Climate Change
Climate change happens! For the last 2 million years, the earth’s climate has fluctuated in and out of numerous Ice Ages. In fact, up until about 13,000 years ago, most of the northeastern United States and Canada were covered by a massive ice sheet more than a mile thick. Natural variation in factors such as the earth’s orbit, volcanic activity, and solar activity has been driving these climate changes for eons.
Over the last 150 years, the global temperature has risen more than 1.5°F, and has risen at an increasing rate over the last few decades. Unlike in the past, evidence indicates that these recent changes are driven in large part by human activities, that these changes are occurring rapidly (at least on a geological timescale), and are predicted to continue and increase in the future.
One cause of global climate change is the greenhouse effect. Our atmosphere acts like a greenhouse windowpane and allows sunlight to reach and warm the surface of the earth, but also traps some of the heat energy that is reflected or re-emitted from the earth’s surface. Some gases in the atmosphere, such as carbon dioxide and methane, are much more effective than others at trapping this heat energy.
