Climate change is the biggest existential threat facing humanity and the planet. In a continent with over a third of its land covered in forests, the impact of climate change in North America cannot be understated. Climate change causes harm to forests and the plants and animals that inhabit them as well as the many people who rely on forests for natural resources. The negative effects of global warming will only continue to increase if we neglect to change our actions that contribute to greenhouse gas emissions and pollution.
Increased temperatures cause many factors that threaten plant life including diseases, threats to plant reproduction, poor growing conditions, and harmful insect populations. Droughts, fires, and pest problems all cause higher tree mortality rates . The first figure below shows the relationship between tree growth and stressors caused directly and indirectly by climate change. Indirectly, stress from climate change leaves trees with fewer resources to manufacture secondary metabolites that they use to defend against insects and diseases.
Directly, climate change causes droughts and warmer weather leads to pest outbreaks. In 2013, 27 species of insects and 22 plant pathogens were found to be detrimental to forests in North America. Particularly in the northwestern part of the continent, various beetle species that thrive in warmer climates have expanded their habitat as temperatures rise. These ecological disturbances have risen rapidly since the early nineteen-nineties. Global warming is rapidly affecting boreal forests more than other biomes causing droughts and increased temperatures that stifle tree growth. Tree species have also shifted northward in response to warming temperatures in the last thirty years.
The North American West has been gradually rising in temperature over the last fifty years. In response to temperature changes, the amount of snow this area receives has also decreased. One dangerous effect of climate change is wildfires which have become larger and more frequent. Droughts and fire suppression efforts increase the likelihood of wildfire. Animal species, as well as plants that dwell in North American forests, have also been affected by climate change, some of which are at an increased risk of extinction. If a species fails to adapt to changing climate or move to a climate that is habitable they could become locally extinct. However, some species cannot migrate to a new habitat. For example, plants and animals that thrive in colder habitats are more sensitive to changes in temperature but climate change leads to the destruction of their habitats, warming the only environment in which they can survive.
While these predictions are based on trends from the last 30-50 years, it is not possible to predict with complete accuracy the effects of climate change on the environment. The future is not set in stone and we are making new discoveries every day. Simulations and models can be created using information from the past to predict the future but it is impossible to be one-hundred percent accurate. Even when correctly predicting an event such as the bark beetle outbreak in northwestern North America, scientists did not predict the extent of the devastation caused by the insects. Additionally, the estimates of climate change and its effect on invasive species vary from different models. Also, while temperature increases are shown to have negative effects on boreal forests in North America, other biomes such as the taiga have not shown dramatic negative effects from climate change according to some studies. People have differing viewpoints when it comes to what to do to combat climate change. The more action is taken to combat climate change and maintain our forests the more contention there is. While climate change is a nearly universally accepted truth among scientists, there are still some people who do not believe that climate change will have detrimental effects on the environment in the future.
We can only hypothesize about the future impact of climate change but while we cannot know what the future holds, we can use trends to predict the effect of climate change on North American forests and use that information for conservation efforts. Following the trend of the last thirty years, we can assume that influxes of insects and diseases will continue and become more prevalent as climate change progresses. In Western North America, wildfires are expected to continue to increase over the next century which will dramatically change our forests and other ecosystems. Scientists have been trying to figure out how to map future wildfires in order to prepare for and combat them. However, fire suppression methods have actually shown to cause fires to become larger and more common because preventing smaller fires by clearing dead sticks and branches from the forest floor causes buildup that only acts as kindling for larger fires . Climate change will continue to increase wildfires and if our methods of stopping them only lead to larger fires we are only exacerbating the problem and leading to a future where massive, devastating fires are common. Tree species have already been documented migrating northward since nineteen-seventy and the makeup of Northern boreal and temperate forests are predicted to continue to change drastically. It is also predicted by eight different models in the 26th edition of the Journal of Climate that in western North America some forest areas will become grassland and populations of evergreens will decrease in response to rising temperatures. If we do not take drastic measures to combat climate change there will be irreversible damage done to our forests.