On December 11th, 1997 Italy and 160 other nations subscribed this document foreseeing the obligation of the industrialized countries to reduce at least 5% of the polluting emissions (carbon dioxide and 5 more greenhouse gases) in the period 2008-2012, in respect of the emissions  registered in 1990 – considered as a basic year.

In case one of the signatory country will not reach the foreseen results, it can recall the ET (Emissions Trading): it allows the exchange of emissions credits between the industrialized countries; a country reaching a higher decrease of its greenhouse gases emissions in respect of its objective, can give (through the ET) its “credits” to one of those countries that were not able to respect their engagements in the reduction of these emissions.