There has been a lot of discussion in the last months and years on the subject of climate change. While this may seem like a relatively modern phenomenon, the fact is that there is nearly a 200 year body of scientific evidence surrounding the issue of climate change. In 1820, Fourier discovered the existence of greenhouse gasses in the atmosphere. The research of John Tyndall in 1869 supported this discovery and in 1860 he proposed that the CO2 played a role in changing the world climate. In 1896 Savant August Arrhenius published a paper in London, Edinburgh and Dublin in which he was the first to quantify how carbon dioxide contributes to the greenhouse effect – carbon dioxide creating a ‘blanket’ in the atmosphere effectively trapping heat near the earth’s surface and leaving the atmosphere above the heat blanket cooler. He later concluded that this blanket of excess carbon dioxide came from the burning of fossil fuels.
In more recent discussions we hear how the heating of the planet is melting the ice caps and raising sea levels. This will most drastically affect coastal states, especially Delaware, Florida and Louisiana. There is also discussion about how climate change is affecting our weather and contributing to more natural disasters. While we are not necessarily experiencing more hurricanes, they are becoming bigger and more intense than in the past as we recently saw with Hurricanes Florence and Michael. Because melting ice caps have altered the jet stream, storms are not moving as fast; stalling and dumping horrific amounts of rain over land as we saw with last year’s Tropical Storm Harvey in Houston. But here in Minnesota we are miles from the costal shores and storms, so are we safe from any effects of climate change in America’s Heartland?
It appears that we are not safe. While it will take a few years, global warming and climate change will drastically change the landscape of Minnesota. Hennepin County Master Gardeners were recently educated on how this is already beginning to happen here in a presentation given by U of M Professor Dr. Lee Frelich, the director of the Center of Forest Ecology and the Environment. According to Dr. Frelich our state’s trees are already beginning to register temperature change. Winter temperatures in northern Minnesota are already 6°-7° warmer in recent years and if emissions are left unchecked average temperatures may rise 15° by the end of the century — and Minnesota will have a landscape, and seasons, more like Kansas. Even with a moderate reduction of carbon emissions we could still be looking a lot like Des Moines. What does this mean for trees in Minnesota?
Urban trees will not be as affected as those in the wild. In the city we are better able to control the growing environment of our trees. We space them apart so they are not competing for resources, we keep them watered and treat them for insects and diseases. Even under those conditions it is projected that of our 38 native tree species we will lose five of them, and 15 will be greatly reduced due to changes in the growing conditions. But the positive news is that 18 of our native species may be greatly increased and there is the potential for 25 new species to be viable in Minnesota, including Ohio buckeye, Pecan, Shagbark Hickory, Sycamore and Scarlet Oak.
The tradeoff for the increase in the variety of urban trees maybe the loss of our boreal forests in northern Minnesota, Wisconsin and Michigan. With the continued emissions of carbon dioxide and rise in temperatures our conifer forest may exit the state. Imagine Voyageurs National Park and the Boundary Waters Canoe area without their iconic spruce, fur and pine. These areas will probably look more like southern Minnesota than the way they do now. We may even have to choose a different ‘state tree’ as the red pine may disappear from here.
The conifer forests are used to a three month growing season of moderate temperatures. Forest areas generally like more rain and have less evaporation than the prairie which experiences less rain and more evaporation. Prairie grasses can withstand more and longer periods of drought than the forests. The North Shore of Lake Superior experienced eight years of heat and drought between 2000 and 2010 and subsequently lost 30 million birch trees. Even now there is evidence of the temperate trees, such as maples and oaks, taking over the boreal forests of the north, and the border between the prairie and forests is moving gradually north and east. By the end of the century Minnesota could be 90 percent prairie and only 10 percent forest.
As the climate warms and the landscape changes so will the rest of the ecology of the state. Where once there were moose now there will be deer, and instead of lynx we may see bobcats. We are already experiencing a decline in the population of cold water loving fish in many of the lakes in the state.
When asked what he would do, if it was up to him, to stem the tide of these environmental changes Dr. Frelich said he would institute a massive renewable energy initiative and at the same time plant trees, trees and more trees. Wilderness areas are better at sequestering carbon than other landscapes.