There’s a popular hypothesis that Earth acts as if it were a living thing. This doesn’t mean that some scientists think that there’s a giant mouth somewhere next to a pair of gigantic eyeballs that are staring at you. No, that would be weird. The thinking that Earth is a living thing is called the “Gaia Hypothesis,” and isn’t so strange once you actually get to thinking about it.
Earth is made up of several different big spheres, or units, that work together. The biosphere contains all living things, the hydrosphere has all of the water, the lithosphere is made up of rock, and atmosphere contains all of the gases. These aren’t separate things in separate places. Consider your body: you are made up of living cells (biosphere) that contain water (hydrosphere) and minerals (lithosphere) which are used to convert oxygen to carbon dioxide (atmosphere). You have a miniature Earth in your body! Creepy!
All of these different spheres depend on each other in order to maintain the equilibrium of Earth. The oceans absorb carbon dioxide and heat from the atmosphere, helping to make sure that the atmosphere has the right balance of gases for living things to survive. Rocks on Earth break and form things like valleys, which often fill with water to catch rainfall from the atmosphere. Some organisms help to break larger rocks up to form soil so that plants can grow and convert carbon dioxide to oxygen. In fact, it took billions of years just for Earth to get to the point where there is a balance, and now due to many destructive activities, we humans are throwing off that equilibrium.
Just like a living thing, Earth transports nutrients, gets rid of wastes, moves energy around and maintains homeostasis. But it’s this last part that we are in danger of messing up: the homeostasis of Earth. Do you remember that homeostasis is the balance between the inside and outside of an organism? Right now, Earth has dangerously high levels of carbon dioxide in its atmosphere, and much of that carbon dioxide is coming from burned fossil fuels that were mined from deep inside the Earth. This is causing temperatures on the surface of Earth (and the oceans) to rise very quickly. Guess what? That’s not homeostasis!
Global warming is the name for this increase in carbon dioxide, methane and other gases that cause Earth’s temperature to rise. 97.5% of climate scientists agree that global warming is happening because of what we are doing: driving, flying, raising cattle and pigs for meat, and destroying forests. Some scientists disagree, stating that Earth always has warmed up and then cooled down in a cycle, and that humans have little to nothing to do with current global warming. What do you think?