In addition to carbon dioxide, there are now two other worrisome greenhouse gases on the rise.  The two gases, methane and nitrogen trifluoride, contribute less to climate change.  However, since neither are included in the usual equations that predict future impacts to the atmosphere, increases are of concern.

Methane comes from landfills, natural gas, coal mining, animal waste and decaying plants.  The decaying plants have mostly been frozen for thousands of years, trapped in permafrost and in the ocean floor.  As the Arctic warms, the billions of tons of methane are thawing out and being released into the atmosphere.

Scientists have been monitoring atmospheric methane levels for years.  According to an AP article in USA Today, after almost eight years of stability, the levels of methane in the air suddenly started rising in 2006.  "The amount of methane in the air has jumped by nearly 28 million tons from June 2006 to October 2007. There is now more than 5.6 billion tons of methane in the air."

Methane is considered the #2 greenhouse gas after carbon dioxide, because of the amount of warming it causes.  It is considered 20 times more potent than carbon dioxide.  "The total effect of methane on global warming is about one-third that of man-made carbon dioxide."  The journal, Geophysical Research Letters is publishing an article on methane in the Oct. 31 issue. 

The other worrisome gas, nitrogen trifluoride, is used as a cleaning agent during the manufacturing process for liquid crystal display televisions, computer monitors and thin-film solar panels.  Nitrogen trifluoride levels in the air have increased 30-fold since 1978, according to Ray Weiss, a geochemistry professor with Scripps Institute of Oceanography, the lead author on a paper on the subject to be published in the November edition of Geophysical Research Letters.

Currently nitrogen trifluoride contributes only 0.04% of the total global warming impact of man-made carbon dioxide.  However it is a very potent gas, thousands of times stronger than carbon dioxide.