The Climate Institute, founded in 1986, is possibly the oldest single-issue group focused on climate change. Its style is more informational than advocacy-driven, and large conferences and symposia are characteristic activities.
The Pew Center on Global Climate Change is supported by the Pew Charitable Trusts, which is ultimately based on the family fortunes of the descendants of the founder of the Sun Oil Co. The Pew climate program is a centrist, non-profit advocacy organization "working to create a policy environment that leads to the adoption of mandatory federal limits on emissions that contribute to global warming." Pew works intensely with Fortune 500 companies.
UNEP is the administrative umbrella for most major UN environmental efforts, including those on climate change. Their site is a good place to look for current and upcoming events, reports, and documents.
The WMO is the U.N.-based international organization for cooperation among national weather agencies on all sorts of weather-related projects, including the instrument observations at a vast network of weather stations that provide basic data on climate. Wikipedia. Press Contact.
The UNFCCC is a treaty that was negotiated at the 1992 Earth Summit in Rio de Janiero, was ratified by some 189 countries, and went into effect in March 1994. It initially had no mandatory controls or deadlines. The 1997 Kyoto Protocol, which did set mandatory limits, was an add-on to the UNFCCC.