Global Warming/Climate Change Discussion Thread

[Danoff]

http://en.wikipedia.org/wiki/Desertification#Causes

"The primary reasons for desertification are overgrazing, over-cultivation, increased fire frequency, water impoundment, deforestation, overdrafting of groundwater, increased soil salinity, and global climate change."

Yea, sorry, not buying it. Trees grow where the desert isn't, they don't cause desert by not being there.

It's basically a nice balance in the ecosystem. Trees and plants need earth rich in nutrients to survive, yet these same trees and plants need to be present to hold in the moisture, nutrients and other good stuff in the ground.

Are you a creationist?

Plus, where there's greenery there's rain,

...but the reverse is not necessarily true - especially when human are in the mix.

 

[homeforsummer]

Yea, sorry, not buying it. Trees grow where the desert isn't, they don't cause desert by not being there.

It's science, not mumbo-jumbo. If you follow the link I posted I'm sure you'll read lots of interesting things you didn't know before.

Or maybe you're just holding out for another opportunity to post a tired meme.

Are you a creationist?

Very much the opposite. I can't tell if you're being sarcastic there or just obtuse. Have a look into the God/evolution threads, you'll see I've made "a few" posts in there.

...but the reverse is not necessarily true - especially when human are in the mix.

Fair point.

 

[Danoff]

It's science, not mumbo-jumbo. If you follow the link I posted I'm sure you'll read lots of interesting things you didn't know before.

I followed it. It doesn't support the conclusion.

Very much the opposite. I can't tell if you're being sarcastic there or just obtuse. Have a look into the God/evolution threads, you'll see I've made "a few" posts in there.

So you think, somehow, that things grew where there were no trees? Lunacy! How is that possible? We need trees to hold the nutrients in place. It is impossible for anything (except maybe cactus) to grow where trees don't exist.

 

[Prosthetic]

Parts of South America where it used to be rain forest are now turning into useless desert land. The roots from tree keep the top soil from blowing away making it useless... I saw a short movie that was done purely from drawings, it was a true story where a guy visited Africa (I think) and he was out in the desert and met a Sheppard who went around planting acorns, he would plant 100 of them a day and give them a little water to sprout. And so the man that visited a number of years later and the man was still there (now without sheep) still planting trees, but much of the land that he has planted over has turned into lush land.

This was in the 1920's I'm pretty sure... And since then it has been cut down.

 

[KSaiyu]

I'm interested to see if there are any statistics about something that was brought up by a recent review of Lotus's Eco Elise by Performance Car. Quite rightly it pointed out that CO2 emissions aren't the be all and end all product of "damage" to the environment, yet is the easiest to tax/penalise. It made me wonder - how long after purchasing a "greener" car would there be any difference to your carbon footprint compared to if you kept your original car? Are there any numbers on the cost in CO2 and other potentially harmful factors per car during production?

 

[Mark T]

I remember reading that deserts are very important as they provide the rainforests with valuable nutrients. When they have those huge sandstorms the sand is blown almost half way across the world.

 

[Famine]

Yea, sorry, not buying it. Trees grow where the desert isn't, they don't cause desert by not being there.

There's a mix, really. You can't very easily create a desert by removing a forest. But if you remove sufficient flora from the edge of an existing desert you can certainly increase the size of one.

On the other hand, you can't easily uncreate a desert by planting a forest, but, and I'm not sure if this has ever been tried, I imagine you could encroach upon desert and shrink them by "reforesting" around its margins...


The exception being salt- and cold-deserts. Where conditions have sod all to do with trees because they won't grow there no matter what.

 

[homeforsummer]

I followed it. It doesn't support the conclusion.

>

"The human causes include overcultivation, overgrazing, irrigation, deforestation, soil erosion, and other patterns, including land tenure, poverty, public policies, and civil conflict"

Link

"What causes desertification: The immediate cause is the removal of vegetation. Unprotected, dry soil surfaces then blow away with the wind or are washed away by flash floods, leaving infertile lower soil layers that bake in the sun and become an unproductive hardpan

But what causes the removal of vegetation? This is driven by a number of factors, alone or in combination, such as tillage for agriculture; too many livestock on too little land; removal of crop residues for feed/construction use; deforestation"
Source: Oasis - Global agricultural research-for-development against dryland degradation and desertification

Link

"* Soil erosion With the loss of a protective cover of vegetation more soil is lost.

* Silting of water courses, lakes and dams This occurs as a result of soil erosion.

* Extinction of species which depend on the forest for survival. Forests contain more than half of all species on our planet - as the habitat of these species is destroyed, so the number of species declines (see Enviro Facts "Biodiversity").

* Desertification. The causes of desertification are complex, but deforestation is one of the contributing factors"

Link

Article: Deforestation and it's influence on desertification

Pdf file link

"Deforestation contributes to erosion by exposing soils to wind and rain... Desertification means means land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including deforestation. Reforestation also helps to prevent desertification and can reverse desertification trends. It is a common misconception that droughts cause desertification"

Link

Please, feel free to stick your fingers in your ears and sing "I'm not listening!" some more. I can provide plenty more examples than those above. If I could be bothered, I'd go to my uni library and find a few dozen books citing deforestation as one of the causes of desertification.

So you think, somehow, that things grew where there were no trees? Lunacy! How is that possible? We need trees to hold the nutrients in place. It is impossible for anything (except maybe cactus) to grow where trees don't exist.

Wow. Sarcasm. Bet it took a lot of research to come up with that.

I'm hardly suggesting that removing a few trees is going to result in a desert, but deforestation can result in a desert. Trees, plants, flora in general all hold moisture and nutrients in the ground, they hold nutritional topsoil in place preventing it getting blown/washed/dried away, and their canopies prevent too much sunlight in hot climates getting to the ground and letting it become arid. If ground becomes arid it becomes a much more difficult environment in which to support life, so even if there were trees etc there originally, it then becomes much harder for plantlife to exist there afterwards.

And not just plantlife, but life in general. Animals who call a forest their habitat, and humans who rely on nutritious ground in which to grow crops.

Finally, I'm not suggesting that deforestation is the only cause of desertification - if I was I'd be contradicting many of the quotes I posted above. But we got onto this because you refused to believe that plantlife - trees in particular - effectively prevent places turning into deserts, as Prosthetic mentioned. Which is wrong, plain and simple.

I remember reading that deserts are very important as they provide the rainforests with valuable nutrients. When they have those huge sandstorms the sand is blown almost half way across the world.

Probably true, though obviously if you have a disproportionate amount of desert then no amount of sand being blown about will help the rainforests. Rainfall is equally important, and much of the rainfall in rainforests is caused by evaporation. And you don't really get evaporation from arid ground, i.e. deserts.

 

[Bram Turismo]

On the other hand, you can't easily uncreate a desert by planting a forest, but, and I'm not sure if this has ever been tried, I imagine you could encroach upon desert and shrink them by "reforesting" around its margins...

But how would you go around to do that? I mean, how can you start to grow flora again in just...bare, loose sand?

 

[Sureboss]

Edges of desserts would be a mix of dessert/the area surrounding that particular dessert. It wouldn't be typical dessert, then bang, flora.

 

[Famine]

Mmmmm... Flora dessert... *drools*

 

[homeforsummer]

Mmmmm... Flora dessert... *drools*

You know the world is getting fat when google search asks you if you meant to type "dessertification" when you're searching for desertification...

Dessertification...the process of becoming a blancmange.

 

[Touring Mars]

I've added a non-anonymous poll to this thread... Please note that there is no "other" option because I would like for people to comment on which of those statements they agree with the most...

It's only to give a rough ballpark figure of how many people support which view, and as such, it is not all encompassing. If your views lie outside the available options, feel free to explain them in the thread

 

[homeforsummer]

I went for "occurring, causes not known". Humans undoubtably play a part, but it's somewhere between a minor part and being the only cause - of which you didn't give the option I disagree with the traditional "green freak" view that humans are the only cause but it's fairly safe to assume that the increasing impact we have on the world does play some part.

At the same time, the Earth has gone through different periods of cooling and warming throughout it's history so it's fair to assume that has a part too.

 

[Sureboss]

Mmmmm... Flora dessert... *drools*

I forgot to exit food mode!

 

[Thiele]

I think it is occuring, but human activity plays only a minor role.

 

[Touring Mars]

I went for "occurring, causes not known". Humans undoubtably play a part, but it's somewhere between a minor part and being the only cause - of which you didn't give the option I disagree with the traditional "green freak" view that humans are the only cause but it's fairly safe to assume that the increasing impact we have on the world does play some part.

At the same time, the Earth has gone through different periods of cooling and warming throughout it's history so it's fair to assume that has a part too.

I didn't add the option to say that humans are the only cause of global warming since the poll is more geared towards the range of opinions to be found in this thread, and no-one (quite correctly) has ever suggested that human activity is (or could even possibly be) the sole driver of global climate... hopefully, the existing options will give us a clearer idea of how many people accept or reject the hypothesis that human activity has anything to do with the current warming trend.

 

[Bram Turismo]

Aargh, I think I've voted incorrectly I was about to tick the option "Global warming is occurring, and humans play a large role in it" untill I realized this option wasn't there

 

[Touring Mars]

Aargh, I think I've voted incorrectly I was about to tick the option "Global warming is occurring, and humans play a large role in it" untill I realized this option wasn't there

Depends what you mean by "large role" - by "minor role", I don't mean "insignificant", but that there are a number of factors influencing the current warming trend, and that human activity is but one of those factors, and not any more or less important than other principal drivers of global climate.

I can swap your vote over if that's what you want, but your name will still appear against the wrong option, I'm afraid...

 

[Leonidae]

went for entirely natural. forests have died and grown again over the millennias before, and it's all part of the cycle of cold and warm periods.

 

[Mark T]

went for entirely natural. forests have died and grown again over the millennias before, and it's all part of the cycle of cold and warm periods.

Same here. I don't believe that our small contribution is causing the planet to heat up. There have been so many cycles of extreme weather in the past without any human input.

I saw an absurd story on Sky News today, can be found here although I picked out some highlights:

Until now, scientists and politicians have maintained that if a rise in the global temperature can be limited to two degrees by 2100, dangerous climate change can be avoided.

A computer model run by the UK's Met Office shows that even in the best case scenario, we only have a 50:50 chance of meeting this goal.

Vicky Pope, head of climate change advice at the Met Office told Sky News Online: "Even with drastic cuts in emissions in the next 10 years our results predict that there will only be around a 50% chance of keeping global temperature rises below 2C."

So far, the world has warmed around 0.7 degrees since the start of the last century.

 

[livemusic]

So TM, you think human activity is the main cause of global warming? Funny that I never got that from your posts... I mean, I saw you arguing with danoff on those rising temperatures' graphs a while back, but I thought you were mainly on the same line of thinking as him and Famine and others.

Could you explain your view for us?

 

[FoolKiller]

Can I get a "global warming appears to be occurring, but current data is too small a sample size to be statistically significant" option?

 

[Touring Mars]

So TM, you think human activity is the main cause of global warming? Funny that I never got that from your posts... I mean, I saw you arguing with danoff on those rising temperatures' graphs a while back, but I thought you were mainly on the same line of thinking as him and Famine and others.

Could you explain your view for us?

Really? That is actually very interesting to know, so thanks for the feedback... 👍

Famine, Danoff and I certainly agree on some aspects, notably the need to keep the debate in perspective and not to buy into the hysteria/hype on either side of the debate. As such, we probably largely agree on the issue of not over-reacting or taking rash actions on how to address the situation generally... We also agree that global warming is indeed occurring and that human activity can influence climate, but we disagree on whether human activity is (or is even likely to be) the principal driver of the current warming trend... I argue that human activity is not only able to influence climate, but that it is by far the most plausible explanation for the current warming trend.

Famine, Danoff and several others have previously said in this thread that they think manmade global warming is a myth, although Famine has more recently argued the case that we simply do not know what (if any) influence human activity has had on the climate because too many uncertainties remain about how anything affects global climate. (Although please don't take my word for it, you will need to read Famine's posts in more detail to fully appreciate his stance on the issue...) I agree to a certain extent - there is plenty about global climate that we simply do not know, but I disagree that the level of uncertainty is so high that we cannot draw any conclusions either way about whether human activity affects global climate or not. Indeed, Danoff, Famine and I have discussed the issue of uncertainty at some length (notably here and prior to), and the IPCC 2007 report also deals with uncertainties in some considerable detail.

