It depends.

If you buy carbon offsets to minimize your guilt about the size of your carbon footprint, then humans cause global warming.

If you continue to intentionaly expand your carbon footprint, without guilt, then global warming is a natural phenomenom.

How guilty do you feel?

Sorry, I didn't get to the part about having some expertise in this area before I wrote this.

I actually had a real point, and that is that we do not have an answer that is conclusive. People's position on this matter is mostly colored by their political affiliation and by how guilty they feel about it.

Or you could just check one of the other 23904902384902384 posts made on this subject in the past 6 months.

not an expert by any means, but i'll take a crack at it.

Humans are loading all kinds of gasses into the atmosphere. CO2 is a major one which contributes to the greenhouse effect. However, there are several confounding effects (which I can't remember the name of), that reduce the greenhouse effect. Some of the gasses we release make clouds MORE reflective, meaning sunlight bounces back into space because of our pollution. This has much less of an effect than C02 emissions, but is still measurable to some extent and therefore significant.

The earth is in a natural warming cycle as it proceeds away from the last ice age. Scientists are pretty much in agreement that the natural warming is a significant contributor to recent global warming.

The debate essentially then is HOW MUCH to humans contribute to the warming of the planet. Based on very complicated models that predict the warming of the globe, scientists are able to compare their theories of what is warming and cooling the globe. The most accurate models are those that do incorporate the human element as a result of increased greenhouse gasses in the atmosphere.

My opinion? Greenhouse gasses contribute in a very real way. While they may not have been the most significant factor in accelerating climate change, if we allow CO2 to continue to build up, it will very quickly overshadow any other factors contributing to this warming cycle.
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Disclaimer: Weather patterns are extremely complicated and we do not know all there is to know. Confounding variables such as El Nino and La Nina make it more difficult (and are why we can go from having Katrina and other huge hurricaines one year, to very few in 2006). Regardless, we need to curb CO2 emissions if for nothing else, than for cleaner air to breathe.

PRO
"Humans are loading all kinds of gasses into the atmosphere. CO2 is a major one which contributes to the greenhouse effect. However, there are several confounding effects (which I can't remember the name of), that reduce the greenhouse effect. Some of the gasses we release make clouds MORE reflective, meaning sunlight bounces back into space because of our pollution. This has much less of an effect than C02 emissions, but is still measurable to some extent and therefore significant"

CON
Water vapor constitutes Earth's most significant greenhouse gas, accounting for about 95% of Earth's greenhouse effect. Interestingly, many "facts and figures' regarding global warming completely ignore the powerful effects of water vapor in the greenhouse system, carelessly (perhaps, deliberately) overstating human impacts as much as 20-fold.Water vapor is 99.999% of natural origin. Other atmospheric greenhouse gases, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and miscellaneous other gases (CFC's, etc.), are also mostly of natural origin (except for the latter, which is mostly anthropogenic).
Human activites contribute slightly to greenhouse gas concentrations through farming, manufacturing, power generation, and transportation. However, these emissions are so dwarfed in comparison to emissions from natural sources we can do nothing about, that even the most costly efforts to limit human emissions would have a very small-- perhaps undetectable-- effect on global climate.

PRO
"The earth is in a natural warming cycle as it proceeds away from the last ice age. Scientists are pretty much in agreement that the natural warming is a significant contributor to recent global warming."

CON
The �little ice age�, which lasted from about 1400 to the latter part of the 19th century. It is hardly surprising that since then, temperatures have warmed up a bit. But it is only a bit � a mere 0.6�C rise in the last 150 years.

PRO
The debate essentially then is HOW MUCH to humans contribute to the warming of the planet. Based on very complicated models that predict the warming of the globe, scientists are able to compare their theories of what is warming and cooling the globe. The most accurate models are those that do incorporate the human element as a result of increased greenhouse gasses in the atmosphere.

CON

Computer modelling is in general a dubious scientific tool. When it comes to climate change, it uses partial data to transform flawed hypotheses into prophecy. It is of little more use than a ouija board.

As for mankind�s involvement in climate change, this is even more debatable. Carbon dioxide, the main greenhouse gas for which industrial man is blamed, accounts for only a minute proportion of the atmosphere.

Hair-raising claims by the warming lobby have been shown to be false. The ice sheets, for example, are not shrinking but are actually increasing overall. Evidence about sea-level rise is contradictory, but in general the seas are not rising.

As for air temperatures, past calculations which mistakenly used the seas as a gauge over-estimated air temperatures as a result by one third. When air alone was measured, it was found to have got cooler, not warmer, over the past two decades.

and in conclusion........

