U.S. President Barack Obama takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama arrives via Marine One helicopter at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (R) greets guests after his remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

An alligator suns itself along the Anhinga Trail at Everglades National Park, Florida April 22, 2015. U.S. President Barack Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

A bird flies over U.S. President Barack Obama as he takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

A Secret Service counter-assault team member keeps watch of the horizon as U.S. President Barack Obama (not pictured) takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

A bird spreads its wings along the Anhinga Trail at Everglades National Park, Florida April 22, 2015. U.S. President Barack Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (C) takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama delivers remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

An alligator suns itself along the Anhinga Trail at Everglades National Park, Florida April 22, 2015. U.S. President Barack Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

Secret Service counter-assault team members (R) keeps watch of the horizon as U.S. President Barack Obama (not pictured) takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

A fan blows on guests as U.S. President Barack Obama delivers remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama delivers remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama's car waits for him while he takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama delivers remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama (2nd L) takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

U.S. President Barack Obama takes a walking tour of the Anhinga Trail at Everglades National Park, Florida April 22, 2015. Obama is visiting the subtropical swamps of the park on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst 

Secret Service agents (L) scan the horizon as U.S. President Barack Obama delivers remarks on climate change at Everglades National Park, Florida April 22, 2015. Obama made an airboat tour of the park's subtropical swamps on Wednesday, part of a push to get Americans thinking and talking about the damage climate change is causing close to home. REUTERS/Jonathan Ernst