Impact of Climate Change on a Lake Near You
Dan Buckley, Ph.D.
The year 2012 was officially the warmest year on record and this is consistent with the global temperature trend over the past fifty years. Those of you who have lived long enough in the Northeast know that our winters are generally not what they used to be (even discounting tales told by your parents of walking to school through three feet of snow) and our summers are hotter. Over 98% of the world’s scientific community, unlike that of politicians or talk show hosts, is convinced that the current warming trend is real and scientists around the world have been studying this phenomenon. The primary causation of this change in climate is a 40% increase in atmospheric carbon dioxide over the past 100 years from the burning of fossil fuels and this increase continues. This sudden release of carbon dioxide (relatively speaking) has increased the amount of heat trapped in the atmosphere resulting in numerous environmental changes that we are just starting to understand. Figure 1 is a NASA representation of the global temperatures showing a 0.8 oC (1.4o F) increase in the last 30 years. Temperature changes are not the only weather changes we are witnessing, local changes in storm frequency and intensity along with increasing drought frequency are impacting agriculture and homeowners alike.
So what does this mean for your local lake? Sixty years of data from Lake Auburn (Auburn, Maine) has shown an increase in water temperature at a depth of 18 feet to be between 1 and 2 oC for ten months out of the year. Part of this increase may be attributed to earlier ice out and later lake freezing allowing more light penetration and heating of the water, another factor is the higher atmospheric temperatures which allow for greater warming. These data along with my research for the past six years show that many Maine lakes now reach 80+oF for a week or more during the summer (typically the 3rd week in July). These warmer summer temperatures place stress on the cold-water fishery (especially Brook Trout) of many shallow lakes and ponds and future temperature increases may reduce some populations to the point of local extinction. Among the other concerns for all lakes raised by lake warming is the potential for declining water quality. Warmer water, increased erosion from more severe storms and a longer ice-free season may increase the amount of algae found in lakes and decrease water clarity. This year there will be a major research effort taking place in Lake Auburn to look for the cause of last summer’s significant algal bloom and associated fish kill. People around the state are concerned that Lake Auburn may be the “canary in the coal mine” with regards to future climate driven changes in water quality.
Climate change is impacting Maine lakes and ponds. They are warmer than they have been historically and this will impact the organisms that live in them. As these habitats warm up it may lead to changes in lake algal species composition and abundances and declines in water quality. Now more than ever it is important to prevent soil erosion into the lake if we are to maintain water quality in our beloved lakes. For more information on these issues you can contact me at Buckley@Maine.edu.