Lecture 5: Understanding Climate Change Fiction, Facts, Uncertainties, Challenges & Impacts Shakeel Hayat 26 th Oct 2011

Lecture Outline 1. Introduction 2. What the unconvinced people are saying 3. Facts 4. Uncertainties 5. Challenges 6. Human impacts on climate change 7. Climate change impacts on humans & the environment 8. What can we do about it? 9. Concluding remarks

What the unconvinced people are saying… 1. “Theory remains entirely unproved.” 2. “One-in-three chance … that experts are wrong.” 3. “Models are incapable of handling … water vapor.” 4. “If the weather folk can’t figure out what’s happening for the rest of the week, how can they tell us what the climate will be for the next 50 years?” 5. “Guess what? Antarctica’s getting colder, not warmer.” 6. “Global warming is still just a theory.”

Facts… 1. Global mean temperature has been going up in the last 140 years. 2. The magnitude of this variability does not exceed natural variability. 3. Concentration of carbon dioxide has been going up as well as other greenhouse gases. 4. Climate change involves the entire “earth system” not just the atmosphere. 5. Future projections face uncertainties in emission production, modeling, and impacts. 6. Several thousand scientists from 40+ countries all over the world have been involved in Ecosystem Assessment

Global Mean Temperature (140 year record)

Global Climate System

Challenges A. Nature of climate system 1. Analysis must consider entire climate system and all of humanity 2. Extensive natural climate variability 3. Global connections for both climate forcing and climatic response 4. Uncertainties in outcomes involve uncertainties in many components 5. A small change in global means can translate to large changes in local means/extremes B. Needs for research 1. Improve data – longer data, error analysis, more global coverage 2. Improve theory 3. Improve models 4. Separating naturally-induced fluctuations from human effects C. Nature of people 1. Implement controls on human impacts on the environment 2. World cooperation 3. Look at ourselves

Human Impacts on Climate Change 1. Types of impacts 2. Focus on greenhouse gases – primarily CO2 3. Driving forces for the future 4. Basic scenarios 5. Scenario outcomes

Types of Human Impacts Increase in greenhouse gases Change in surface conditions (e.g. albedo, wind, evaporation) Change in clouds (e.g. contrails, pollutants, etc.)

Driving Forces for Future Human Impacts 1. Population 2. Economy (income per capita and regional differences) 3. Technology a. Energy production – fossil fuels and non-fossil fuels b. Energy use efficiency c. Land use 4.Energy structure: Coal – Oil/Gas – Renewable / Nuclear 5.Land use: Forests – Croplands & Energy Biomass -Other (grasslands, etc.) 6.Agriculture

Climate Change Impacts on Humans & the Environment A. Terrestrial ecosystems 1. Agriculture 2. Forests 3. Desert and desertification 4. Hydrology and water resources B.Ocean systems 1. Sea level 2. Coastal zones and marine ecosystems C.Human “systems” 1.Settlements, energy and industry 2.Economic, insurance, and other financial services 3. Human health a. Vector borne diseases b. Water-borne and food-borne diseases c. Food supply d. Air pollution e. Ozone and ultraviolet radiation D.Atmospheric systems 1. Weather 2. Storms 3. Floods and droughts 4. Extremes

Water Availability Resources Water availability in 2050 for the present climatic conditions and for three transient climate scenarios. (m3 / year / person)

Sea Level Rise Impacts

Vector-Borne Disease Susceptibility

Human Responses to Climate Change Why should we care? Modify our own life style Mitigation and adaptation Modify national and global practice Influencing public policy

Why Should We Care? 1. We don’t know exactly what will happen with global warming or what the impacts will be. And where or when they will hit hardest. 2. But scientists have a pretty good general idea of what’s to come. They tell us the possible impacts could be far-reaching and could cause serious problems: 3. Sea level will continue to rise, eroding beaches and increasing the damage from storms and leading to loss of wetland habitats. Some island nations will disappear. 4. Increasing temperatures are likely to affect human health: Warmer temperatures mean mosquitoes will spread in areas that were previously too cold for them to survive. Mosquitoes carry infectious diseases like malaria and encephalitis. Ground-level ozone pollution will likely worsen, increasing respiratory diseases like asthma. Deaths from heat waves will rise. Some plants and animals may face extinction if habitat changes. 1. Changing weather patterns could affect agriculture. Northern states could actually experience longer growing seasons. The U.S. Great Plains could have frequent droughts. 2. Some forests may disappear, leading to extinction of wildlife species— changes in biodiversity. 3. Economic effects: Billions of dollars in property damage from sea level rise and worsening storms.

What Can We Do About Global Warming? There are simple steps each of us can take that will help reduce our emissions of greenhouse gases. Just a few examples: Recycling saves the energy required to manufacture new products. Give your family car a day off by riding your bike, taking the bus, or walking. Plant trees – they absorb carbon dioxide. Read and learn about global warming. Save electricity by turning off the TV and lights when you’re through with them. Go solar – a solar system to provide hot water can reduce your family’s carbon emissions by about 720 pounds a year. Encourage others to take these simple actions. Preserve forests – they act as carbon dioxide “sinks” – in other words, they absorb carbon dioxide. Develop renewable energy technologies to reduce dependence on fossil fuels. Use energy more efficiently. For example, the federal government has a variety of voluntary partnership programs with industry to reduce greenhouse gas emissions by using energy more efficiently.

Concluding Remarks 1.Research activities continue to increase a.North-South Carbon Program b.Climate modeling enhancement c.Regional climate change studies 2.Government Plans a.Enhanced support for research b.Research technology to help in mitigation (e.g. Hydrogen car) 3. Still a long way to go