Download Drought in the Anthropocene Authors: Anne F. Van Loon et al (2016)

Drought in the Anthropocene
Authors: Anne F. Van Loon et al (Nature, Feb 2016)
Kimberly Duong
March 1, 2016
Background
• This paper describes:
– human influences on drought
– potential feedbacks between drought and society
• Land use changes by humans alter hydrologic
processes (evapotranspiration, infiltration,
surface runoff, etc)
• In order to cope with future drought, we must
consider human influence as much as we do
natural climate variability (yes, it’s that
significant!)
Redefining Drought
• Drought is traditionally considered a natural
phenomenon only
– This way of thinking hinders effective drought
monitoring and management
• Authors suggest including human-caused water
shortages in definition of drought
– New definition = exceptional lack of water compared
with normal conditions
• Drought is an episodic phenomenon, which is
different from water scarcity (a long-term
imbalance between supply and demand)
Classifications
1. Soil moisture drought: below-normal soil moisture levels
2. Hydrological drought: below-normal river discharge,
groundwater, lake, reservoir levels
• In regions without heavy anthropogenic modification of
the water cycle, these droughts are caused by
meteorological anomalies.
• However, in most places, significant human
development results in changes in surface/subsurface
water abstraction and land use change
• Therefore, we should distinguish between climate
induced, human induced, and human modified droughts
Shift between
different types of
drought
Climatic drivers
Human drivers
Hydrological
catchment
processes
Alterations by
human activities
Changes to
human influence
on drought &
climate variability
• Authors show simulated water supply that considers only natural
drivers will underpredict (or not predict at all) the presence of a
drought. This type of drought (middle example) would be purely
human-induced
• Drought that has both natural and human influences (on right side)
will have underestimated severity if simulations only consider natural
drivers
Drought Research
• Properly attributing drought to both human and natural
drivers is essential
• Why? Because it informs drought management on
whether to focus on adaptation (in response to natural
drought) or on prevention of human-induced drought
• Researchers can use virtual models to assess groundwater
levels and streamflow in the absence of human influences
• Research gap: feedbacks on soil moisture, streamflow and
aquifer water levels are rarely quantified
– In California, near-future groundwater legislation will impact
California water resources, but it is unclear how it affects
droughts
• Societal adaptation to drought results in a new “normal”
water level for that society
Conclusion
• We need to consider drought as an interaction
of both natural and human influences!
• We need to integrate natural and social
sciences when doing drought research so that
we can better predict, manage, and prevent
future droughts.
• (Shout out to Australia for combining
technology, education, and pricing during the
Millennium drought)
References
Van Loon et al. “Drought in the Anthropocene.”
Nature Geoscience, Vol 9, pg 89 – 91, Published
online: 02 February 2016.
Web link:
http://www.nature.com/ngeo/journal/v9/n2/ful
l/ngeo2646.html
Hi Stan!