Do you think Tau Ceti e is inhabited?

[James Kerman]

41 minutes ago, magnemoe said:

Not talking about the ice moons but exoplanets. Bacteria under the ice will require an landing and an dive. 

Sorry, Mate, I misunderstood.

[DDE]

On 2/11/2019 at 9:27 PM, Green Baron said:

Another interesting question is, if there was a global ice age (the earth near its equilibrium temp), how did the earth get out of it ?

Ditto for periods of extreme global warming. The Great Dying comes to mind.

Dammit, Siberia.

[KerikBalm]

On 2/12/2019 at 2:06 PM, Green Baron said:

The assumed lack of biogenically induced cloud nuclei (presented without explanation) does not exclude life. Essentially, the cited BIFs are assumed to be in vast parts the outcome of biological activity

You haven't defined your acronym BIF (Biologically induced Formation... of clouds?). Anyway, it need not exclude the presence of life... I'm just saying what you cited there doesn't argue that life was responsible for the warming.

And as for the radiogenic heating: note it was never argued that radiogenic heating was providing the heating to keep the Earth from freezing. The argument was that radiogenic heating was driving the outgassing and other geological processes that lead to a larger greenhouse effect, that trapped more heat from the sun's rays.

[Green Baron]

It is a common shortcut for banded iron formations (attention, wikipdia, not everything is necessarily correct :-)). I thought you knew. Kindly suggest to go through it, as these are very frequently used for the analyses of early life on earth and a climate indicator as well in various forms.

30 minutes ago, KerikBalm said:

 I'm just saying what you cited there doesn't argue that life was responsible for the warming.

Nor did i. But i did and do say that life as part of the natural evolution is hugely (not solely) responsible for the climatic stability of earth. I think we all agree here :-) Earth's endogenic factors (those below the crust) are often overrated in pop science, especially when it comes to short or medium term effects. They influence more the long term (10s and 100s of millions of years) processes.

Outgassing is a huge field. What brings CO2 back into the atmosphere these days ("modern style tectonics") is what has been dragged down before in subduction zones (and was built up by life forms as long as it was above surface), and this recycling style is thought of to be required for CO2 outgassing. The effect was probably even stronger in times when the crustal renewal processes were faster, e.g. during the Archaean, but i don't know if one can say that outgassing rates and for example mantle temp. are necessarily connected or if it is rather the speed of crustal processes that is responsible for CO2 out and in. I vote for the latter :-)

Edited February 13, 2019 by Green Baron