For many youth, a warming world is more than an abstract threat. Within the lifetimes of today's young adults and children, climate change could lead to food shortages, changing coastlines and catastrophic storms. An October 2009 Pew Research Poll found that young Americans are more likely than any other age group to view climate change as "a very serious problem." About 2,000 young people voiced those concerns at the 2009 United Nations climate talks in Copenhagen, where world leaders tried – and failed – to agree on a treaty to curb heat-trapping gases. Despite the collapse of the talks, youth activists vowed to continue pressuring politicians to put a stop to climate change.