The Only One who Loves Change Is a Wet Baby


The Amazon Basin is the largest rainforest in the world. It’s been shaped by the second longest river in the world, and molded by geologic forces that are still active. While all of the Amazon basin isn’t rainforest, much of it is. Read more at


At one time (about 15 million years ago) the river flowed westward. Then the Andes Mountains rose. About 10 million years ago a combination of tectonic and sea level forces changed the direction of the Amazon from westward to eastward. Today, the river drains almost 7 million square kilometers of South America toward the Atlantic. It carries almost a million cubic meters per second of water into the Atlantic, with millions of tons of suspended sediment. But even this massive system is subject to change.


Delicate relationships within the rainforest are easily disrupted. The actual extent of clear cutting in the rainforests is not known. By some estimates, over half of the Amazon forest area is already gone. But the remaining rainforest is being destroyed, too. The Peruvian government is providing land grants to people who might formerly have been nomadic. Claims that their “selective cutting” represents an ecological compromise can be easily refuted by a little biology. But since there were so few quantitative records in the rainforest a century ago, much of what we know about these changes comes from the oral histories of indigenous peoples.


Mining and drilling are also potent dangers. In Lima, two of the three ivers that feed the city are too polluted to use for irrigation. The Amazon and Napo are protected by government regulations, because the people use them for drinking and washing, but the government has few representatives there. Even eco-tourism can be part of the problem. So as you observe, tread carefully and with respect.


Changing the Rules=Changing the World

Today, the rainforest is changing again. It’s been clearcut and drained, invaded by exotics and by humans with their industries. By now, you’ll understand that just allowing new light into the understory changes all the rules. So does removal of trees, cutting roadways and canals (erosion) and even creating noise from generators.


The effects of climate change are even seen in the dark, humid heat of the rainforest. Average river levels have changed. Clear cutting has changed the water balance of the entire region, including drought. Insects and other invertebrates have changed their range. (As exothermic animals, they react more quickly to such changes.)  Crop yields have changed, too. Some plants (like North America's poison ivy) have stronger toxins.


In May of 2007, the director of NASA made headlines with a highly controversial interview on NPR. He suggested that although global warming was an incontrovertible fact, it might be inappropriate to try to change the process. Immediately almost every other climate scientist in the world cried “Foul!”


It’s certainly clear that the world is warming; at least an average of 3o Celsius in the first half of the 21st Century seems unavoidable. It’s also clear that this process is causing changes all over the world:

ž    Higher ocean water levels

ž    Droughts in agricultural areas

ž    Stronger tropical storms

ž    Increased range of disease-producing insects

ž    Changes in rainforests


But hasn’t this happened before in Earth’s history? Certainly! The sea levels have been as much as 2 m higher in this era alone. About 100,000 years ago climate change caused a decimation of our human-like ancestors; we have evidence that their population “bottlenecked” to perhaps 7,000. There have been major extinctions in every era. But that doesn’t mean that our current human society can live as we do now with these challenges. As you tour Peru, watch carefully for signs of changes wrought by humans and by the climate they influence. In the next few weeks, you’ll be asked to observe and journal a number of observations in the rainforest.


Preparing for Your Trip