.
Bermuda-Labrador Basin Transport Index
The transport index estimates the strength of the baroclinic gyre
circulation in the North Atlantic, or the strength of the Gulf Stream
and North Atlantic Current system. It has been trending down for the
last decade.
Pacific Decadal Oscillation
The multi-decadal signal can be most easily seen in the Pacific
Decadal Oscillation (PDO). This a pool of water that shifts from cool
to warm modes over 20 to 30 years. It is marginally positive at 0.08
degrees C – but is currently in a cool mode that may persist for 2 to
3 decades from 2000.
The Pacific Decadal Oscillation (PDO) is a multidecadal climate signal
in the north east Pacific. Verdon and Franks (2006) used ‘proxy
climate records derived from paleoclimate data’ to investigate the
long-term behaviour of the PDO and ENSO. They found that ‘during the
past 400 years, climate shifts associated with changes in the PDO are
shown to have occurred with a similar
frequency to those documented in the 20th Century. Importantly, phase
changes in the PDO have a propensity to coincide with changes in the
relative frequency of ENSO events, where the positive phase of the PDO
is associated with an enhanced frequency of El Niño events, while the
negative phase is shown to be more favourable for the development of
La Niña events.’ The most recent El Niño is of moderate strength in
the ENSO monitoring regions. ENSO is a 2 to 7 year cycle but has
multidecadal changes in the intensity and frequency of ENSO events.
El Niño are less intense during cool PDO modes.
Enhanced fridig deep ocean upwelling over 20 to 30 years results in
increased heat uptake by the ocean from the atmosphere in acordance
with the 2nd law of thermodynamics.
On Jan 15, 3:22 pm, James Annan <[email protected]> wrote:
> Robbo wrote:
> > In the shorter term, all of the ocean/climate indices -
> >http://ioc-goos-oopc.org/state_of_the_ocean/all/- are indicating
> > cooling this year and over the next decade or so.
>
> I bet you a thousand UKP that the trend over the next decade is positive.
>
> James
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