"Ecosystems can range in size from a small pond to the frigid tundra that covers most of the northern part of planet. There are countless ecosystems including terrestrial, or earth-based ecosystems, ocean-based marine ecosystems, and freshwater ecosystems in lakes and rivers. While individual ecosystems might not appear to be connected, when one is destroyed, a chain reaction can results, causing harm to others that are linked to the system. A mass extinction is taking place in the twenty-first century. Large numbers of species have disappeared-or are expected to-as the climate warms"--