The top 2 inches of topsoil on all of Earth’s landmasses contains an infinitesimal fraction of the planet’s water — less than one-thousandth of a percent. Yet because of its position at the interface between the land and the atmosphere, that tiny amount plays a crucial role in everything from agriculture to weather and climate, and even the spread of disease.
Those who live along the “wet coast” – which is what people living in Puget Sound or the lower mainland of British Columbia and Vancouver Island affectionately call their home – might think that they live in the wettest place on Earth. Then again, people living in the Amazon rain forest might think that there lush and beautiful home is the dampest place in the world.
For hundreds of millions of years, Earth’s climate has remained on a fairly even keel, with some dramatic exceptions: Around 80 million years ago, the planet’s temperature plummeted, along with carbon dioxide levels in the atmosphere. The Earth eventually recovered, only to swing back into the present-day ice age 50 million years ago.
How do you find your food? Most animal species, whether they rummage through a refrigerator or stalk prey in the wild, obtain nutrients by consuming living organisms. Plants, for the most part, adopt a different feeding, or “trophic,” strategy, making their own food through photosynthesis. There are, however, certain enterprising species that can do both: photosynthesize and consume prey. These organisms, found mostly in certain ocean plankton communities, live a flexible, “mixotrophic” lifestyle.