1. Effects of Climate Change on the Great Lakes
ELIORA BUJARI
May 5, 2009

2. Objective
Look at streamflow, precipitation, and temperature measurements over the past fifty eight years to study any statistical trends that indicate the effects of climate change on the Great Lakes.
Use these trends to evaluate future predictions.

3. Location of the Lakes
Contain about 6 quadrillion gallons of water, and combined the lakes provide approximately 18% of the world’s freshwater supply.

4. Statistical Analysis Mann-Kendall Analysis
Non-parametric method used in hydrologic data analysis to detect trends, using the S and Zs statistic.
Null hypothesis : there is no monotonic trend in the data.
Simple Linear Regression Analysis
Y = m x + b and R2 statistics
Used to test the slopes of the trend lines and estimate future values.

5. Lake Levels
At a 95% confidence interval the tests showed an increasing trend for the lake levels, except for Lake Superior
Mann-Kendall:
S-score = 1819
Zs = 6.34
Result = Increasing Trend
Simple Linear Regression:
Water Level = *Year
(77.92) (7.78)
R2 = Se = F = 60.58

6. Lake Levels

7. Temperature Trends Temperature = -6.806 + 0.009*Year (-0.569) (1.54)
No statistically significant trends on overlake temperatures for Lake Erie, Huron, and Ontario, but there is an increasing trend for Lake Michigan and Lake Superior.
Mann-Kendall:
S-score = 135
Zs = 0.92
Result = No Trend
Simple Linear Regression:
Temperature = *Year
(-0.569) (1.54)
R2 = Se = F = 2.17

8. Flow Trends
There are no Statistically Significant Trends for streamflow

9. Precipitation Trends Precipitation = -224.4 + 0.150*Year
Statistically Significant Increasing Trends for Lake Huron and Lake Ontario.
Mann-Kendall:
S-score = 423
Zs = 2.83
Result = Increasing Trend
Simple Linear Regression:
Precipitation = *Year
(2.269) (3.00)
R2 = Se = F = 8.975

10. Conclusions
No statistically significant conclusions can be drawn about assessing potential future predictions.
The increasing trend for the
lake levels can be explained
by looking at short term
fluctuations caused by strong
winds, storm surge and ice
development in the
connecting channels; and
long term crustal rebounding
and increase consumption
use.

11. Future Work
Look at the mass balance of the whole system and each lake individually to observe the contributing inflows and outflows and see how they have changed through time.
Analyze which factors are statistically important.
Compare the simple regression results with Global Climate Models.

12. Questions?