{"id":48,"date":"2021-03-10T18:16:13","date_gmt":"2021-03-10T23:16:13","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/physgeoglabmanual1\/chapter\/lab7\/"},"modified":"2021-04-05T22:30:39","modified_gmt":"2021-04-06T02:30:39","slug":"lab7","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/physgeoglabmanual1\/chapter\/lab7\/","title":{"raw":"LABORATORY 7: CLIMATE CHANGE \u2013 PART 2","rendered":"LABORATORY 7: CLIMATE CHANGE \u2013 PART 2"},"content":{"raw":"

LABORATORY 7<\/strong><\/span>: CLIMATE CHANGE - PART 2<\/strong><\/h2>\r\n

LEARNING GOALS<\/span><\/h1>\r\nIn this laboratory, we will examine the nature of past and future predicted climate change on the Earth.\r\n\r\nUpon completion of this laboratory you will be able to:\r\n
    \r\n \t
  1. Describe trends in historical climate data as they relate to human-caused [pb_glossary id=\"674\"]global warming[\/pb_glossary]<\/strong>.<\/li>\r\n \t
  2. Examine and interpret the output from climate simulation models.<\/li>\r\n \t
  3. Understand the possible climate change outcomes in the future under the best-case and worst-case greenhouse gas emission scenarios.<\/li>\r\n<\/ol>\r\n

    HUMAN CAUSED CLIMATE CHANGE<\/strong><\/h1>\r\nAn examination of climate data from meteorological measurements across our planet\u2019s land and ocean areas over the last 119 years reveals obvious patterns of climate change (Figure 7.1<\/strong><\/span>). In North America, South America, Europe, Asia, and Africa annual temperatures at most meteorological stations were appreciably colder at the beginning of the 20th century. From the 1920s to the 1950s temperatures became warmer. Colder temperatures returned once again in the 1960s, and continued until the mid-seventies. A warming trend followed these cooler years, and has continued ever since with some of the warmest years in the 20th and 21st century being recorded in just the 30 years. Interestingly, these patterns mirror trends found in the [pb_glossary id=\"675\"]annual mean global temperature[\/pb_glossary]<\/strong> record (Figure 7.2<\/strong><\/span>).\r\n\r\n\"\"\r\n\r\nFigure 7.1.<\/em><\/strong><\/span> Historical trend in annual mean surface temperatures over the period 1901 to 2019 (119 years). Areas in grey have insufficient data. Image Copyright: Michael Pidwirny. Date Source: <\/em>NASA<\/em><\/a> - <\/em>Goddard Institute for Space Studies<\/em><\/a> - <\/em>Surface Temperature Analysis<\/em><\/a>. Land Data from GISS Analysis, Ocean Data from Hadl\/Reyn_v2: SST 1880-Present.<\/em>\r\n\r\n \r\n\r\n\"\"\r\n\r\nFigure 7.2.<\/em><\/strong><\/span> Global mean annual temperature measurements from 1880 to 2019. Green line represents 7-year moving average. The red dashed line shows the average global mean for the period 1880-1950. Image Copyright: Michael Pidwirny, Data Source: <\/em>http:\/\/data.giss.nasa.gov\/gistemp\/graphs_v4\/<\/em><\/a>.<\/em>\r\n\r\n \r\n\r\nOver longer periods of time, non-instrumental climate data also indicates that weather has been quite variable in North America and across the Earth. For example, over the past 800,000 years, there have been several great [pb_glossary id=\"677\"]ice ages[\/pb_glossary]<\/strong> during which 30% of the continental surface of the Earth was covered by glacial ice several kilometers (miles) thick. Each glacial period lasted about 100,000 years and was followed by a warmer [pb_glossary id=\"678\"]interglacial[\/pb_glossary]<\/strong> period persisting for roughly 10,000 to 12,500 years.\r\n\r\nFor the past 10,000 years, the Earth has been enjoying the warm temperatures of the latest interglacial period. During this period the Earth's average global temperature fluctuated up and down by about 2\u00b0C (3.6\u00b0F) over short periods of time (less than 500 years). These moderate and relatively slow fluctuations in climate have not led to drastic changes in the Earth's environment. Today\u2019s annual mean global temperature is about 15\u00b0C (59\u00b0F).\r\n

