Global Climate Change (PDF)

Third Canadian Edition 14 Global Climate Change PowerPoint® Slides prepared by Stephen Turnbull 14-1 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Upon successfully completing this chapter, you will be able to...

Third Canadian Edition 14 Global Climate Change PowerPoint® Slides prepared by Stephen Turnbull 14-1 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Upon successfully completing this chapter, you will be able to Distinguish weather from climate and explain key factors influencing global climate change Summarize approaches to climate research including the application of direct versus proxy indicators Summarize the key evidence for climate change, AND evidence that is caused by human activities. Outline current and future trends and impacts of global climate change Distinguish how different types of evidence help respond to key and distinct questions about climate change. Explain mitigation, adaptation and intervention focused approaches to responding to climate change 14-2 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Central Case: The Retreat of The Athabasca The Athabasca Glacier is currently retreating at a rate of 2-3 meters per year and has lost half its volume since 1844 Is this retreat due to climate change or is it just a natural continuation of the retreat of glacial ice that began 12,000 years ago? The Rockies may be ice-free by the end of this century 14-3 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Our Dynamic Climate 14-4 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  What is climate change? Climate: an area’s long-term atmospheric conditions Temperature, moisture content, wind, precipitation, etc. Weather: conditions at localized sites over hours or days Global climate change describes trends & variations in Earth’s climate Temperature, precipitation, storm frequency. Global warming: an increase in Earth’s average temperature. Earth’s climate has varied naturally through time The rapid climatic changes taking place now are due to human 14-5 activity: e.g. fossil fuel combustion, deforestation, etc. Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada The Sun and atmosphere keep Earth warm Three factors exert more influence on climate than all others: The Sun (supplies planet’s energy) The atmosphere (absorbs incoming solar radiation, moderates temperature – Earth would be much colder) What is the third, and the role it plays?? Albedo: reflectivity of a surface (related discussion) 14-6 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Greenhouse gases warm the lower atmosphere Some solar radiation is reflected back to the atmosphere by clouds and Earth’s surface, other radiation is adsorbed. As Earth’s surface absorbs solar radiation, the surface increases in temperature and emits longer wavelength infrared radiation. 14-7 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Greenhouse gases warm the lower atmosphere Some gasses in the lower atmosphere (troposphere) adsorb infrared radiation very effectively as it makes its way out to space. After absorbing radiation emitted from Earth’s surface, GHGs re- emit infrared energy of slightly longer wavelength - Some goes out to space, some back down to Earth 14-8 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Greenhouse gases warm the lower atmosphere Greenhouse effect: the warming of Earth’s surface and lower atmosphere caused by infrared energy that is absorbed and re-emitted downward by GHGs in the atmosphere, warming the troposphere and the Earth’s surface. 14-9 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Greenhouse gases warm the lower atmosphere Greenhouse gases (GHGs): are atmospheric gases that absorb infrared radiation (i.e. they are radiatively active gases): GHGs include water vapor, ozone, carbon dioxide, nitrous oxide, methane, chlorofluorocarbons (CFCs) Without natural levels of greenhouse effect the average earth temperate would be approx. minus 18 degrees Celsius 14-10 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Other GHGs besides carbon contribute to warming Methane from fossil fuels, livestock, landfills, and crops such as rice (which fossil fuel mainly?) Nitrous oxide from feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers Ozone from photochemical smog Halocarbons (CFCs and HFCs) Water vapor: the most abundant greenhouse gas and contributes most to the greenhouse effect 14-11 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Other GHGs besides carbon contribute to warming Global warming potential: the relative ability of one molecule of a given greenhouse gas to contribute to warming Expressed in relation to carbon dioxide (potential = 1) E.g. nitrous oxide is 296 times as potent as carbon dioxide 14-12 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Carbon dioxide (CO2) is the anthropogenic greenhouse gas of primary concern CO2 is not the most potent greenhouse gas, but it is extremely abundant The major contributor to global warming Natural sources of CO2 are greater than the human contribution. They come primary from decaying organic material. But human activities have boosted atmospheric concentrations from 280 parts per million (ppm) in the 1700s to more than 400 ppm in 2015 (right) 14-13 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Human activity has released carbon from sequestration in long-term reservoirs Natural fluxes of CO2, e.g., photosynthesis and respiration, normally cancel each other out, creating an even balance sheet But human (anthropocentric) activities add to and change natural fluxes, resulting in a shift to the overall balance, i.e. a net accumulation of CO2 versus the historical balance. 14-14 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Human activity has released carbon from sequestration in long-term reservoirs Burning fossil fuels transfers (flux) CO2 from reservoirs in the ground (e.g. coal) into the atmosphere Deforestation transfers CO2 from terrestrial reservoirs into the atmosphere 14-15 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  There are many feedback cycles in the climate system Positive feedback cycle: warming leads to water vapour which leads to further warming (water vapour is a radiatively active gas) causing still more evaporation. Negative feedback cycle (self-regulating or self-limiting feedbacks): warming leads to evaporation which leads to water vapour causing increased cloudiness slowing global warming (clouds reflect solar radiation back into space). Systems are complex, e.g., the actual effect water vapour would depend on whether the resulting clouds are higher or lower elevation. Remember this example? 14-16 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Radiative forcing expresses change in energy input over time Radiative forcing: the amount of change in energy that a given factor (such as albedo) exerts over Earth’s energy balance Positive forcing warms the surface; Negative forcing cools it Compared with the pre- industrial Earth, Earth is experiencing radiative forcing of 1.6 watts/m2 Enough to alter the climate 14-17 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  The atmosphere is not the only factor that influences climate Ocean absorption: the ocean absorbs CO2 from the atmosphere [e.g. through solubility of gas; photosynthesis]. Oceans holds 50 times more carbon than the atmosphere (acts as a sink and helps slow global warming) Ocean circulation: ocean water exchanges tremendous amounts of heat [also helping regulate climate] with the atmosphere, and ocean currents move energy from place to place. Milankovitch cycles: periodic changes in Earth’s rotation and orbit around the Sun (influenced glaciation) Variations in solar output: drive temperature change on Earth’s surface We need to rely on science to explain which 14-18 factors are or are not responsible for global warming today. Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  The Science of Climate Change 14-19 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada 15-19  Proxy indicators can tell us about the past [but not only the past, per below] Knowing about climate trends in the past, e.g., what were CO2 and corresponding temperature like, gives us a baseline to which we can compare trends in climate today. But we can’t go back & directly measure temperature 1000 years ago Therefore, Proxy indicators are types of indirect evidence that serve as substitutes for direct measurements, e.g., Ice caps, ice sheets, and glaciers hold clues to past climate 1000s of years ago Trapped bubbles in ice cores show atmospheric composition, greenhouse gas concentration, temperature trends Tree rings, coral. 14-20 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Proxy indicators cont. E.g., The Science Behind the Story pg. 430 Ice core data going back 800,000 years Methane & CO2 rise and fall in tight correlation with temperature Methane today CO2 today What does the correlation show?? (recall Ch 2 pg 31 experiment types) Causation, or correlation / relationship? Why is this graph important, i.e. what KEY EVIDENCE does it 14-21 provide about potential causes of Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada climate change? Direct indicators can tell us about the present Atmospheric CO2 increased from 1850 to present; AND human CO2 emissions also rose. Do you see a relationship / correlation? What is a KEY PIECE OF EVIDENCE we can take from it, and what type climate change question does it respond to? Besides things the past, in what other circumstances are proxy indicators helpful? 14-22 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Models help us understand climate Climate models combine what is known about past atmospheric processes, interactions, feedbacks, and use that knowledge to simulate what might happen in the future. Entering past data about climate can help us understand potential future conditions. E.g., if we saw that temperature was correlated with CO2 and methane levels in the past, what might even higher GHG levels do to temperature in the future? 14-23 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Models help us understand climate The effectiveness (e.g. the accuracy) of models is tested by entering data from the past and running the model toward the present If the model can make an accurate prediction of actual conditions today, then it is likely to be useful in predicting future conditions. 