BY ANNELIESE MOLL
For the UAS Whalesong
We live in a greenhouse. The life we see around us depends on the energy we receive from the sun. Only about half of the light from the sun that reaches the Earth passes through the atmosphere. Once it’s through it’s absorbed and radiated back up in the form of infrared heat. From there roughly 90% of the heat is absorbed by greenhouse gasses and is ultimately radiated back to the surface, which causes warming of the surface. The Earth is an average nice, life-supporting, 59 degrees Fahrenheit.
It’s true that the Earth goes through natural cycles of warming and cooling. However, when humans and our activities are added into the equation, we grossly overset the balance.
Human activities have caused for huge increases in atmospheric carbon dioxide, which have caused increases to the concentrations of greenhouse gases. Currently, the largest source of carbon dioxide emissions comes from the combustion of fossil fuels. This is about 87% of human produced emissions. Before the industrial revolution, atmospheric carbon dioxide was at 280 parts per million (ppm), and, within the last 150 years, we have raised that to over 400 ppm.
Due to this change in temperature, we have observed changes in weather patterns. For example, some regions have been receiving more snow than typical, while others have received little to none. For the human residents a lack of snow in their region may not necessarily seem like a negative, but for many of the region’s animal inhabitants who change color this is very bad.
For example, the snowshoe hare is known widely for it’s large hind feet and its seasonal color change. Without snow, they stand out like a light in the dark during snowless winter months. In Montana snowshoe hares were captured and then released with a radio collar. The results from that study showed that mismatched hares suffered a loss of 7% in their weekly survival rate (Zimova et al. 2016). It has also been said that this is one of the clearest demonstrations of mortality within a wild species in relation to climate change. Since hares that are unable to change back to brown quickly enough are being removed from the population, natural selection will favor those individuals. However, the question of the hour is whether or not the snowshoes hares will able to adapt quickly enough. Current estimates are not in their favor. Estimates are predicting severe declines in snowshoe hare populations.
Other studies involving snowshoes hares have found that the lack of snow within their range is causing them to move out of their historic range (Sultaire et al. 2016). Researchers at the University of Wisconsin, Madison have found results supporting this move in a recent study. They have reported that the hares are moving north at rate of about five and a half miles per decade. While five miles may not seem significant to some, the ecological consequences may be significant. Snowshoe hares are not only a game species within several states, but also a source of food for several species of animals and raptors.
This issue is larger than just snowshoe hares though. There are at least 14 other species worldwide that are going to be affected due to color mismatch. Global climate change is an even larger problem for many other species that do not change color seasonally. The high levels of carbon dioxide are also causing ocean acidification; any organism with a calcium carbonate structure is being affected. In short, we need to be aware that our actions have widespread and lasting effects.
Zimova, M., Mills, L. S., & Nowak, J. J..2016. High fitness costs of climate change‐induced camouflage mismatch. Ecology Letters.
Sultaire, S. M., Pauli, J. N., Martin, K. J., Meyer, M. W., Notaro, M., & Zuckerberg, B..2016. In Proc. R. Soc. B (Vol. 283, No. 1827, p. 20153104). The Royal Society.