Types of specific impacts (both predicted and observed) include:

• Extreme weather: storms, floods, heat waves, wildfires, droughts, etc.
• Sea level rise: occurs on a scale of a few feet (due to thermal expansion of a warming ocean) and on a scale of tens and hundreds of feet (due to melting of large ice sheets on Greenland and the Antarctic)
• Food insecurity: declining crop yields, esp. in Africa
• Water shortage: due to the disappearance of the glaciers which provide water to over a billion people, especially in India, China, and South America.
• Species extinction: with only 2°C warming, 15-40% of species are expected to go extinct. Ocean acidification is expected to severely affect coral reefs, plankton, and ocean food webs.
• Disease: warmer temperatures and shifting rainfall patterns provide increased opportunities for vector-borne diseases such as malaria and Dengue fever.
• Runaway effects: some effects are likely, past a certain threshold, to become irreversible because they feed on themselves. These include the melting of the large ice sheets, the drying (and dying) of the Amazon rainforest, the warming of the Poles, and the shutdown of the Atlantic ocean circulation.