The Proof Is in the Atmosphere


People on small boat in arctic climate

How do we know the amount of greenhouse gases in the atmosphere is increasing?

Scientists measure the amount of greenhouse gases in the atmosphere in several ways. They use satellites and other instruments to measure the amount of greenhouse gases in the air all around the world. They also collect samples of air from specific places and then analyze these samples in a laboratory.

The Earth also gives us clues about the levels of greenhouse gases that existed in the past. For example, ancient air bubbles trapped deep in the ice of Greenland and Antarctica reveal how much carbon dioxide was present long ago.


This graph has a line that shows the amount of carbon dioxide in the atmosphere from the year 650,000 BC until today. Current levels of carbon dioxide are much higher than any other time period shown in this graph.

Scientists can compare the amount of carbon dioxide in the atmosphere today with the amount of carbon dioxide trapped in ancient ice cores, which show that the atmosphere had less carbon dioxide in the past. Source: EPA's Climate Change Indicators (2014).

Scientists have carefully examined all this evidence and made a startling discovery. There's more carbon dioxide in the atmosphere now than at any other time in at least 650,000 years! And the amount of carbon dioxide and other greenhouse gases is continuing to increase.