Card #20: Disruption of the Water Cycle
Hotter oceans and a hotter atmosphere lead to stronger evaporation, causing rainclouds and rainfall. Hotter land and a hotter atmosphere also lead to stronger evaporation, this time causing the ground to dry out.
This card is important. It alone shows why we used to talk about global warming and now about climate change.
Temperature increase is in itself a problem, but you can see on the Fresk at the end that disruption of the water cycle has much more effect.
To illustrate that evaporation takes place at the surface of the water, place cards 17 and 21 on the table, place the lower edge of card 21 against the upper edge of card 17, then place card 20 at the boundary of the two, perpendicularly, to mark the surface of the water (between water and air).
- Deforestation Vegetation retains water. When it is cut down, the risk of flooding increases.
- Melting ice sheets It's a bit technical, but the blue part of the map of Antarctica on card 19 represents a gain in mass due to an increase of precipitations. The red part represents a loss in mass. In total, Antarctica is losing mass.
- Vectors of disease The Vectors of disease card is generally linked to the Terrestrial Biodiversity card because disease vectors are a sub-part of biodiversity, but it can also be linked to the same causes as the biodiversity card, i.e. Disruption of the Water Cycle and Rising Air Temperatures.
- Melting Sea Ice The melting of the Arctic ice pack, but also the melting of Greenland's glaciers may lead, in the distant future, to a disruption of the thermohaline circulation (which gives rise to the Gulf Stream). But the "Water Cycle" card does not refer at all to thermohaline circulation.
- Rising Sea Levels No, more rain is not going to cause the oceans to overflow! This is a rare mistake to be made, but if it happens to you, ask the players where rainclouds come from...