http://www.sciencemuseum.org.uk/exhibitions/energy/site/EIZCaseStudy18Item2.asp

http://www.windows.ucar.edu/sun/Solar_interior/Nuclear_Reactions/Fusion/dt_fusion.gif

Middle-aged Sun 4.6 Billion years old

http://en.wikipedia.org/wiki/Image:Sun_Life.png

http://astronomy.nju.edu.cn/astron/AT3/AT31709.HTM

The Faint Young Sun Paradox. Solid line is solar luminosity relative to present (S/S0). Ts is Earth’s surface temperature and Te is Earth’s effective radiating temperature. Thick vertical bars are glaciations. SOURCE: Modified from Kasting and Catling (2003).

http://www.nap.edu/books/0309095069/html/64.html

A faint young sun~4 billion years ago the sun was 70% as luminous as today

http://www.scotese.com/images/precamb_events.jpg

http://www.resa.net/nasa/images/mars/stromatolites.jpg

The Faint Young Sun Paradox. Solid line is solar luminosity relative to present (S/S0). Ts is Earth’s surface temperature and Te is Earth’s effective radiating temperature. Thick vertical bars are glaciations. SOURCE: Modified from Kasting and Catling (2003).

http://www.nap.edu/books/0309095069/html/64.html

Less solar radiation (70 W/m2)so Earth should be frozen, BUT it wasn’t!

The Faint Young Sun Paradox. Solid line is solar luminosity relative to present (S/S0). Ts is Earth’s surface temperature and Te is Earth’s effective radiating temperature. Thick vertical bars are glaciations. SOURCE: Modified from Kasting and Catling (2003).

http://www.nap.edu/books/0309095069/html/64.html

Less solar radiation (70 W/m2 less) so Earth should be frozen, BUT it wasn’t!

What compensated for theWeak radiation (heat)?

The Faint Young Sun Paradox. Solid line is solar luminosity relative to present (S/S0). Ts is Earth’s surface temperature and Te is Earth’s effective radiating temperature. Thick vertical bars are glaciations. SOURCE: Modified from Kasting and Catling (2003).

http://www.nap.edu/books/0309095069/html/64.html

Less solar radiation (70 W/m2 less)so Earth should be frozen, BUT it wasn’t!

What compensated for theWeak radiation (heat)?

Compensation ON Compensation OFF

http://www.huxley.ic.ac.uk/Local/EarthSciUG/ESFirstYr/EarthMaterials/mrpalmer/EarthMaterials/earth/earth1/f4.gif

Heat from below – Geothermal heat

http://www.huxley.ic.ac.uk/Local/EarthSciUG/ESFirstYr/EarthMaterials/mrpalmer/EarthMaterials/earth/earth1/f4.gif

Heat from below – Geothermal heat

0.3 W/m2 more heat….

Not enough to make up for 70 W/m2 less solar heat.

Maybe enough to keep the deep ocean from freezing.

What about albedo? Was it much lower in Earth’s early history?

What about albedo? Was it much lower in Earth’s early history?

Redistribute the Carbon – put more Carbon in atm

Super greenhouse world

Super greenhouse world

But where did all the atm CO2 go?

So where did the CO2 come from that isn’t still supplying it at the same rate today?

So where did the CO2 come from that isn’t still supplying it at the same rate today?

So early Earth had more volcanic outgassing.

Why didn’t the CO2 that was emitted early on just build up in atm?

Must be more to the story….

Is anything removing the atm CO2 that didn’t before?

Carbon in the Earth

Super greenhouse world

Earliest life

Super greenhouse world

Earliest life

Once the continents are built then they can be chemically weathered – this removes atm CO2

Long Term Climate Thermostat = Chemical weathering of continents

What type of feedback is this?

So volcanic outgassing was the main input of CO2 in early Earth

and chemical weathering was the main drawdown of atm CO2.

limestones

The Faint Young Sun Paradox. Solid line is solar luminosity relative to present (S/S0). Ts is Earth’s surface temperature and Te is Earth’s effective radiating temperature. Thick vertical bars are glaciations. SOURCE: Modified from Kasting and Catling (2003).

What about life? What role did it play in atmospheric evolution of Earth?

http://www.eas.slu.edu/People/CEGraves/Eas138/fg02_18.jpg