NORMAN — Editor, The Transcript:
John Baugher is correct when he writes, “Global warming is happening” (The Norman Transcript, Sept 25, 2012), but a simpler explanation may be more understandable.
Greenhouse gases of importance in Earth’s atmosphere include carbon dioxide. Increased burning of fossil fuels by humans, owing to new scientific discoveries with advanced technologies and increased numbers of humans, has caused this gas to increase remarkably since only 70 years ago. The volume of CO2 in Earth’s atmosphere is now a third greater than its highest level during the 850,000 years ended in mid-20th century, as determined by analyses of air bubbles trapped in ice cores.
A greenhouse gas tends to block infrared radiation, but is substantially transparent to visible light. Solar radiation thus comes through Earth’s atmosphere but heats the ground, which at much lower temperature than Sun, radiates back to space mainly in the infrared range. As carbon dioxide increases, radiation from Earth’s surface tends to be more blocked, and the surface temperature rises. At the higher temperatures, stronger vertical air currents carry excess solar heat to the high atmosphere, where, as before, it is radiated to space.