I'm late to this party, but I must agree with Iains above that....the population IS the major ongoing issue. It is not the immediate 'cause' in formal terms, as all the forms of pollution science is trying to combat are the specific 'causes'... but the underlying, seldom referenced issue IS population. Why?
   Because if we 'solve' the energy questions and get rid of fossil fuels and eliminate plastic bags & styrofoam cups...etc., we still have the effluent production and water use and over-fishing and soil degradation and limited arable land ... which cannot be controlled in any useful time sequence. Population growth has fallen a bit, but the totals are still rising, and we simply cannot support 75 trillion people....*

* "what's that you say, Bill? Don't be silly, we're not going to have 75 trillion people!"

Oh, right... 22 trillion..

"You are being ridiculous! 22 trillion is nonsense!"

Ummm... sure... then YOU tell ME how many people you think the Earth can support! And while you're at it, tell me what YOU think will end the growth patterns? And suppose the answer is..um.... 17 billion (which is forecast by 2100 in some models).... where do you think these people are going to live and what are they going to eat?

People need 'space'...personal space. Look up the "rats in the cage" experiments, where rats were provided with food & water, but no restrictions on breeding. Eventually, there were fights just due to stress and unhappiness. Look up how the people on Pitcairn Island coped after the mutiny on the Bounty. It ain't pretty in many parts.

Real solutions? Restrictions on fertility... how? Well might you ask! China tried it, but has largely just 'encouraged' smaller families. Put anti-fertility drugs in the drinking water? *shrug*.. good luck!
Perhaps giving every girl, randomly, at puberty, an implant, 2/3of which are anti-fertility? Maybe.... but you KNOW there would be accusations of NON-random selection.

Of course, population growth WILL be contained, and maybe even reversed long before any "trillion" enters the count. Nature will deal with us... but I don't like the images.

Call me a sensationalist fear-monger... I'd make a bet, but I won't be around to collect my winnings. Max says Mudcat will be here as long as he can keep it going. Maybe someone in 20 MORE years will read this and nod at my prediction as "things happen". Maybe *I* will live to 97 and either apologize or say "I told you so."