Financial Tribune - The gradual expansion of renewable energy since 2009 has allowed Iran to reduce greenhouse gas emissions by as much as 2.24 million tons.

Reducing greenhouse gas emissions is among the major challenges nations big and small are grappling with to various degrees.

Greenhouse gases are capable of trapping the earth's emitted radiation, which otherwise escapes back into space. The primary greenhouse gases in the atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.