# [ExI] Fwd: 98% hoax

spike spike66 at att.net
Mon Sep 5 00:48:43 UTC 2016

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From: extropy-chat [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of William Flynn Wallace
Sent: Sunday, September 04, 2016 4:07 PM
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: Re: [ExI] Fwd: 98% hoax

BillW, it is extremely difficult to deny that man causes global warming.  What we don’t know is how much of the observed global warming is man-caused.  1%?  10%  20%?  80%?  100%?  That part is unknown.

spike

Yes, well, it's being done by my friend.  What can convince her?  bill w

Why do you need to?  Do you know the answer to the question of how much?  Do any of us?

Here’s one idea: we know the input from the sun, we know the greenhouse value of CO2, we can estimate if all else is equal, how much the increasing CO2 level should be increasing temperature.  But all else is unequal, for the observed warming is lower than would be expected if we use only that one term.  So we start to refine our model.  We can add in a term for increasing surface temperature causing increased evaporation from the sea, which absorbs energy and increases clouds which scatters incoming solar energy into space and traps heat down at the surface.  That term is net negative (would cause global cooling.)  Then we work in a term for reduced albedo from increased plant growth (from higher CO2 levels and calculate a theoretical impact of that.  Then add in the impact on albedo of increased rainfall or decreased rainfall (in some cases) add in a term for increased alpha T^4 from Stefan-Boltzmann’s law, and estimate the impact of increased wind, which seems to me like would increase evaporation off the surface of the sea, and increased albedo from higher snowfall from increased evaporation in some places and lower snowfall in other places from higher temperatures, increased this and decreased that and unknown effect of the other.

Pretty soon you come to the same conclusion I did: human activity does cause global warming, but we don’t know what fraction of global warming is human caused.  Estimates vary wildly and can even go negative in some models (human activity causes global cooling or slows natural global warming) and can go over 100 percent (the planet would be cooling naturally but human activity is causing it to warm.)

With that, we get the odd situation we now see: denial of any impact by human activity is one simple extreme.  The other is assuming all observed global warming is human caused, which is a perennial political favorite (perhaps because it is simple.)  But that assumes the planet’s climate never changes without human activity, which we know is not the case, and invites comparison to Mars which is currently thought to be warming presumably without human intervention.

So what happens if we generally agree that human activity causes global warming but no really one knows how much?

spike

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