SCIENCE – Learn about climate change and how it affects shipping on the Great Lakes.
Learning Objectives:
Describe the historical context around ocean shipping. Explain how Great Lakes shipping differs and how climate change affects how much cargo a ship can carry.
Education Standards:
NGSS – Grade Level Disciplinary Core Ideas (2)
- MS-ESS3.D.1 (Grades 6-8 ): Human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth’s mean surface temperature (global warming). Reducing the level of climate change and reducing human vulnerability to whatever climate changes do occur depend on the understanding of climate science, engineering capabilities, and other kinds of knowledge, such as understanding of human behavior and on applying that knowledge wisely in decisions and activities.
- HS-ESS2.D.6 (Grades 9-12 ): Current models predict that, although future regional climate changes will be complex and varied, average global temperatures will continue to rise. The outcomes predicted by global climate models strongly depend on the amounts of human-generated greenhouse gases added to the atmosphere each year and by the ways in which these gases are absorbed by the ocean and biosphere.
College, Career, and Civic Life (C3) Framework (2)
- D2.Geo.6.6-8 (Grades 6-8): Individually and with others, students: Explain how the physical and human characteristics of places and regions are connected to human identities and cultures.
- D2.Geo.10.9-12 (Grades 9-12 ): Individually and with others, students: Evaluate how changes in the environmental and cultural characteristics of a place or region influence spatial patterns of trade and land use.
Time Needed for Implementation: 2-3 class periods.
Beginning Task – Expert Input: (15-20 minutes)
The earth’s climate is changing. Our planet’s climate has changed before, but this time, people are causing these changes. The climate changes we see today are bigger and are happening faster than any modern society has ever seen.
The United States Environmental Protection Agency website has resources on discussing climate change indicators for oceans.
Learn about climate change’s effects on freshwater at the National Oceanic and Atmospheric Administration website.
Check out this resource from Sea Grant New York on the Great Lakes.
Background Essay (from PBS Learning Media):
Did you ever wonder where the steel in your washing machine came from, or how grains from the Midwest breadbasket reach the rest of the world? If you were to trace the life journey of these products, chances are they traveled the Great Lakes-St. Lawrence Seaway shipping system, a major world trade route connecting the Midwest and the Atlantic, supporting 30,000 jobs and $3 billion of business every year. How will this major thoroughfare be affected by climate change? It depends on the relative importance of two opposing impacts: lower water levels and shorter duration of ice cover on lakes.
Climate models predict that the Great Lakes region will experience higher temperatures and thus higher rates of evaporation. Though precipitation is expected to increase in winter and spring, the amount of summer precipitation is expected to decline (but we may see more frequent heavy precipitation events). According to most climate models, the net effect of all these factors will be to lower Great Lakes water levels by approximately 1 to 2 feet over the next century. Lake levels are also subject to natural fluctuation over the course of decades; UW-Madison lakes researcher John Magnuson predicts that the combination of these normal ups and downs and climate change impacts will result in “lower lows” every 15–25 years and less frequent “high” years.
Lower lake levels could mean major trouble for Great Lakes shipping and thus for businesses and consumers. A ship’s draft, or the distance between the waterline and the bottom of its main body, determines both the minimum depth of water it can safely sail and the maximum weight of cargo it can carry. Lower lake levels mean lower draft; for every one inch of lost draft, a 740-foot vessel loses 100 tons of capacity, and a 1,000-foot vessel loses 270 tons. Researcher Harry Caldwell and colleagues say the costs of Great Lakes shipping could increase as much as 30 percent, due in part to this “light-loading” of cargo when waters are low, increasing the number of trips needed.
The other method of mitigating lower lake levels is also costly: dredging connecting channels and harbors. Currently, the federal government maintains 27-foot depths in these channels, but dredging projects greater than 27 feet require authorization of Congress. Hydrologist Frank Quinn predicts that these current levels will be inadequate in many channels within 30 years, requiring deeper dredging. However, dredging in the Great Lakes may be complicated by the presence of toxic contaminants in sediments from decades-old industrial waste.
Some of the detrimental effects of lower lake levels may be counterbalanced by longer shipping seasons. Based on climate models that forecast more ice-free days, Quinn predicts that the shipping season may be one to three months longer and costs may drop somewhat as ice-breaking expenses decrease. One thing is certain: Great Lakes shipping, an industry predicated on stable lake levels, will need to adapt to more uncertain conditions.
Modern cargo handling “ship and shore” method from the George G. Sharp Collection, SSHSA Archives.
Middle Task: (40 minutes)
Have your students watch this oral history with Doug Tilden on the History of Ocean Shipping and the Rise of Containerization to learn about the historical context of shipping.
Learn how water level and shipping season affect the amount of cargo a ship can carry in this video from PBS Learning Media. Come aboard with Pilot Randy Hayes on the Isa, a Great Lakes cargo ship carrying steel to the Port of Milwaukee and explore the impacts of climate change on Great Lakes shipping.
Evaluation and Reflection
(can be group discussion or questions to answer individually in class or as homework)
- How is Great Lakes shipping different than ocean shipping?
- What cargo do they carry on the Great Lakes? How does it differ from what can be carried in containers?
- What is draft?
- How does climate change affect Lake Michigan?
- How does climate change affect draft and how much cargo can be carried?
Extensions:
Research projects—groups: Have students research the environmental impact of shipping by boat versus rail or highway transport. Calculate and compare costs for each type of transport, in terms of dollars, energy use, and release of carbon dioxide into the atmosphere. Have groups determine if current shipping trends make environmental and financial sense.
Math – Have students calculate draft based on tons of cargo and sea level.
