Final Study Guide AOSC123
Final Study Guide AOSC123 AOSC123
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This 18 page Study Guide was uploaded by Trang Le on Tuesday May 17, 2016. The Study Guide belongs to AOSC123 at University of Maryland taught by Rachel Pinker in Winter 2016. Since its upload, it has received 84 views.
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Date Created: 05/17/16
1 AOSC123 FINAL EXAM REVIEW Now that we’ve learnt about scientific knowledge on implications of climate change such as water vapor, greenhouse gases etc, we will be tested on a major topic for this Final exam: basically how we approach this matter both from scientists perspective (the reports, the models, IPCC) and from communities perspective (vulnerability, adaptation, mitigation, resilient). IPCC report is the core of almost everything we learnt this second part of the semester! PLEASE NOTE that there will be certain concepts from the first exam that you should remember for this exam! If you don’t know what they are, you can either find out through looking at the materials below (pretty sure it will ring a bell), or you can check Dr. Pinker’s last lecture for reference (maybe my first exam review too, it’s out there) A. One way for the scientists to study and to convey what they found on climate change implications such as effect/amount of greenhouse gases or sea level rise is through MODELS: Here we will recall the difference between weather forecasting and climate prediction, and find out more (again) about climate models and what we can understand from them. Definition of a model: it’s a conceptual and qualitative description of a system that provides some understanding of how the system works but does not allow one to describe its detailed behavior. Basically it’s like a commercial, it introduces the products, but you can never tell what all the ingredients in it are. Weather: conditions over short periods, such as hours or days. Numerical Weather Prediction Models (NWP) are used to predict weather. On the other hand, climate is the average atmospheric conditions measured over a long time. General Circulation Models (GCMs) is used to construct climate projections. Next, we will explore in more details the difference between predicting weather and project climate conditions (make sense right! They use different models anyways). For weather prediction, present conditions must be known. To get this, there must be the following steps: Data acquisition • Assembling Data • Global network of land based 2 stations ships and radiosondes • Data analyses. They may use different equipment to get all measurements they need. Example: radiosondes (remember the balloon thing?) measuring atmospheric conditions; or observations on oceans taken by buoys (fancy looking cones floating on oceans). Three possible weather forecasts: Advisories (potential dangerous conditions); Watch (atmospheric conditions favoring hazardous weather like flash flood, severe thunderstorm or tornado); and Warning (occurring hazardous weather over a region in time). In order to complete the above forecasts, they use Numerical Weather Prediction (NWP) Models. It is used because it can simulate the primary fields of motion in the atmosphere. It is implemented on a grid with constant grid spacing in latitude and longitude (representing as units for what is happening). Forecasts are not always correct! Also, different models forecast different values. Now let’s look at climate models: GCM – General Circulation Model (sometimes Global Climate Model) which includes the physics of the atmosphere and often the ocean, sea ice and land surface as well. Ensemble model: a single run of the climate model that represents only one range of possible outcomes. It is usually constructed with ensemble mean taken from several ensemble runs. The reason why its use is necessary in predicting climate change is because climate models are not perfect and are mostly always subject to have uncertainties. Ensemble runs use a range of values for climate parameters that have uncertainties. Here, we will use GCM throughout the whole review because it is the primary major type of model that is employed for analysis in the IPCC report of 2007 and 2013 – the backbone of our review. Wait, what is the IPCC you ask? We’ll touch on it very soon! Remember, all the information under here revolves around 3 big ideas: climate change (how it’s predicted, are there any limits/critics to it and how it affects us), IPCC (mainly its 2013 report) and the GCM models predictions. 