    HUMAN ENHANCEMENT OF THE GREENHOUSE EFFECT<\/strong><\/h1>\r\nThe chemical nature of the atmosphere is an important factor in determining the Earth's climate. Heat energy from the Sun is trapped in the Earth's lower atmosphere by a natural process called the [pb_glossary id=\"535\"]greenhouse effect[\/pb_glossary]<\/strong>. The amount of heat trapped depends primarily on the concentrations of the various [pb_glossary id=\"680\"]greenhouse gases[\/pb_glossary]<\/strong>, such as carbon dioxide, water vapor, ozone, methane, and nitrous oxide. The two greenhouse gases with the largest concentration in the troposphere are carbon dioxide and water vapor. Over the past 160,000 years, estimated levels of water vapor in the lower atmosphere have remained fairly constant while the levels of carbon dioxide have fluctuated in-sync with the warming and cooling of the Earth.\r\n\r\nStarting about 300 years ago, humans began significantly altering the concentration of [pb_glossary id=\"533\"]carbon dioxide[\/pb_glossary]<\/strong> in the atmosphere. Measurements indicate that from that time (about 1700) to today, carbon dioxide increased in concentration by about 45% (Figure 6.3<\/strong><\/span>). Much of this increase was caused by human-driven activities such as the burning of [pb_glossary id=\"681\"]fossil fuels[\/pb_glossary]<\/strong>, the conversion of natural habitats into agricultural fields, and deforestation. By the year 2050, scientists predict that carbon dioxide content in the atmosphere may increase by about 100% when compared to values before human industrialization. This increase will occur because of the continued human participation in activities that release the greenhouse gases carbon dioxide (CO2<\/sub>), methane (CH4<\/sub>), and nitrous oxide (N2<\/sub>O) into the atmosphere.\r\n\r\n \r\n\r\n\"\"\r\n\r\nFigure 7.3.<\/em><\/strong><\/span> The following graph illustrates the rise in atmospheric carbon dioxide from 1744 to 2018. Note that the increase in carbon dioxide's concentration in the atmosphere is exponential in nature. An extrapolation into the immediate future would suggest continued annual increases. Image Copyright: Michael Pidwirny. Data Source: Neftel, A., et al. 1994. Historical carbon dioxide record from the Siple Station ice core. pp. 11-14. In T.A. Boden, D.P. Kaiser, R.J. Sepanski, and F.W. Stoss (eds.) Trends'93: A Compendium of Data on Global Change<\/strong>. ORNL\/CDIAC-65. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tenn. USA and Dr. Pieter Tans, NOAA\/ESRL (<\/em>http:\/\/ www.esrl.noaa.gov\/gmd\/ccgg\/trends\/<\/em><\/a>) and Dr. Ralph Keeling, Scripps Institution of Oceanography (<\/em>http:\/\/scrippsco2.ucsd.edu\/<\/em><\/a>).<\/em>\r\n\r\n \r\n\r\nSince 1750, the atmospheric concentration of the greenhouse gas [pb_glossary id=\"534\"]methane[\/pb_glossary]<\/strong> (CH4<\/sub>) has increased by more than 150% (Figure 7.4<\/strong><\/span>). The primary sources for the additional methane added to the atmosphere (in order of importance) are rice cultivation, domestic grazing animals, termites, landfills, oil and gas extraction, and coal mining.\r\n\r\n\"\"\r\n\r\nFigure 7.4.<\/em><\/strong><\/span> The following graph illustrates the rise in atmospheric methane from 1008 to 2015. Note that the increase in methane's concentration in the atmosphere is exponential in nature. An extrapolation into the immediate future would suggest continued annual increases. \u00a0Image Copyright: Michael Pidwirny. \u00a0Data Source: D.M. Etheridge, L.P. Steele, R.J. Francey, and R.L. Langenfelds. 2002. Historical CH<\/em>4<\/em> Records Since About 1000 A.D. From Ice Core Data. In Trends: A Compendium of Data on Global Change<\/strong>. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., USA. and NOAA Earth System Research Laboratory<\/strong>, Trends in Atmospheric Methane, <\/em>http:\/\/www.esrl.noaa.gov\/gmd\/ccgg\/trends_ch4\/<\/em><\/a>.