Ever since its formation, Earth’s climate has existed in cycles. It has ranged from extreme, uninhabitable heat to freezing ice ages. Major events have shaped the surface of the world drastically. According to nasa.gov, carbon dioxide levels are rising, and with that, the Earth will keep changing.

• 2.4-2.1 billion years ago: The Huronian glaciation occurred, according to history.com.
• 410 million years ago: The first plants appeared, according to globalecologist.org.
• 360-300 million years ago: Coal began to form, according to globalecologist.org.
• 360-260 million years ago: The Karoo glaciation occurred, according to history.com.
• 230-65 million years ago: The dinosaur age began, according to globalecologist.org.
• 65 million years ago: The first mammals appeared, according to globalecologist.org.
• 15 million years ago: Carbon dioxide levels were about 400 parts per million according to globalecologist.org.
• 2.6 million years ago: The Quaternary glaciation (also known as The Ice Age) occurred, according to history.com.
• 800 thousand years ago: Carbon dioxide levels ranged from 180 and 300 parts per million, according to climatecentral.org.
• One thousand years ago: Carbon dioxide level was about 280 parts per million, according to climatecentral.org.
• 250 years ago: The Industrial Revolution began, according to newsroom.ucla.edu.
• 40 years ago: Ice cap coverage began declining at a substantial rate, according to nasa.gov.
• Current: Carbon dioxide levels are 387 parts per million, according to livescience.com.