Dear Alistair,
> Yes, but your link refers to the entry into the Younger Dryas when
> temperatures dropped. If you look at the figure on your web page of
> the Younger Dryas you will see there was an even larger jump, to a
> higher temperatures at the end of the Younger Dryas. If we are
> warming the Earth with CO2 will the jump be to a cooler state or to a
> warmer state?
I don't know - I am inclined to think that cooling is more likely -
simply because we at a Quaternary warm extreme. What factors are
implicated in a switch from warm to cold? Not known with any
certainty.
> It is claimed by everybody that we know why there was a sudden cooling
> - the draining of a pro-glacial lake stopped the THC. But what caused
> the sudden warming - did a pro-glacial lake fill from the Atlantic?
> Even if the cause was a resumption of the THC why was it so sudden?
> And if fresher water in the Arctic is going to cause an ice age, why
> didn't we flip into one during the Little Ice?
>
> It seems to me more likely that the draining of Lake Agassiz caused
> the GIN (Greenland, Iceland, and Norwegian) seas to freeze over. Fresh
> water has a higher freezing point than salty. It was the ice cover
> which caused the cooling, and the stopping of the THC. When that sea
> ice melted suddenly due to the ice albedo effect, the climate suddenly
> warmed and the THC resumed. The THC is a symptom not a cause. When the
> Arctic sea ice disappears it will do so suddenly, and temperatures
> will jump due to the change in albedo.
>
> That is a chaotic system with positive feedbacks (e.g. ice-albedo) and
> non-linear effects such the surface warming when ice melts. And it is
> predictable to an extent - when will the ice disappear?
Facile and specious reasoning. You assume that the details of events
that happened 12,000 years ago can be known with any certainty. Some
things are known approximately through proxies. Many elements can't
be known with any confidence. You need to assess the quality of data
and the limits of knowledge. You construct scenarios based on one
dimensional concepts of climate dynamics.
> - I came across an aphorism form Neils Bohr - one of the original
> - quantum physicists. 'Prediction is very difficult, especially if
> it's
> - about the future.' Most people have been thinking about climate as
> - ordered forcing by greenhouse gases on one side or natural climate
> - cycles that come and go like the seasons on the other.
>
> Well that is where they go wrong. Climate is both forcing by
> greenhouse gases AND natural cycles. In fact the greenhouse effect is
> secondary to the solar cycle.
> - Climate is a cascade of
> - powerful systems - ice, cloud, dust, oceans, heat transport,
> - atmosphere, biology - that is characterised by abrupt, rapid and
> - sometimes extreme climate change. Classic behaviour of a dynamic and
> - complex system in chaos theory.
>
> - Climate is a chaotic system and it is free to jump around like a
> - spinning top on a rough surface - limited only by the strange
> - attractor phase space topography.
>
> No, chaos does not necessarily mean random. It is actually stable with
> bounds.
There are multiple equilibria - it is not stable but jumps around
unpredictably. It is by theory 'chaotic'. There are no bounds unless
by which you mean 'strange attractors'. But there is no guarantee
even that climate phase space is stable. "Stable with bounds' is an
absurd characterisation.
> - I have to admit I was much more
> - sanguine about climate change when I thought there were climate
> - cycles.
>
> Well I don't think you are unusual. The problem is to get others to
> accept that climate is not only driven by natural cycles.
>
The political problem is that the planet is not warming as a result of
1 possible equilibria state - the possibility is that this will
continue for another decade or 2. Both sides are wrong in this debate
because you insist on thinking in terms of simple cause and effect.
Robert
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