Uncertainty in science? Is that normal? Of course it is, and researchers can typically quantify the degree of certainty they hold in their conclusions. For example, a research report might read, “Our data analysis indicates with 95% certainty that X is causing Y.” But some research results are not so linear and one-dimensional as those in the example. Rather, sometimes a precise prediction of a change in Y from a unit change in X is not possible, despite excellent observations, data collection, and analysis.

ScienceDaily published a story about global warming with this headline: Like It Or Not, Uncertainty And Climate Change Go Hand-in-Hand (October 27, 2007). Initially, a reader’s reaction might be, “See, scientists really have no good evidence that climate change even occurs.” That couldn’t be further from the truth. The article reports, “University of Washington scientists believe the uncertainty remains so high because the climate system itself is very sensitive to a variety of factors, such as increased greenhouse gases or a higher concentration of atmospheric particles that reflect sunlight back into space.”

Thus, science has revealed several different causes for climate change as well as their various sources. The causes and sources are not in question. What is uncertain is the possible ways these different sources of climate change can interact and the possible outcomes of each kind of combination of interaction. Gerard Roe and Marcia Baker are the UW scientists who developed a theory, a mathematical model, that “helps modelers understand built-in uncertainties so that the researchers can get meaningful results after running a climate model just a few times, rather than having to run it several thousand times and adjust various climate factors each time.”

Most predictions dealing with climate change use data gathered over time on a single factor and project the future based on the historic pattern of change in that factor. For example, based on ice core samples and other kinds of evidence, the carbon dioxide level of the atmosphere is known for the past couple of hundred years. This pattern is used to predict future levels of atmospheric CO₂. The predicted concentration of atmospheric CO₂ then is used to predict temperature increases. This assumes a fairly simple cause-and-effect relationship. But, Baker and Roe point out that as the predicted CO₂ level rises and as temperatures rise, these two factors contribute to other factors, such as increased water vapor in the air, that can additively contribute to the original factors and alter the initial predicted outcome. Their model attempts to account for those additive effects, or “climate feedbacks — physical processes in the climate system that amplify or subdue the response.”

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The UW scientists’ work is directly related to the National Science Education Standards of Science as Inquiry, Physical Science and Earth and Space Science. If you ask middle school students for their definition of science, likely responses include “facts,” “truths” and perhaps “a rigorous method used to ‘prove’ things.” Uncertainty does not usually make it into their science definitions. This news story presents an opportunity to underscore the nature and methods of science. Science is the quest for understanding the workings of natural systems with a high degree of certainty, but simultaneously we understand science to be a human endeavor, subject to human error, and always open to revision upon new evidence. Thus, uncertainty is inherent in science.

Ask students, “So how do scientists deal with this idea of uncertainty?” Students may have had a recent laboratory experience in which they had to articulate what might have contributed to any variations in their findings (uncertainty) when compared with others’. That experience can be called upon as students consider the question. Challenge your students by asking them whether pursuit of questions like “What will be the condition of the atmosphere one hundred years from now?” is worth it. After all, there are many potentially confounding variables likely to result in rather vague predictions. Lead students to the understanding that not all variables are controllable, but they can be understood and then factored into theory in order to decrease uncertainty in predictions, as the scientists in this news story have done.

Here are some additional resources that are part of the NSDL Middle School Portal Collection to facilitate your instruction regarding climate change, the nature of science, and science process skills: Climate Watch, Ocean and Climate, An Investigation of Student Engagement in a Global Warming Debate, and Science Sampler: The scientific method — Is it still useful?

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