There are just too many pieces of evidence that support the idea that manmade global warming is real, and not enough evidence (but plenty of conjecture) to contradict it. The rather unaptly named 'skeptics' view is that there is not enough evidence that human greenhouse gas (GHG) emissions are affecting the climate. My view is that there is no evidence that human greenhouse gas (GHG) emissions are not affecting the climate. But either way, the current warming needs to be explained by something, and in my view, the evidence pointing toward human activity is currently by far the most compelling.

Global mean temperatures have risen, and increasing levels of CO2 in the atmosphere is known to be a mechanism by which more heat can be retained by the planet. CO2 is not the most powerful GHG, but it is the most significant in terms of its increasing affect on climate (climate forcing), mainly due to its longevity and hence ability to accumulate in the atmosphere. CO2 levels have already risen to levels unseen in the history of humanity, and we know from observed changes in the relative abundances of carbon isotopes in the atmosphere that the main reasons for this rise are the human use of fossil fuels and depletion of carbon sinks (as opposed to some unspecified "natural" phenomena). We also know that we are depleting the Earth's natural ability to absorb CO2 because the proportion of CO2 being retained by the atmosphere per unit emission is increasing. This fact is bolstered by the observation that the oceans are acidifying due to excess CO2 absorption, and it is happening at a rate unprecedented in human history...

I have little doubt that human activity is the major culprit in the current warming trend, not just because of what we know about human activity, but also because of the simple lack of a credible alternative explanation.

 

[Danoff]

I voted "causes uncertain". I'm still not entirely sold on whether global warming is indeed occurring in any significant way (as FK mentioned), but I believe that option best reflected my viewpoint from the ones available.

I have little doubt that human activity is the major culprit in the current warming trend, not just because of what we know about human activity, but also because of the simple lack of a credible alternative explanation.

I simply think we lack any credible explanation. I do not see a reason to make the "it's our fault" position the default in the absence of any other explanation. Until we know whether something as simple as cloud cover heats or cools the earth, I think we've still got work to do.


(Not to worry Homeforsummer, I haven't forgotten about you. You'll get a response.)

 

[Touring Mars]

I do not see a reason to make the "it's our fault" position the default in the absence of any other explanation.

It isn't the "default" position at all, it is simply that the most credible explanation so far happens to be related to our activities. In any case, it is not about establishing who or what is at fault, but simply about understanding how/why it is happening...

 

[Mark T]

What studies are there in relation to methane as I've read that it has 20x the heat trapping effect of CO2.

Also on the graph below, do we have any ideas as to what caused the massive fluctuation in temperature?

Image taken from worldclimatereport.com

One other question- If we are sending lots of particles into the air through our pollutants would the suns rays be blocked by these particles? Would it cause less heat to enter the atmosphere?

 

[Touring Mars]

What studies are there in relation to methane as I've read that it has 20x the heat trapping effect of CO2.

It is a far more powerful GHG than CO2, but it has a much shorter lifespan in the atmosphere, meaning that the net forcing on climate from methane is less significant than that of CO2...

Also on the graph below, do we have any ideas as to what caused the massive fluctuation in temperature?

What massive fluctuation? At face value, this graph shows that there has been practically no net change in global climate over the last two thousand years, with a maximum temp change of 1.2 +/- 0.6 degrees in an ~800 year period (ca. 800-1600), gathered from temperature proxies... note that this is by no means the only or the authoratative paleoclimate reconstruction. (The IPCC report in 2007 uses many such reconstructions). Compare that to an observed change in global mean temperature of 0.74 ± 0.18 °C in just 100 years (from 1905 to 2005), and suddenly the "massive" fluctuations shown in this graph don't seem so massive..

One other question- If we are sending lots of particles into the air through our pollutants would the suns rays be blocked by these particles? Would it cause less heat to enter the atmosphere?

Yes, aerosols (such as soot and dust) contribute to global cooling - hence why volcanoes contribute a net cooling effect (despite the fact that they belch out tonnes of GHG's too)... indeed, the effect aerosols have on climate is one of the major sources of uncertainty in climate modelling...

 

[Prosthetic]

The influx of methane is from all the cows we have for masproduced beef.

 

[Sureboss]

Stop giving them baked beans then!