Re: "Washington Post Accidentally Admits Earth at Coolest Point in the Last 485 Million Years"

James Nicoll wrote:

In article <vd9rlv$1dcog$1@dont-email.me>,
William Hyde  <wthyde1953@gmail.com> wrote:

of direct observation does not agree with this view.
>
As to the current warming the question is academic, as the pattern of
warming shows us clearly that this is not due to  an increase in solar
output.

 Is this a good time to mention the faint young Sun paradox?
 For people unfamiliar with it, is the question of how to
reconcile the young sun being 30% dimmer with the young Earth
having liquid water. All things being equal, the Earth should
have been well below freezing (on average) but it wasn't. So
all things weren't equal.

Always a fascinating topic for me.
This is not resolved, but the most common idea is that the thick atmosphere of the young earth, filled with CO2, H20 and possibly other infrared absorbers (NH3, for example) kept the earth warm. But there is no consensus on the composition of that atmosphere.  Perhaps there wasn't much in the way of greenhouse gases.
Long ago Dirac came up with an idea, not often mentioned, that certain fundamental constants of the universe change over time, while maintaining constant ratios with one another.
One of these constants was G, which according to this idea should decrease over time.  Petr Chylek mentioned this idea to me, and I was intrigued because solar output varies as G**7 according to a monograph by A. D. Vernekar.
Using a simple climate model I was able to put an upper limit on the Dirac change by considering the early earth.    If the greenhouse effect of that atmosphere was zero, a given increase in G would account for early climates, a larger one would make the earth too warm.
I went through a bit of a career change at the time and the work, though presented at a number of seminars, was never submitted for publication. As there is (or was at the  time) little interest in Dirac's idea it would have been difficult to get it in print anyway and more recent ice ages beckoned.
While looking for some online reference to Dirac's idea I was reminded yet again of how much Dirac actually did.  Even if he had never come up with the Dirac equation and predicted antimatter, he'd still have been one of the great scientists of the 20th century.
William Hyde