Clearly, cities are playing an increasing role in responding to climate challenges and are therefore in need of knowledge to aid in their policy development. The First Assessment Report on Climate Change in Cities (ARC3), a project of the Urban Climate Change Research Network (UCCRN), is particularly useful in this regard. The ARC3 provides a scientific assessment of climate change in cities, presenting the information necessary for sound mitigation and adaptation decision-making on a sector-by-sector basis. By specifically addressing climate change in cities, the ARC3 supports the work of local governments, officials and researchers, and complements the work of the Intergovernmental Panel on Climate Change (IPCC).

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) provided the global community with up-to-date knowledge about the impacts of climate change. It projected that climate change will lead to a number of consequences for urban areas, including declining air quality, an increased number and severity of heat waves in cities in which heat waves already occur, increased pressure on infrastructure, and augmented stress on water resources. Furthermore, the Fourth Assessment Report noted that residents of some cities in the world, including some in Europe and the USA, have experienced high levels of mortality due to the impacts of extreme climate events.