Phenology and Climate Change

 

last update: 30 Dec  2018

Phenology

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Phenology

Phenology is the study of periodic plant and animal life cycle events, and how these are influenced by climate, elevation, etc.  Recently the field seems to have broadened to include other periodic events related to ecology and climate, such as ice cover.  Certain events are very sensitive to climate change and can be useful indicators of such changes,  and in historical instances become proxies for what the climate was actually like.  Quoting Wikipedia, “viticultural records of grape harvests in Europe have been used to reconstruct a record of summer growing season temperatures going back more than 500 years.  In addition to providing a longer historical baseline than instrumental measurements, phenological observations provide high temporal resolution of ongoing changes related to global warming.

Lake Scugog Climate Change signal

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 Lake Scugog Climate Change signal

Here we present some data related to periodic phenomena associated with our area.  The most striking is a very long set of data set relating to “Ice Out” dates on Scugog Lake.  It shows a correlation with annual mean temperatures that could be interpreted as a global warming signal. (See fig 3 ). Fig 3 discussion below.

 Fig 1: Scugog Ice Out dates 1873-2017

The Ice Out date was published yearly in the Port Perry Star, and was kindly provided by the former editor and owner, Peter Hvidsten. See fig 1 scugog ice out 1873-2017.

Because of the long timescale, a 3rd order polynomial trend line was employed, rather than a linear trend line (catches inflections up and down).  It is interesting to see that the curve is relatively flat from 1900 to 1970, and then starts to dip, indicating that the ice is coming out, on average,  earlier each year.  Scugog is a shallow lake, and fairly regular, without a lot of embayments, and so once it starts, the ice likely comes out very quickly.  There seems to be a climate change effect here.

Fig 2:  Peterborough Annual Mean Temperatures  1866-2015

Dr Peter Lafleur graciously supplied temperature records for  Peterborough from 1866-2016. See fig 2 ptbo temps 1866-2015

Fig 3: Comparison of Scugog Ice Out dates with Annual Mean Temperatures in  Peterborough 1884-2015

Fig 3 plots figs 1 & 2 on the same graph.  The 3rd polynomial trends basically mirror one another!  (The data is only compared from 1884 since the Scugog data before this date is not continuous.)   see fig 3 Scugog temp and ice out 1884-2015

The correlation between the ice out date and the annual mean temp is -0.49, which is pretty strong (-ve sign means an inverse relationship).  As one might expect, the highest correlation is with the mean temp for the month of March, rising to -0.75.    However, plotting against the annual mean is likely a better overall signal of climate change.

Chandos Ice-Cover

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Here is the latest graph for  “Ice-In” that includes the data point for 2018/19.  The data is from Cathy Burgess.  The trend line is a likely indicator of global warming.

Historical Ice in Data dec 2018

 

Below is the graph for “Ice-Out from the winter of 1985/86 to 2017/18.  It is from Cathy Burgess.  The 2018 Ice Out date of 2 May 2018 is the latest she has recorded in 32 years.

Interestingly, if one  looks at the ice cover data, ie, how long the lake was iced over in a given season, 2017/18 only had ice for 129 days.. 1989/90 holds the record with 139 days. (Dec 5- 23 April).

Another very interesting phenomenon is that the trend line  for Ice-Out is virtually flat at 18 April, while the Ice-In trend line indicates that the ice is coming in later and later.

Historical Ice Out Data April 2018

Chandos Lake “Ice-In”, “Ice-Out “, and “Ice Cover” data

Ice Cover on Chandos Lake

Ice cover is the number of days that the lake is frozen.  For Chandos, the 2018 trend line yields 129 ice cover days .   The trend line for 1986 gives 114 days of ice cover, so the ice cover season is getting shorter.  It has been as high as 139 and as low as 69.  For 2018 the trend line indicates that the ice comes in around January 5, and goes out around April 18, as compared to the 1986 trend line values of  27 Dec and 18 April.

The “Ice-In” date is trending later each year.  The “Ice-Out” date trend is fairly flat.

For a discussion of the fall and spring turnovers, see the tab “Chandos in Winter”.

 Fig 4:  Burgess 31 year data for Ice In and Ice Out on Chandos lake 1986-2017 (needs to be updated to  2018)

Cathy Burgess has been recording the dates of  Ice-In and Ice-Out since 1986.

From Cathy’s vantage point at the south end of the main lake she can see up to the Public Beach at the north end.  The graph of her data can be seen here: fig 4 chandos ice cover 1986-2017 burgess

Here is a summary of her 31 years of data relating to Fig 4:  (following data and discussion needs to be updated to  2018)

Fig 4 summary data

 

Combining Ice-In and Ice-Out gives us a decrease in ice coverage of 13.2 days over the 31 years.

There are a variety of factors, not related to global warming, that also affect the ice cover in any given season.  This is apparent in the middle part of Fig 3, where there is lots of variability in the Ice-Off dates in the absence of global warming indications.

Fig 5:  Bruels 10 year data for Ice in, Ice Out on Chandos Lake 2008-2017

Clark Bruel’s data spans the last decade, looking out on the main lake from the Antelope Trail. See fig 5 chandos ice cover 2008-2017 Bruels

Here is a summary of his 10 years of data:Fig 5 summary data

Again,  the cautions with Cathy’s data, Fig 4, apply here.  The data are few and scattered and do not make a great fit to a straight line, as partially indicated by the RSQ, the goodness of fit indicator.  Certainly the trend can be discerned, however, and has a strong warming  signal.

