The importance of international directives on pollution control and carbon reducing initiatives

Why is co-operation needed between countries around the world?

Air pollution does not stop at international borders and therefore cooperation is needed between countries worldwide if air quality and global warming issues are to be effectively addressed. 
E.g: The earth summit in Rio de Janeiro in 1992 marked the first real international attempt to cooperate to reduce emissions. Richer countries agreed there would be no increase in emissions. 

Timeline of international directives

Earth Summit - Rio 1992

First real international attempt to cooperate to reduce emissions. Richer countries agreed there would be no increase in emissions. 

Kyoto protocol 1997

Agreement for the industrialised countries to reduce greenhouse gas emissions by 5% below 1990 levels between 2008 and 2012
The treaty became legally binding in 2005 - enough countries responsible for 55% of the total emissions signed. By August 2011 there were 191 signatures. 

Bali Conference 2007

New targets established to replace those agreed at Kyoto. No figure was decided but there was a recognition that there would need to be 'deep cuts in global emissions' 

Durban Conference 2011

A legally binding deal was agreed. This comprised of all countries, including USA, China and India. It will be prepared by 2015 and take effect in 2020.