So why have so many scientists produced �evidence� to support a theory which doesn�t stand up to serious scrutiny? The brutal explanation is that they don�t get grant money or the approval needed for promotion unless their work supports the politically motivated theory of the times.

Look at what�s happened to Dr Bjorn Lomberg, a Danish statistician and former member of Greenpeace. In his book The Sceptical Environmentalist, he shows how green doom and gloom has been wildly exaggerated.

Natural resources are not running out but becoming more abundant; only a tiny fraction of species is likely to become extinct in the next fifty years and � heresy of heresies � richer countries are cleaner countries.

just showing there will always be two sides to every debate.......... thats just life.

RE: -AG-

I posted this first part previously in response to this same arguments:

RE: little ice age etc:

The Medieval Warming period, the Holocene climatic optimum, and all these other temperature shifts have been researched and studied ad nauseum in the scientific community. Posting that information (as valuable as it is to know) as if it disproves Anthropogenic Global Warming is quite silly. Yes, the Earth has been warmer before - science knows this. The Scientific community in support of AGW know this. They have researched it. (In fact, I think they're the ones who discovered it!)... But these periods only mean that it is possible for the Earth to warm from natural variables (which all science agrees upon); it does NOT mean that the Earth is currently warming from natural variables. All the data suggests that current warming trends are not caused by natural CO2 fluctuations, Milankovitch cycles, or any of the other possible culprits.

RE: "Most CO2 occurs naturally in the environment (over 95%)."

You also leave out deforestation when talking about human contribution to the greenhouse effect. I know all the arguments and counter arguments as well as the facts. Just as your Holocene argument means little in relation to current warming trends, you stating that the large majority of CO2 is emitted naturally also means little (assuming you were doing so as a counter argument to the AGW supporters.) The reason? Well, it shows a lack of understanding in how the environment works. The earth has a natural carbon cycle, and there is a natural carbon dioxide sink that absorbs the natural CO2. The reason <span>some of our emissions end up in the atmosphere is because we're producing CO2 faster than the ocean and biosphere can absorb it. Small percentages only sound insignificant. But it's true that these things look pretty damning at first glance.

* * *

</span>RE: "'Natural resources are not running out but becoming more abundant; only a tiny fraction of species is likely to become extinct in the next fifty years"

ABSURD! How do non-renewable resources become more abundant through increased use? That just isn't logical. (And concretely, to use an example, oil is running out. Peak Oil: go research it. War in Iraq: go research it. "Oil is unique in that it is so strategic in nature. We are not talking about soapflakes or leisurewear here. Energy is truly fundamental to the world s economy. The Gulf War was a reflection of that reality." - Dick Cheney, speech at the Institute of Petroluem, 1999.) And: a tiny fraction of species extinct? Go research the Holocene extinction event.

Of course there will be opposing sides to every point of view, so? This issue isn't a philosophical debate. This is a debate where one side is wrong and one side is right. (Like debating whether or not the Earth is flat.) Of course the industry and everything that the world is based upon economically has to say that things are improving, otherwise we wouldn't let them poison our land and food with pesticides, our air with depleted uranium and CO2, our milk with bovine growth hormone, etc etc etc. And all the other things you posted are either false or misleading, but people who care about Truth can find that out for themselves.

Just so I understand.

You're saying it's not worth the time or money to stop polluting the environment. Is that a fair summary?

However, I think you would agree with me that there is an answer to the question, right? You might not think we know it yet, but there is an answer that is completely independent of how you or I feel about the issue.

Des > *

How is a discussion of emissions in the atmosphere different than poisons in the rivers? Both affect people's health, and need to be stopped. Even without global warming, it is important to cut air pollutants, but once you also consider the fact that global warming could change the face of the planet in the next 10/20/100 years, it becomes a very important issue for ALL people (hungry, homeless, everyone!)

Ways global warming will affect the world:
1. Increased extreme weather conditions (see last month's Scientific American)
(New orleans residents might care, in addition to South Pacific, East Asia, Carribbean, and other residents of the globe)
2. Rising oceans
(estimated 1 billion people living within 30 vertical feet of the ocean - that's a lot more hungry homeless people probably getting diseases too!)
3. Air quality worsens
(not a result of global warming, but a result of continuing to pollute the atmosphere, the cause of both).
4. Drought
(you talk of wanting to help hungry people. When Africa gets hotter, think that will help their crops?)

These are not extreme loonybin worst case scenarios. We are beginning to see these effects already.

ice ages happen about every 1000,000 years...thers that 10,000 year window of stable weather that we're in now...it has to do with the earths orbit that tends to be more egg shaped 90% of the time...2-3% variation