“I touch the future … I teach” — a quotation associated with Christa McAuliffe — captures something essential about the motivation and hope that keeps most of the teachers I know doing what they do. One of the things that makes teaching about climate change difficult is that it can seem to cast a shadow on that hope.
This past Monday my colleague Hannah Webber and I teamed up with a young climate change biologist named Chris Nadeau to offer a pair of workshops at the 2017 RiSE Center Conference. Chris, a research fellow supported by the Second Century Stewardship program at Schoodic Institute, focuses on understanding how climate change will affect plants and animals. You can learn more about his research here. The big idea behind our workshop was that as soon as you start trying to think about how increases in temperature due to climate change might impact different species in different parts of the world, you quickly find that you need to use a lot of what we know about ecology, evolution, and the geography of climate and climate change to construct plausible scenarios. We decided to involve teachers in such scenario building to see what they thought of it as a way to get their students thinking scientifically. We hoped it might provide a different approach to engaging kids with climate change–getting them thinking about it as a problem to understand rather than as this massive, frightening thing that is too big to comprehend. The teachers in the workshops (about 35 in all) ranged from Kindergarten through high school.
Development of Ideas in the Workshop
We began by reviewing what we know about how seasonal temperature variation differs for temperate and tropical regions of the globe. There is much more seasonal variation in temperate zones (in some places, 8o°C over a typical year) than in tropical zones (about 2o°C). This was familiar ground for the teachers, but it was important to be sure that we shared similar understandings.
The teachers then broke into groups; each group included teachers working at different grade levels. Each group made lists of the behaviors, capabilities, and other characteristics possessed by plants and animals living in temperate regions that enable them to survive such large temperature swings. In their responses, teachers identified a wide range of adaptations, including migration, hibernation, changes in activity level, seasonal timing of reproduction, protective coats, color changes, loss of leaves, bark color and texture, and more.
Chris then shared what scientists agree to be the projections for changes in temperature over the rest of this century, given different rates of reduction in CO2 emissions. Again, we distinguished between changes in temperate and tropical regions. Temperatures will rise more in temperate regions — about 2°C if we reduce CO2 dramatically and 5°C or more (with some areas seeing as much as a 10°C increase) under business-as-usual scenarios. In tropical regions the increases are projected to be between 1°C and 3°C over the different scenarios. In short, temperature increases in temperate regions are expected to be about twice as large as in tropical regions.
We also brought global warming down to a local scale by looking at results from a recent paper that examines different models of regional temperature change.1 Globally, temperature increases are expected to cross the 2°C threshold sometime between 2043 and 2055; again, the timing depends on how aggressively people reduce emissions. Interestingly, the contiguous United States is warming more quickly than the world as a whole and is expected to cross the 2°C threshold between 2031 and 2035. Even more interesting, the part of the contiguous U.S. that is warming most quickly is our own Northeast region: we are already crossing the 2°C threshold in some years and will be crossing it consistently within the next 5-10 years. Put simply, the question of how temperature increases will affect plants and wildlife is one that has real, near-term meaning for students in Maine. Decisions about how to manage changes in forest health and wildlife populations depend on identifying the species that are likely to adapt to temperature increases and those that are more likely to disappear locally.
Armed with these projections about future temperature increases, we asked the teachers to get back together in their groups to think about the following question: Are plants and animals in temperate regions more likely to adapt to increasing temperatures, or is it the tropical species that are more likely to have the advantage? On the one hand, temperate species already have a variety of adaptations that enable them to deal with a lot of variation in temperature; on the other hand, they will have to contend with greater temperature increases. We know that species will go extinct both in temperate and tropical regions, but where will the impact be the greatest?
The discussions that followed were lively. Sometimes there was clear disagreement, with different teachers making strong arguments for each position. Other groups, using local knowledge about temperature impacts on moose, red pine, and other species, came to a consensus that loss of species, and therefore of biodiversity, would be greatest in temperate regions due to the large amount of change in a short time. Other groups argued that temperate regions would see change, in part due to northward movement of more southern species, but the overall biodiversity loss would be greatest in the tropics.
In most cases the teachers’ arguments included complex interactions among species, such as the effects of invasive species, mismatches in timing of migration and availability of food, northward movement of new pests for which species do not have good defenses, increased mortality from pests due to stress from temperature, and co-evolution of species.
Climate Change Adaptation: A Space for Real, Evidence-Based Argumentation
After teachers reported out on their conjectures, Chris summarized current thinking by climate change biologists about biodiversity loss due to temperature increases. He noted that that the models being developed by scientists are still much simpler than the scenarios that the teachers were constructing, usually looking only at the effects of temperature on particular species. The reason for this one-species-at-a-time focus is that data on complex species interactions and how those interactions will change under climate change is generally lacking, difficult to collect, and the complexity is hard model. Climate change biologists are just starting to collect the necessary data to make complex models of how entire ecosystems will respond to climate change that include the types of mechanisms that many of the teachers highlighted.
