Seasonal Changes Are Impacted by Climate Change

For us humans, especially in urban settings, the seasons come and go with regularity and cause relatively painless changes in our lives — longer days, shorter days, setting clocks forward or backward as we just did. But for most other animal species seasonal changes do not go unnoticed.  Further, when climate change impacts patterns of seasonal change, animals can be affected.

For example, pregnant caribou depend on particular plants to nourish them while they nurse their calves. The spring calving season is short and the window for peak plant nourishment coincides with that short season. However, these plants are emerging or germinating earlier in the season, in response to warmer temperatures, reaching their peak before calving occurs. Thus, nursing caribou are receiving less nourishment, calves are suffering, and mortality rates are increasing, as reported by ScienceDaily. Researchers believe this is just one example of the impact of climate change that will be documented repeatedly in the near future

caribouCaribou are cued to move to new grazing patches by increasing day length. The plants, however, are cued to emerge or germinate by increasing temperature. This causes a “trophic-mismatch.” If the trend continues, caribou will not survive unless they can find a substitute for their nourishment needs. This may be possible in one of two ways. One is an additional plant species, useful to caribou, becomes established in the ecosystem made possible by the longer growing season. The second way caribou could thrive is if the caribou alter their migration patterns to better align calving with plants at their peak nutrition. Doing so would be a case of the caribou population shifting its      range.

According to a second ScienceDaily article, “One of the main predicted effects of climate change is a forced shift in species’ distribution range.” This comment was made in reference to a plankton scientists have decided was able to change its range to further north in the Atlantic after the last warming trend in climate 18,000 years ago. They attribute this ability to a lot of genetic variability within the species and large populations. This, they say, is good news since it indicates the species can react and adapt appropriately in order to survive and avoid extinction. It is also a cause for optimism since plankton is the base of the food chain.

Conversely then, small, less variable populations are at risk of not adapting to and surviving climate change. What if anything can or should be done?

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

The National Science Education Standards in life science states students should gain understanding in (1) structure and function in living systems, (2) regulation and behavior, and (3) diversity and adaptations of organisms. Climate change affords opportunities to touch on those areas as well as topics in Science and Society, and Earth Science concepts in climate.

Ask students what caribou are, where they live and how they behave. Or direct students to do their own research. This Natureworks site provides a succinct reference for students.  Most will probably know caribou migrate and live in Alaska, but students may not know they also live in Greenland. Many will say caribou are reindeer. Though they are related, they are different. Reindeer are domesticated and live in northern Asia actually.

Students may know caribou migrate, but they may not be fully aware of the adaptations the caribou have, enabling the thousands of miles of migration accomplished each year. Ask students what cues caribou to migrate north in the spring: increasing day length or increasing temperatures? Since temperatures vary, it is adaptive perhaps that caribou respond instead to increasing day length, which is rather constant in its annual pattern.

Now focus on the plants of the tundra. What signals plants it’s time to emerge? Warming temperatures rather than light. After all, an underground root system or a buried seed cannot sense light. To track average temperatures from 1995-2003, students can access Excel files of the data from the Arctic Long Term Ecological Site. In pairs or groups of three, students can find tundra temperature data for a specific year and then share. They can have the program calculate the average temperature each year for the month of June or the first week in June. Graph the data points. What is the pattern?

Tundra plants are low to the ground and small. Caribou have to do a lot of grazing to meet their needs. Turn student attention to the calving and nursing period. Calves nurse for about one month. Nursing caribou need lots of nutrition during that period. What if calves were born one week after plants had reached their maximum? How might this impact the herd over time? Remind students of the two different cues plant and caribou respond to: light and temperature. How might the plant diversity be impacted by a warming trend?

Share the plankton story with students. In sum, two things can happen in response to climate change: adapt or go extinct. Life on the planet survived the last warming trend; thus it may survive this one too. However, human contributions to this warming trend were not present 18,000 years ago. It remains to be seen what difference that makes.

Here are additional related resources from the Middle School Portal 2: Science and the Polar Regions and The Reason for the Seasons.

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This post was originally written by Mary LeFever and published November 5, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.