Climate change is in the news. Scientists who study this phenomenon base their claims on evidence gathered over multiple years. This lesson challenges you to graph an authentic, long-term data set of rainfall collected from a rainforest in Costa Rica. After graphing, you will apply a best-fit line (or trend line) to the graphs to help you draw conclusions about emerging patterns. Ultimately, you will answer the question, “Does the rain data set from La Selva support evidence of a shift in climate patterns?” You now become the scientist to answer this important question.
In 2011, a team from Conservation International visited La Selva Biological Reserve in Costa Rica. As they toured the rainforest, the guide mentioned that one of the climate change observations he had witnessed was the pattern of rainfall in the forest. He thought that the average amount of rainfall in the last forty plus years had been about the same but that storms had become larger with time, resulting in less rain in between. He stated that many of the plants have evolved to stay constantly moist in the rainy season, not exposed to periods of plentiful rainfall followed by multiple days of no or little rain. The question here is—does the extensive data set taken at La Selva support the guide’s anecdotal evidence?
Directions - Part 1
1. As a class, look over the “5 Year Average Total Rainfall for La Selva, Costa Rica” data set, looking for a pattern in the data.
2. Answer the pre-graphing questions in your science notebooks.
3. Graph the data set (by hand or using a computer depending on your teacher’s instructions).
4. Draw a best-fit line through the data points on your graph. You can do this by using a ruler. Draw a straight diagonal line at the point where approximately half of the points are above the line and half are below the line.
5. Discuss any patterns that emerge.
Authentic data for the first graph:
5 Year Average Total Rainfall for La Selva, Costa Rica (mm)
Directions – Part 2
1. Graph the maximum rainfall averaged over 5 year time periods for La Selva.
2. Draw a best-fit line on the graph.
3. Discuss any patterns that emerge. Do these data support the guide’s claim?
Authentic data for the second graph:
5 Year Average Maximum Daily Rainfall for La Selva, Costa Rica (mm)
Questions – Part 1
Questions – Part 2
While looking at both graphs, answer and discuss these questions: