If the current warming trend isn't because of anthropogenic CO2 emissions...?

Just to comment on Mike's point, since I think it is an interesting one.

Instead of average surface temperatures, a better tracker of global warming may be the total energy content of the Earth, which would include energy that goes into things like melting ice in addition to heating the atmosphere and of course the ocean.

I was searching around, and it looks like this "total Earth energy" was recently estimated:

http://www.sciencemag.org/content/328/5976/316.sum...

Although, there really is not much of a difference between ocean heat content (blue region) and total energy of the planet (red line), as you can see from this graph, which also illustrates the well-known 'missing heat' problem.

http://www.skepticalscience.com/images/Trenberth_e...

Not surprisingly, the denier answers are a total joke. A couple "it's the Sun" and a couple denying that the planet is even warming.

I think OM's answer may be the worst because while the others are raving deniers, he pretends to be an open-minded intelligent person. Yet his answer is basically "I don't even know that the planet is warming". WTF?

Let's see how many lines of evidence of global warming I can come up with off the top of my head. The surface temperature record. The satellite temperature record. Melting glaciers. Melting Arctic ice. Earlier spring. Migrating species. Sea level rise. Satellite measurements of the top of the atmosphere energy imbalance. And yes, measurements of increasing ocean heat content:

http://www.skepticalscience.com/graphics.php?g=4

I mean holy sh*t, if you can't even admit that the planet is warming in the face of all these lines of evidence, you're a hardcore denier. On top of that, even if you don't know why the planet is warming, why would you ignore the conclusions of virtually every single climate scientist on the planet that human greenhouse gas emissions are causing it? Even most of the 'skeptic' climate scientists don't dispute that.

It just irritates the hell out of me that deniers want to throw out the last 50 years of climate science research, throw their hands up in the air, stick their heads up their butts, and say "durrrrrrr I dunno, so I guess we should just wait and see what happens."

To answer your question though, the only remotely plausible alternative hypothesis I've heard is Roy Spencer's "internal forcing" concept. Basically he seems to think that some natural (totally unknown) factor causing cloudcover to change, and thus change the Earth's albedo, could be causing a significant amount of warming. Of course he doesn't deny that humans are a significant contributing factor as well, he just thinks our contribution is less than the consensus conclusion because climate sensitivity is lower because we're not accounting for this mysterious "internal forcing" factor. Frankly I think it's just a bunch of hand-waiving nonsense with roughly zero supporting evidence, but technically it's plausible.

The next-best is the galactic cosmic ray warming theory, but numerous studies have all but disproven that one.

http://www.skepticalscience.com/cosmic-rays-and-gl...

I also think it's pretty pathetic that I was able to come up with two far better answers than any 'skeptic'. Just goes to show which side of the 'debate' truly understands the science.

politicians like glenn beck don't think it exists you know. because the scientist's have hidden agenda to get more money for grant's and to take another step we would definitely keep drilling on the ocean floor because it's so safe and we have been assured by many conservatives christians that the earth will be re regulated by go son don't worry about it and i'm sure europe isn't freezing now and i'll probably get deleted for question answer format even though this is the truth

Well, "Global Warming" are caused by nature and human. Some examples of natural factors contributing to climate change are volcanic eruptions, solar cycles, cosmic rays and water vapors. But still, nature can recover to itself (climatological cycle). Until humans have contributed MORE to climate change (specially during Industrial Revolution), thus, ACCELERATING the natural climatological cycle of Earth. In general, the PRIMARY gas that contributes to Global Warming is "CO2". Plus, the massive "deforestration".

To the denial community, anything but CO2. Climate fairies would be a better explanation for the anti-science brigade.

They need to explain surface warming AND stratospheric cooling AND diminishing day-night temperature differences.

OM's reasoning seems to be: "Despite this, I'm not convinced, because I don't find it convincing, that anthropogenic CO2 is responsible. I can't think of anything else that would be, but that doesn't prove anything. And the proof that it is not convincing is that I'm not convinced." In which case, it's fair to ask OM what he would regard as convincing.

The current warming trend to me is...The new furnace and updated insulation

in our new house. What a difference it is making on these very cold Wisconsin winter

nights.:]

Unlike Mr. Gore and all the other alarmists, that are making so much mula on these scare

tactics, we cant afford to be wasting fuel ;{

I'll quickly answer this by saying I don't know. But I'll put in a logical qualifier in that my answer in no way means that it has to be CO2 if we otherwise don't know. That's illogical.

Edit: And as for "global average temperature", I'm not sure why we are leaning so heavily on that type of metric. First, one has to wonder how useful it is in the first place. If it being used to show that overall the Earth is gaining heat, then there is a good argument for using ocean heat content as a metric for that.

On top of all that, I think getting an accurate average global temperature is a lot harder than it seems. That means significant error bars and confidence intervals. These are rarely discussed.

Did Orwell really give "the sun" as an answer and then gave a link that suggested things should be cooling, instead of warming?

Doublespeak again.

It is impossible to measure but I would vote for the sun we are far from understanding how solar radiation interacts with our atmosphere.