I think that people are aware of the potential impacts of climate change on Arctic species. You know, everyone has seen the pictures of the poor pola… - Elizabeth Kolbert

The definition, I suppose, would be many, many organisms across many, many different groups. And that is, really, what we are seeing and that is what makes scientists fear ... that we're in a mass extinction. ... About a quarter of all mammals are considered endangered. ... About 40 percent of all amphibians are considered endangered. But we're also seeing organisms, invertebrates, for example, are endangered ... many species of reef-building corals are now considered very, very endangered. So you're seeing extinctions across a wide variety of groups, and that, I think, would have to be one of the defining characteristics of a mass extinction.

Looking out your window today, the weather you see doesn’t really tell you what’s going on. The earth is big and complicated — and there’s a big time lag in the system. People need to understand that. You know, many people, many scientists, many journalists keep trying to impress that upon the public. It obviously isn’t working very well, but we keep trying.

After a mass extinction, it has generally tended to take many millions of years for life to recover. It's not something that you bounce back from, from one day to the next.