3 GCM model is a combination of Atmospheric General Circulation Models (AGCMs) and Ocean General Circulation Models (OGCMs). That’s why sometimes GCM is also called Atmosphere–Ocean General Circulation Model (AOGCM). Like when you make anything else, you must think about what is needed. Same here for GCM: what is needed to construct such model? The answer is we are not sure, it’s a very complex matter. But the scientists have to make them anyways, and that’s why they use what’s called Parameterization to build their GCMs: it’s a method in which a known variable and an unknown one is compared with each other for an observed relationship; data is collected and combined into a form of a sub-grid scale for parameterization. Still sound too abstracts? Here’s an example: clouds is used for analysis of humidity and temperature base on today’s observation of the climate. Here’s an image of IPCC report 2007 part A 184.108.40.206 Clouds (sub-grid scale): Ensemble runs and ensemble models are accounted for the variability and error part of GCM. Lately, GCM models are developed to become Earth System Models, basically a summative big model that includes a variety of sub-models from different areas for prediction of climate as a whole (atmosphere, land surface, ocean, aerosols, carbon cycle, dynamic vegetation etc). This helps to construct a broader, better picture of climate change with different areas corresponding to each other. GCMs models are developed globally and they all come together in one big report. Someone needs to compile all of these complex yet sophisticated stuff together plus review them right? *drum roll please* The Intergovernmental Panel on Climate 4 Change (IPCC)! It’s in charge of reviewing and assessing “the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change”. And when you think about it, hundreds of scientists worldwide gather data from many parts of the world to create an IPCC report. But not all of them can have the same predictions: some are cheerfully similar, but some are different and even worse, some are conflicting. That’s why, besides sticking to what’s happening with climate change, the IPCC’s purpose is also to provide an overall agreement, or consensus, on the scientific view of global warming. There are THREE working groups that contribute to the IPCC report: Working Group I Report on The Physical Science Basis; Working Group II Report on Impacts, Adaptation and Vulnerability and Working Group III Report on Mitigation of Climate Change. The report is also divided into three parts: Part A for Physical Science stuff, Part B for the history of climate change and Part C for vulnerabilities, adaptation and mitigation. Enough with the introduction, let’s dig deeper into IPCC report! The latest one is the 2013 IPCC report. It builds from the last IPCC report which was released in 2007. Therefore, there’s a need to understand briefly what was found in IPCC 2007, and from there continue to what the IPCC 2013 has to say. First, let’s look at the information from Group I about the findings in physical science: The following are summaries of what was established in IPCC 2007 Changes in atmosphere: greenhouse gases have increased significantly from pre- industrialized time. Three notable ones are carbon dioxide, methane and nitrous oxide (also recall that the two gases that regulate greenhouse effect are water vapor and CO2). The sources of the increase in carbon dioxide are fossil fuel use and land use. Also, the primary source of the increase in methane is very likely to be the result of a combination of agricultural activities and fossil fuel. There’s a general warming of the earth, or global warming is happening: there’s an increase in temperature. Hot days, hot nights, and heat waves have become more 5 frequent. Warming in the last 100 years has caused about a 0.74 °C increase in global average temperature. Ocean temperatures have increased to depths of at least 3000 m. And the average Arctic temperature increases almost twice as fast as the global rate. Extreme weather conditions: There has been an increase in hurricane intensity in the North Atlantic since the 1970s, and that increase correlates with increases in sea surface temperature. However, there’s not a clear sign that there’s been an increase in the number of hurricanes. Also, it’s more likely that this trend is partly caused by anthropogenic activities. Ice, permafrost and oceans: Mountain glaciers and snow cover have declined on average in both hemispheres, in which land ice (ice sheets) melting from Greenland and Antarctica is very likely the source that cause sea level rise over recent years. There’s a decline of permafrost coverage. Oceanic temperature increases (causing sea water to expand) and there’s been substantial losses in Arctic sea ice. Last but not least, there’s a decrease in snow cover across Northern Hemisphere. Now, let’s look at the newer observations from IPCC report of 2013 to see if the above trends continue or if there’re any deviations: Changes in atmosphere: confirm the above changes that involve greenhouse gases. Methane is the fastest growing gas with a 150% increase since 1750. Next is CO2 with a 40% increase, and then nitrous oxide. Agriculture and land uses are still two major sources of contribution. Warming: it’s certain that the overall temperature is rising (the rising trend is described as a linear trend), each of the past three decades has been significantly warmer than all the previous decades. However, please note that within this trend, there’s variations in the rate of warming annually. The rate of warming is continuing, not slowing down Extreme weather conditions: number of cold days + nights decrease while that of hot days + nights increases. Also, it’s likely that frequency of heat waves increases. Precipitation: medium confidence in heavy precipitation events over land has increased in more regions than it has decreased. High confidence in more precipitation for North America. There’s no clear trend for drought across the globe. 