New Zealand needs to balance its environmental responsibilities with its economic opportunities, because the risk is that if you don't do that - and you want to lead the world - then you might end up getting unintended consequences.

Our work on light bulbs wasn't an arbitrary mandate. We didn't just pick a standard out of the air, or look for a catchy sounding standard like 25 by 2025 not based in science or feasibility. Instead, we worked with both industry and environmental groups to come up with a standard that made sense and was doable.

Without international participation, jobs and emissions will simply shift overseas to countries that require few, if any, environmental protections, harming the global environment as well as the U.S. economy.

The main environmental challenge of the 21st century is poverty. When you don't know where your next meal is coming from, it's hard to consider the environment 100 years down the line.

In the rich world, the environmental situation has improved dramatically. In the United States, the most important environmental indicator, particulate air pollution, has been cut by more than half since 1955, rivers and coastal waters have dramatically improved, and forests are increasing.