Top Predator Losses Disrupt Ecosystems

This is Scientific American 60-Second Science. I'm Christopher Intagliata. Got a minute?
What human activity has the biggest impact on the planet?
I took an informal poll of New Yorkers:
"Driving, day to day commuting."
"Eating too much meat."
"Using too many resources, I think."
"Factory farming."
"Driving."
Here're something I didn't hear: killing off the world's top carnivores, like tigers, wolves and bears.
Scientists say it's an overlooked problem with effects that ripple through ecosystems in unexpected ways.
When otters disappear, for example, urchins take over, decimating kelp forests.
Researchers reviewed the conservation status of 31 of the world's largest carnivorous mammals.
They found that some two-thirds are threatened, living on a fraction of their former range.
And nearly all are decreasing in number, apart from a few exceptions, like grizzlies and black bears.
Their analysis appears in the journal Science.
The loss of top carnivores could alter the dynamics of disease and wildfires, they say, and have unintended consequences for ecosystems.
So either we learn to coexist with these predators or their disappearance may come back to bite us.
Thanks for the minute, for Scientific American 60-Second Science. I'm Christopher Intagliata.