4° Act now

When Earth absorbs sunlight it heats up. Like the sun, Earth emits energy, but because it is cooler than the sun, Earth emits lower-energy infrared wavelengths. Greenhouse gases in the atmosphere (methane, carbon dioxide, etc.) let light pass through, but absorb infrared light i.e. causing the atmosphere to heat up. The warmer atmosphere emits more infrared light, which tends to be re-absorbed, perhaps many times, before the energy eventually returns to space.  

Since the industrial age began around the year 1750, atmospheric carbon dioxide has increased by 40% and methane has increased by 150%. Such increases cause extra infrared light absorption, further heating Earth above its typical temperature range. In other words, energy that gets to Earth has an even harder time leaving it, causing Earth’s average temperature to increase and therefore producing global climate change.