Join us on Twitter: Ask a NOAA scientist about the annual ozone hole that forms over the Antarctic during a Tweet Chat on @NOAALive on Friday, Oct. 26!

Bryan Johnson.

Bryan Johnson is an atmospheric scientist at NOAA's Earth System Research Laboratory. (Credit: NOAA)

An annual hole still forms in the ozone layer over Antarctica every Southern Hemisphere spring. Ozone helps protect the planet’s surface from harmful ultraviolet radiation that can cause skin cancer in humans and damage other biological life. This year, NOAA and NASA measured the hole at about the size of the United States, Canada and Mexico combined – that’s actually smaller than in recent years.

The South Pole ozone hole forms because of several factors: ozone-depleting chemicals still in the atmosphere, cold temperatures and polar stratospheric clouds that can form in the cold, providing tiny ice crystals necessary for the chemical reactions that eat away at the ozone layer.

Why does a hole form in the ozone every spring in Antarctica, and why does ozone re-form later in the spring? Why do we care about ozone in this distant part of the world? Does the same phenomena occur in the Arctic? Why does it have to be cold for ozone-depleting chemicals to eat away at ozone?

Get answers to these questions and more during our Ozone Chat.

Tweet Chat Details

About our expert

Bryan Johnson is a scientist in the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo. The Global Monitoring Division provides the best possible information on atmospheric constituents that drive chemical change, stratospheric ozone depletion, and baseline air quality.


NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.

Posted on 10/24/12