Water and Climate

OUTLINE Factors affecting climate Projecting future climate scenarios Climate change and water supplies Management of impacts of climate change

Interannual variation of rainfall in Meghalaya

Interannual variation of rainfall in Meghalaya

What causes climate: Solar energy heats different continents and Oceans to different extents This creates pressure differences Which lead to wind and ocean Currents These currents strongly influence Precipitation and temperature

Another factor that affects climate: Greenhouse gases that act as a blanket

Wind currents Example: India monsoon

Ocean currents: Warm & cold Skeleton coast, Namibia Pacific Coast, Peru

A warming world… Glaciers on Mount Kilimanjaro have lost 85 percent of their coverage since 1912 The Quelccaya ice cap in southern Peru – the largest tropical ice field on Earth, has retreated 25 percent since 1978 Ice fields in the Himalayas that have long shown traces of the radioactive bomb tests in the 1950s and 1960s have since lost that signal as surface melting has removed the upper layers and thereby reduced the thickness of these glaciers All of the glaciers in Alaska’s vast Brooks Range are retreating, as are 98 percent of those in southeastern Alaska.  And 99 percent of glaciers in the Alps, 100 percent of those in Peru and 92 percent in the Andes of Chile are likewise retreating Sea levels are rising and the loss of ice coverage in the North Polar region continues to increase annually.

What is the IPCC? IPCC = Intergovernmental Panel on Climate Change Established in 1988 by the World Meteorological Organization and the United Nations Environment Programme Objective: produce an assessment of the potential impacts of human-induced climate change and ways to adapt to and mitigate these impacts

IPCC Fourth Assessment Report (2007): Global mean surface temperatures have increased 0.74ºC (±0.18) over the past 100 years Warming rates are accelerating: 11/12 warmest years since 1850 occurred between 1995 - 2006 Changes in precipitation: amount, intensity, frequency, and type General declines in the tropics; general increase in temperate and northern latitudes Extreme hydrologic events appear to be becoming more frequent Droughts, hurricanes, floods Even where total precipitation has decreased, number of intense events show an increase Ref: Cooley, 2009

Projecting future climate scenarios General Circulation Models (GCMs) used to understand potential impacts of various greenhouse gas (GHG) emission scenarios on future climate conditions Tested with simulations of features of recent climate and historical climate record Climate change depends on future GHG emissions, which are uncertain, influenced by socioeconomic, demographic, and technological factors Special Report on Emissions Scenarios (SRES) Outlines 4 ‘storylines’ that include many different ‘scenarios’ Ref: Cooley, 2009

Storylines and scenarios of climate change A1: ‘A future world of very rapid economic growth Global population peaks in mid century Rapid introduction of more efficient technologies Convergence among regions Capacity building Reduction of regional differences in per capita income A1 storyline is differentiated according to energy sources (fossil intensive vs. non-fossil fuel intensive) HIGH greenhouse gas emissions Ref: Cooley, 2009

Storylines and scenarios of climate change A2: ‘self-reliance and preserved identities’; population growth increase but slow economic and technological growth B1: population growth increase; change towards a service and information economy; reduction in material intensity and introduction of clean and efficient technology LOWER greenhouse gas emissions because of emphasis on sustainability B2: continuously increasing global population; intermediate economic development; less rapid technological change Ref: Cooley, 2009

16 GCMs on rainfall prediction for Tanzania www.climatewizard.org

Precipitation projection for Wami Basin, Tanzania at a 50 km grid scale resolution

Changing climate conditions will affect water resources While predicting climate is fiendishly complex… Changing climate conditions will affect water resources

Surface water Alterations in the amount and timing of flows would affect water supply Snow-dominated basins will experience earlier peak flows, greater winter flows, lower summer flows Rain-dominated basins will be most influenced by changing precipitation patterns, with predictions of greater winter flows and lower summer flows

Groundwater Impacts less well understood Climate change could affect recharge rates and supply Evaporation rates could affect quality of groundwater Demand for groundwater could increase as surface water supplies change

Hydrologic extremes Climate change = greater climate variability Higher risk of hydrologic extremes Droughts - more frequent, more intense, longer lasting Floods - shift in frequency, more intense

Water quality Expected increase in temperature in lentic systems Lower oxygen Moe algal and bacterial blooms Intense rainfall events could wash more contaminants into water bodies Increased salt water intrusion from rising sea levels

Water demand Remains to be studied in more detail Certain sectors may be more sensitive to climate change Agriculture - irrigation water Urban areas of the US - lawn care water use Industry - need for more cooling water requirements

Changing climate conditions will require water resource management interventions

Palmer et al. 2008: Likely to require management intervention: 300,000 km2 of basins with no dams 10 million km2 of dam-impacted basins 7% of world’s area; 1 billion people live in that area Certain to require management intervention: 700,000 km2 of basins with no dams 5 million km2 of dam-impacted basins 4.2% of world’s area; 365 million people in that area

Climate change assessments must be interdisciplinary

Climate change assessments: “Vulnerability and Adaptation” Vulnerability: a function of the magnitude of impacts of CC and sensitivity to the impacts Developing countries are considered more vulnerable to climate change? Stationarity: systems designed and operated based on historical climate conditions Adaptation: initiatives to reduce vulnerability of natural and human systems to CC Proactive vs. reactive management (No Regrets) Structural vs. non-structural Supply-side vs. demand-side

Adaptation assessment: practice of identifying options to adapt to CC Consider availability, benefits, costs, effectiveness, efficiency, feasibility of options Approaches: Down-scaled GCMs and scenarios - mathematical relationships Hypothetical modifications of temperature and precipitation (e.g., 10% increase) Regional models then used to simulate future water conditions under altered climates

Ref: Gleick, 2009; Cooley, 2009

Adaptation Policy Framework (UN Development Programme approach) Evaluation of vulnerabilities to current climate variability and extremes May be more qualitative, used in data-limited areas National Adaptation Programs of Action Least developed countries Address urgent needs related to CC Build adaptive capacity, formation of expert groups May not be adequate for addressing impacts of CC over long-term

CC Adaptation: Other considerations Stakeholder participation Economic costs of adaptation measures UNFCCC - estimates adaptations for meeting water demand in 2030 associated with CC and socioeconomic trends: $720-900 billion USD Equity and ethical concerns Who pays for adaptation measures? Ref: UNFCCC 2007; Cooley, 2009

Watershed Restoration – enhance local water storage