14-24 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Models show that current global temperatures would not be possible through only natural factors, i.e., human GHG emissions must be responsible for the current rise in temperature. What key question does this evidence help us answer? 14-25 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada What is the model-based evidence for cause and effect? https://www.ipcc.ch/report/ar6/wg1/figures/summary-for-policymakers/figure-spm-1/ Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Current and Future Trends and Impacts 14-27 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  The IPCC summarizes evidence of climate change and predicts future impacts Trend: a pattern that persists within a data set, even after short- term fluctuations and anomalies have been accounted for Intergovernmental Panel on Climate Change (IPCC) 2015: Fifth Assessment Report: Broad consensus of climate research on trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, and other factors. What question does this evidence help answer? 14-28 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada Surface temperature increases will continue The IPCC report concludes that average surface temperatures on earth have been rising since 1906, with most of the increase occurring in the last few decades (0.85 ̊ C) The period from 1983-2012 among the 30 warmest years on record for the past 1400 years (EVIDENCE?) IPCC predicts average surface temperature will be 1.5 ̊ C to 3.0 ̊ C (we’ll discuss recent updates to these projections) 14-29 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Changes in precipitation and storm activity will vary by region Some regions are receiving more precipitation than usual, and others are receiving less Droughts have become more frequent and severe - Harming agriculture, promoting soil erosion, reducing drinking water supplies, and encouraging forest fires Heavy rains have contributed to flooding 14-30 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Extreme weather is becoming “the new normal” Since 1950s, summer temperatures more variable Weather records are being broken Extreme weather events more common Northern polar jet stream influences weather in Canada Atmospheric blocking pattern: loops of polar jet stream get blocked into one position for a long period - Can cause droughts and flooding 14-31 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Melting ice and snow have far-reaching effects Mountaintop glaciers are disappearing - Risks of sudden floods as ice dams burst - Reducing summertime water supplies As ice melts, darker, less- reflective surfaces are exposed and absorb more sunlight, causing more melting (FEEDBACK) Together the trends signified by these seven major indicators are evidence of warming climate [which question does this help answer?]. Copyright © 2017 Pearson Canada Inc. 14-32 © 2010 Pearson Education Canada  Canada’s Arctic is changing dramatically Permafrost: perennially frozen ground, characteristic feature of the Arctic: accelerated release of soil gases due to melting could accelerate climate warming (which type of feedback?) Less snow cover. Melting ice sheets (Greenland ice sheet); ice shelves have shrunk by 90% over the past 100 years (Ayles Ice Shelf) Warming is accelerating …as snow & ice melt, darker, less-reflective surfaces are exposed, and Earth’s capacity to reflect light decreases (a change in albedo, which FEEDBACK?) 14-33 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Rising sea levels will affect millions in coastal zones and on islands As glaciers and ice melt, increased water will flow into the oceans What’s another cause of rising sea levels due to climate change? 14-34 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Climate change affects organisms and ecosystems Global warming modifies temperature-dependent phenomena Timing of migration, breeding, feeding, e.g., discussion re budworm on Vancouver Island (p 466) Spatial shifts in the range of organisms Animals and plants will move towards the poles or upward in elevation [why?] If they can’t migrate will they be able to change / adapt fast enough? 20-30% of all species will be threatened with extinction 14-35 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Climate change exerts societal impacts – and vice versa Agriculture: growing seasons shortened, drought, production will decrease, worsening hunger (and conflict, civil strife, human migration) Forestry: - increased insect and disease outbreaks, - increased wildfire Human health Economy Other examples?? 14-36 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Are we responsible for climate change? The IPCC concluded: is more than 90% likely that most of the global warming recorded over the past 50 years is due to the well-documented increase in greenhouse gas concentrations in our atmosphere due largely to fossil fuel combustion and land-use, e.g. agriculture, deforestation. 97% of scientists agree Can you make a logical summary of the evidence we’ve summarized so far? 14-37 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  IPCC 2001: TAR CLIMATE CHANGE 2001: THE SCIENTIFIC BASIS https://www.ipcc.ch/report/ar3/wg1/technical-summary/ Evidence-long-term trends [what question does this respond to?] Were direct or proxy indicators used to produce this graph? 