6 Extreme weather conditions: because of insufficient data the confidence is low for long-term changes in frequency and intensity of events like tropical cyclones and storms. Ice, snow, permafrost and ocean: same as above. Ice cover in the Arctic was measured with the NOAA GFDL model. As you have probably guessed by now, a lot of issues we’re dealing with has to do with increasing temperature and changes in the atmosphere. So, here we go: Recall that because of presence of greenhouse gases, instead of the average of -18ºC, we have an ave. temperature of 15ºC? That reflects the global mean energy budget. We have incoming solar radiation (shortwave), albedo of reflecting longwave radiation from land, radiation absorption by clouds and gases etc. How will this change with global warming? We can think of many scenarios: decrease in albedo due to oceans and land absorbing more radiation, possible increase in clouds can trap heat AND prevent radiation from reaching land, aerosols in atmosphere may result in cooler temperature etc Greenhouse gases! In order to measure each gas contribution to global warming, we use radiative forcing (W/m)^2. For our familiar friend CO2, we analyze Climate sensitivity - the amount of global average surface warming following a doubling of carbon dioxide concentrations. Other things lurking in our atmosphere: aerosols. They’re are fine solid particles or liquid droplets, in air or another gas (dust, smoke, fine particles as pollutants etc). Their concentration can be measured using some equipment such as Sky radiometer and satellite sensors. The parameter of aerosols for climate models is Aerosol Optical Depth (AOD), important for evaluating aerosol-radiation interactions. It is projected that aerosols has decreased for eastern USA and Europe while increased over eastern and southern Asia. Different models can specify in identifying different things, while different models accessing similar subjects can yield different results. Therefore, the WCRP's Working Group on Coupled Modelling decided on a new set of coordinated climate model experiments in the Coupled Model Inter-comparison Project 7 (CMIP5) to assess mechanisms associated with difference in models and examine climate predictability. CMIP5 have the following experiments (Representative Concentration Pathways): RCP2.6: exploring the possibility to keep global mean temperature increase below 2°C RCP4.5: radiative value – predicts radiative forcing at 4.5 Watts per meter squared in the year 2100 without ever exceeding that value. Also includes long term global emissions of greenhouse gases and land uses in a global economy. (Lecture 14 has detailed descriptions of each experiment so if you want to know check it out) Phew, too much abstract model stuff already! Let’s move on to a more scientifically clear topic: climate projections, like what we have after collecting data and analyzing all of the above models. We will first touch on the hot issues: rising temperature, sea level rise, changes in precipitation, change in thermocline circulation and Antarctic ice sheet projections. These can be found under PART A – physical science of the IPCC report. The overall temperature is predicted to increase. However, this trend doesn’t occur uniformly in every part of the world. In fact, there’s great variation in rate of warming as well as the impact it has on specific region. Data from NASA satellites shows that sea level rise is happening quite steadily. The causes include: Thermal expansion of ocean water; Melting of glaciers and ice caps; Melting of Greenland ice sheet and Melting of Antarctic ice sheet. It’s also projected that the rate of rise will increase with time (Relate to CMIP5: RCP2.6 and RCP8.5). Water cycle changes: Because the saturation vapor pressure of air increases ~7% with each ºC, it is expected that the amount of water vapor in air will increase with a warming climate => positive feedback! Increase of temperature <-> increase in water vapor <-> more heat trapped in atmosphere so hotter. Tropospheric water vapor will also increase at large spatial scales (globally it has risen 3.5% in the past 40 years). The water vapor change can be attributed to human influence with medium confidence. 