In general, these single-species models suggest that plants and animals in temperate regions are more likely to be able to adapt to temperature increases. For readers interested in the details of the arguments that Chris presented, I summarize them briefly at the end of this blog post. For readers less interested in the details, the key idea is that although we have good information about how individual species might react to climate change, scientists have not yet collected the necessary data to model of how these species will interact. But ecosystems are all about interactions. So, in making decisions about how to manage local ecosystems as temperatures increase, the best that we can do at this time is to consider the knowledge that we DO have and then use it to construct arguments in support of conjectures about likely models. This makes climate change adaptation a potentially useful problem area where students can put disciplinary knowledge to work while getting experience in arguing from evidence and thinking about stability and change in systems at different scales. It is an area where there really are questions for which we do not yet have good answers.
Putting these Ideas to Use in the Classroom
One middle school teacher described the studies of amphibian populations in vernal pools that she and her students have been doing over the past decade. She said that her classes already had evidence that changes in temperature over that time were threatening the survival of amphibians in particular vernal pools. She noted that one particular pool that they had studied for years was now in its fifth year of failing to produce a new group of adults, a time span that is at the end of the expected life span for the current adults. Her students are finding that it is not so much the increases in average temperature over the decade that matter, but the increase in the number of very hot days that heat the pool up and dry it up quickly.
Another teacher said that she expected to be teaching science for at least another 20 years or so and that the workshop gave her a new insight that went something like this: So, I think you are saying that if my students begin developing models of what adaptation to climate change will look like for different species in our area, then my classes over the next ten years or so will be able to test and refine those models and can collect data about what is really happening, which parts of the models are most important, and things like that … Right?
And, in doing that that, her students will learn not only that climate change is real, but also that it presents questions about resource management that they can understand and think about. This will help them, as young members of our own species, learn how to adapt to climate change.
Returning to the idea of teaching as a way to touch the future … for today’s students, the effects of climate change will be the source of many of the most important problems that they will deal with as adults. Giving young people real experience, now, in engaging with climate change–understanding that it is not just something that governments deal with at a worldwide scale, but also something that ordinary people will have to make informed decisions about at local scales–is, in my mind, critical, essential learning. Equally essential: students need practice in seeing that science is something they can use to think about the future and to make decisions, rather than just being a subject in school or something that you study if you want to pursue a scientific or technical career.
As always, I am interested in your thoughts, particularly if you teach, work with teachers, or work in other ways with young people. What do you think about this idea of engaging students in developing models and arguments in defense of models that predict how different species will fare as temperatures increase?
A Bit More … The Arguments
What follows is additional information about how Chris and other climate change biologists are thinking about the impacts of temperature increases in temperate and tropical regions.
Chris summarized two arguments in support of the idea that temperature increases will have a larger impact on tropical species than on temperate species. The first is that is that temperate species have evolved to tolerate a broad range of temperatures because they are exposed to a broad range of temperatures over their lifetimes. Tropical species, on the other hand, can only tolerate a very narrow range of temperatures because that is what they experience in nature. In addition, temperate species tend to occur in locations that are cooler on average than tropical locations. Being able to withstand a broad range of temperatures and living in cooler locations will allow many temperate species to withstand the large increases in temperature projected for many temperate regions. In contrast, even small increases in temperature in the tropics could be stressful or lethal for many tropical species.
The second argument is a bit more complicated. It builds on the idea that since there is a lot of seasonal variation in temperate zones, a species could potentially avoid the very hottest times by shifting its active life cycle to a time earlier in the year. The figure below summarizes the idea. In the upper graph, an imaginary temperate zone insect is able to persist under climate change by shifting its two-month life cycle ahead a month so that it will experience the same temperatures when it is active. But in the bottom graph, the lack of variation in temperature over the seasons rules out this kind of shift for an imaginary tropical zone insect.
Chris acknowledged that these simple models fail to take into account the interactions between species within an ecosystem that the teachers were considering. For example, if the insect larvae depend on availability of a particular food source that is only seasonably available, this kind of shift can work only if the availability of the food source shifts too. Also this model does not apply to plants and animals that are active over the entire year.
Chris also noted that all the things we had talked about together looked only at changes in temperature over time in very large geographic regions. Temperatures also change over much smaller, local spaces. Here on the coast of Maine, or in places where there are substantial changes in elevation, small changes in location can be associated with substantial changes in temperature. The possibility that plants and animals might adapt to temperature increases just by moving to a different, nearby location is yet another reason to hope that, if we can build useful local models of what might happen, we can make better decisions about how to conserve and manage critical areas that might help reduce biodiversity loss.
1Karmalkar, A. V., & Bradley, R. S. (2017). Consequences of Global Warming of 1.5 °C and 2 °C for Regional Temperature and Precipitation Changes in the Contiguous United States. PLoS ONE, 12(1). http://doi.org/10.1371/journal.pone.0168697