Climate Change: Difference. What changes climate? The Greenhouse Effect 1/30/14. Fi3ng the pieces together. Changes in:

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1 Climate Change: Fi3ng the pieces together Based on your current knowledge, which statement is closest to your thoughts about the scientific evidence for global climate change? A. There is no evidence; it s a scare tactic promoted by environmentalists and some politicians. B. There is evidence for climate change, but no evidence that human activities are involved. C. There is some evidence that humans are having an effect on climate. D. The evidence is clear that humans are significantly affecting climate. 2 Climate and Climate change Climate = a region s long-term pattern of atmospheric conditions Global climate change = changes in Earth s climate, including temperature, precipitation, and other variables Global warming = an increase in Earth s average surface temperature Climate changes naturally, but the recent rapid warming of the planet and its change in atmospheric composition are widely thought to be due to human activities. GLOBAL WARMING is the increase of the Earth s average surface temperature due to a build-up of greenhouse gases in the atmosphere. Difference CLIMATE CHANGE is a broader term that refers to long-term changes in climate, including average temperature and precipitation. What changes climate? Changes in: Sun s output Earth s orbit Dri@ing conanents Volcanic erupaons Greenhouse gases The Greenhouse Effect 6 1

2 Earth s surface absorbs heat from the sun and then re radiates it back into the atmosphere and to space. Greenhouse effect Much of this heat is absorbed by greenhouse gases, which then send the heat back to the surface, to other greenhouse gas molecules, or out to space. Though only 1% of atmospheric gases are greenhouse gases, They are extremely powerful heat trappers. By burning fossil fuels faster and faster, humans are effecavely piling on more blankets, heaang the planet so much and so quickly that it s hard for Mother Nature and human socieaes to adapt While there are many substances that act as greenhouse gases, two of the most important are water and carbon dioxide, or CO2. Greenhouse Gases Atmospheric gases that absorb the emanating radiation are greenhouse gases. Nitrous oxide Carbon dioxide Methane By absorbing and re-emitting this radiation, they warm Earth s atmosphere and surface, like a greenhouse. This is popularly called the greenhouse effect. Water Sulfur hexafluoride Global warming potential = the relative ability of one molecule of a given greenhouse gas to contribute to global warming. 9 How much does each GHG contribute to climate change? Energy retention in the atmosphere depends on the abundance and effectiveness of the GHG. CO 2 Carbon dioxide Carbon dioxide = primary greenhouse gas But molecule for molecule, methane traps 23 Ames the heat of CO 2 nitrous oxide traps 296 Ames the heat of CO 2 HFC 23 traps 12,000 Ames the heat of CO 2 The diagram shows how much each gas contributed to warming from 1750 to 2005 (termed radiative forcing). CH 4 N 2 O 11 2

3 Global Atmospheric Concentration of CO 2 Carbon dioxide increase Due mainly to: Burning of fossil fuels: We remove and combust carbon-rich fuels from the ground where they have been stored for millions of years, sending CO 2 into the atmosphere. CO 2 concentra,on has increased 33% in the past 200 years. Deforestation: Cutting down trees, removing vegetation from the land, decreases the sink for carbon. It is now at its highest level in 400,000 years, and probably 20 million years. Increase of other greenhouse gases Methane: Up 151% since 1750 From fossil fuels, landfills, cattle, rice crops Nitrous oxide: Up 17% since 1750 From feedlots, chemical plants, auto emissions, agricultural practices How do we study climate? 16 Studying climate change: Ice cores Ice caps and glaciers accumulated over thousands or millions of years. Long-term variation of temperature and of CO 2 in air bubbles preserved in the Vostok ice core They contain bubbles of gas preserved from the time when each layer formed. Scientists drill cores and analyze the gas bubbles in each layer to see what the atmosphere was like then. 18 3

4 When did CO2 and other GHG begin to increase? Detailed analysis of ice cores and measurements shows: CO2, CH4, and N2O changed slowly after the end of the last Ice Age, but began to increase rapidly about 200 years ago. 19 Studying climate change: Pollen analysis Scientists also drill cores into the sediments of ancient lake beds. By identifying types of pollen grains in each layer, they can tell what types of plants were growing there at the time. Sources of this type of indirect evidence are proxy indicators. Studying climate change: Direct sampling Scientists have recorded carbon dioxide levels in the atmosphere directly since 1958, at a station in Hawaii. Studying climate change: Modeling To predict what will happen to climate in the future, scienasts use climate models: The data show a steady upward climb from 315 to 373 ppm. Computer simulaaons that use known behavior of past climate to analyze how climate should behave as variables are changed (The up and down zigzags are from regular winter-summer fluctuations.) Coupled general circula,on models (CGCMs) are models that combine, or couple, the effects of both atmosphere and ocean. Studying climate change: Modeling Today s highly complex CGCMs incorporate many factors in order to predict future climate changes. How can scientists decide which factors are actually responsible for climate change? Natural or anthropogenic factors ONLY = poor fit. BOTH types of factors = excellent fit. Human factors are par2cularly important in explaining the rapid temperature increase in the last three decades. 4

