Maybe you're skeptical that they're man-made. If so, why not put the quotes around "man-made" instead of "greenhouse gases"?

Unfortunately we are stuck with this misleading terminology in what is an already complex and politically charged area.

The speed at which it's occurring and it's correlation with man-made CO2 emission levels.

Uh, yeah, that'd be it. What with all the massive extinction events and all, it might be in our interest to minimize the effects.

Consider that our ancestors were fighting for survival in the midst of an ice age. Sure, its "pre-written-history" but it isn't "pre-human-history".

There is a common set of exchanges that occur in climate discussions that go like this:

Person A: "Here is climate change without humans" (person A in this context is trying to argue that change will occur because there are other sources of change)

Person B: "That was millions of years ago" (person B in this context is often trying to argue that what ever caused climate change 'back then', doesn't apply to current change)

Neither person directly addresses the emotional argument/fear, and neither person tries to establish a common frame of reference.

In context, kjackson2012 was making the 'things change' argument and your (snowrestler) response about the 'cold comfort' was in the context of the emotional argument.

It is kind of like an exchange that goes "Oh we ordered too much food for the party." followed by "That's cold comfort to Ethiopians who are starving."

On its face it seems like an argument that had we ordered less party food, there would be more food for Ethiopians. And yet the link between this party's food budget and that country's food problems is tenuous at best and generally a non sequitur.

The point I was trying to make was that responding to the comment about change with a statement about timelines is a common one in climate discussions.

Had I not reflexively responded to what I see as a common fallacy in the debate, I might have more constructively asked this:

Given that coastal dwellers are now aware that the sea level will change, possibly significantly, for their great grandchildren. And that we know that there is nothing known to science today or predicted by our models that can stop it, how do you suggest we comfort these coastal dwellers of the present?

BTW, I interpretted your post to be something like "houses have burned down throughout history. Let's start trying to make all our stuff fireproof just in case." To which I think a reasonable response is "let's figure out how fires are most likely to start, and do what we can to prevent a fire in the first place."

The fundamental question is whether we can do anything to slow or stop the global warming trend that we see today. Scientifically speaking, we know that the answer is yes: if we reduce the rate at which we produce greenhouse gases, we will reduce the expected warming. Whether that is politically feasible is a whole 'nother question.

The same body of science that you appeal to has noted that relative to the geologic record we are 'overdue' (or 'about due' depending on who you read) for a glacial event (aka an Ice Age). Given that, how would you score the sequence of events that humans managed to scale back their CO2 emissions and the world then subsequently plunges into an ice age which probably destroys civilization as we know it?

You may find that question is not as much a straw man as it first appears (or a false dichotomy), ice ages are a perfectly valid climate 'state' on our planet. Some literature would have you believe that the planet is usually an ice ball and periodically warms, but I haven't found those papers as compelling.

However, that we cannot, with certainty, rule out another ice age occurring as the 'normal' course of events suggests to me that the next millenium's climate is going to be different regardless of our actions. So I tend to favor a policy where we invest in survivability and mitigation and research, in that order.

The climate has such a huge impact on human society that we cannot invest to mitigate all outcomes equally. A major reason to fund scientific study of the climate (beyond the intellectual joy of finding things out) is to rigorously and continuously quantify the likelihood of potential climate changes, so we know where to invest.

The overwhelming conclusion right now is that warming is the most likely change in the near future. If you surveyed 1,000 climate researchers tomorrow, I'd be surprised if even 1 said that imminent glaciation is more likely than imminent warming.

Now, that could change, but if it does then the same scientific research that warned us of global warming would warm us of global cooling. But right now it's not, so it would be wasteful to start sending parkas to Florida.

Now, you might ask how we should invest our money in the face of coming warming, and that is a very good question. How much should we invest in changing our energy sources vs., say, building sea walls around low-lying cities like New York or Washington, DC?

To have such a discussion we would first need to accept the information we are getting from scientists--but it is here that we are stuck as a society. People simply do not want to accept it, so right now there is little investment in any direction.

Not actually true, and in any case a much more gradual warming over a longer timescale; it's well summarized at http://en.wikipedia.org/wiki/Medieval_Warming_Period

I can't help being struck by the contrast between climate skeptic's loud insistence on greater scientific rigor in discussions of the present climate, and their hand-waving invocations of the MWP as a general-purpose tool of dismissal. I mean, all you need to do is look at a graph of the temperature data to see how different the rate of change is between the MWP and today.

First and foremost: The black line is an actual temperature measurement, while all the other lines are estimates based on proxies. Except of course: Secondly all the proxies appears to be correlated to the black line, because they have been chosen to do so. That is, the correlation to the black line is manufactured, and not a finding.

The rest of the graph is made in a completely different manner, and the proxies are allowed to carry the signal for themselves. I think it is very interesting that you can see a small medieval warming period from the proxy data, but nevertheless one shouldn't be too eager to compare the right part and the left part of the graph, as the methods used are actually not the same.

One can also show that the noise in the proxies will tend to pull the data towards the average and away from the extremes, which is exactly the lower rate of change and lower peaks you see. So that graph is really not very good, at all...