I must, firstly, state that I am as concerned as anyone about pollution and 'global warming'. I just don't fly halfway across the world (like Dame Emma) to demonstrate about it; nor do I disturb London's traffic, or leave piles of empty plastic bottles, etc, as a reminder of where I've glued myself to a lamp post.
What I do do, however, is to treat nature with respect, and not as a dustbin. I grow a lot of what we eat in as 'eco' a way as possible. And we keep our throw-away rubbish to a minimum. I buy my wine 'loose', and I stick price labels directly onto whatever I'm buying, rather than use plastic bags.
In other words, I practice what I preach, and I don't pollute or cause chaos in order to demonstrate what a cynical, hypocritical, environmentalist, do-gooder I am.
It's right that students complain about issues that concern them; students are professional thinkers. But, please, please, do your demonstrating in a park, don't leave the place littered with rubbish, don't park some silly pink boat in Oxford Circus, and please leave the police to do what they are there for; to fight friggin' crime.
If you do otherwise, you'll lose whatever support you might have had.