He was also director of California Climate Change Center (2003-2006), member of the Environmental Economics Advisory Committee at US Environmental Protection Agency (2000-2006), and lead author of the IPCC Fifth Assessment Report (2011-2014).
Tamén foi director do Centro de Cambio Climático de California (2003-2006), membro do Comité Asesor en Economía Ambiental da Axencia de Protección Ambiental dos Estados Unidos (2000-2006) e autor líder do Quinto Informe de Avaliación do IPCC (2011-2014).