The Science of Climate Change

The Basic Science of Climate Change

Laser Talk

Question:  What’s the actual science behind global warming?

Answer: The sun heats the earth, which then sends part of that heat back into space as infrared radiation. Certain gases – ‘greenhouse gases’ – interact with this outgoing heat radiation, keeping the surface temperature higher than it would be without them. Although water vapor has the greatest effect, carbon dioxide, CO2, plays a pivotal role. If there was no CO2 in the atmosphere, most or all of the earth’s surface would be frozen,[1] but just a tiny amount keeps it warm enough to support life as we know it.

For about 10,000 years, atmospheric CO2 levels have been quite steady, giving us a stable climate in which to live and grow. But as we learned new ways to extract energy from coal, oil, and gas, we proceeded to burn them faster and faster, converting ‘fossil’ carbon that’s been buried for millions of years into CO2, exceeding the natural level we had for millennia.

Scientists have understood the greenhouse effect since the 1850’s, [2,3] but it wasn’t until 1958 that we began regularly measuring and tracking atmospheric CO2. [4] Just since that time, it’s climbed by more than 30 percent, [5] about 100 times faster than any natural cycle can explain. [6]

Not only is this raising the global temperature, but a sizeable fraction of the CO2 we produce is going into the oceans, causing the water to become more acidic. That’s detrimental to important marine life. [7]

Human activity, mostly fossil fuel burning, currently adds over a thousand tons of CO2 per second to the atmosphere and the oceans. [8] Natural cycles, volcanoes, and the sun have all been ruled out as the cause of the current heat buildup. [9] They are either too small, too slow, or going in the opposite direction. It’s us.

In a Nutshell: Global temperatures are now rising at an accelerating rate, which began in the 1800s. This is entirely due to greenhouse gas buildup from human activity, mainly the burning of fossil fuels.

  1. Voigt, A. and J. Marotzke. “The transition from the present-day climate to a modern Snowball Earth.” Climate Dynamics 35, 887-905 (9 Jul 2009).
  2. “The Discovery of Global Warming.” American Institute of Physics (Feb 2018).
  3. “Meet the woman who first identified the greenhouse effect.” Climate Home News (9 Feb 2016).
  4. Harris, D.C. “Charles David Keeling and the Story of Atmospheric CO2 Measurements.” Analytical Chemistry 82 7865-7870 (1 Oct 2010).
  5. Specifically, from 315 to 414 parts per million (ppm). “Global CO2 Levels.” 2° Institute (accessed 29 Dec 2019).
  6. Lindsey, R. “Climate Change: Atmospheric Carbon Dioxide.” NOAA Climate.Gov (19 Sep 2019).
  7. “Ocean Acidification.” NOAA Fisheries (28 Jun 2017).
  8. Ritchie, H. and M. Roser. “CO2 and Other Greenhouse Gas Emissions.” Our World in Data online (2018).
  9. Roston, E. and B. Migliozzi. “What’s Really Warming the World?” Bloomberg Business Week (24 Jun 2015).

This page was last updated on 08/08/21  at 20:09 CDT.