In 2001 the Intergovernmental Panel on Climate Change (IPCC; Houghton et al. 2001) concluded that climate is changing, humans are contributing, weather has become more extreme, and biological systems on all continents and in the oceans are responding to the warming. From the fourth IPCC assessment (Alley et al. 2007) and the Arctic Climate Impact Assessment (ACIA 2004), we now know that the deep oceans have accumulated 22 times more heat than has the atmosphere, ice melt is accelerating, wind patterns are shifting (thatÕs particularly ominous), and nonlinear surprises are very likely in store for the climate system and for the impacts on systems such as forests and coral reefs (Epstein and Mills 2005; Stern 2006). The implications for public health and well-being are daunting, as illustrated in articles throughout this monthÕs Environews section.