Extreme weather events like droughts and floods are growing more frequent, and rising CO2 emissions are a big reason why. But how are carbon dioxide and the greenhouse effect linked? This viewer question comes from Malavika V. in India.
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00:00How does carbon dioxide cause global warming?
00:05CO2 is a gas that occurs naturally in the atmosphere.
00:09It's colorless and odorless and is one of a group of compounds we call greenhouse gases.
00:15Others include water vapor, methane, nitrous oxide, and ozone.
00:20Together they contribute to a naturally occurring greenhouse effect.
00:24It works like this.
00:26The sun emits radiation that warms the Earth's surface.
00:29Much of it is reflected back towards space as heat.
00:34Some of that, however, reacts with greenhouse gases along the way.
00:38They absorb the heat and reflect it back downwards.
00:42This process is what ensures relatively constant temperatures on the surface of our planet.
00:49Without the natural greenhouse effect, the average temperature on Earth would be minus 18 degrees Celsius,
00:55far too cold for most life forms.
00:58But back to the question.
01:00Although the fraction of CO2 in the atmosphere is very small,
01:04it has an outsized influence on the greenhouse effect.
01:08Carbon dioxide causes between 20 and 30 percent of it.
01:12That's because of its molecular structure.
01:15Only molecules made up of three atoms or more,
01:18like CO2, methane, or water vapor, interact with the heat Earth radiates back into space.
01:25It causes those molecules to start vibrating, and they generate heat in turn.
01:31Most of the other gases in the atmosphere don't play a role in the greenhouse effect.
01:39Since the beginning of the Industrial Revolution,
01:42carbon dioxide levels in the atmosphere have risen by around 50 percent.
01:47And they might double by the end of the century.
01:50So, more heat is being retained in the atmosphere.
01:54Research shows that the rise in CO2 concentration is a major contributor to climate change.
02:01And more of the gas increases the frequency of extreme weather events,
02:06like droughts, floods, and storms.
02:11To slow the effects of climate change,
02:14we have to significantly cut our emissions of carbon dioxide.