8 Changes in precipitation: it is expected that average precipitation will gradually increase, at a slower rate than that of tropospheric water vapor (2% vs. 7%). Changes in precipitation in warmer areas will not be uniform. Data for this trend is presented through model A1B, in which it illustrates that higher latitudes will likely to experience more rain while arid/semi-arid areas will likely to have less. Global hydrological cycle: must consider three factors of frequency and duration, intensity and phase (in the form of snow or water droplets). But this is not just about the amount of rain: the IPCC also look at projections for floods and droughts and storms etc, or extreme weather conditions. According to Trenberth: surface and lower tropospheric water vapor pressure increases over time, and therefore there’ll be more moisture available for storms and an enhanced greenhouse effect. Of course, more precipitation in the air can lead to more clouds and more rain. Too much rain at a relatively short period can cause severe flooding. But what about drought? *baam* Palmer Drought Severity Index (PDSI), this measures intensity, duration, and spatial extent of drought/. Now, we can look back to the IPCC report. How can it deal with this gigantic amount of information and even potential conflicting views? Please look again at the treatment of uncertainty and summary of IPCC 2013 report in Lecture 15. The truth is, about 67% scientists believe climate change is at least partly caused by human activities. The remaining 33% think that it occurs naturally and may or may not be boosted by human activities. The argument also includes points such as the cause of global warming is unknown, or the report is too conservative/contain vague and not up- to-date information + inadequate models. That’s it for part A, physical science. Let’s move on to PART B: Climate change history. I think this is important to understand because there have always been climate variation in the past, plus this plays an important part in the whole global warming argument (especially for those who believe global warming now is a natural process). Here we go! 9 First, let’s define “Climate variability”: the fluctuation in weather conditions that occur within a 30-year interval. What about climate change? It’s significant difference between average weather conditions or in the pattern of variability between two time spans. Usually, climatologists look for trends in a bunch of data to determine these things. Dr. Pinker includes two slides that have information on how the Earth formed in lecture 16, so you can check that out. There are two types of climate change: short term and long term. To better understand the climate in the past, we have palaeoclimatology - the study of past climates; past climates can help us to predict future climate conditions Short-term climate change - variability occurs on the hundred- to a millennium (1000 years) time span. How can we figure out climate in the past? Scientists use proxies - imprints created during past climate – to interpret what we need to know. Microbial life, such as diatoms, forams*, and corals; ice cores, sediment cores and tree rings serve as useful climate proxies. If you find some of these names strange, I’ll go on and explain some down here… Diatoms and Foraminifera are microfossils that can tell us about past conditions like ocean acidification levels, sea surface temperatures, ice cover and concentration of carbon dioxide and oxygen in the atmosphere. Diatoms are microscopic plants (algae), and can be found in many body of water. are useful for climate studies as they are sensitive to different conditions and preserve well in the fossil record. Example: it can be used to determine ice cover by examining how much light can penetrate and enter water body for diatoms to photosynthesize. The data collected from the above proxies are called proxy data. Another method to determine past climate is through geochronology - the science of determining the age of rocks, fossils, and sediments. Hold on, now we need to wonder, where can we get some of these things for proxy data? *drum rolls please* Sediments can be found in the lithosphere – basically the outer solid crust of the Earth (recall that Earth consists of four layers: Crust, Mantle, liquid Outer Core and solid Inner 10 core). The crust has two types: oceanic crust (denser but thinner) and continental crust (lighter but thicker). Many processes occur here to produce different types of rocks. And guess what, the lithosphere is not static! There are pieces of it that move (slowly) around, and when each piece meets, they produce plate tectonic results. **More details can be found in Lecture 19** this is the foundation to why there’s volcanoes; earthquakes etc that have the potential of creating short term climate variability, at the same time provide evidence for them. Okay. So what about the ice thing? Well, ice and snow is one part of the cryosphere (the God of ice dun dun dun, basically it’s everything very cold/frozen in this planet). Because polar regions are some of the most sensitive to climate shifts, the cryosphere may be one of the first places where scientists are able to identify global changes in climate. Wait up, there’s also a thing that lives in the oceans and is super sensitive to changes in its environment too: Corals! It’s helpful in analyzing oceanic issues because it responds to a variety of things including water temperature, freshwater influx, pH changes, and wave action. A summary of how proxy data from these guys are analyzed? CHECK THE LAST SLIDE OF LECTURE 19. Example: sediment layers lie upon each other in a superposition manner; meaning that the oldest layer will be at bottom, and younger ones on top. This process can be used to observe natural history as well as find any fossil pieces of ancient creatures. Or there’s also correlation of strata that is used to find out age relationship between rocks from one location to another. Last but not least, scientists often assume that similar natural processes in the past also continue to appear today, hence the idea of Uniformitarianism in dating objects. Proxy climate data and analysis of past climates can be inferred from several sources as you can see. We can find what we need in proxies, in glacial variations, biological data and/or anthropogenic data (historical accounts). A more detailed explanation for more examples of the mentioned categories above can be found in lecture 16 (towards the last few slides). So now we’re talking short-term climate variability in the past. Here’re some indications/things that caused this to happen: 11 Variation in solar luminosity due to sunspot activities. More sunspots generally lead to a hotter, brighter sun and more radiation to Earth and vice versa. There’s been correlation between sunspot cycle length and Northern Hemisphere temperature anomalies. Volcanic eruptions: sulfur dioxide emission from these eruptions acted as aerosols reflecting radiation back into space and preventing it from reaching ground => cooler climate. Sea ice distribution: this is particularly important for higher latitudes. Considering the positive feedback: rising temperature <-> melting of ice cover <-> decrease in albedo <-> melting of more ice and higher rate of temperature rise. Greenhouse gases: there’s a methane burp from the oceans about 55 million years ago that significantly increase the global temperature. This is a typical example that shows the warming effect of greenhouse gases. Changes in ocean circulation pattern: A change in this circulation can lead to rapid decrease in atmospheric temperatures in the North Atlantic. **Some review on thermohaline circulation: https://www.esr.org/outreach/climate_change/basics/basics2.html. “The “thermohaline” circulation of the ocean refers to the flow of ocean water caused by changes in density. This can occur as the ocean is warmed or cooled at the surface by radiation and contact with the atmosphere, or by the addition of fresh water (rain, snow, and river runoff) or salt (from formation of sea ice)”. http://pmm.nasa.gov/education/videos/thermohaline-circulation-great-ocean-conveyor-belt There have been evidence that point to a warmer and a colder climate period in the history of Earth. The warmer period: the Holocene (last 10000 years that follow after the Ice Age). But of course, Mother Nature thought a little deviation here and there wouldn’t hurt, so there have also been small-scale climate shifts like this "Little Ice Age" between about 1200 and 1700 A.D. The very beginning of the Holocene was the Younger Dryas Event – a turning point from about 11,000 to 10,000 BP, marking the transition (also known to lie in the Early 12 Holocene period). This is considered a relatively short-term climate shift, with increase abundance in a tundra flower Dryas. Evidence in climate variability can also be explained through the Earth’s movement in space. This is when Milankovitch Theory steps in: it describes the collective effects of changes in the Earth's movements upon its climate. Variations in eccentricity, axial tilt, and precession of the Earth's orbit influence climatic patterns on Earth through orbital forcing. Apparently the above three cycles can affect how much and where solar heat reaches the Earth, thus influencing climate patterns. Evidence that proves this theory can be found from Benthic forams and Vostok ice core (from Antarctica) - two distinct proxies for past global sea level and temperature, from ocean sediment and Antarctic ice respectively (the ice thing was drilled by the collaboration between the US, Russia and France). The Earth's orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The angle of the Earth's axial tilt (Obliquity) is also notable here: less tilt means less variation in seasons between the Northern and Southern Hemisphere and vice versa. Oh, let’s not forget that our Earth also rotate around its axis. Precession is the change in orientation of the Earth's rotational axis, affecting the direction of the axis. **Almost forgot, the ice as proxy data have some unique features with two isotopes of oxygen that you should know (I think). So basically sea ice and sea water contain different concentration of a lighter and a heavier oxygen isotope (ice generally have more of the lighter oxygen). Melting returns light oxygen to the water, and reduces the salinity of the oceans worldwide. Higher-than-standard global concentrations of light oxygen in ocean water indicate that global temperatures have warmed, resulting in less global ice cover and less saline waters. More details can be found in Lecture 20 at the beginning slides. Ice proxies can also be used to determine carbon dioxide and methane abundances through ice bubble measurements. OKAY, so we’ve been through two major methods to figure past climate conditions. Now here’s another one (bear with me please, I don’t find this quite divine either): 13 Some scientists decide that no, they hate the cold, and they don’t want to touch some rocks that’s boring. They’re going to do Radiocarbon dating - using the decay of carbon- 14 (14 C ) to estimate the age of organic materials, because why not, and because staring at some dead hundreds-year-old organisms is so much fun. Basically 14 C will decrease as it decays with the organism’s body. So just measure the amount of 14 C left in a piece of evidence to guess its age. If you’d like more details, I suggest go look at the last few slides of Lecture 20 because honestly I have no more comment. PART C!!!! So with this overwhelming bunch of info throwing at our faces, I thought well damn, what are we going to do with climate change? PART C everyone, the impacts, vulnerability, and mitigation. Finally! Always remind yourself that there’s a whole debate that goes with climate change. It can either be natural or anthropogenic; be due to natural internal processes or external forcing. We like to label things clearly, so that’s what the United Nations Framework Convention on Climate Change (UNFCCC) did. They make a distinction between climate change attributable to human activities altering the atmospheric composition, and climate variability attributable to natural causes as they define “climate change” as follow: “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”. Want some definitions of impact, exposure, vulnerability and risk? Look at the slides in Lecture 21! Climate change can cause multiple impacts: they can lead to changes in geographical system and cause more flood, drought and sea level rise -> physical impact. They can also cause other impacts to our economy and our health. An important point to note is that the vulnerability of us to experience all these 14 Some of our big concerns lie in relocation and loss of coastal areas because of sea level rise, extreme weather conditions (flooding, drought, storms, hurricanes etc) and crop yields. Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts (high confidence). Coupled climate, ecosystem and carbon modeling can be used to identify the importance of ecosystem-climate feedbacks. Observed impacts relate mainly to production aspects of food security rather than access or other components of food security. Let’s touch on specific vulnerabilities shall we: In many regions, changing precipitation or melting snow and ice are altering hydrological systems, affecting water resources in terms of quantity and quality due to increased temperature; increased sediment, nutrient, and pollutant loadings from rainfall. It’s projected that climate change will reduce the renewable surface water and ground water resources. Also, in dry areas drought frequency will likely increase by the end of the 21st century under RCP8.5. This is not uniform: it’s expected that higher latitudes (the poles) will have more water resources. It’s projected that oceans will be acidified (decrease in pH, which is dangerous for marine organisms) A large fraction of both terrestrial and freshwater species faces increased extinction risk under projected climate change during and beyond the 21st century. Sea level rise: oh it’s happening alright. The rate is expected to rise gradually with time, and it brings many negative effects. Excess melting of ice means we’re losing a valuable source of fresh water. At the same time, sea level rise causes flooding and erosion to coastal areas, threatening to bring major economical and social setbacks. There’s likely an increase in concentration of carbon dioxide in the atmosphere. “Climate change will impact human health mainly by exacerbating health problems that already exist (very high confidence)”. 15 Of course, not all places experience the same risks because they are at different place, with different ecosystems and also there’s variation in population and GDP or gross income. I have messed this up more than one time, so I’m just going to throw this out there: there’s a difference between mitigation and adaptation! Mitigation, as defined by Dr. Pinker, is taking action now—before the next disaster—to reduce human and ﬁnancial consequences later. While adaptation means that a disaster is already happening and we just do things to live with it. “Mitigation requires that we all understand local risks, address the hard choices, and invest in long-term community well-being”. Some mitigation tactics: Climate change mitigation generally involves reduction in human (anthropogenic) emissions of greenhouse gases. This can be achieved through the following: reforestation; using renewable, green energy like solar or wind energy; increase carbon sinks and geoengineering or climate engineering. The main international treaty on climate change is the United Nations Framework Convention on Climate Change (UNFCCC). In 2010, UNFCCC agreed that future global warming should be limited to below 2.0 °C. This will require global emission to drop significantly after 2020. Also, to create lasting climate change mitigation, the replacement of high carbon emission intensity power sources, such as oil, natural gas, low-carbon power sources as an alternative is required. To add to the increasing of carbon sinks, some suggest that the