Is Global Warming a Real Threat? Views and Opinions on the Controversial Topic

[matthyaouw]

Since there seems to be a lot of controversy about this, I thought I'd do a little poll to collect the oppinions of you guys. Is global warming a real threat caused by us, a purely natural occurrence or a cross between misleading figures and political spin?
Views & opinions appreciated.

 

[Andre]

Good initiative. A few remarks though before I vote.

The question actually is fourfold.

A - Global warming is happening: True - depends - false
B - Humans cause global warming: true- in between - false.
C - Warming is a real and bad threat: Yes - depends - no.
D - More carbon dioxide in the atmosphere is: good-in between- bad

I think it is like this:

A: Global warming is happening: Depends. There are a lot of cycles active. Global warming was happening somewhere between 1880 and 1940 and again between 1985 and 1998. Since then the warming has leveled of. Global cooling has happened between 1950 and 1980.

B: Humans cause global warming: in between, to be honest, but certainly close to "false". Considering the logaritmic relationship between greenhouse gas concentration and effect, the increase in anthropogenic greenhouse gas effect is a minor factor.

C - Warming is a real and bad threat: We have no clue whatsoever. Seeing the multiple cycles involved the temperature is bound to go down in the near future. If the warming would persist, catastrophic events like racing sealevel rise is still humbug, but even if it wasn't, there is virtually nothing we could do.

D - More carbon dioxide in the atmosphere is: good. Definitely. The Greehouse gas effedct -as said- is minor and we even don't know if it is bad or good. But if we want to continue feeding the exploding world population, we need biomass, lot's of it. Carbon dioxide is the basic building stone of biomass. Tree rings in the last century have increased thickness in the last century, not because of warming but because of enhanced growing speed due to increased building stones. Furthermore, CO2 is radioactive due to cosmogenic radioactivity. Fossil fuels are depleted of radioactive carbon (14C) hence a higher CO2 level due to fossil fuels is healtier for the living creatures.

 

[matthyaouw]

Carbon dioxide is the basic building stone of biomass. Tree rings in the last century have increased thickness in the last century, not because of warming but because of enhanced growing speed due to increased building stones. Furthermore, CO2 is radioactive due to cosmogenic radioactivity. Fossil fuels are depleted of radioactive carbon (14C) hence a higher CO2 level due to fossil fuels is healtier for the living creatures.

I've never heard of these concepts before, but I'm intrigued. Do you know of anywhere I could read up on them? Where did you learn this?

 

[Phobos]

Tree rings in the last century have increased thickness in the last century, not because of warming but because of enhanced growing speed due to increased building stones.

What's the state of the research on this? My impression is that it's still pretty sketchy. (i.e., associating wide-scale vegetative growth in response to increased atmospheric CO2 levels)

One thought I have on this is...yeah, extra CO2 means extra food for plants which could increase growth rates; however, carbon is probably not the "limiting factor" in plant growth (more likely to be nitrogen or phosphorous or some other nutrient needed by plants). In other words, in an excess of carbon, plant growth would not greatly increase unless the amount of other essential nutrients also increased.

 

[Andre]

That's the spin indeed Phobos. And it also shows how terrible the AGW lobby has to bend things that are right to be wrong.

[http://earthobservatory.nasa.gov/Newsroom/NasaNews/2002/200205169337.html]

The authors found that without enhanced rainfall and humidity, CO2 increases and temperature changes have a lesser effect on plant growth.

Greenhouse gases warm the air, and warmer air can hold more water, which impacts the hydrologic cycle. Changes in the hydrologic cycle may mean more rainfall in some regions and less in other places, affecting plant growth and carbon absorption, which in turn affects future concentrations of greenhouse gases, Nemani said

I detect a rather high baloney level here. There is always one element (water - minerals - CO2) that limits the growth. If CO2 is not the limiting factor, then the concentration of CO2 will not make the difference. Most certainly water is the limiting factor in deserts. In our moderate sea climate with plenty of water, farmers use dung to fertilize the soil. Why, because in addition to minerals, dung produces CO2, right where it is most needed. Articifical mineral fertilization has always inferior results - no carbon dioxide. For that reason the gas heatings in our greenhouses have no chimey. The smoke (CO2) is lead directly into the greenhouses and enhances crop harvest enormously.