14-38 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Responding to Climate Change 14-39 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada 15-39  Shall we pursue mitigation or adaptation, or intervention? Mitigation: pursue actions that reduce greenhouse gas emissions to lessen severity of future climate change Renewable energy sources, farm practices to protect soil integrity, preventing deforestation. Adaptation: accept climate change is happening and pursue strategies to minimize its impacts on us (sometimes criticized as sidestepping the issue) Assisted migration (Ch. 10); build or raise a sea wall; restrict coastal development; modify agriculture to use less water; use less water on our lawns, etc. Discussion: what are the pros and cons of each of these and should we be doing one or both? 14-40 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Intervention: set of possible large-scale technological modifications to the global climate system: Geo-engineering E.g., increasing Earth’s albedo Cloud seeding, Etc. What are the potential benefits and concerns about the use of these approaches? 14-41 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  We should look more closely at our lifestyle and transportation methods Are these Energy conservation and efficiency mitigation or - High-efficiency light bulbs and appliances adaptation focussed - Life-style choices actions? Alternate energy sources Automotive technology fuel-efficient, hybrid & electric cars Drive less, walk more, use public transportation 14-42 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  We will need to follow multiple strategies to reduce emissions Advances in agriculture, forestry, and waste management Renewable biofuels Reduce deforestation Etc. There is no single magic bullet for mitigating climate change Most reductions can be achieved using current technology so we can begin right away How quickly and successfully we translate science and technology into practical solutions for reducing emissions depends on policies and the market economy (Chapter 20-22) 14-43 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada We began tackling climate change by international treaty The Kyoto Protocol (2012) nations must reduce emissions of six greenhouse gases to levels below those of 1990 [Canada withdrew in 2011]. The more recent Paris Agreement (what was committed?) What are some ongoing factors that limit effectiveness of these treaties? Ongoing annual UN Climate Change conferences, e.g.: 2023 UAE 2024 Azerbaijan What has been a recent negotiation focus, e.g., in 202 14-44 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  The IPCC bases its climate models on differing scenarios of human response to climate change, e.g., we significantly reduce emissions in future, or we don’t reduce. Based on the data at right is Canada meeting its GHG reduction targets? Also see, e.g.: https://www.nzab205 0.ca/ https://climateinstitut e.ca/ 14-45 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Market-based tools are being used to address climate change (Chapters 20-22) Cap-and-trade programs – Examples? Carbon offset: a voluntary payment to another entity intended to enable that entity to reduce the greenhouse emissions that one is unable or unwilling to reduce oneself: Example offset programs? Carbon tax: negative incentives to change industry or individual consumer behavior by making it costlier to emit GHGs. Example carbon tax programs in Canada – consumer versus industry? Incentives: positive incentives to encourage desired behavior, like subsidies for buying an electric cars, solar panels, taking the bus, Carbon footprint: expresses the amount of carbon we are responsible for emitting (either as individuals or defined by region or state, industrial sectors etc.). Carbon neutral=no net emissions. 14-46 Discussion: Adaptation action examples Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  Concluding thoughts Many factors influence Earth’s climate - Human activities play a major role Climate change is well underway - Further emissions will cause severe and diverse impacts More and more scientists are urging immediate action - Mitigating and adapting to a changing climate What is the key logic and evidence for: - Climate change? - Its significance? - That climate change is caused by human activities? 14-47 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  QUESTION: Review A “proxy indicator” is …. a) Based on the direct measurement of a variable of interest, e.g. temperature b) Indirect evidence that substitutes for direct evidence c) Direct evidence d) Direct evidence that substitutes for indirect evidence 14-48 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada  QUESTION: Review What happens as glacial ice melts? a) More solar radiation is reflected back into space b) Glaciers get larger c) Exposed soils absorb heat and make melting worse d) Sea level decreases 14-49 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada QUESTION: Interpreting Graphs and Data Which statement is supported by this figure? a) CO2 emissions have stabilized recently b) CO2 emissions fluctuate only in Hawaii c) CO2 emissions have increased drastically d) CO2 emissions average 320 ppm 14-50 Copyright © 2017 Pearson Canada Inc. © 2010 Pearson Education Canada