<\/em>\r\n\r\n \r\n\r\nThe average concentration of [pb_glossary id=\"683\"]nitrous oxide[\/pb_glossary]<\/strong> (N2<\/sub>O) is now increasing at a rate of 0.2 to 0.3% per year (Figure 7.5<\/strong><\/span>). Nitrous oxide is another greenhouse gas. Its part in the enhancement of the greenhouse effect is minor relative to the other greenhouse gases already discussed. Nitrous oxide also contributes to the artificial fertilization of ecosystems. In extreme cases, this fertilization can lead to the death of forests, eutrophication of aquatic habitats, and species die-offs. Sources for the increase of nitrous oxide in the atmosphere include land-use conversion, fossil fuel combustion, biomass burning, and soil fertilization. Most of the nitrous oxide added to the atmosphere each year comes from deforestation and the conversion of forest, savanna, and grassland ecosystems into agricultural fields and rangeland.\r\n\r\n\"\"\r\n\r\nFigure 7.5.<\/em><\/strong><\/span> The following graph illustrates the rise in atmospheric nitrous oxide from 1978 to 2015. This increase appears linear. An extrapolation into the immediate future would suggest continued annual increases. \u00a0Image Copyright: Michael Pidwirny. Data Source: National Oceanic and Atmospheric Administration's (NOAA) Climate Monitoring and Diagnostics Laboratory, <\/em>http:\/\/www.esrl.noaa.gov\/gmd\/hats\/combined\/N2O.html<\/em><\/a>.<\/em>\r\n

    REPRESENTATIVE CONCENTRATION PATHWAYS<\/strong><\/h1>\r\nThe most recent [pb_glossary id=\"684\"]Intergovernmental Panel on Climate Change[\/pb_glossary]<\/strong> 5th Assessment Reports use four different future emission scenarios of greenhouse gases to model future climate conditions on our planet. These emission scenarios are called Representative Concentration Pathway<\/strong><\/a> 2.6 (RCP 2.6<\/strong>), 4.5 (RCP 4.5<\/strong>) 6.0 (RCP 6.0<\/strong>), and 8.5 (RCP 8.5<\/strong>) and are based on four assumptions of how future human population growth and socioeconomic development will unfold during the 21st century. The general socioeconomic characteristics associated with each of these scenarios are described in Table 7.1<\/strong><\/span>.\r\n\r\n\"\"\r\n\r\nMany scientists believe RCP 4.5<\/strong> (best-case scenario) is a most likely outcome than can occur with reasonable future efforts in climate change mitigation by our planet\u2019s various nations. RCP 8.5<\/strong>\u00a0(worst-case scenario) represents what would happen if very little mitigation took place in the future to tackle climate change. Figure 7.6<\/strong> <\/span>shows the predicted future change in the atmospheric concentration of the greenhouse gases carbon dioxide (CO2<\/sub>), methane (CH4<\/sub>), and nitrous oxide (N2<\/sub>O) from the year 2000 to 2100 for these two Representative Concentration Pathways.\r\n\r\n\"\"\r\n\r\nFigure 7.6. <\/em><\/strong><\/span>Estimated carbon dioxide, methane, and nitrous oxide atmospheric concentrations for the period 2000 to 2100 according to the RCP4.5 and RCP8.5 emission scenarios used in the 5th IPCC Assessment Reports. Image Copyright: Michael Pidwirny. Data Source: RCP Database Website - <\/em>http:\/\/tntcat.iiasa.ac.at:8787\/RcpDb\/<\/em><\/a> .<\/em>\r\n\r\n \r\n

    LABORATORY 7 QUESTIONS<\/strong><\/span><\/h2>\r\n

    QUESTION 1<\/strong><\/h1>\r\nNASA maintains a dataset of land-based weather station (Global Historical Climatology Network \u00a0- GHCN Version 4<\/a>) and sea surface temperature (Extended Reconstructed Sea Surface Temperature - ERSST Version 5<\/a>) measurements that are commonly used to calculate our planet's annual mean global temperature. Using this dataset, NASA has been able to determine annual global mean temperatures back to 1880. You can access this dataset and do some simple comparative analyses using a utility that creates global maps at the following web address:\r\n\r\nhttps:\/\/data.giss.nasa.gov\/gistemp\/maps\/index_v4.html<\/a>\r\n\r\nThe screen capture below shows a comparison of average annual (Dec-Nov) global mean temperature for the decade 1980 to 1989 to a baseline thirty-year period from 1951-1980 (NASA's preferred climate normal<\/strong><\/a>). The map produced shows the temperature difference or anomaly between the two periods. This web tool also calculates the global temperature difference between the averages of these two periods for the entire surface of our planet. In this comparison, it tells us that the average of the ten-year period 1980-1989 was 0.25\u00b0C warmer than the 1951-1980 thirty-year average (see red circle).