Is punishment the way to go?

Britain has just announced a new plan to cut carbon emissions down 60% by 2050 in 5-year intervals. Although this has not the first time a country or state has set goals to reduce carbon emissions, this is the first time a nation has put it into law. In other words, if they don't carry though, then they can be sent to court.

I think it's a great idea that they are taking this more drastic step towards fighting global warming and helping to sustain our world, but is punishment the real way to turn? Have we come to a point where we have to threaten ourselves to do good? Since we were small, we had always been taught to do good, whether or not you get an reward and whether or not you get punished if you don't do it. It seems like these values disappear on an international scale. If you think about WWII, when Hitler refused to follow the Munish Agreement, we see that major figures in international politics are an exception to the rule that we have learned as kids and as students. He stepped over the boundary that they set out for him, looked around and realized that no one could stop him, and so he went on his way to invade Poland. And war begun. More specifically, many nations have failed to reach the agreements in the Kyoto Protocol (like Canada) and have given up. No punishment? No punishment.