2004-12-17

NPOV blues

The wiki page on Global warming is having a bout of warfare. I'm going to write about the process, since its interesting (to me).

The virtue of wiki is that it is a constructive process. There is debate, but the article grows and grows better, usually. Unlike, say, newsgroups where there is quite often intelligent debate but no end product. And the collaborative process is good too: many points of view get put in. But... of course the downside is that its one person one vote. Skill and knowledge count for something: those who are foolish eventually realise this or, ultimately, get kicked off if they push things too far. But it can be a long road. It also makes referring to wiki pages a bit of a lottery: it may have been (temporarily) turned into rubbish by the time you read this.

Anyway, the current (2004/12/17) version of the GW page is the subject of an NPOV dispute. Which means someone (a septic in this case) doesn't like the text. Now, of course, I'm right and they are wrong, but rather than bias you further I'll direct you to the version of the talk page I mean and you can judge for yourself:

Talk:Global_warming#NPOV_disputed.

4 Comments:

Anonymous Anonymous said...

Hi William:

Nice Blog! I just read the Wiki page and found this:

"For a third, there are theories containing feedback mechanisms such as biomass increase which could balance out GHG levels, or feedback mechanisms which could cause temperature to stabilize. So it's complete POV to say "all" models predict human GHG emission will raise temperature. — Cortonin | Talk 23:48, 16 Dec 2004 (UTC) "

I have had to do some digging about that topic on another board and would like to offer the following comments.

First, there is no evidance that an increase of CO2 will significantly increase ocean bio-uptake. Recent research does show an increase in coral growth, but over all bio-uptake should be constant. There was a good paper a while back that tracked an iron induced plankton bloom and showed that if you remove iron there are other limits to growth.

Second, there appears to be an increase in bio-uptake on land although it seems to be more due to additional warming at high latitudes than enhanced CO2 growth. Using the Mauna Loa data I looked at the annual change in CO2 between May and October (seemed to show the growing season best). The results do show an increase but with a very small r^2 factor. For the 45 years of data the increase for the CO2 uptake 6.8%, while at the same time CO2 has increased by 18.1%. Or the CO2 uptake is about 1/3 that of the CO2 increase. In other words - it is not keeping up. Of course I have assigned all change in the levels to plant growth and thus ignore changes in CO2 production, ocean uptake, etc. Just some (non plant) food for thought.

I have bookmarked the blog.

Regards,
John Cross

7:40 pm  
Blogger Belette said...

Thanks for your comment! You win the prize for the first comment - I guess my hordes of other readers are just shy :-)

The text you quote is from the wiki discussion page, not the article page. I hope that was clear to you - if not I maybe ought to blog on the distinction briefly.

I'm not much on the bio side though. I've followed the iron fertilisation stuff with some interest - as you say, there may well be other limits. Certainly pinning all your hopes on that, as some seem to, is rather premature.

Bio on land: I've seen some stuff (where? Nature?) about greening around cities from UHI... but OTOH I've seeen stuff from the Hadley model predicting die-back of the amazon forests around 2050 which reverses the fertilisation and leads to extra CO2 sources. Its hard to know.

11:56 pm  
Anonymous Anonymous said...

Hi Again:

Yes, your post was quite clear but I was not so clear in my wording. Anyway, no need for changes.

In regards to land based growth, I recall seeing a paper on the "greening" of the north slope of Alaska. I believe they based their results on NDVI results with some ground truthing and came up with a value of about 170 g/m2 increase in plant bio-mass. Again, it appears that this is mostly due to warming not CO2 enhancement. I have the paper at work and will post a reference tomorrow.

Great site! Keep it up.

Regards,
John

2:36 am  
Anonymous Anonymous said...

Hi Back Again:

The paper I was thinking about was "Greening of arctic Alaska, 1981 - 2001" in Geophysical Research Letters Vol 30, No. 20 (2003). They looked at the Alaska tundra using satellite date (NDVI) over a 21 year period and found an increase of 171 +/- 81 g/m2 in above ground plant biomass.

However, in terms of a CO2 sink it appears to be not quite as good as would appear. To quote from: Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization (Nature 431, 440 - 443 (23 September 2004))

"Here we present the results of a long-term fertilization experiment in Alaskan tundra, in which increased nutrient availability caused a net ecosystem loss of almost 2,000 grams of carbon per square meter over 20 years. We found that annual aboveground plant production doubled during the experiment. Losses of carbon and nitrogen from deep soil layers, however, were substantial and more than offset the increased carbon and nitrogen storage in plant biomass and litter."

Anyway, enough of this. Wish you and your readers the best of the season.

Until the new year.

Regards,
John

2:48 pm  

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