gases from industrial processes can be stored in safe tanks instead of releasing them into the atmosphere. These are just brief summaries of the point that I think we must know. For more details, please check Lecture 23. In order to make mitigation tactics work, there’s a need for clear and feasible guild lines for implementing them. This is a very complex and difficult matter. There are often obstacles in the form of uncertainties that hinder this process: 16 Paradigmatic uncertainty results from the absence of prior agreement on the framing of problems, on methods for scientifically investigating them. Epistemic uncertainty: lack of knowledge on characterizing or labeling phenomena. Translational uncertainty results from scientific findings that are incomplete or conflicting. Although there’s so much going on that mitigation guide lines seem impossible, there’s a success story that Dr. Pinker wants us to know The Montreal Protocol for Ozone hole problem! The abundances of the ozone-depleting chemicals were steadily increasing in the atmosphere linked to growing production and use of chemicals like chlorofluorocarbons (CFCs) for refrigeration and air conditioning. In response, the governments of the world crafted the 1987 United Nations Montreal Protocol to address a global issue. The ozone hole is defined as the area having less than 220 Dobson units of ozone in the overhead column between ground and space. An increase in chlorine monoxide depletes the ozone at the Antarctica. The depth and area of the Antarctic ozone hole are governed by the temperature of the stratosphere and the amount of sunlight reaching the South Polar Region. These factors can be altered greatly through the presence of excess frozen crystals that make up polar stratospheric clouds provide a surface for the reactions that free chlorine atoms in the Antarctic stratosphere. In addition, polar stratospheric clouds (PSCs) are an important component in the destruction of ozone molecules in a sense that they can alter solar energy influx. The formation temperature is dependent on concentrations of nitric acid and water vapor, and the potential temperature of the air. PSCs can be formed from sulfate aerosols, nitric acid trihydrate (NAT), or ice. They are formed under the influence of Antarctic polar vortex. A summary of how Ozone hole is formed (with the Antarctic polar vortex as an agent that form clouds with ice crystals that facilitate chemical reactions destroying the ozone) can be found in Lecture 24 the later half. The Montreal Protocol consists of amendments that basically eliminate or minimize the production and use of products that have the harmful compounds listed above plus those that have potential in destroying the ozone. 17 The WGII AR5 of the IPCC report considers how impacts and risks related to climate change can be reduced and managed through adaptation and mitigation. It assesses needs, options, opportunities, constraints, resilience, limits and other aspects of adaptation. Adaptation and mitigation are closely linked together and should both be implemented for the best outcome. Otherwise, with adaptation alone, it will be much more costly and with less pros. Adaptations are carried out in various levels of communities. Adaptation planning is occurring in the public and private sectors and at all levels of government. Some are established by federal government but carried out in local communities. However, there are great limitations: limited funding, policy and legal impediments, and difficulty in anticipating climate-related changes at local scales. Therefore, not many policies have actually been made official. More details can be found in Lecture 25. Like it or not, only slightly more than half of all local communities in the US are engaging in some adaptation planning. Most adaptation efforts to date have occurred at local and regional levels. Some adaptation tactics include land-use planning; provisions to protect infrastructure and ecosystems; regulations related to the design and construction of buildings, roads, and bridges; and emergency response. Companies as private sectors also take part in the adaptation process in the hope of not only minimize the risks but also explore new opportunities arising from a changing climate. Let’s wrap this up with the Kyoto Protocol – what we’re doing to address and solve climate change problems. Montreal Protocol is crucial landmark that is suggested as a model for solving other problems like greenhouse gases. And so the Kyoto Protocol is established to set binding obligations on industrialized countries to reduce emissions of greenhouse gases. “According to the UNFCC website, the Protocol "recognizes that developed countries are principally responsible for the current high levels of GHG emissions in the atmosphere as 18 a result of more than 150 years of industrial activity, and places a heavier burden on developed nations under the principle of 'common but differentiated responsibilities'”. Guess what, The United States signed but did not ratify the Protocol and Canada withdrew from it in 2011. Good job America. Wow.
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