• This warming during the Holocene introduced a humid climate (300 millimetres of rain per year), which paradoxically was less warm in the humid regions, with a multitude of small lakes connected to an aquifer that was full to the surface, situated about 50 metres above the level of the present one.

• Thunderstorms form when heating of the ground causes warm, humid air to rise and condense in colder air above.

• In Quebec 's forests, for example, the combined effects of higher carbon dioxide concentrations, warmer temperatures and more humid conditions could help increase average forest growth by 2050 by some 50 to 100 % .

• Large-scale deforestation in the humid tropics (e.g., South America, Africa, and Southeast Asia) has been identified as the most important ongoing land-surface process, because it reduces evaporation and increases surface temperature.

• Desertification was defined at the Rio Earth Summit in 1992 as "land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors including climatic variations and human activities".

• Tropical rainforests in particular are very wet and humid places.