mozzaok wrote on Sep 7^th, 2010 at 1:25pm:


Now that's a variation on "the Butterfly Effect", that I haven't heard before.
http://en.wikipedia.org/wiki/Butterfly_effect

perceptions_now wrote on Sep 7^th, 2010 at 6:49pm:



Really perceptions??? You've never heard of the difficulty in predicting the behaviours of complex systems, due to small changes (or errors) having massive effects on the outcome???

Oh and Christ (if he existed at all ) was more likely a rebel trying to reclaim the secular throne from the puppet king the Romans had installed......

Since there is NO god, it's pretty unlikely it could have had a 'human' son.......

gizmo_2655 wrote on Sep 7^th, 2010 at 10:26pm:




Temperature

Over the last 400.000 years (but it was probably alike since the beginning of ice ages, in the early quaternary era), these astronomic variations have generated 4 cycles almost identical, lasting a little over 100.000 years each, during which it was cold for almost 100.000 years (the average temperature was 5° C lower compared to what it is today) then much warmer during 10 to 20.000 thousands year (corresponding to the present average temparure, more or less)

It is remarkable that over the last 400.000 years, the maximum of the yearly average of the temperature exceeded the present values by just 1 to 2 °C (average temperature on earth was then 16 to 17 °C compared to 15 °C today) ; the last time that we reached such values was 130.000 years ago.

A couple of important conclusions can be drawn from what preceeds :

We are already in a "warm" period regarding the natural evolution of our climate. If everything evolved in a "business as usual" context, we should get near the end of the present interglacial period ans the climate should have a natural tendancy to get cooler.

But such a cooling of the climate does not occur in a single century, even if the above graph seems "steep" when an ice age starts (going to the left). The fastest evolutions on the above graph are the loss of a couple degrees (Celsius) in ....5 to 10.000 years, whereas the present simulations predict a similar change in magnitude, the other way round, in.....one century. It is 50 to 100 times faster.Link -
http://www.manicore.com/anglais/documentation_a/greenhouse/past.html
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The current warming event started around 20,000 years ago, as the last Ice Age ended.
On the basis of past events, we are now overdue for the Peak in this warming cycle.
Then the next Ice Age cycle will begin. Future generations will see whether the onset of that Ice Age is over the usual time span or whether it will be faster.

OK,

Now let me answer your post. I was somewhat pre-occupied by real life last night

gizmo_2655 wrote on Sep 7^th, 2010 at 1:29pm:


Not nearly as many, but I'll explain in more detail in subsequent posts. Weather forecasting requires stochastic modelling. Compared to that, general circulation modelling is relatively straightforward and deterministic. They operate on pure deterministic physics. Most are built around the Navier Stokes equation.  I'll expand on that too if you want.

Meteorology uses some complex stochastic modelling, not unlinke Stockmarket models. It's a much tougher job to predict local short-term variations than overall trends.

I know what you mean by the butterfly effect (not the band). I've worked on General Circulation models and I've also seen Weather forecasting models in action. Which do you think take up the most Gigabytes?

Quote:


Good! I'm against that too. At least we agree on that. A strong economy will be necessary through all of this. As I said on another thread, our best allies may come from unlikely sources. (Like Bob Katter with his green corridor)

The worst enemies will probably come from the real deep greens, who I'm convinced want us to return to hippy communes and eating organically produced food. They are the ones who will sabotage the nuclear power plants that we'll eventually have to build (p_n - as an interim fix. I know it's not long-term).  

It's not even about saving the polar bears or the Great Barrier reef for that matter. It's about survival of our species and our way of life.

I like the fact that you are listening and I also like the fact that you don't have any eschatological misconceptions. Now if I can just find some time, I'll explain some more.

gizmo_2655 wrote on Sep 7^th, 2010 at 10:26pm:


I'd dispute parts of the highlighted analysis, but the explanation will take longer than this post.

We are in an interglacial, but most people with the exception of geologists use the terms "Ice Age" and glaciation interchangeably.

The actual terminology is not important. We can see from the ice core records that there is cyclic variation in global temperatures due to the Milankovich cycles. The actual period of those cycles changed about 1 million years ago from around 41,000 years to about 100,000 years.

The next glacial period is due in around 50,000 years. That will happen regardless of  what we do to the atmosphere in the next 100 years.

Again, it's all too easy to talk about a slow warming. You need to look at the actual data to see what is actually occurring. We can do that if you like.

muso wrote on Sep 8^th, 2010 at 11:10am:


Muso,
The highlighted area would be me, I think.

Perhaps there is a discussion about correct terminology, but whatever we call the various periods, one end is too bloody cold for a complex society such as we now have and the other end is too bloody hot!

Enough of the levity!

The facts are clear that -
1) We (humans) have impacted the recent part of this warming cycle.
2)  The Peak between the top of this warming cycle, compared to other recent gaps, shows that this current gap is already longer than usual.
3) As we have both said, it is certain that once the current warming cycle finishes, it will be followed by another Ice Age/Glacial period.
4) In my humble opinion, the sort of complex human society we see today, will have an uphill battle to survive the next Ice Age/Glacial period, whenever it arrives.

Video: 2010 Arctic sea ice update

Here is a discussion of Barber’s peer-reviewed research:  Where on Earth is it unusually warm? Greenland and the Arctic Ocean, which is full of rotten ice:  New study supports finding that “the amount of [multi-year] sea ice in the northern hemisphere was the lowest on record in 2009″

Related Post:
•Study: “It is clear … that the precipitous decline in September sea ice extent in recent years is mainly due to the cumulative loss of multiyear ice”:  Physicist: “If temperatures change just a few tenths of a degree then this oh-so-thin ice cap is doomed.”
Link -
http://climateprogress.org/2010/09/13/video-2010-arctic-sea-ice-update/
============
It has been said that science could be wrong on Cliamte Change and that is entirely possible, science & scientists are by no means perfect.

That said, in addition to the risks being over-stated, it could be that the risks may be under-stated?