Chapter 1 Introduction of Impact of Climate Change

Chapter 1. Introduction of Impact of Climate Change on Water Resources: With Modeling Techniques and Case Studies Dr K. Srinivasa Raju, Professor, Department of Civil Engineering, BITS Pilani Hyderabad Campus, India Dr D Nagesh Kumar, Professor, Department of Civil Engineering, Indian Institute of Science, Bangalore, India

Topics of Coverage Introduction, Climate Feedback Forcing Mechanism, Aerosols, Greenhouse Gases Atmospheric Chemistry, Palaeo Records Monsoon Variability, Holocene, Climate Scenarios Teleconnection Patterns, Impact of Climate Change 1 Chapter 1 Introduction

Introduction Hydrology Occurrence as well as distribution of water Atmosphere, surface and below surface of the Earth Climatology Scientific Study of Climate Hydro climatology Spatio-temporal variation of climate in hydrologic cycle Global Hydrologic Cycle Logical unifying theme for Hydroclimatology Terrestrial Atmospheric Branches 2 Chapter 1 Introduction

Introduction (Contd. ) Climate Average state of the atmosphere Represented by temperature and precipitation Based on Hydrosphere, Cryosphere, Lithosphere, Biosphere Climate Change Continuous increase or decrease in the statistical properties of climate variables Climate Variability caused by El-Nino Southern Oscillation Two different Phases La Nina for Cooling El Nino for Warming 3 Chapter 1 Introduction

Climate Feedback Climate system: Subjected to incoming solar radiation and expected to be balanced by the outgoing terrestrial radiation; Neither Earth continues to indefinitely cool down nor heat up When the climate system responds to the forcing inequilibrium state Fraction of the output + Input of the system Further modifies the output 4 Chapter 1 Introduction

Climate Feedback (Contd. ) Resultant loop Feedback; May accelerate (positive feedback); decelerate the process (negative feedback) Positive feedback: When the reaction to primary climate forcing follows the same direction as the initial forcing factor Supplements the climate response to the forcing Amplifies warming or cooling trends 5 Chapter 1 Introduction

Climate Feedback (Contd. ) Negative feedback: Reaction to primary climate forcing acts in the opposite direction to that of the initial forcing factor Reduces the climate response to the forcing 6 Chapter 1 Introduction

Forcing Mechanism Radiative and Non-Radiative Forcing Radiative forcing: Difference between outgoing terrestrial radiation and incoming solar radiation Causes: Variations in atmospheric composition, solar radiation, volcanic activity and Earth's orbit around the Sun Non-radiative mechanisms: Do not directly effect the atmosphere energy budget 7 Chapter 1 Introduction

Forcing Mechanism Random and Periodic Forcing(Contd. ) Random Forcing: Chaotic and complex climate system behavior resulting in a large proportion of the unpredictable climate variation Periodic Forcing: Identifying the forcing mechanisms + impact on the global climate framework enables to ascertain future climate changes Outcome: Depends on the response of a climate system 8 Chapter 1 Introduction

Forcing Mechanism External and Internal Forcing (Contd. ) External forcing: Agents acting from the extraterrestrial systems (including galactic, orbital and solar variations) Internal forcing: Agents operating within the climate system Orogeny, volcanic activity, ocean circulation, land-use/land cover changes and variations in atmospheric composition (including aerosol content and greenhouse gases) 9 Chapter 1 Introduction

Aerosols Scattering and absorption of solar radiation by aerosols Visibility in the atmosphere (direct radiative forcing) Indirect: Increases the formation of clouds, influences the properties and gas chemistry of aerosols Aerosol content change in the atmosphere: Due to natural and anthropogenic factors 10 Chapter 1 Introduction

Green House Gases Solar radiation emitted by the surface of Earth held by greenhouse gas molecules; Diffused into the atmosphere in all directions Warming of Earth’s surface Carbondioxide (CO 2), Water vapor (H 2 O), Nitrous oxide (N 2 O), chlorofluorocarbons (CFCs) and Methane (CH 4) Anthropogenic and natural factors Content change in Greenhouse gases in the atmosphere 11 Chapter 1 Introduction

Green House Gases (Contd. ) Natural factors: Changes in atmospheric CO 2, CH 4 concentrations, vegetation and weathering of rocks Anthropogenic factors: Forest clearing, fossil fuel burning, and other industrial processes Variations in rainfall, ice caps, glacier melting, temperature, likelihood increase in frequency of floods and droughts, acidification due to carbonic acid formation 12 Chapter 1 Introduction

Global Climate Models (GCMs) Evaluate the plausible responses of the climate system to the changes in the behavior of natural and human systems either separately or together Climate models perform better at continental and large regional scales compared to smaller spatial scales Coupled Model Intercomparison Project (CMIP) Phase 3: CMIP 3 & Phase 5: CMIP 5 13 Chapter 1 Introduction

Atmospheric Chemistry and Palaeo Records Chemistry of the Earth's atmosphere and that of other planets Capable of identifying and analysing atmospheric effects: Global warming, greenhouse gases, photochemical smog, ozone depletion and acid rain Palaeo Records Information about the past for analysing changes in the Earth’s system 14 Chapter 1 Introduction

