# Step-by-Step

In this Section

Part 1: How has the temperature in the Lake Champlain region changed over the last century?

Part 2: How much ice forms on Lake Champlain?

Part 3: How has ice formation on Lake Champlain changed over the last several decades?

Part 4: How will temperatures and ice formation change over the next century?

## Part 1: How has the temperature in the Lake Champlain region changed over the last century?

Winter (December, January, and February) air temperature data are summarized in the MS Excel spreadsheet (Lake_Champlain_Data_File.xlsx). Data are available for each year from 1896 to 2008. These data have been processed somewhat to make the module suitable for the targeted grade; however more advanced students can be asked to retrieve and process the data themselves from the NASA GISS surface temperature analysis web tool.

1. Access data:
1. For use of the existing Excel spreadsheet: Open the MS Excel spreadsheet, click on the “Burlington Winter Temperature” tab at the bottom of the workbook.
2. For downloading data: Follow the steps in the NASA GISS tutorial to access weather station data.  Find the data set for Burlington VT and complete all steps for accessing monthly data and opening these data in MS Excel.
2. Annual temperature trends: Create a graph to illustrate the how annual winter temperature has changed over time. Fit a linear equation to the data (see the Excel tutorial if additional Excel help is required).  Include the equation for your trendline on your graph.
1. Using the annual winter temperature data, find the average winter temperature in each decade from 1900-current.
2. Create a graph to illustrate how decadal average winter temperature has changed over time. Fit a linear equation to the data. Include the equation for your trendline on your graph.
4. Answer the following discussion questions:
1. Has the annual average or winter temperature in Burlington Vermont changed very much over this time period?
2. What trends do you see in increasing or decreasing temperature?
3. Does observing the average the winter temperatures over each decade (1900-1909, 1910-1919, etc.) help you evaluate long term changes in temperature?

## Part 2: How much ice forms on Lake Champlain?

The following section uses MODIS satellite pictures of the lake, which are available for viewing and download at http://www.erh.noaa.gov/btv/html/lake.php. You will need to scroll down to the paragraph labeled “Lake Champlain Ice Coverage (MODIS Satellite Imagery)”, toward the bottom of the page. It may be helpful to download these images and arrange them chronologically beforehand to facilitate viewing in class. A sample set of images from December 2010 to April 2011 is available in Champlain_Ice_Cover_2011.pdf.

1. Review the images available.
2. Discussion questions:
1. How does the ice coverage change over the course of the winter?
2. Of the pictures available, what were the approximate dates that you can see ice coverage beginning and ending?
3. Did the Lake freeze completely?  If not, what are the characteristics of the areas of the lake that did or did not freeze?
4. When did Lake Champlain fully melt?

## Part 3: How has ice formation on Lake Champlain changed over the last several   decades?

The dates that ice coverage on Lake Champlain has closed are provided by NOAA (http://www.erh.noaa.gov/btv/climo/lakeclose.shtml ), and have been compiled into the MS Excel spreadsheet.

2. Review the annual closing date of the lake.
3. Question:
1. Do you notice any trends in the number of times the lake is “Not Closed”?
2. Count the number of times the lake did not close in each decade between 1900 and 2010 (denoted as “n/a” under Julian Closing Date). Plot a column graph of number of times the lake did not close with respect to decade. Fit a linear equation to the data.
3. Questions:
1. How many times has the lake not closed, over every decade for the time period shown?
2. Are there any trends in the frequency of non-closing years over time?
4. Review the data for the years where the lake did close (not including “n/a” entries). Plot the Julian closing date as a function of the year. Fit a linear equation to the data.
5. Questions:
1. Are there any trends in these dates over time?
6. Create a graph to examine the relationship between lake closing and temperature.  Plot “Number of ‘Not Closed’ Per Decade” as a function of “Decadal Average Winter Temperature” (from the “Burlington Winter Temperature” sheet). Fit a linear equation to the data.
1. Is there a relationship between the number of non-closings per decade and winter temperature?
2. Make an hypothesis about the relationship between winter temperature and number of non-closing occurrences.

## Part 4: How will temperatures and ice formation change over the next century?

Scientists predict that the temperature in New York State will continue to rise throughout the 21st century.  The predictions of the possible temperature rise depend on the expectations of how our populations will grow and what technologies are developed over this time period.  Mathematical models of our climate were used to predict temperature in New York State.  The results are available through the Northeast Climate Data Center.  Predictions are provided for two cases.  The A1 scenario is the worst case and B1 a less severe case, with expectations that we take a global and environmentally oriented approach to development over the next century.  Use the tutorial for the Northeast Climate Data Center web site to find maps of predicted winter monthly or seasonal temperatures for the end of the 21st century.

1. Discussion questions:
1. What are the average future winter temperatures expected to be?
2. What increases in winter temperatures for Lake Champlain region does each scenario predict relative to the current temperature?
3. Plug the winter temperature predictions into the equation derived in Part 3, Step 8, where “x” is equal to the predicted winter temperature. Note: If the equation output is greater than 10, the lake is not predicted to close at all that decade, and if the equation output is negative, the lake is expected to close each year.
4. Discussion questions:
1. What do you expect will happen to the number of years in each decade that Lake Champlain will not close?
2. How will these changes in ice coverage over the next century affect the Lake as an ecosystem? How might they affect people, habitat and society?
3. What are the potential errors in your approach and analysis?  Discuss the values and limitations of your work.