 

[matthyaouw]

I'm going to have to disagree with you there Andre. Do artificial fertilisers always produce inferior results? Many farmers choose to use artificial fertiliser due to a number of reasons, including it having the specific nutrients nessecary for plant growth in readily avaliable forms, where as manure is as it comes out of the cow, and requires organic breakdown before plants can absorb anything. If natural fertilisers have any advantage over artificial ones, it is that they promote the development of a humus layer in the soil, which retains nutrients for plants to use, and improves soil texture significantly, where as an artificial fertiliser is often water soluable and washes away during any significant rainfall. Even if CO2 levels in the atmosphere (not CO2 levels reaching the plant itself, as matters are complicated by humidity levels, rates of diffusion and opening/closing of stomata) were a limiting factor, I think you would be hard pressed to find any noticable change in the CO2 levels above a manure fertilised field and an artificially fertilised one.

 

[Andre]

Well that are all testable ideas I guess. It must have been done already. And if the soil is emitting carbon dioxide it still had to pass the leaves from below to up before it finally dillutes. What, if it was visible like smoke, would your intition still say that at the leafs height it would no longer be traceable?

Many plants thrive better if their crown is pruned, allowing for more air = CO2 to pass. Obviously the growing restriction is to little CO2 in the air. In Holland there are greenhouses that get the exhaust gasses of power plants directly. Oops...Stupid ... that is a secret to get the largest crops in the world. I didn't tell you that.

Any idea why most stomata are at the bottom side of leafs?

 

[iansmith]

For plants, other nutrient are a limiting factor. Some plants grow better when they form symbiotic relation with soil bacteria, such as Rhizobium. The bacteria fix nitrogen for plant. The yield of crops increases when bacteria are present. All the CO2 in the world, will not fix that.

Also, bacteria can be a problem. If the soil if fertilized and then flooded, the soil bacteria will eat up the plant nutrient and the soil will not be appropriate for the plant growth.

New research is should that overfertilization is also causing problem with plant-microbe interaction. Several farm and crop management are pointed as the source of the problem.

Also, will an increase in CO2 give advantage to all plant or just certain plants. You have to remember that plant are well adapted the environment as we known it and plant crops have receive several genetic modification. If only part of the plant kingdom is favor, will it be pest plants rather than plants that advantageous for the animal kingdom, especially human.

The stromata are on the underside of the leaf because it allows the plant to reduce the amount loss to transpiration. If the stromata were on the topside the plant would lose too much water because the guard cells are light sensitive and open, in part, according to sunlight.

 

[pebrew]

Experiments have shown that CO2 increases raise plant growth levels fairly equally across species. I could swear some one posted the link in this forums the past month or so. I don't have the Mozilla physicsforums.com searcher, maybe some one could try and find this for us? Though I do remember that a doubling of CO2 results in less than a doubling in plant carbon-intake (+70% ?). No surprise there, but significant.

This statement, however,

D - More carbon dioxide in the atmosphere is: good. Definitely.

I strongly disagree with. We definitely do not understand CO2's role in the many facets of the environment well enough to say more CO2 is "good" or "bad". All global warming issues aside, CO2 has a profound effect on most of the major ecological systems that sustain the environments of humans and all other living creatures. We know that a doubling of CO2 should not have a major greenhouse effect due to its already high concentration level, but we don't know how a doubling of concentration would affect other important mechanisms in the ecosystem. Most notably the ocean acidity rises as the ocean absorbs CO2, which dissociates into carbonic acid. And if ocean acidity rises (and rises 'historically' rapidly as our current output should cause it to) it could very possibly destroy the ocean's food web by harming organisms (such as coral reefs and plankton) that rely on calcium carbonate structures to live in. Here's a newsblip about it: http://www.llnl.gov/pao/news/news_releases/2003/NR-03-09-07.html
Ocean acidity/marine life may be the largest environmental system affected by CO2 (on a short time scale) besides the atmosphere, but its not the only one. While I don't think 100 ppm CO2 increase will cause much global warming (at least not directly), that doesn't mean that CO2 is a 'good' thing by any means. Even if it does increase crop yields.

 

[Andre]

Pebrew, You said "strongly disagree". Now how could I reflect about this neutrally, when you polarlize yourself.

I guess by now it should be clear that there are always two sides to that kind of news as you have reflcected upon earlier. Actually four. Does the writer want to prove antropogenic global warmer or does he detest it? and who is funding the study, the enemy seeking leaders or the oil compagnies?

The current CO2 content of the ocean is a order magnetude higher than the atmosphere. Doubling the CO2 in the atmosphere would be equivalent only to perhaps a few percent in the ocean.

http://www.specialedprep.net/MSAT SCIENCE/cycleCO1.htm

Oceans store 50 times more carbon dioxide than the atmosphere as a gas and in the form of carbonate compounds (carbonates are polyatomic ions -CO3).

