Confidence Level & Projection (Worldwide through 2100)
“Virtually certain” globally; ”very likely” over land - Extreme temperatures: Increasingly frequent and intense heat waves and record warmth; decreases in extreme cold.
“Very likely” - Coastal flooding: Rises in the average sea level will contribute to more frequent bouts of “extreme high coastal water levels.”
“Likely” - Heavy precipitation: Frequency of heavy precipitation or the percentage of total rainfall coming from heavy rainfall will increase in many areas.
“Likely” - Stronger tropical cyclones (hurricanes, tropical storms, typhoons, etc.): Average maximum wind speed will increase, but the number of tropical cyclones will decrease or remain unchanged.
“High confidence” - Mountain weather: Heat waves, glacial retreat, and reduced permafrost will affect high mountain terrain, including landslides and floods from glacial lakes.
“Medium confidence” - Drought: More intense droughts in parts of Europe, the central U.S. through Mexico and Central America; northeast Brazil; and South Africa. Other areas are “low confidence.”
“Low confidence” - Severe thunderstorms: Tornadoes and hail are too small-scale and involve too many complexities for climate models to forecast confidently.
“Low confidence” - River flooding: Limited evidence and local complexities prevent a confident forecast of changes in flooding.
“Low confidence” - The various climate models do not agree about future changes in large-scale patterns such as El Nino or monsoon seasons.