I don't understand this statement. How can a conference decide not to raise global temperature over 2.8 degrees? For that matter, is there any scientific evidence that humans can actually take collective action to slow or stop global temperature increases?

It's all well and good to say that if I personally generate less CO2 then I personally will have less impact on temperature rise, but collectively, the impact depends on lots of other people's decisions, on population growth, on animal populations particularly cows. And of course if we are already on a trajectory that will increasingly release methane from clathrates, then what if that dwarfs changes in human activity?

There does seem to be some evidence that things like carbon taxes are mainly a bureaucratic boondoggle to enrich some people and to hide CO2 production by shifting it to some place that people don't look at too closely. We must never forget that bureaucracy drives corruption no matter what the underlying political system is. So if people are truly serious about collective human action to slow CO2 production or reverse it, we must be even more serious about cleaning out corruption at all levels in all countries.