This article accompanied part three of a five part radio series. To listen, visit WFDD's website.
The impact of global warming on the Arctic poles is well documented and easy to see. But scientists are just now beginning to understand the impact of rising temperatures on tropical forests around the equator.
In the Peruvian village of Pisac, not too far from Machu Picchu, tropical scientists from around the world met last month for the 10th annual meeting of the Andes Biodiversity and Ecosystem Research Group. Two experts focused their talks one morning on how climate change was dramatically affecting Peru’s vast rain forests in the Amazon Basin. Patrick Meir, an ecosystem scientist from the University of Edinburgh in Scotland, believes climate change is bringing the potential for loss of species:
"If they are truly constrained by warming temperatures at the lower end of their range, and their range becomes compressed because there is a lid on how far they can move upwards, then literally land area in which that species might be happy existing declines, and that’s going to result in some populations of species becoming nonviable. There is the potential for species loss. That’s the really worrying view.”
Yadvinder Mahli of Oxford University in England is one of the world’s leading tropical biologists. He says that even small changes to our tropical forests extend out to affect the entire world. Tropical forests are the functional lungs of the earth. They pull greenhouse gases from the air and store that carbon in their limbs, trunks and roots. That process of carbon storage helps slow the rate of global warming. But tropical forests also play a critical role in international weather patterns, in rainfall and in the availability of fresh water. They do this through the process of transpiration.
“Think of transpiration as the world’s water pump," says Greg Goldsmith, an American biologist now working as a post-doc at Oxford University. "It’s what takes water that’s fallen as precipitation and landed in soil and puts it back in the atmosphere.” Goldsmith says the water that goes back into the atmosphere forms clouds. And those clouds begin as vapor rising from the leaves in tropical forests, like perspiration from your skin.
“This is a big water pump," says Goldsmith. "Millions of billions of gallons of water in the tropics is being recycled into the atmosphere. And that’s the water that we drink, that’s water that we use to grow crops, that’s the water that drives the climate that we experience on the daily basis – whether you’re going to have a thunderstorm at four in the afternoon or not.”
The process of pulling greenhouse gases from the air and producing the clouds that dictate our weather are fundamental services that tropical forests perform to support our lives on earth. In lecture after lecture, the biologists meeting in Pisac explained how global warming is threatening those services.
“I think we have to be prepared for a world that is 5 or 6 degrees warmer," says Mahli. "We should do everything we can to avoid that world, but that world is coming faster and closer than we realize.”
Because biologists work in eons and epochs, not years or decades, fast to Mahli means 50 to 100 years. If that seems like a long time, consider this: it’s the lifetime of our grandchildren. And Mahli cautions that the rate of warming is unprecedented in human history. “Many aspects of the planet we live on will change. The functioning of ecosystems, the life support systems of the planet. Some things will be resilient. Some things will be vulnerable. But it’s certainly the largest change this planet has experienced since the last Ice Ages, before there were any cities or civilizations.”
Ken Feeley, a tropical biologist from Florida International University, says there is still time to act. But the conversation on how to cope with global warming needs to broaden beyond the melting ice caps. “It’s almost ironic," he says. “We look at the huge amount of species that we have and the amount of attention we give to them and it’s rather depressing."