Global warming

The folks at uncommondescent seem to quite unanimously think that global warming is not due to human causes. I'm not going to advocate neither for or against the extent to which humans are contributing to rising temperatures but merely point out what I find interesting with the ID-crowds conclusion. Intelligent design proponents tend to make a "design inference" (conclude that something has an intelligently designed cause) whenever they feel that mere known natural processes are not enough to account for a certain outcome. And yet, in the global warming debate, there seems to be evidence that causes such as changing levels in solar output are not enough to account for the increase in global temperatures. Because of this (and given that CO2 which we pump out quickly is a green-house gas), climate scientists have made a "design inference" and are claiming that humans are responsible for at least some of the warming. Usually, the ID crowd loves when scientists think that they can detect intelligent design of any kind (think archaeology and SETI), but in this instance, they seem to flat out refuse to even consider the possibility that intelligence might be at work. Why would this be? Comments such as:

"Global Warming: why it is the Left’s last best chance to gain a
stranglehold on our political system and economy… and how we can fight
back"

and

"Given the way Darwin defenders go about defending evolution, why should we
expect the science of global warming to be any different. "

seem to imply that the exisence of evidence of design is secondary to other agendas.