Atmosphere Basics

What we'll explore in this module

In this module, we will review the basics of the science explaining how anthropogenic (i.e. caused by humans) climate change happens. We'll first discuss Earth's atmosphere (including its layers and composition), then move into Earth-Sun Relations, and finally end with greenhouse gases and the underlying mechanisms of climate change.

What is the Atmosphere?

The atmosphere is essentially everything above the ground on Earth. It begins on Earth's surface and extends over 6200 miles (or 10,000 km). 

The atmosphere is the sum of all inhalations and exhalations of life interacting on Earth's surface across time, held in place by gravity. As a result, atmospheres can and do change over time, but very slowly - our current atmosphere is probably the fourth general atmosphere in Earth's history!

Earth's prebiotic (or pre-life) atmosphere did not have sufficient oxygen for humans to survive. Microfossils dating back 3.5 billion years suggest that some form of photosynthesis existed by then. Earth's modern atmosphere is estimated to have emerged between 600-900 million years ago.

The atmosphere and the biosphere are highly interconnected. The ways that nutrients such as oxygen, carbon, and nitrogen cycle throughout the biosphere are very important for regulating their atmospheric concentrations. For instance, think back to the processes of photosynthesis and respiration - both of these processes regulate levels of oxygen and carbon in the atmosphere.

Photosynthesis releases oxygen and fixes carbon dioxide (CO2) into sugars, which store energy and become plant matter.

What does the atmosphere do?

The atmosphere acts like a filter for incoming solar energy, a.k.a. insolation. Specifically, it helps remove harmful wavelengths and radiation before they reach Earth’s surface.