Anthropocentrism

Andre

Let's do another one.

The idea that humans can and have had a big impact on climate is increasingly thriving. Apparently we are the central factor -Anthropocentrism. It started with Ruddiman who had produced a study His point is that the current Holocene shows an unique rise in carbon dioxide (measured in Antarctic ice cores) from some 255 ppm to 280 ppm. The other end of icing stadial spikes that indicate the start of interglacials show a (sometimes very) slow decline after the intial spike as seen here.

How come, well the paleolithic man started to change his environment, cutting down forests to build villages, burn fires and have land for agriculture. This would remove the carbon sink function and would increase the CO2 in the air.

So what do you say about that?

pattylou

Hi Andre!

Pretty depressing, eh? As I recall, we agree that deforestation is a "bad thing."

It sounds like you read the SciAm article (based on the timing of your post.) The original is 3 years old and speaks about rice paddies too.

What do I think? Either the idea is too far fetched, or it's right - in which case a runaway greenhouse seems inevitable.

What do you think?

Mk

Why is deforestation bad?

pattylou

becomes harder and harder to sequester carbon dioxide, whether the CO2 is produced by man or not. (IOW, the forests-are-good thing is easier to agree on than the source or causative ffect of CO2vs.warming.)

Well, deforestation also reduces habitat. That may be the basis for me and Andre agreeing that deforestation is bad, assuming that my memory is right and we agree that it's bad.

Yeah, I know, this is almost unreadable. Flag me if I don't make any sense.

Andre

Good to see you, Patty. Yes we agree, deforestation is bad for biodiversity, soil preservation, food chains and microclimate and some more. And the reason for the thread was this article (may be the same as the SciAm? another study.

It argues that the bubonic plague decimated the population in the medieval period reversed the antropogenic deforestation. They see concurent CO2 level changes in leaf stomata

Counting stomata (pores) on ancient oak leaves provided van Hoof's team with a measure of the fluctuations in atmospheric carbon dioxide for the same period.

"Between AD 1200 to 1300, we see a decrease in stomata and a sharp rise in atmospheric carbon dioxide, due to deforestation we think," says Dr van Hoof, whose findings are published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

But after AD 1350, the team found the pattern reversed, suggesting that atmospheric carbon dioxide fell, perhaps due to reforestation following the plague.

The researchers think that this drop in carbon dioxide levels could help to explain a cooling in the climate over the following centuries.

I had a discusion with the author showing him that his leaf stomata CO2 reconstruction, which correlated positively with ice cores, did not correlate with the more recent multiproxy climate reconstruction known as Moberg 2005 here.. This should put some question marks at that CO2 - global temperature relationship.

Moreover the period of interest of Ruddiman, the second half of the Holocene, shows similar patterns: rising CO2, lowering temperatures.

The graph shows the temperature reconstructions based on the Greenland Ice cores (black) and the Antarctic ice cores (grey) versus CO2 (red)

So CO2 is still not a major climate driver and I have loads of new evidence. But posts should not be too long. Interested?

pattylou

No, not particularly, though it's nice to see you as well. (Have you noticed that the conversations on message boards don't really go anywhere?)

I've enjoyed being less active on the internet and I don't wish to get too into message boards again.

Nothing personal.

Andre

Well hoping to see you around very occasionally.

Indeed conversations here are mostly a conflict of interest. Each party's objective being to make a point and being right, rather than a common desire to find the truth.

It's probably all about the observations of T.C. Chamberlin, (highly recommended to read in full)

The habit of precipitate explanation leads rapidly on to the development of tentative theories. The explanation offered for a given phenomenon is naturally, under the impulse of self-consistency, offered for like phenomena as they present themselves, and there is soon developed a general theory explanatory of a large class of phenomena similar to the original one. This general theory may not be supported by any further considerations than those which were involved in the first hasty inspection. For a time it is likely to be held in a tentative way with a measure of candor. With this tentative spirit and measurable candor, the mind satisfies its moral sense, and deceives itself with the thought that it is proceeding cautiously and impartially toward the goal of ultimate truth. It fails to recognize that no amount of provisional holding of a theory, so long as the view is limited and the investigation partial, justifies an ultimate conviction. It is not the slowness with which conclusions are arrived at that should give satisfaction to the moral sense, but the thoroughness, the completeness, the all-sidedness, the impartiality, of the investigation

That's why I'm trying to scrutinize everything.

