Post-Glacial Sea Level Variability
The study of post-glacial sea level variability (PSLV) has been a topic of considerable interest to earth scientists for several decades. With numerous regional variations in glaciers, and the addition of regional variations in ocean circulation and climate, our understanding of the complexities of sea level fluctuation during the past 13,000 years of relative global climate stability has rapidly increased. Some regions have experienced dramatic sea level changes during this period while others experience much less variability.
PSLV is of particular interest due to its potential effects on global climate change. Global climate models suggest that changes in sea level will be one of the most visible external indicators of future climate shifts. In this article we examine the post-glacial sea level variability in the Embayment,a region bordered by the Great Lakes, Hudson Bay and James Bay. Analyses of climate, ocean circulation and glacial dynamics suggest that PSLV in the Embayment has been fairly consistent since the beginning of the late Quaternary.
The Northern Midwest of North America, also known as the Laurentian Great Lakes, is a region made up of 8 Great Lakes and numerous smaller lakes. This region is almost entirely dependent on a few major streams entering the lakes and supplying them with fresh water. The lakes are generally open, and not surrounded by any landform barriers (other than those created by periodic glaciation events) which keeps the Great Lakes separate from the Atlantic and Caribbean seas.
The streams that feed the Great Lakes are based largely on glacial deposits left by large, ancient glaciers that receded as temperatures warmed some 13,000 years ago. As the glaciers melted, they left sediment as well as a large freshwater storage area: the Great Lakes. At the same time, ocean currents changed considerably, allowing lighter and warmer waters to enter the area.
A number of researchers have used geophysical and sedimentological methods to study the long-term evolution of lakes in the region. These investigations have concluded that PSLV in the Embayment has been fairly consistent since the late Quaternary (about 13,000 years ago) and has not shown major changes over time. The PSLV stability has been primarily due to the large area of lakes providing sufficient buffering capacity to absorb minor changes.
More recently, researchers have focused on the effects of climate change on PSLV in the Embayment. It was found that global warming since the Industrial Revolution has had a marginal effect on the sea levels in the region. Smaller areas near the edges of the embayment have experienced minor changes in sea level, but this has not had an overall effect in the region.
However, climate change over the next century is likely to have a substantial effect on PSLV in the Embayment. The Intergovernmental Panel on Climate Change (IPCC) has projected global sea level rise of at least 0.3–1m between 2000 and 2100, depending on the amount of global emissions produced by human activity. The amount of sea level rise ultimately depends on the amount of warming in the region and over time, with polar regions and equatorial regions experiencing the greatest amount of sea level rise due to the ice melting in the polar regions and because the equatorial regions are already warmer.
In the Embayment, researchers predict higher than average sea level increases due to its shallow depth, which will increase the percentage of land covered by water by a significant amount. Additionally, the region relies on a few major river outlets that could be blocked by the rising waters, possibly leading to a decrease in freshwater inflow and thus an increase in salinity levels.
In conclusion, post-glacial sea level variability has remained fairly consistent for the past 13,000 years in the region of the Great Lakes. However, human activity in the form of global climate change is expected to have a significant impact on the post-glacial sea level variability of the region in the future.
