The Global Water System Project Dennis P. Lettenmaier for MAGS 10 th Annual Scientific Meeting Vancouver, B.C. November 5, 2004

Global Water System Project (GWSP) IGBP Health

Global Water System Project IGBP – IHDP – WCRP - Diversitas Rational: Humans have begun to affect the Global Water System significantly without adequate understanding of how the system works Mission: Improve knowledge of, and responsible interaction with, the Global Water System e.g. global observation consolidation of global data sets predictive and coupled modelling Definition: The Global Water System (GWS) is defined as the suite of physical, chemical, biological, and human components [of the global water cycle] and their interactions

Global Water System Project IGBP – IHDP – WCRP - Diversitas Central Tenet: Human-induced changes to the Global Water System are now globally significant and are being modified without adequate understanding of how the system works

What is Global Change? Global Change is more than Global Climate Change It has natural PLUS human/social dimensions A constellation of changes, many global in domain For example, we see large changes in: U.S. Bureau of the Census NOAA Vitousek (1994) Mackenzie et al (2002) Richards (1991), WRI (1990) Reid & Miller (1989)

Water Supply-- Doubling of Global Nitrogen Pollution Green et al. 2003

Humans are Key Agents of Direct Hydrologic Change Pandemic Distortion of Hydrographs –Impoundment –Consumptive Use –Flow Diversion –Land Cover Impacts (direct & weather-mediated) Macro-scale models of human runoff distortion now being developed

Population exposed An Acceleration of the Hydrological Cycle? Will climate become more variable? Will people move into harm’s way? Sources Of Extreme Precipitation Damage Baseline Climate 53% All other changes 47% Climate 12% Population 73% Interaction 15 %

DIA/Q < 0.4 DIA/Q > 0.4 > to to 10 > to to 10 Population (in 1000s) Sahel Horn of Africa Southeastern Africa Drought Also Is A Key Issue _______________ Population Above and Below Water Stress Threshold During Drought year duration statistics 0 Population (millions) Mean 30-yr drought SahelHornSoutheast 45 Vörösmarty et al. 2003b Continental total: Mean --> 25% population w/ stress 30-yr drought --> 40%

Global Water System Project IGBP – IHDP – WCRP - Diversitas Science questions I. What are the magnitudes of anthropogenic and environmental changes in the Global Water System and what are the key mechanisms by which they are induced? II.What are the main linkages and feedbacks within the Earth system arising from a changing Global Water System? III.How resilient and adaptable is the Global Water System to change, and what are sustainable management strategies?

Joint Water Project IGBP – IHDP – WCRP - Diversitas Building blocks from the GEC programmes:

Vörösmarty, 2000 Crisis of Global Water Resources in 2025: Climate or Population Growth Global assessment of water scarcity Global Water System Project IGBP – IHDP – WCRP - Diversitas

Global Water System Project IGBP – IHDP – WCRP - Diversitas Human modification of hydrological systems

Global Water System Project IGBP – IHDP – WCRP - Diversitas

Global Water System Project IGBP – IHDP – WCRP - Diversitas Ludwig 1996 Riverine carbon fluxes

Global Water System Project IGBP – IHDP – WCRP - Diversitas Scoping team meetings: January, 2002 Reading (initial meeting) May, 2002 Paris (Scoping document finalized) January 2003, Bethesda MD (Scientific framework initialized) March 2003, Kyoto May 2003, Amsterdam October 2003, Portsmouth, NH (Open Science Conference) Scoping team: WCRP (2), IGBP (2), IHDP (2), Diversitas (1) Post-OSC Scientific Framework finalized Summer 2004 Chairs and Directors to appoint SSG (in progress)

Global Water System Project IGBP – IHDP – WCRP - Diversitas References: Scoping Document: Draft Scientific Framework: Open Science Conference: