Penn StateNASA

Module 11: Terrestrial Ecosystems in Peril

Introduction

Imagine this. Martians come back to Earth 10 million years from now to study the apparent disappearance of what is described as a once thriving planet. They find textbooks with diagrams of the geological time scale and its divisions into eras, separated by the main mass extinctions. Then they take cores and sample bones in sediment deposits. What they find is the final mass extinction that took place 9.8 million years before their arrival, and 200,000 years before that, the beginning of a new era, the Anthropocene.

Now the Martian part of this tale is fiction, but sadly the Anthropocene part is not. We have already entered that era and paleontologists and ecologists combined believe that the sixth largest mass extinction event in Earth’s 4.6 billion year history has already begun. Rates of species loss are as high as any other time in the last 65 million years, since the time the dinosaurs went extinct. And without a revolution in our stewardship of the planet we call home, these rates are bound to accelerate in the future.

Terrestrial ecosystems are in peril. Let's make it clear, climate change is not the sole culprit here. Humans have messed with ecosystems in numerous other ways. In this module we will see how this has happened and what is at stake in the future. We will begin by presenting how extinction happens from a theoretical view. Then we will present one threatened representative from many of the major phyla to observe the impact of human activities on them and attempt to predict their future fate. Finally, we will observe a few “winners” of the loss of global species diversity.