The moment one has offered an original explanation for a phenomenon which seems satisfactory, that moment affection for [one's] intellectual child springs into existence, and as the explanation grows into a definite theory [one's] parental affections cluster about [the] offspring and it grows more and more dear ... There springs up also unwittingly a pressing of the theory to make it fit the facts and a pressing of the facts to make them fit the theory ..

Therefore, despite the apparant exhaustive dealing with the subject of Anthropogenic Global Warming, I would like to suggest one question whenever the next alarmist message emerges about sealevels glaciers, storms, what have you: "Suppose that the cause of that warming is something else than antrhropogenic greenhouse gas effect?".

And that something else can be found here: Fortunately a short thread.

pattylou

"Suppose that the cause of that warming is something else than antrhropogenic greenhouse gas effect?".

Well, that's easy. Then nothing we do will really matter - unless we identify the non-anthropogenic effect and reverse it somehow.

But, since we won't reach certainty that it is not anthropogenic (ie there will always be some concern that human activity contributes), it continues to make sense to try to reduce emissions, reduce population load, look at the long term consequences, and continue to try to research the situation.

We do have a much better understanding of climate than thirty years ago, after all, and that's because science has been trying to understand the factors that contribute to climate.

(I'm still not here. I mean it.)

Andre

Quote by pattylou

Well, that's easy. Then nothing we do will really matter - unless we identify the non-anthropogenic effect and reverse it somehow.

Well I guess that the (huge) albedo changes may or may not have cyclic interaction with ocean surface temperatures and for some reason that cycle is somewhat stronger than the last one in the 1940ies. But that's very tentative.

But, since we won't reach certainty that it is not anthropogenic (ie there will always be some concern that human activity contributes), it continues to make sense to try to reduce emissions, reduce population load, look at the long term consequences, and continue to try to research the situation.

We do have a much better understanding of climate than thirty years ago, after all, and that's because science has been trying to understand the factors that contribute to climate.

We could have a good understanding if it wasn't for the continuous attempt to overestimate the sensitivity to GHG forcing due to positive feedbacks. If there were positive feedbacks life at earth would have ceased to exist long time ago. As the albedo research suggests the feedback -actually gain- may be strongly negative or we're dealing with a gain of less than 0,5. With the psysical measurable (Stefan Boltzman) forcing of 0,7 degrees dynamically initially to 1,2 degrees steady state after some centruries for doubling CO2. The negative feedback would make that less than half. Which suggests that whatever good reasons there are to cutback emisions, climate is not one of them.

(I'm still not here. I mean it.)

Then, have a good time elsewhere.

scott1

Quote by Mk

Why is deforestation bad?

Because plants help take in the carbon dioxide we breath in and turn it into oxygen that we can breath.If hunans > plants that makes the air balance so we have less air to breath.
The Rain forest helps alot with truning carbon dioxide into oxygen and cutting them down would make things very unblanced.

Mk

Quote by scott1

Because plants help take in the carbon dioxide we breath in and turn it into oxygen that we can breath.If hunans > plants that makes the air balance so we have less air to breath.
The Rain forest helps alot with truning carbon dioxide into oxygen and cutting them down would make things very unblanced.

How quickly is it going? I remember Thomas Malthus wrote about the population bomb in the 1700s, which could've happened without technology.

Mk

Quote by Andre

Well I guess that the (huge) albedo changes may or may not have cyclic interaction with ocean surface temperatures and for some reason that cycle is somewhat stronger than the last one in the 1940ies. But that's very tentative.

Are they really huge or are you sarcasticizing?

I never read that paper somebody posted in the global dimming thread. I even saved it too.

Then, have a good time elsewhere.

Wow you guys civilly really don't like each other.

Andre

Quote by Mk

Are they really huge or are you sarcasticizing?

I never read that paper somebody posted in the global dimming thread. I even saved it too.

