jk: since when do they need a reason? Reason implies logic. Logic implies rational persons.
The ex-communists who run the UN and it's subordinate organizations like the IPCC just aren't "Progressive" enough for this lot of "environmental" protestors. They were calling for the Copenhagen Summit to be turned into a "Peoples Assembly" long a goal of World Government advocates.
The "environmental activists" at Copenhagen appear to be from the People's Movement on Climate Change. Here is the 5-point plan that the PMCC calls the "Peoples' Protocol on Climate Change:"
1. "...differentiated and equitable" global effort to "stabilize CO2 concentrations at 350ppm and hold global average temperature rise to 1.5 degrees Celsius."
2. "...reparation of Southern countries and the poor by Northern states..."
3. Reject ... corporations from harming the environment, new and greater opportunities for profit, corporate control over natural resources and technologies.
4. "Struggle for ecologically sustainable, socially just, pro-people, and long-lasting solutions.
5. Strengthen the PMCC.