Monsoons are a pattern of rainfall that seems to be particularly sensitive to
global change because they are driven by
the temperature contrast between water and land.
Large scale changes in the climate can change these temperature contrasts,
really change the patterns of rainfall that are to be expected.
More so than the normal storm kind
of rainfall that you get other parts of the world.
The American southwest is not usually considered a monsoonal system,
but the rainfall there is very heavily impacted by the temperature
contrasts between the land (the desert)
and the water temperature in the Pacific or the the Gulf.
The American southwest is in drought
today and we know from proxy data from the medieval time that there were droughts
in the American southwest that were vastly larger than anything we have experienced.
The dust bowl was a picnic compared to
the droughts that clobbered the classic Mayan civilization, for example.
The African Sahel,
according to Lynas' book, is expected to be impacted at about one degree C
of temperature change and is supposed to
get wetter according to the climate simulations.
The China highlands are supposed to get drier
at about two degrees of global warming.
The Asian monsoon is supposed to get
stronger and stormier under that two degree C
of warming.
Every place is cutting
a different deal with global warming.
It's not all the same impact. It varies from place to place.