Climate Change

Question 1

What chemical is responsible for the hole in the ozone layer?

Answer 1

Widespread use of chlorofluorocarbons (CFCs) are responsible for the “hole in the atmosphere.
CFC’s have one or two carbon atoms and chlorine or fluorine. They do not degrade with time and persist in the atmosphere until they migrate into the upper atmosphere where the inert chlorine become reactive with ozone (O3) to form O2. Production of reactive chlorine requires sunlight. Ultimately the process is chlorine plus ozone results in chlorine monoxide and diatomic oxygen. The chlorine monoxide (ClO) can form a dimer with another chlorine monoxide (Cl2O2) molecule and complete this cycle infinitely many times effectively destroying the ozone (O3) in the ozone layer.

Question 2

Who cares about CFC’s?

Answer 2

A single CFC molecule is 4750 to 10900 times more effective at trapping heat than a single molecule of CO2; greenhouse gas effect (trapping heat re-radiated from Earths surface).
A decrease in ozone concentrations in the upper atmosphere from reactions with stratospheric chlorine results in more UV radiation reaching Earths surface.
Increased UV radiation not only harms people (increased risk of skin cancer, eye damage, and suppression of immune system), but it damages marine phytoplankton and crops.

Question 3

An international treaty signed in 1987 to ban the use and production of CFC’s and ODS’s (ozone depleting substances) by the year 2000 in economically developed countries. In this treaty funds were also allocated to help developing countries take similar steps

Answer 3

Montreal Protocol

Question 4

What are the results of the Montreal protocol?

Answer 4

• the ozone layer has not significantly thinned since 1998 and appears to be recovering
• emissions of ODS’s ozone depleting substances has been declining and the total inorganic chlorine concentration in the stratosphere appears to have peaked in 1997 and 1998
• some estimate suggest that the antarctic ozone levels could recover and return to pre-1980 levels by the year 2075.
• use of hydrochlorofluorocarbons HCFC’s, hydrofluorocarbons (HFC’s), and perfluorocarbons (PFC’s), instead of CFC’s