he does look like joel cohen. one of the cohen brothers. >> yeah. >> seth: yeah. >> i'll take that. >> yeah. >> seth: i wanna -- we were talking backstage you are on this fantastic new show called "goliath" on amazon. >> right. >> seth: which i really like. but also last, i guess now two years ago, or so you were in "fargo." we've been mentioning joel cohen. >> right. >> thank you. >> seth: and i loved it for a lot of reasons but here is your -- this is a very unique look. >> oh yeah. >> seth: for those that haven't seen it. you play a cold hearted hit man and that's not what you think, when you -- that's a weird hair cut. >> yeah. what happened was i got a bad hair cut. >> seth: in real life. >> yeah, in real life. >> seth: by accident? >> yeah. it was an accident. tell. it's normally this color. but anyway so i looked at myself in the mirror before we started growing the beard out like that ???hthisas an iconic look." >> seth: yeah.mi?j >> and that's methg you're going toemember and if this know? >> seth: yeah. >

one demographer, joel cohen, from rockefeller university, a few years ago, looked at all the estimates made of population size and sustainability -- trying to answer the question, "how many are too many?" and it really came down to a huge array of estimates and depended on what kind of life you wanted. and that's what really goes into this equation. it's a matter of trade-offs. narrator: while farnsworth riche's research is based mainly in the united states, deborah balk's studies have a predominantly global perspective. with 6.5 billion people currently living on the planet, it's estimated that world population mapeak at around 9.1 billion in the next 50 yrs. scientists predict that climate change linked to greenhouse-gas emissions will lead to changes in the global environment, including a rise in ocean levels. in developing nations, the majority of population growth is projected to take place in cities. many of these cities are situated in low-lying coastal areas -- eas most at risk for climate-change effects. balk: we know climate change will lead to sea-level rise, and that, of co