Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not involved

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Where did they conclude that?

This press release refers to one point in time, 3.8 billion years ago.

A chart if CO2 levels that I'm looking shows high levels 0.5 billion years ago, a difference of more than 3 billion years.

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Who's going to quibble over a few billion years?



Tom

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Who are "they"? If by "they" you mean Fox News and whatever denier site you get your information from....then yes, "they" have always had the assumption that there's no global warming and "they" have to grasp at straws to confirm their assumptions.

If you actually bothered to read the conclusions of the scientists, they're discussing the prehistoric models of the Earth during abiogenesis. They are claiming that there were less CO2 levels then what was thought. The dynamics of the atmosphere are obviously different now that there's complex life on Earth. This was before there was multicellular organisms like plants and animals. So of what relevance is this now? Besides, I thought your demagogue was Dr Seitz. The same guy that was claiming smoking is good for your health.

I'm still waiting to hear your theory about what the current CO2 levels have to do with the source of fossil fuels (from the other GW thread) My suggestion, spend less time looking at anti-global warming sites on the web and go take some science classes. If not that, at least talk to a real life scientist.

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Your conclusion is quite a disconnect from the actual research.

They're talking about conditions that existed before there were large continents and before multi-celled life existed. What this shows is that there's more than one way for global warming to occur, which we already knew anyway, just not really this particular variation on it. This article certainly does not disprove AGW in any way or is even relevant to that, other than giving them more test data to improve their models.
(I'm already waiting for the articles when you discover the 'Snowball Earth' time period).

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

I have read that paper and it is quite a challenge for a non-minerologist to summarize. So others may wish to improve upon the following:

1. Rosing et al. have used mineral phase relationships to constrain atmospheric CO2 to about 3 times the current level, and methane about 300 times current.

2. Based on what the solar output probably was, and based on well-known infrared absorbances of those gases, the surface temperature would have been below the freezing point of water. So they looked at other components of the earth's energy balance.

3. At those times, there was (probably) less land mass above sea level, and (certainly) less biological source of cloud-condensation nuclei. Therefore, global albedo was low - I percieve this as a 'mostly blue' planet with not so much 'white' (clouds).

4. Modeling that (which might give pause to those who doubt contemporary climate models), they conclude that surface temperatures would have been above freezing. So, the ocean would have been liquid, as strongly argued by other evidence.

I found no indication in the paper that the energy-balance effects of CO2 and methane were treated differently than in contemporary climate models. They worked with CO2 concentrations lower than others had supposed for those times, but higher than now. Methane, substantially higher than now. It is prhaps unfortunate that the Science editor's summary of the work says "Minik Rosing et al. suggest that there is no need to invoke greenhouse warming". It would, I think have been more appropriate to say that with this revised early-earth albedo, there is no need to invoke atmospheric CO2 concentrations 70 times higher than current, to keep the ocean unfrozen.

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Thanks that makes more sense.

Now the big question? Are there practical ways to reflect the suns rays to reduce this heating without causing a bigger environmental problem.

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Google "cool roof".

White roofs are helpful, and are rapidly becoming the norm for new construction here (Virginia). My daughter's school just had the roof replaced, and the county government went for white. My church just replaced the roof of our administration building, ditto. For commercial (membrane-type) roofs, the word is getting out that white roofs have lower lifetime costs than black roofs, at least in the South. In California, it's code for commercial flat-roof construction: put on a white roof or beef up the roof insulation. DOE says white roofs reduce utilities costs as far north as Chicago (depending on the exact configuration of roof, insulation, and building).

Here's the DOE calculator.
DOE Cool Roof Calculator for Low-Slope or Flat Roofs

For shingle roofs, new products are coming out that have high reflectance and high infrared "emissivity" -- so they reflect light and shed heat. A traditional "white" shingle actually reflects maybe 25% of the light hitting it. The newer ones roughly triple that.

Tests show mid-summer roof temperature reductions on the order of 50F, from (say) 160 to 110. That difference is hard to grasp until you experience it.

I coated the roof of my (large) flat-roofed porch with Henry 287, available from Home Depot:
Henry 5-Gallon 287 White Roof Coating - HE287SF871 at The Home Depot

They claim 90% reflectivity when new. All I can say, the roof was actually painful to look at in sunlight -- worse than being out in snow. Sweated through the first coat, didn't sweat at all doing the second coat -- because the roof wasn't black. Cool stuff.

You can't use elastomeric (as above) on a shingle roof, but Berh paint (and I guess others) makes paint formulated for painting asphalt shingle roofs. I'm still going back and forth with my wife about painting the roof of the house. Think I'm going to try it on the garage, see how it looks and lasts.

"Cool neighborhoods" is the same concept, but applied to pavement as well. Fresh asphalt has an albedo of about 0.05, weathered asphalt of about 0.2. Concrete can be made "white" and will have a modestly higher albedo. Basically, the notion is, minimize your large black surfaces (duh).

Edit: Attached are Google Maps shots of the school before and after re-roofing.

 

Re: Early Earth stayed warm because its ocean absorbed more sunlight; greenhouse gases were not invo

Edit: Duplicate post