In recent decades, changes in climate have caused impacts on natural and human systems on all continents and oceans. In many regions, changing precipitation or melting snow and ice are altering hydrological systems, affecting water resources in terms of quantity and quality.

Based on many studies coverings a wide spectrum of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts. Currently the global burden of poor human health from climate change is relatively small compared to the effects of other stressors and is not well quantified. Differences in vulnerability and exposure arise from factors other than climate and from multidimensional inequalities often produced by disparate development processes.