Yes they are, seriously, 10-11% is huge:

http://home.wanadoo.nl/bijkerk/albedo-temp.GIF
http://home.wanadoo.nl/bijkerk/albedo2.GIF

which gives Earth blackbody temperature variations of about 3 degrees Kelvin/Celsius, as I said, it dwarfs the greenhouse factor with only a few tenth C at the most.

you guys civilly really don't like each other.

No, your perception is wrong. Its just that I'm non native tongue and not very good at subtly conveying emotions. I do wish Patty all the best.

After all, running a family is priority #1.

Mk

which gives Earth blackbody temperature variations of about 3 degrees Kelvin/Celsius, as I said, it dwarfs the greenhouse factor with only a few tenth C at the most.

Are you approximating Earth to a black body to get its black body temperature?

*quantumcarl*

Quote by Andre

Let's do another one.

The idea that humans can and have had a big impact on climate is increasingly thriving. Apparently we are the central factor -Anthropocentrism. It started with Ruddiman who had produced a study His point is that the current Holocene shows an unique rise in carbon dioxide (measured in Antarctic ice cores) from some 255 ppm to 280 ppm. The other end of icing stadial spikes that indicate the start of interglacials show a (sometimes very) slow decline after the intial spike as seen here.

How come, well the paleolithic man started to change his environment, cutting down forests to build villages, burn fires and have land for agriculture. This would remove the carbon sink function and would increase the CO2 in the air.

So what do you say about that?

Deforestation happens. Landslides, volcanos, fires, infestation, disease and floods. They all kill trees/plants. All these factors have happened long before humans chopped down trees to make paper and houses.
Did the climate change because of these natural occurances? Yes. Sometimes the climate would change drastically and globally to the point of a volcanically induced nuclear winter.

However, naturally occuring deforestation happens randomly and usually to the benefit of the environment, spurring new growth with more sunlight and so on. Whereas humans continue to deforest everything in sight, leaving little time for reforestation between clear cuts. I can see how this could push deforestation and the climate a little further than the occassional blight of bugs or volcanic blow out... perhaps all the way to the extinction of those concerned.

Andre

Quote by Mk

Are you approximating Earth to a black body to get its black body temperature?

Have a look here

See expression 5: (sorry Latex not working on this machine)

G = σTe^4 = (1-A) S / 4

Te is the blackbody temperature,

A is albedo, normal 0,3

S is solar flux

σ is the Stefan Bolzman constant (5,67 * 10-8)

Reworked in expression [5] to solve temperature:

Te = ((1-A) S / 4 σ)^1/4

Solving this equation with S = 1376.6 and Albedo 0,3 gives a blackbody temp of 254.9K. You can check with google that 255K is indeed quite synonym to black body temperature. So far, so good.

So what would a 10% variation of albedo give?

A = 0.27: Te =257,6K (+ 2.7 K)

and

A = 0.33: Te = 252.1 (- 2.8 K)

This would be the average temperature of a rotating (heating and cooling) earth without any secondary thermal effects like GHG or latent heat or heat transport, conduction, etc.

So if none of those effects would have worked the 10% albedo change of the last decade should have given an average global temperature change of 2.8K

But it was only 0.5 - 0.6 K.

Now you can model whatever you like but reducing such a enormouos insolation difference by a about a factor 5 (or 20% feedback) would suggest a very strong negative feedback from al the thermal processes. The same strong negative feedback could nullify changes in greenhouse effect.

Andre

Quote by quantumcarl

.... Whereas humans continue to deforest everything in sight, leaving little time for reforestation between clear cuts. I can see how this could push deforestation and the climate a little further than the occassional blight of bugs or volcanic blow out... perhaps all the way to the extinction of those concerned.

Anthropogenic deforestation is a big problem but there are positive sounds. In Africa there is a single woman fighting it, succesfully. She won the nobel price for peace. Meet Wangari Maathai and have deep respect for such an accomplishment.

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Post-justifying Anthropocentrism	General Discussion	130

pattylou	Hi Andre! Pretty depressing, eh? As I recall, we agree that deforestation is a "bad thing." It sounds like you read the SciAm article (based on the timing of your post.) The original is 3 years old and speaks about rice paddies too. What do I think? Either the idea is too far fetched, or it's right - in which case a runaway greenhouse seems inevitable. What do you think?