Last week I began to consume the science of the waxing and waning of ice ages (much more extreme than interglacial periods influenced by the Earth's orbit).  

Something just leaps off the page... that the Earth's climate is highly sensitive to CO2, far more sensitive than the wobbles of Earth's orbits around the sun.  The theory is that ice covers rock, restricting CO2 removal, causing a CO2 buildup, which eventually ends the ice age with global warming caused by CO2.  The ice melts, the exposed rock absorbs some CO2, and the cycle starts over again.

By definition, we are still in an ice age (a hot ice age) because of ice in the Antarctic, the Arctic, and Greenland.  Once this ice melts (rapidly) the exposed rock will accelerate CO2 removal (requires a very very long time).  Other big influences include continental shift, ocean currents, and albedo.

I now better understand the panic of scientists.  The amount of CO2 humans generate far exceeds the CO2 embodied in these sensitive cycles.  The expected increase in anthropogenic CO2 will cook the Earth far beyond the level at which life (as we know it) can survive.

Yes, the climate is always changing. And species appear and disappear. I have to admire your optimism that the human species will be able to ride out the warmest period of its entire existence, even if -- especially if -- you think we've been around for only 6000 years. I also have to admire your optimism that you or your decendents will be among the survivors.

In the past, as seal levels rose and fell... as ice retreated and advanced... as deserts expanded and contracted... it was possible for our ancestors -- from primitive shrews to modern humans -- to move with the shifting environment. But now, it is a bit more crowded. Non-human animals are confined to fragmented habitat and do not even have safe corridors to move through from one region to another. And humans -- in case you did not notice -- pretty much occupy or at least lay claim to most of the Earth's surface. Where do you, Mr. Global Warming Skeptic, plan to go if your home becomes surrounded by desert or submerged by salt water? And, Mr Global Warming Skeptic, how are you going to handle 100s of thousand of refugees when they show up in your neck of the woods because there is nowhere else for them to go.

The CONSERVATIVE thing to do is to preserve the climate we have and understand, the climate we can grow food in, the climate our various nations developed in.. unless you do not mind yourself or your decendents perishing. Afterall, just like the climate is always changing, species are always going extinct.

That is what I have to say to Mr. Global Warming Skeptic.

An issue I am not hearing in the discussion of renewable energy in the form of wind farms is the "colateral damage"--birds and bats. Some major wind farms have been placed directly in the flyways of migratory birds   Many owners of wind farms are failing to take into account the placement of their farms. Larger Wind Farm corporations are placing obstacles in the way of monitoring bird kills.  

Energy no matter how it is created is never "free". There is always some consequence. As wind farms lead to greater profits, greed will take precedence over environmental concerns.  

Where is the discussion of energy conservation?  If this country focused on cutting back our consumption of energy we wouldn't need to build so many wind farms.

This isn't much of a rebutal of the original claim.

You say "Noting that something happened before without humans does not demonstrate that humans are not causing it today."

That helps you argue with somebody who believes that they can "prove" that global warming isn't happening.

It hurts against a personal who is skeptical of global warming because it reminds us that historical data that supports a hypothesis is not sufficient to prove it.

I consider myself to be more of a skeptic, but I have become fairly convinced of the anthropogenic component of global warming because of the RAPIDITY of the current warming trend. I'd consider leading with something like:

"Although the planet has warmed before, it has never warmed on anything approaching the time scale of the current global warming phenomenon."

and give specific numbers and data to support that.