Basic Science of Climate Change
This page was updated on 05/06/18.
Question: What’s the actual science behind global warming?
Answer: The earth radiates some of its heat out to space naturally, but certain gases – ‘greenhouse gases’ – trap a portion of this heat radiation. Carbon dioxide, CO2, is an important greenhouse gas. Even at a very low concentration, CO2 has a powerful effect on the earth’s temperature. If there was no CO2 in the atmosphere, we would freeze, but just a little is enough to sustain life.
For about 10,000 years, the CO2 level was quite steady, giving us a stable climate in which to live and grow. But when we discovered all the things we could achieve with fossil fuels, we started burning them at an accelerating rate. Burning those fuels converts carbon that’s been buried for millions of years into CO2 that is steadily building up.
Scientists discovered the greenhouse effect in the 1850’s, [1,2] but it wasn’t until 1958 that we were able to measure CO2 in the atmosphere and measure how fast it increases.  As of May 2018, it had climbed from 280 to 410 parts per million (ppm). 
That amount of CO2 accounts for about half of the fossil carbon we’ve burned in modern times.  What happened to the rest of it? Most of it has gone into the ocean, causing the water to become more acidic, which is detrimental to important marine life. 
Human activity, mostly fossil fuel burning, currently adds over 1,000 tons of CO2 per second to the atmosphere. 
Natural cycles? Volcanoes? The sun? These have all been ruled out.  They are either too small, too slow, or going in the opposite direction. It’s us.
Related: Where Scientists Stand on Climate.
- “The Discovery of Global Warming.” American Institute of Physics (Feb 2018).
- “Meet the woman who first identified the greenhouse effect.” Climate Home News (9 Feb 2016).
- “Charles David Keeling.” Wikipedia (1 Apr 2018).
- “Global Climate Change: Vital Signs of the Planet.” NASA (accessed 6 Apr 2018).
- Gonzalez, R. “NASA’S CO2-tracking satellite deconstructs earth’s carbon cycle.” Wired (12 Oct 2017).
- “Ocean Acidification.” NOAA Fisheries (28 Jun 2017).
- Ritchie, H. and M. Roser. “CO2 and Other Greenhouse Gas Emissions.” Our World in Data online (2018).
- Roston, E. and B. Migliozzi. “What’s Really Warming the World?” Bloomberg Business Week (24 Jun 2015).