5 Why do we think that CO 2 released by human activities is causing the increase in the atmosphere? Do the models prove that humans are causing climate change? Seasonal cycles in CO 2 result from photosynthesis and respiration. Such short-term flows of carbon cannot explain the upward trend The trend has to result from carbon that has been stored for long periods of time, such as in fossil fuels and soils. Models cannot prove that humans are involved; however, they show that the changes observed so far are consistent with human causes. Models do not account for some complexities of climate, such as the feedback effects of water vapor and cloud formation. Scientists consider the models sufficient to say that it is very likely (>90% probability) that the climate change observed in the last 50 years is not a result of natural effects alone. 25 What do climate scienasts really think? Is there consensus among scientists? 27 What do climate scienasts really think? IPCC: Putting the Pieces Together. 5

6 Climate change and the IPCC report Climate change and the IPCC report First, the IPCC report established that global temperature is rising. In 2001, the world s climate scientists combined to produce the single most comprehensive and authoritative research summary on climate change: The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which summarized all scientific data on climate change, future predictions, and possible impacts. Direct measurements from thermometers since 1860 demonstrate this along with indicators of temperature (from pollen, ice cores, etc.). The IPCC report The IPCC also reported findings on physical changes: Average sea level increased centimeters (4 8 inches) during 20 th century. 2 weeks less ice cover on northern lakes and rivers. Arctic sea ice thinned 10 40% in recent decades. Mountain glaciers melted back worldwide. Snow cover decreased 10% since satellite observations began. Growing season lengthened 1 4 days each decade over the past 40 years. The IPCC report Biological changes were also found by the IPCC: Geographic ranges of many species have shifted toward the poles and up in elevation. In spring, plants are flowering earlier, birds migrating earlier, animals breeding earlier, and insects emerging earlier. Coral reefs are bleaching more frequently. Climate change is affecting our lives Focus: Impacts of Climate Change 35 6

7 Climate change predictions: Impacts The IPCC and other groups have predicted future impacts of climate change. Predictions for the U.S. include: Temperature will rise 3 5 C (5 9 F). Droughts, floods, snowpack decline, and water shortages will create diverse problems. Temperature extremes will cause health problems; tropical diseases will move north into the U.S. Sea level rise will flood coastal wetlands, real estate. Ecosystems will be altered; some will disappear. Agriculture and forestry may have mixed results. Portage Glacier Sea-level rise Global warming is causing glaciers to shrink and polar ice shelves to break away and melt. The increased flow of water into the oceans lead to sea level rise. Sea level is also rising because ocean water is warming, causing water to expand in volume. Higher sea levels lead to beach erosion, coastal flooding, intrusion of saltwater into aquifers, etc. Larsen B ice shelf-- Antarctica Alaska Photos: NOAA Photo Collec2on and Gary Braasch WorldViewOfGlobalWarming.org Consequences ArcAc sea ice Alpine glaciers 7

8 Sea-level rise Sea-level rise Storm surge = temporary and localized rise in sea level caused by high tides and winds associated with storms Storm surges impact small islands as well as low-lying coastal areas in countries like the U.S. This vulnerability became dramatically apparent in 2005 when Hurricane Katrina struck New Orleans and the Gulf Coast of the U.S. A 51-centimeters (20-inches) sea level rise would inundate wetlands (red) and drylands (orange) on all U.S. coasts. Effects of Global Climate ChangeChanging Precipitation Patterns Sea-level rise Some areas will get more water, some areas will have greater droughts Areas on all U.S. coasts would suffer erosion. Ex: Hurricanes will likely get stronger Drama,c flooding from storm events like Hurricane Katrina could become more frequent. EVENT Year Hurricane Michelle 2001 May/June Flood Rains 2002 Hurricane Charley 2004 Hurricane Ivan Category C o s t ( $ J Impact billions) (% GDP) people were killed by Hurricane Sandy in the U.S. Hurricanes Dennis & Emily ,000 homes were damaged or destroyed. Hurricane Wilma Hurricane Dean Tropical Storm Gustav Tropical Storm Nicole How bad was the super storm sandy? 8.5 million lost power, some for months

9 Why is Global Hurricane Activity Changing? Global frequency of events constant, but Intensity is increasing DuraAon is increasing Frequency is increasing in the AtlanAc (11% of global total) High sea surface temperatures lead to the evaporaaon of moisture, which provides fuel for the storm. Effects of Global Climate ChangeEffects on Organisms Zooplankton in parts of California Current have decreased by 80% since 1951 Effecting entire food chain Decline in krill around Antarctica Caused decrease in penguin populations Species have shifted their geographic range Migrating birds are returning to summer homes earlier Food is not available at this time Colorado River Effects on Organisms - Coral Reefs Coral reefs can be bleached (right) due to increase in water temperature Arizona Affects coral symbiotes and makes them more susceptible to diseases to which they would otherwise be immune June 2002 Effect on Organisms - Vegetation Beech Tree Range Dec 2003 Effects on Human Health Increased number of heat-related illnesses and deaths 9

10 Effects on Agriculture Difficult to anticipate Productivity will increase in some areas and decrease in others Rise in sea level will inundate flood plains and river valleys (lush farmland) Effect on pests is unknown Warmer temperatures will decrease soil moisturerequiring more irrigation Location (i.e. elevation and altitude) where certain crops can be grown may have to change Developed vs. Developing countries International Implications of Climate Change Differing selfinterests Differing ability to meet the challenges of climate change Dealing with Global Climate Change What can we do? To avoid the worst of climate change, CO 2 levels must be stabilized at 550ppm 50% higher than current levels Two ways to attempt to manage climate change Mitigation Focuses on limiting greenhouse gas emissions to moderate global climate change Adaptation Focuses on learning to live with to the environmental changes and societal consequences brought about by global climate change 57 Emissions reduction: More efficient generation and usage Electricity generation is the biggest source of greenhouse gas emissions in the U.S. So solutions include: Improved technology at plants Cleaner-burning coal Energy conservation by consumers Emissions reduction: Renewable energy Another solution is to switch to renewable energy sources: Hydroelectric power Geothermal energy Photovoltaic cells Wind power 10

11 Emissions reduction: So many cars Transportation: the 2nd largest source of greenhouse gases. 1/3 of average U.S. city devoted to cars Emissions reduction: Inefficient autos Cars use energy very inefficiently. We could do better. Average U.S. family makes: 10 car trips/day $200 million/day on road construction and repair Number of cars in U.S. will soon exceed number of people Emissions reductions: Biking and walking Reducing automobile usage would also lower emissions. More and more people are choosing to live closer in and bike or walk to work. If Americans used public transportation at the rate Europeans do, the U.S. would no longer need Saudi Arabian oil. Emissions reductions: Public transportation Using public transportation like buses and trains lowers emissions of many pollutants which has a public health benefit as well. Our Goal Billions Gigaton of Metric Carbon Tons Carbon 2007 Reduc2ons in CO 2 Per Year Produce electricity efficiently Use electricity efficiently Vehicle efficiency Solar and Wind Power Biofuels Carbon capture and storage Produce more fuel efficient vehicles Reduce vehicle use Improve energy efficiency in buildings Develop carbon capture and storage processes Triple nuclear power Increase solar power Decrease deforestaaon/plant forests Improve soil carbon management strategies 11

12 Emissions reductions: International treaties 1992: UN Framework Conven2on on Climate Change Voluntary approach; naaons were asked to cut emissions Failed 1997: Kyoto Protocol By 2012, reduce 6 greenhouse gases to below 1990 levels Emissions reductions: Kyoto Protocol Reductions required under Kyoto are scaled to nations contributions. Germany decreased emissions 18.9% while its economy grew strongly. Emissions reductions: Kyoto Protocol The Kyoto Protocol has been ratified by 127 nations, enough to make it binding. Emissions reductions: Kyoto Protocol The U.S. administraaon has said the treaty is unfair because it does not force developing naaons like India and China to share in the burden of reducing emissions. Developing naaons say industrialized naaons like the U.S. created the problem, so they should be the ones to take the lead in cleaning it up. The U.S. continues to refuse to ratify the treaty. Supporters and opponents of Kyoto agree, however, that the treaty alone is not enough to turn around greenhouse gas production worldwide it would just slow it down. Climate has changed Climate will con2nue to change Climate demands change Act Now! 12