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Environment and Biogeography

As you know from reading about biogeography, the Earth's continents and climate have not always been the same. Climate has changed many times throughout Earth's history, and some species have gone extinct while others have evolved. Current climate change is a bit different from other climate changes in the past.

For one thing, human activity is responsible this time around—fossil fuel burning released tons of carbon dioxide into the atmosphere, heating up the planet. However, this is not the first time an organism's activity changed the atmosphere. Over thousands of years, the growth and reproduction of lots of cyanobacteria early on in the history of life on Earth released a lot of oxygen into the atmosphere, and paved the way for oxygen-breathing life to move onto land.

Another difference with current climate change is the speed at which it is happening. According to the US Environmental Protection Agency (EPA), temperatures in the US have been rising since the early 1900s, but most rapidly since the 1970s. Even if we stop putting greenhouse gases into the atmosphere today, temperatures will continue to rise for at least 50 years.

Image from here.

So what does this mean for the distribution of species around the Earth? Species basically have three options: adapt, move, or go extinct. We will probably see some of each of these things happen. Bird species in the US have started spending their winters further north than they used to because of warmer temperatures. A few species have moved as far north as 400 miles, but others have not moved at all. Plants are also able to survive further north, as average low temperatures have increased.

Conservation biologists who try to preserve habitat for endangered species are left with a dilemma: do they focus on where species live now or where they might live in the future? How far into the future can they hope to have an influence? These are questions that land managers, scientists, and policy makers have to consider. Unfortunately, there is no easy way to deal with climate change or predict how it will influence every species.

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