Thread by @DustyBowl

Okay, so what can we actually say about climate change and drought? As a basic concept, drought just means less water available than normal. 1/x

BUT! Drought is a complex, interdisciplinary phenomenon at the intersection of a variety of physical, biological, and even sociopolitical processes. One should therefore be wary of over-broad, generalized statements (e.g., "droughts are getting worse/better globally") 2/x

For example, how one defines drought is REALLY important when considering the impacts of climate change! Precipitation, snow cover, streamflow, soil moisture, groundwater all can respond very differently to warming. 3/x

Drought is also highly regional! The dynamics and sensitivity of drought to climate change will be different in the Southwest US vs the Mediterranean vs East Africa vs India, etc. 4/x

Where do we have strong evidence that climate change is ALREADY beginning to make droughts more frequent or severe? A non-exhaustive list of studies: 5/x

Western North America:

Williams et al (2020): bit.ly/2P8xPSZ
Xiao et al (2018): bit.ly/3kfi1sV
Berg & Hall (2017): bit.ly/3sl9Jm9 6/x

The Mediterranean:

Hoerling et al (2012): bit.ly/3dCf58j
Gudmundsson et al (2016): bit.ly/3pKPBbl
Kelley et al (2015): bit.ly/3dFpm3J 7/x

Southern Africa:

Otto et al (2018): bit.ly/2ZJwrYM
Pascale et al (2020): bit.ly/3kfTeoA 8/x

Southwest Australia:

Delworth & Zeng (2014): go.nature.com/3pN2XUk
9/ad infinitum

Chile:

Garreaud et al (2020): bit.ly/3dBHZ8I 10/ad nauseum

There are other regions where we think climate change will make drought worse, BUT we cannot say with any confidence that this drying has begun (e.g., Central America, the Southern Plains of the US) 11/make it stop

There are also still a lot of uncertainties, especially regarding the role of plants and climate change:

Swann (2018): bit.ly/2ZL84tI
Mankin et al (2019): go.nature.com/3aM7u5f

But it's pretty clear, for a lot of regions, warmer=drier

12/almost done

Finally, some recent work that we feel nicely summarizes the state of our understanding re: climate change and drought

Review Paper: bit.ly/3qNm6qM
Blog Post: bit.ly/3qQUh0S
Results from the latest climate model projections: bit.ly/3buHA5j

13/fin