Ocean water is a strong natural buffer, capable of absorbing a lot or carbon dioxide without changing pH significantly.

It would not be the first study that attempts to debunk the obvious. Moreover, the oceans and the Earth have survived a multitude of the present carbon dioxide level without much problems:

http://calspace.ucsd.edu/virtualmuseum/images/raw/CCC_Fig4_2_1.jpg

 

[Andre]

Incidentely http://earthobservatory.nasa.gov/Newsroom/MediaAlerts/2004/2004021516533.html is a study to the effects of carbon dioxide fertilisation.

For the last six years, Norby and colleagues at ORNL have examined the responses to elevated carbon dioxide levels in a stand of sweetgum trees a few miles from ORNL. The experiment consisted of pumping tons of carbon dioxide into the plots, raising the concentration of carbon dioxide in the tree stand from the ambient level of about 370 parts per million (ppm) to 550 ppm, and studying the effects. One of the goals of the project, called the Free-Air CO2 Enrichment (FACE) experiment, is to examine how forests will respond to the increasing level of carbon dioxide in the atmosphere and...

In every year since the FACE project began, net primary productivity, which is the total amount of carbon dioxide fixed into organic matter such as leaves, stems and roots, has been higher in plots given extra carbon dioxide. The average increase has been 24 percent,

Talking about growth, that's also tree ring growth and carbon dioxide fertilisation actually started in 1850 when the carbon dioxide level started to rise from a steady 280 ppm to abut 370 ppm nowadays. Tree rings must have reacted to that. And tree ring growth is the mainstay for climate research in the past millenium.

See http://www.wsl.ch/staff/jan.esper/publications/Science_2002.pdf for instance. See that he also opposed to the hockeystick. I wonder why this publication (Science, Vol 295, Issue 5563, 2250-2253 , 22 March 2002) never got the attention.

Low-Frequency Signals in Long Tree-Ring Chronologies for Reconstructing Past Temperature Variability

Jan Esper,1 Edward R. Cook,2* Fritz H. Schweingruber1

Preserving multicentennial climate variability in long tree-ring records is critically important for reconstructing the full range of temperature variability over the past 1000 years. This allows the putative "Medieval Warm Period" (MWP) to be described and to be compared with 20th-century warming in modeling and attribution studies. We demonstrate that carefully selected tree-ring chronologies from 14 sites in the Northern Hemisphere (NH) extratropics can preserve such coherent large-scale, multicentennial temperature trends if proper methods of analysis are used. In addition, we show that the average of these chronologies supports the large-scale occurrence of the MWP over the NH extratropics.

Anyway, what strikes me is fig 2 - C, the apparent average tree ring growth that started to rise after roughly 1850.

Now I read all kind of corrections but perhaps I'm overlooking a correction for carbon dioxide fertilization. Obviously the tree rings should have reacted on that.

I wonder if any of the tree ring wizards (Storch?) corrected for carbon dioxide fertilisation. If none of the authors did (but I don't have a clue at the moment) then the 1850 - present increase in tree ring thickness should be partly caused by direct increase of growth due to carbon dioxide fertilisation. A possible correction for that would drop the assumed temperature rise in that period, cooling down the apparent warming.

 

[Andre]

Lets talk oceans again.

Another thought about anthropogenic moving around of carbon, because that is what we do.

Pebrew, you were worried about the effect of carbon dioxide to the oceans. But humanity has already commited a serious crime against the oceans, by fishing these empty. Consequently removing a lot of biomass and carbon out of the oceans, ultimately turning them into lifeless deserts.

What we see now is the return of carbon to the oceans. Not in the form of biomass yet. But all kind of micro-organisms (algae) could thrive on that, being on the bottom of the food chain. And this could be the start of restoring biomass to the oceans.

Of course there is a lot of unbalance right now and that will be hurting the micro-organisms like foraminifera. Mass extinctions of them are not uncommon. The last disastreous one was in the mid-pleistocene some 1,000,000 to 700,000 years ago (- giving a substantial basis for my hypothesis as important piece of the puzzle). But as a whole the oceans would need the carbon dioxide to restore normal life.

 

[pebrew]

indeed, CO2 will help repopulate the oceans and that is important. but if the oceans' pH changes appreciably in the next few decades, that is only going to be a bigger problem, exacerbating the lifelessness of the oceans. and that might be okay on the timescale of hundreds of thousands of years; no the Earth will not implode. but it would be a problem for modern humans and their civilizations.