On Friday, June 15, 2018 at 10:43:29 AM UTC-6, Mike Collins wrote:

Gary Harnagel wrote:

Since the earth is 71% ocean and 29% land, and only 3% of the land is
covered by infrastructure (including roads), that could have at most a
1% change in insolation. But it would be less than that because the
of ocean is 0.07 and the albedo of land is about 0.2

http://curry.eas.gatech.edu/Courses/...do_Surface.pdf

(Table 3), so most of the earth's insolation comes from the oceans.

Shall we paint the oceans white? :-)

Was it you, John, that mentioned a project in Europe covering many
hectares with used plastic film? Seems like space-based mylar mirrors
in stationary orbit over the oceans would be a way to go ...

Gary


No that was me.

Sorry, Mike. Guess I need to get some Prevagen :-)

And it wasn’t a project. It was just farmers using greenhouses ( often
makeshift) to grow crops. You may not be aware of a similar effect in the
USA.

http://www.sciencemag.org/news/2018/...ts-own-weather

Thanks, Mike, that's VERY interesting, although some of the speculation
about what is causing it seems counter-intuitive. For example, they say
it might be due to photosynthesis releasing H2O, but H2O is a greenhouse
gas and should have an opposite effect.

But other crops can have the opposite effect and cause warming.

Their photosynthesis DOESN'T release H2O? :-)

The takeaway, then, is grow more corn?

At a large scale crops can affect CO2 as demonstrated by the fall in
atmospheric CO2 from the rapid regrowth of the Amazon forest after the
population collapse. This ended the medieval warm period.

The end of the Medieval warm period was coincident with other processes,
too, one being large volcanic eruptions around the world. Such eruptions
produce lots of greenhouse gas, so wouldn't that offset the rainforest
growth effect? The Maunder minimum didn't occur until later, but it may
have exacerbated the situation.