ENVIRONMENTAL LITERACY TEACHER GUIDE SERIES Changing Climate A Guide for Teaching Climate Change in Grades 3 to 8 The Climate System 1 and Greenhouse Effect by Lindsey Mohan and Jenny D Ingber “Climate is what you increased risk of drought, wildfires, and of this natural phenomenon is now expect, weather is plant and animal extinctions. causing a range of changes throughout In order to make well-informed Earth’s system. what you get.” decisions that will enable humans and In this chapter we consider the Robert A. Heinlein other organisms to continue to thrive on differences between climate and Earth into the future, today’s students weather, look at the climate system in arth’s global climate is changing, need to have at least a basic scientific more detail, discuss what it means for bringing numerous changes to the understanding of our planet’s climate climate to change, and take a closer E planet and the organisms that live system and the role that humans are look at the Greenhouse Effect and what on it. Validated records from instruments playing in changing it. students know about this important around the world show that our global The climate system encompasses a phenomenon. temperature increased by around one complex set of processes that affect degree Celsius (almost two degrees conditions around the world. One of Our Experience Fahrenheit) during the second half of the most important features of the of Climate the 20th century. Consequences of this climate system—the Greenhouse Weather and climate are a part of observed warming include substantial Effect—is necessary for life on Earth. our daily lives. Throughout history, melting of glaciers, rising sea levels, and However, human-induced amplification human settlement patterns and 10 The Climate System and Greenhouse Effect GRADE STANDARD EEI UNIT are only a short distance apart from one another. Measurements of temperature, Grade 3 3 1 a precipitation, wind, humidity, and 3 2 b pressure are all a part of weather. Grade 4 Climate, unlike weather, is a concept rather than an observable phenomenon. Grade 5 5 4 a To make a complete description of your 5 4 c-d current climate, you would need to Grade 6 6 3 d consult historical weather records and 6 4 a-b,d-e calculate average values for parameters such as temperature and precipitation. Grade 7 7 6 a Climate is the long-term average of 7 6 f weather conditions experienced at a Grade 8 location over a period of 30 years or more. Climatologists often use the last three decades (for instance, from migration routes show that climate has southerly ones that allow them to avoid 1981 to 2010), or the 100-year period a profound influence on where humans harsh winter conditions. from 1901 to 2000, as a base period live and how they interact with Earth. Our experience of climate is often to calculate average climate values. Historically, populations in milder confused with our experience of Descriptions of climate sometimes focus climates have thrived relatively easily weather. Weather is the observable exclusively on average temperatures, compared to those that settled in more state of the atmosphere at a given time but average values for precipitation and extreme polar or desert regions. A and place. You can step outside your other weather parameters are also part region’s climate controls the types of door to see what your weather is right of a location’s climate. plants and crops that can grow there now. If you check a thermometer and The natural vegetation that thrives and, in turn, the types of animals that note how it feels outside, you can come in a place can be a good indicator of the plant life can support. Today, we still up with a fairly complete description its climate. For instance, if you see see an effect of climate in the “snowbird of your current weather. Weather is desert vegetation in a location, you can effect,” the annual retreat of retired highly variable: it can change within infer that its climate is hot and dry. If a people from northern latitudes to more minutes and be different in places that place has the lush vegetation of a rain CHAPTER OVERVIEW Student Thinking: Climate and Weather 14 Weather is the current state of the atmosphere at a given time and place. Student Thinking: Climate, on the other hand, is the statistical average of weather over a long Greenhouse Gases 19 period. This distinction gave rise to the common phrase, “climate is what Pictures of Practice: you expect, weather is what you get.” Greenhouse Gases: Understanding climate change involves understanding both climate norms Good or Bad? 20 and deviations from that norm over time. When changes start becoming Representations of Science: usual across many decades, one can say an area’s climate is changing. Analogies for Greenhouse Effect 21 The Greenhouse Effect is necessary for life on Earth, but students struggle Pictures of Practice: with understanding this effect, and the gases responsible for the life- Greenhouse Gases and sustaining conditions on Earth. Students also confuse the Greenhouse the Ozone Hole 22 Effect with climate change and with ozone depletion. The Climate System and Greenhouse Effect 11 forest, you can deduce that its climate is incorrect ideas about climate when warm and wet. Latitude, elevation, and they experience warmer-than-average proximity to features such as mountains, or cooler-than-average weather. Daily deserts, and bodies of water are the major weather rarely matches the long-term factors that control a location’s climate. average values for climate, but some In general, places at low latitudes and people mistakenly believe that any elevations are warmer than high latitudes deviation in weather from the average and elevations. Being close to or far from climate is evidence of a cooling or different types of geographic features can warming climate. When measurements affect climate in a range of ways. of extreme weather are averaged into a 30-year period that defines climate Weather is the observable though, each event accounts for just state of the atmosphere at a 1/30 of the cal culated average, so single given time and place. weather events are not considered as indicators of climate, no matter how Climate is the long-term unusual they may be. average of weather conditions Two girls shelter themselves from A convenient way to communicate a place has experienced. the rain in Bali, Indonesia. how weather compares to climate is to express weather measurements as the Calculating Climate. The climate all the temperatures, the resulting difference between observed conditions for a location on a specific day of the average represents all the conditions and the long-term average, or “normal” year can be calculated from long-term that occurred. The value you calculate value, of the same conditions. Values records of weather. For example, you shouldn’t be considered as a prediction that represent the difference between could look up the average temperature of the temperature for the next June 1, observed weather and normal climate observed on June 1 in each of the last but in a stable climate, the average from values are called anomalies. 30 years, and then average the values the past 30 years would provide a good together. Similarly, you could look up idea of the next value. When the Unusual precipitation amounts, humidity levels, Students (and adults!) who don’t Becomes Usual cloud cover, and wind speeds observed under stand the difference between Scientific organizations such as the on that date over the previous 30 years weather and climate can develop Intergovernmental Panel on Climate and calculate average values for each of those parameters. The set of average values you end up with from this exercise would be a valid description of the climate for that location on June 1. (Climatologists also calculate other statistics from the records, including measures that indicate how much the individual values vary from the average.) The 30 separate temperatures you found in the records would span a range of values, reflecting the natural variability of weather over time. For instance, the weather on June 1 of some years may have been cool and stormy. Other years, the date may have been unusually warm. Because climate descriptions report Scientists study many of the same variables to learn about weather and climate, the arithmetic mean, or average, of and climate is determined by long-term averages of these variables. 12 The Climate System and Greenhouse Effect JULY 2010 TEMPERATURE ANOMALIES climate is to calculate climate averages Departures from the 1971–2000 Normal for a base period of at least 30 years, and then compare those values to averages calculated for an earlier or later period of the same length. Mathematical techniques can reveal if differences between the averages from two different periods are large enough _______________________Departure from Normal 8 oF to be “statistically significant,” or if they 6 oF are so small that they don’t represent 4 oF 2 oF real change. 0 oF -2 oF Consider that most of Florida has -4 oF a subtropical climate: It is generally -6 oF -8 oF warm and wet, with a good chance for afternoon thunderstorms in the summer. Occasionally, a single summer This map shows how much warmer or cooler locations in the contiguous or a string of three or four summers United States were during July of 2010 compared to their average temperatures during July from 1971 to 2000. might be cooler than normal, with fewer thunderstorms than average. This Red areas on the map show locations that were warmer than average, and blue areas show locations that were cooler than average (National Climatic situation would not mean that Florida’s Data Center, U.S.