Monsoon Variability Differential heating between ocean and land Monsoon: Seasonal migration of the intertropical convergence zone Close correspondence between El Nino and deficit Indian monsoon rainfall 15 Chapter 1 Introduction

Holocene: Geological epoch began after the Pleistocene at approximately 11, 700 years before present Marked by variability over century to millennial both at low and high latitudes Close interaction between human cultural elements and persistent multi century climate shift Chronology of events during the Holocene in the Indian subcontinent spread over 7 time zones 16 Chapter 1 Introduction

IPCC Climate Scenarios Climate scenarios: Possible impacts of anthropogenic climate alterations and variations of natural climate in future Suitability: Impact assessment, physical plausibility, consistency with global projections, accessibility and representation AR 3 and AR 5 Perspective 17 Chapter 1 Introduction

Special Report on Emissions Scenarios (SRES) (AR 3 Perspective) Based on: Improvements of processes of greenhouse gases, changed geopolitical landscape, availability of more driving force data on emissions Four sets of scenarios, A 1, A 2, B 1, and B 2 (Table in next slide) Storylines: Describe each scenario relating to demographic, economic, technological and social changes 18 Chapter 1 Introduction

Special Report on Emissions Scenarios (SRES) (AR 3 Perspective) Scenario A 1 A 2 B 1 B 2 Representative characteristics that may emerge in future Very rapid economic growth and global population that peaks in mid-century and declines thereafter; More efficient and new technologies introduction Sub-classifications: non-fossil energy sources (A 1 T), fossil intensive (A 1 F 1), balance across all sources (A 1 B) Very heterogeneous world with preservation of local identities and self-reliance as underlying theme Convergent world (similar global population as that of A 1) with reduction in material intensity, rapid and significant changes in economic structures, and initiation of clean as well as resourceefficient technologies Environmental, Social, Economic sustainability with increase in global population, more diverse and less rapid technological change, intermediate levels of economic development 19 Chapter 1 Introduction

Representative Concentration Pathways (RCPs) (AR 5 Perspective) Alternative scenarios in aerosol concentrations with greenhouse gas as their origin point Emission and socioeconomic scenarios : RCPs 2. 6, 4. 5, 6. 0, and 8. 5 RCP 2. 6: One pathway where radiative forcing peaks at approximately 3 W/m 2 before 2100 and then decline RCPs 4. 5 and 6. 0: Two intermediate stabilisation pathways where forcing is stabilised at approximately 4. 5 W/m 2 and 6. 0 W/m 2 after 2100 20 Chapter 1 Introduction

Representative Concentration Pathways (RCPs) (AR 5 Perspective) RCP 8. 5: One high pathway for which forcing is greater than 8. 5 W/m 2 by 2100 and continues to rise for some more time Temperature Anomaly (0 C), CO 2 (ppm) and pathway shape for RCPs 2. 6, 4. 5, 6. 0, 8. 5 are 4. 9, 1370, rising; 3. 0, 850, stabilisation without overshoot; 2. 4, 650, stabilisation without overshoot; 1. 5, 490, peak and decline respectively RCP 8. 5, RCP 6. 0, RCP 4. 5: Temperature anomalies equivalent to SRES A 1 F 1, SRES B 2, SRES B 1 scenarios 21 Chapter 1 Introduction

Teleconnection Patterns El Niño (warm) + La Niña (cold) phases El Niño-Southern Oscillation (ENSO) Describe temperature fluctuations between the atmosphere and ocean in the East-Central Equatorial Pacific which have large-scale impacts on global weather, ocean processes, climate El Niño influences marine fisheries, ocean conditions, weather patterns across significant portions of the globe; La Niña effects tend to be opposite 22 Chapter 1 Introduction

Other Teleconnection Patterns North Atlantic Ocean East Atlantic Pattern Tropical/Northern Hemisphere Pacific Transition Pattern Equatorial Indian Ocean Oscillation Ocean Land Temperature Contrast 23 Chapter 1 Introduction

Impact of Climate Change: Hydrology Greenhouse gases concentration Change the atmosphere radiative balance Temperature changes and associated changes in precipitation patterns Amount of precipitation, spatial distribution, intensity and frequency changes effect the runoff Climate change Discharge into Rivers Stretching infrastructure 24 Chapter 1 Introduction

Impact of Climate Change: Hydrology (Contd. ) Water quality and temperature are effected by warming of lakes and rivers Effects hydrological cycle parameters 25 Chapter 1 Introduction

Impact of Climate Change: Water Resources Impacts freshwater resources Effects functioning and operation of existing water infrastructure Groundwater availability Indiscriminate pumping + Unpredictable climate change 26 Chapter 1 Introduction

Impact of Climate Change: Urbanisation Change in precipitation levels, mean temperatures, sea level Energy demand + Reduction of the sewers’ capacity Floods, droughts, heatwaves and landslides Livelihoods of urban population, property and quality of life Extreme rainfall events Flood hazards + landslides Create stress on existing infrastructure + health hazards Higher insurance expenses + Societal disturbances 27 Chapter 1 Introduction

Impact of Climate Change: Hydrologic Extremes Huge amount of damage Extreme precipitation, temperature and rise in sea levels Climate change impacts All climate variables and extreme events 28 Chapter 1 Introduction

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