This activity is part of the Climate Change Challenge unit.

1. Show a video and prompt students to identify and describe in detail the effects of rising ocean temperatures.

• Prompt students to revisit their Ocean Impacts handout from the Oceanic Impacts activity to review the three main effects of climate change on the oceans: ocean acidification (covered in the Ocean Acidification: The Evidence activity), sea temperature rise (the subject of this activity), and sea level rise. 
• In a Think-Pair-Share, ask students to consider whether they think the marine organisms affected by ocean acidification are likely to be the same or different from those affected by rising ocean temperatures.
• Explain to students that the Rising Ocean Temperatures are "Cooking" Coral Reefs video (2:52) will give greater detail on this impact. Assign students to add any new information on the causes and consequences of sea temperature rise to Part 1: Causes and Part 2: Consequences of the Ocean Impacts handout as they watch.
• Project the video and then solicit volunteers’ responses.

2. Model and support students as they summarize linear trends in sea surface temperature using a digital data set.

• Ask students to predict how they think the rate of change in sea surface temperature will compare to the rate of change in dissolved carbon dioxide or pH, based on the Ocean Acidification: The Evidence activity.
• Project the EPA Climate Change Indicators: Sea Surface Temperature graph, and distribute a copy to each student.
• In a Think-Pair-Share, ask students to respond to the following questions:
• How would you describe the data trend on this graph? (Sea surface temperature has been increasing since about 1910.)
• Is the slope (m) of this trend positive or negative? (The slope of this trend is positive because the line shows an increase in sea surface temperature, overall.)
• What do you think the term anomaly means in the graph’s y-axis? (This term describes not the temperature itself, but how far above or below the temperature falls compared to the 1971-2000 average; see Tip.)
• It may help students to reach this conclusion if you draw their attention to the 1971-2000 average, depicted as a horizontal dashed line on the chart.
• Click on the spreadsheet link below the graph to project the sea surface temperature data set, prompting students to focus on the Year and Annual Anomaly columns only.
• Distribute the Sea Temperature Trends handout to students. Using an I Do, We Do, You Do format, support students as they calculate slope digitally or by hand during three decades in this dataset (1880-1889, 1940-1959, and 2000-2009), as the class did in the Ocean Acidification: The Evidence activity. Prompt students to record their calculations in Part A of the handout.
• Note that students are now using data directly, rather than interpreting from a graph (as in the Ocean Acidification: The Evidence activity). So, calculations from all students and the teacher should match in this activity. For example:
• Decade: 1880-1889
• Point 1 = (x1, y1): (1880,-.470)
• Point 2 =  (x2, y2): (1889,-.472)
• Rise  = y2-y1: .002 degrees
• Run = x2-x1: 9 years
• m = rise/run: .002/9 = 0.00022 degrees/year

3. Model and support students as they use the slope to predict future sea surface temperature from a digital data set.

• Ask students:
• How might the slope of a trend help us to predict the future?
• Using an I Do, We Do, You Do format, support students as they calculate a prediction of the change in sea surface temperature. Use the same three decades of data from the previous step and prompt students to record their calculations in Part B of the Sea Temperature Trends handout.
• For the first row, 1880-1889, rewrite the slope (m), calculated in Part A of the handout.
• To predict the change in sea surface temperature over the next 100 years based on the decade of data between 1880 and 1889, multiply the slope (m) by 100.
• Decade: 1880-1889
• Slope = m: 0.00022 degrees/yr
• Sea temperature change in 100 years = 100(m): 0.02 degrees/century
• Calculate the prediction for the period from 1940-1949 alongside students.
• Direct students to perform the calculations independently for the period from 2000-2009.
• Project the EPA Climate Change Indicators: Sea Surface Temperature graph again and ask students to Think-Pair-Share in response to the following questions:
• Which decade of data predicts the greatest temperature change in the next 100 years? (The decade 1940–1949 predicts the greatest temperature change because this was a decade of particularly rapid change (see Tip).)
• Why do the three decades of data predict different temperature changes for the next 100 years? (The prediction for each decade depends on the slope. If the temperature happened to increase or decrease during this decade, it would predict a temperature change that matches this local trend within the overall global trend of increase. This is why these are predictions: they are not certain but are educated guesses based on the data.)
• Which decade of data do you think makes the most accurate prediction of temperature change over the next 100 years? (2000–2009 makes the most accurate prediction, because it contains the most recent data, and because this decade matches those that came before and after it well (the trend in this decade is similar to the overall trend).)
• Revisit the class Know and Need to Know chart, incorporating students' evolving understanding of sea temperature rise’s rate and impacts.