Climate Change

Global climate change is a fervently discussed topic in the news, and scientists agree that the Earth's climate is changing. But before going into what causes climate change and how scientists study it, let's clarify a few terms. The word climate is often used interchangeably with weather, but there is a difference.

Weather describes the atmospheric conditions, such as temperature, in a region over a short period of time, like a day. Climate, however, records the same conditions for the same region but over an extended period, average annual temperature for example. Global climate refers to the same variable analyzed and compiled across the entire planet. If you look at the data for average global temperature since 1880, you will see that it has been on the rise, and this is what people refer to as global warming.

One major contributor to global warming is the greenhouse effect caused by greenhouse gases, such as carbon dioxide, water vapor, ozone, and methane. These gases got their collective name because they form a layer around the Earth that is similar to the glass shield of a greenhouse. Just like the greenhouse, this layer of gas allows the Sun's rays to penetrate and then traps them, letting only a portion of the reflected rays escape back into the atmosphere and leading to a rise in temperature near the Earth's surface. Some cover of greenhouse gases is essential to ensure that the Earth's temperature stays habitable, but human activity, such as fossil fuel burning, have led to the concentration of some of these gases like CO2, which has risen above optimal levels, fueling global warming.

One major impact of this climate warming is the melting of glacial ice, which in turn results in sea level rise. This melting is exacerbated due to a phenomenon called the albedo effect. Albedo, derived from the Latin word, “albus”, meaning “white”, refers to the ratio of proportion of reflected to total solar radiation. This value will be close to one for fresh, white snow because it reflects most of the radiation. Bare soil, in contrast, has an albedo of only around 0.2, and open ocean only 0.1, and so these reflect significantly less - and so, as the climate warms, the snow melts, resulting in lower albedo, meaning that the Earth reflects less and retains more of the radiation as heat. This, in turn, causes the snow to melt more, creating a positive feedback loop and rising sea levels.

Another impact of climate change can be seen in species distribution. Species are found across a geographical area known as their range. As the climate warms, the resulting environmental changes, like melting ice caps, can cause a shift or decline in the habitable range of some of the species. Scientists have been studying these range shifts for different organisms in response to a variety of environmental variables. Using these data, they can model future changes in climate patterns and predict the likely fate of a species.

In this lab, you will assess greenhouse effects on an artificial microclimate, compare melting ice in different conditions, and study historical species' range shifts following environmental change.