There are preliminary indications that some human systems have been affected by recent increases in floods and droughts. Natural systems are vulnerable to climate change, and some will be irreversibly damaged. Many human systems are sensitive to climate change, and some are vulnerable. Projected changes in climate extremes could have major consequences. The potential for large-scale and possibly irreversible impacts poses risks that have yet to be reliable quantified.
Adaptation is a necessary strategy at all scales to complement climate change mitigation efforts.
Those with the least resources have the least capacity to adapt and are the most vulnerable. Lower emissions scenarios require different patterns of energy resource development. Forests, agricultural lands, and other terrestrial ecosystems offer significant carbon mitigation potential. Although not necessarily permanent, conservation and sequestration of carbon may allow time for other options to be further developed and implemented. There is no single path to a low emission future and countries and regions will have to choose their own path.