Business Green: Christiana Figueres has today formally taken up her post as executive secretary of the United Nations Framework Convention on Climate Change (UNFCCC), receiving the reins of the international climate change secretariat from Dutch diplomat Yvo de Boer. The Costa Rican negotiator becomes the fourth executive secretary of the UNFCCC and will immediately begin preparing the groundwork for the next major UN climate summit in Cancun, Mexico in November. She will also be required to …