Discussion on Chandos Ice Cover Data

Both Clark’s and Cathy’s “Ice Out” data agree remarkably well. Both trend lines indicate Ice Out around April 17-18.  It seems that the Ice-Out dates are not affected by climate change as much as the Ice-In dates are.

However, there is less agreement in their “Ice In” data.  This is likely because it is much harder to decide if the lake surface has completely iced over, plus it also depends on from where you are viewing.  Various parts of the lake definitely freeze at different times,  based on wind/wave action and depths.  In addition, as noted earlier, the Goodness of Fit is lousy, so the numbers are kind of fuzzy..

There is a lot more variability within each of the “ice in” data sets.   In fact looking at the 31 year data set, there is as much as 46 days difference in “Ice In” dates over the last 3 decades!  With the “Ice Out” data, the range is 36 days.  The ice cover has been as high as 139 days and as low as 69, giving an astounding max/min variation in ice cover of  70 days!…

Both sets of data show a trend toward a later and later “ice in” date, which could be a signal of climate change.  Over Cathy’s 3 decades, the “ice In” trended date has moved about 11 days later,  over a third of a day per year.

Discussion on Lake Scugog vs Chandos Lake “Ice Out” data

if one  plots a linear trend line for the last 3 decades of Lake Scugog Ice Out data, and compares it to Cathy’s Chandos Ice Out data, one finds that the Ice Out date for Scugog has retreated 7.4 days vs only 2.3 for Chandos.  As shown in fig 3, the Scugog data seems to inversely track the change in mean annual temps fairly well.  Chandos  inversely tracks the annual mean temp also, but without as much amplitude.

Snowmobiling-season-start-dates

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Snowmobiling season start dates

For the last 30 years Cathy Burgess has recorded the date when snowmobiles first appear on the lake. As with the “ice in” dates, the snowmobile season is starting later and later, now approximately 10 days later than in the mid 80’s.  On average the snowmobile appearance dates are about 12 days after “ice in”.

On January 2, 2010, 4 sleds went through the ice.  This occurred just north of the Gilmour Bay narrows.  It appears that Gilmour Bay had frozen early (more protected, and shallower), while the main lake was only partially frozen.  Cathy ‘s “ice in” date for that year is Jan10.

fig 6 Burgess sleds on lake 1986 -2017

Hummingbird Arrivals and Departures, since 1986

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Hummingbird Arrivals and Departures, since 1986

Cathy Burgess has been recording the Hummingbird season at her Chandos Lake feeder since 1986.
The 2017 trend-line indicates that the birds arrive around May 9, and depart around September 15, for a season about 130 days long.  (So they are away quite a bit longer than they are here)  The season has lengthened by about 5.8  days over the last 31 years.

fig 7 Burgess hummingbird arrivals and departures 1986-2017

Here is  a summary of the Hummingbird data:

cathy hummingbird data summary 2017

For a neat animation of the migration of Ruby-throated hummingbirds, based on reported sightings, check out animated migration

Also see June Hitchcox ‘s Apsley Voice article on Ruby-throated hummers  from 2006, reprinted in May 2017, here:   June HItchcox ruby-throateds 2006

Climate Change at Chandos

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Climate Change at Chandos

The climate has been changing over the last few decades at an elevated pace.  This will bring changes to Chandos Lake and to the surrounding natural environment.

In 2016 The Muskoka Watershed Council published a booklet called “Planning for Climate Change in Muskoka”, which provides an excellent layman’s discussion about how the climate is expected to change by mid century, and what the effects will be on the Muskoka Lakes.  It is available for downloading from their website:   http://www.muskokawatershed.org/

A copy of  their report can also be found here:ClimateChange_Muskoka-2016 

They address how they might try and minimize or exploit these changes.  Many of the conclusions and findings are applicable to Chandos.

Here are just a few summarized remarks;

By mid century the rising mean temperatures of about 3-4 degC will:

  • increase the +30 degC days in the summer.
  • shorten the ice cover period  to about 6-8 weeks.
  • increase the lake water temperatures, which in turn will increase the algae production and the likelihood of algal blooms.  Algae populations will also shift.

The increased water temperatures will severely stress our lake trout.  This will happen because the time between the spring and fall turnovers will lengthen meaning that whatever oxygen is at depth in the spring may drop to below critical levels by the fall.  In addition the thermocline will lower, thereby reducing the volume of cold water available for the trout.

Although there will be more annual precipitation, most of it will be in the winter, with drier summers. The warmer summer weather will mean more evapotranspiration, which will lower lake levels, and increase the risk of forest fires.

Tree species mix will change as our “native” species move north to be replaced by carolinian trees from the south.  The Kawarthas climate will be marginal for White Pine and Sugar Maple;  the White Spruce will migrate to James Bay.

Although we cannot stop climate change, we can do a few things  to at least minimize the local impact.  The Muskoka report talks about these.  In our particular situation,  we might consider damming our lake to keep water levels up during the summer, and also preparing to fight wildfires.  (see the tab  Chandos Lake Fire History