\r\n\r\nCareful examination of the map indicates that the warming during the decade 1980-1989 was not spatially homogeneous. The warming in the Southern Hemisphere was quite similar over land and ocean surfaces measuring about 0.2 to 0.5 \u00b0C. There are some smaller areas where the warming was a bit higher reaching between 0.5 to 1.0 \u00b0C. A few areas over the oceans show no change and a couple of spots along the edge of Antarctica actually show a cooling trend. In the Northern Hemisphere, warming seems to be greater on land surfaces. There is a large area of warming in central North America and Siberia measuring between 0.5 to 1.0 \u00b0C. Most of the ocean surfaces in the Northern Hemisphere show no change in surface temperature. There are two areas of colder temperatures occurring over the middle of the North Pacific Ocean and around the bottom of Greenland.\r\n\r\n\"\"\r\n\r\n \r\n\r\nUsing NASA's climate dataset and mapping website described above, answer the following questions.\r\n\r\n1.1)<\/strong> Generate a map showing the difference between the decade 1990-1999 and the 1951-1980 thirty-year climate normal using the input values shown below.\r\n\r\n\"\"\r\n\r\n1.1a)\u00a0<\/strong>Globally, how much warmer was the average of the decade 1990-1999 than the 1951-1980 climate normal in \u00b0C?\r\n\r\n \r\n\r\n1.1b)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the generated anomaly map of 1990-1999 vs the 1951-1980 climate normal. What is the relationship of the warming with latitude? Is there greater warming over land or over ocean surfaces? Is one hemisphere warming differently than the other?<\/span>\r\n\r\n \r\n\r\n1.2)<\/strong> Generate a map showing the difference between the decade 2000-2009 and the 1951-1980 thirty-year climate normal using the input values shown below.\r\n\r\n\"\"\r\n\r\n1.2a)\u00a0<\/strong>Globally, how much warmer was the average of the decade 2000-2009 than the 1951-1980 climate normal in \u00b0C?\r\n\r\n \r\n\r\n1.2b)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the generated anomaly map of 2000-2009 vs the 1951-1980 climate normal. What is the relationship of the warming with latitude? Is there greater warming over land or over ocean surfaces? Is one hemisphere warming differently than the other?<\/span>\r\n\r\n \r\n\r\n1.3)<\/strong> Generate a map showing the difference between the decade 2010-2019 and the 1951-1980 climate normal using the input values shown below.\r\n\r\n\"\"\r\n\r\n1.3a)\u00a0<\/strong>Globally, how much warmer was the average of the decade 2000-2009 than the 1951-1980 climate normal in \u00b0C?\r\n\r\n1.3b)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the generated anomaly map of 2010-2019 vs the 1951-1980 climate normal. What is the relationship of the warming with latitude? Is there greater warming over land or over ocean surfaces? Is one hemisphere warming differently than the other?<\/span>\r\n\r\n \r\n\r\n1.4)<\/strong> Generate a map showing the difference between the year 2016 and the 1951-1980 climate normal using the input values shown below. Climatologist has identified 2016 as the warmest year in the historical record dating back to 1880.\r\n\r\n\"\"\r\n\r\n1.4a)\u00a0<\/strong>Globally, how much warmer was the year 2016 than the 1951-1980 climate normal in \u00b0C?\r\n\r\n \r\n\r\n1.4b)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the generated anomaly map of 2016 vs the 1951-1980 climate normal. What is the relationship of the warming with latitude? Is there greater warming over land or over ocean surfaces? Is one hemisphere warming differently than the other?\r\n\r\n \r\n

    QUESTION 2<\/strong><\/h1>\r\nUse the following link to go to Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a>.\r\n\r\nhttps:\/\/climatereanalyzer.org\/reanalysis\/monthly_maps\/<\/a>\r\n\r\nOne very interesting dataset available for analysis on the Monthly Reanalysis Maps webpage is climate simulation model forecasts for individual years from 2005 to 2100. This output was produced by the Community Climate System Model<\/a> version 4 (CCSM4) Global Climate Model (GCM) developed by the University Corporation for Atmospheric Research<\/a> (UCAR) at Boulder, Colorado, USA. \u00a0Output is available for all four greenhouse gas emission scenarios: RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5.\r\n\r\nThe next three maps were produced to examine the spatial change in surface mean temperatures (2 meters above ground level) under the RCP 2.6 greenhouse gas emission scenario annually<\/strong>, for summer<\/strong> (June, July, and August), and for winter<\/strong> (December, January, and February). In these three maps, the forecasted average conditions for 2071-2100 are compared to a 15-year base period of 2006-2020.\r\n\r\nThe RCP 2.6 greenhouse gas emission scenario assumes that we begin our path to lowering emissions of greenhouse gases starting in the year 2020 and eventually reaching zero emissions by 2100. This scenario also assumes that humans invest heavily in technologies to remove carbon dioxide from the atmosphere.\r\n\r\nThe first map<\/strong> compares the forecasted annual mean temperature in 2071-2100 to the base period of 2006-2020.\u00a0The first thing to recognize on this anomaly map is that the predicted temperature change is not uniform across Earth's surface. In general, \u00a0warming increases in strength as we move from the equator to the poles. Regional hotspots (> 1 \u00b0C) occur over Alaska and in the Arctic Ocean north of Scandinavia. No or little warming occurs around northern Mexico and Texas, the Himalayas, and two patches in the ocean surrounding Antarctica.\r\n\r\n\"\"\r\n\r\nThe second map<\/strong> (below) compares forecasted summer mean temperature in 2071-2100 to the base period of 2006-2020. It differs from the annual map in that the degree of warming occurring in the Northern Hemisphere is muted. Much of the Arctic Ocean and the edge of Greenland show little or no warming.\u00a0Hotspot areas in Antarctica and in the ocean between South America and Australia are somewhat greater than what was seen in the annual map.\r\n\r\n\"\"\r\n\r\nThe third map<\/strong> (below) compares forecasted winter mean temperature in 2071-2100 to the base period of 2007-2020. It differs from the annual map in that the degree of warming occurring in the Northern Hemisphere is much greater especially at higher latitudes.\u00a0Hotspot areas on Antarctica and in the ocean between South America and Australia is somewhat less than what was seen in the annual map.\r\n\r\n\"\"\r\n\r\n \r\n\r\n2.1) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted annual mean temperature in 2071-2100 to the base period of 2006-2020 using the best-case RCP 4.5 greenhouse gas emission scenario (see image below for input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.1a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of annual mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 4.5 emission scenario compare to RCP 2.6?\r\n\r\n \r\n\r\n2.2) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted summer mean temperature in 2071-2100 to the base period of 2006-2020 using the RCP 4.5 greenhouse gas emission best-case scenario (see image below for input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.2a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of summer mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 4.5 emission scenario compare to RCP 2.6?\r\n\r\n \r\n\r\n2.3) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted winter mean temperature in 2071-2100 to the base period of 2007-2020 using the RCP 4.5 greenhouse gas emission best-case scenario (see image below for input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.3a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of winter mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 4.5 emission scenario compare to RCP 2.6?<\/span>\r\n\r\n \r\n\r\n2.4) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted annual mean temperature in 2071-2100 to the base period of 2006-2020 using the worst-case RCP 8.5 greenhouse gas emission scenario (see image below of input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.4a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of annual mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 8.5 emission scenario compare to RCP 2.6?<\/span>\r\n\r\n \r\n\r\n2.5) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted summer mean temperature in 2071-2100 to the base period of 2006-2020 using the worst-case RCP 8.5 greenhouse gas emission scenario (see image below for input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.5a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of summer mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 8.5 emission scenario compare to RCP 2.6?<\/span>\r\n\r\n \r\n\r\n2.6) <\/strong>From the Climate Reanalyzer<\/strong>,\u00a0Monthly Reanalysis Maps<\/a> website, create a map that compares the forecasted winter mean temperature in 2071-2100 to the base period of 2007-2020 using the worst-case RCP 8.5 greenhouse gas emission scenario (see image below for input settings). Answer the question that follows.\r\n\r\n\"\"\r\n\r\n2.6a)\u00a0<\/strong>Describe the patterns of warming and\/or cooling seen in the map produced for the comparison of winter mean temperatures forecasted for 2071-2100 to the base period 2006-2020. How does the RCP 8.5 emission scenario compare to RCP 2.6?<\/span>\r\n\r\n \r\n

    QUESTION 3<\/strong><\/h1>\r\nClimateNA<\/strong> is a computer database that can downscale North American climate data to the local level. From this climate database, we can generate historic (1901 to 2019) and future climate data for any location in North America. Future forecasts are based on the output generated from a number of global circulation models programmed with a variety of different greenhouse gas emission scenarios.\r\n\r\nThe ClimateNA<\/strong> computer model can be run from an Internet browser like Google Chrome<\/strong>, Firefox<\/strong> or Safari<\/strong>. To begin this process, you must go to the following URL:\r\n\r\nhttp:\/\/www.climatewna.com<\/a>\r\n\r\nAt this URL you will see the following web page:\r\n\r\n\"\"\r\n\r\nThe ClimateNA<\/strong> model input window above shows the Normal 1961-1990 output for Kelowna. To run the ClimateNA <\/strong>model four pieces of information must be entered: latitude and longitude of the location, the location\u2019s elevation, and the select period (Historical or Future)<\/em>.\r\n\r\nFor the output shown above the period<\/em> selected was Normal 1961-1990<\/strong> from the historical drop-down button. Note that a variety of different options can be selected to produce Historical\u00a0<\/strong>output. Historical output can be generated for a single year between 1901 to 2015, or an average for a 10-year period, or an average for a 30-year period.\r\n\r\nTo generate Future<\/strong> output, we need to select the drop-down button labeled Future<\/strong>. Once again, a number of options are available. These options include the outputs of three different computer models, three different future greenhouse gas scenarios, and three different future time periods. The following information describes some of the specifics related to these model inputs.\r\n\r\nComputer Models<\/strong>\r\n