Apparently he never travelled to India, China, Pakistan, Indonesta et al. The US environment is one of the cleanest on the planet. With of course the exceptions like San Francisco and Los Angeles.
when Saint David says it:
11 Nov 2016: ScienceAlert: David Attenborough Has an Important Warning About Human Population
by JOSH HRALA
“We are a plague on Earth. It’s coming home to roost over the next 50 years or so. It’s not just climate change; it’s sheer space, places to grow food for this enormous horde,” Attenborough told Radio Times back in 2013...
Attenborough is also a supporter of the UK-based charity Population Matter...
Attenborough doesn’t shy away from adding a bit more controversy to an already difficult issue by saying that famine-stricken countries like Ethiopia have a population problem that is contributing to famine.
“We keep putting on programmes about famine in Ethiopia; that’s what’s happening. Too many people there,” he told The Telegraph.
“They can’t support themselves - and it’s not an inhuman thing to say. It’s the case. Until humanity manages to sort itself out and get a coordinated view about the planet, it’s going to get worse and worse.”
It’s not clear what his plan for the future would entail in developing countries, but his message is simple: humans need to chill out a bit because it’s getting crowded here...
https://www.sciencealert.com/the-time-david-attenborough-said-humans-are-a-plague
when Saint Hillary says it:
1 Nov 2014: The Atlantic: The Climate-Change Solution No One Will Talk About
Studies have shown that improved access to birth control can be a valuable tool in slowing global warming, but many politicians are afraid to broach the subject.
by Jason Plautz and National Journal
Just look at what happened to Hillary Clinton in 2009, when as Secretary of State she acknowledged the overpopulation issue during a discussion with Indian environment minister Jairam Ramesh. Clinton praised another panelist for noting “that it’s rather odd to talk about climate change and what we must do to stop and prevent the ill effects without talking about population and family planning.”...
Right-wing critics pounced, with the Alex Jones-run Info Wars calling her comments “Malthusian.”...
The U.N. Intergovernmental Panel on Climate Change has noted the burden of “population pressures” on natural resources, while separately looking at the health impact of family planning...
https://www.theatlantic.com/health/archive/2014/11/the-climate-change-solution-no-one-will-talk-about/382197/