There is always a percentage that don't agree with an accepted...

There is always a percentage that don't agree with an accepted modal, and this is healthy in science, their reasons may be many though which is why its important to look at their science and they will be judged on the science they present. Those who go against the grain on scientific consensus must provide exceptional research with reproducible results that withstands the peer-review process and be published and respected journals. If these things occur then what they have accomplished will be taken as science that can be expanded upon.

I'm not really sure how you want me to approach the website desmogblog.com you have provided. A bit of research about the site brings up more red flags. Webpages like this provide confirmation bias for those against the consilience of anthropogenic global warming, there are similar sites against evolution etc.

Unfortunately science is not a democracy so I'm not really sure what this petition is trying to achieve? You can disagree with how we should deal with the problem, but raising petitions to have decades of science thrown out the window is just not how science works. Science is science, it doesn't require you to agree with it. As I said earlier, clear the slate and go to google scholar and read, for weeks if you have to because there is a blog for any bias you want confirmed.