On 12/26/2011 9:42 PM, John Clark wrote:
On Mon, Dec 26, 2011 at 4:56 PM, meekerdb <meeke...@verizon.net
"What law of physics do they [ Dyson spheres] violate?"
Professor Dyson certainly didn't think his spheres were unstable and he was pretty
smart, exactly where do you think he went wrong?
"We have the technology right now to build Thorium fission reactors that
us far more energy than oil ever could."
"But do we have the will?"
Not if environmentalists have their way, there solution is we all freeze in the
I'm an environmentalist and my solution is (a) efficiency (b) liquid thorium reactors (c)
renewable energy and (d) lower population. Do you see any non-environmentalist doing
anything except mining coal and digging tar sand?
"But there's good reason to think that 3degC hotter would be a very bad
There would certainly be big changes, but overall would it be a bad thing? I'm not so
sure, far more people freeze to death than die of heat stroke, and anyway it will be a
very long time before we see a massive 3 degree C increase.
Sure, 1degC would probably be a net improvement. The problem is that we're on a course
for 3degC or more and accelerating.
"and I don't think a Venusian runaway can be ruled out".
I think it can be ruled out. During the late Ordovician period, 450 million years ago,
there was a HUGE amount of CO2 in the atmosphere, about 4400 ppm verses 380 today, and
yet the world was in the grip of a severe ice age. During the last 600 million years the
atmosphere has almost always had far more CO2 than now, abut 3000 ppm on average. The
only exception was a period that lasted from 315 million years ago to 270 where there
was about the same amount of CO2 as we have now. The temperature was about the same then
as it is now too. During the late Ordovician that I mentioned it was much colder, but
other than a few very brief ice ages during the last few million years the temperature
has always been warmer than now and occasionally MUCH warmer; at least that's the way
things have been during the last 600 million years.
Jim Hanson points out there is uncertainty on the order of 1000ppm regarding the ancient
atmosphere. This, combined with other positive feedback factors like methane from bogs
and hydrates doesn't allow much confidence in ruling out a runaway.
It's not surprising that environmentalists make exaggerated claims, it's the way they
stay employed. and without scare tactics many environmental groups would be out of
And it's not surprising that nobody who's comfortable wants to take seriously a problem
that might upset their world.
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