The big goal was to look at how the European Union set up its emissions trading system to fight climate change and see what lessons we can learn for global policies. Europe's system is different because each country within the EU gets to pick its own target for cutting emissions and decide how to manage trading permits. The EU's program is designed to meet climate change goals like the ones set in the Kyoto agreement, even though it only covers about half of the EU's total emissions. By studying how this system works, we can see how to make trading programs effective, fair, adaptable, and get everyone to stick to the rules - Useful lessons for a worldwide system to tackle emissions.