Climate change is one of the greatest threats to modern civilization. Earth is currently experiencing a rapid increase in mean temperature. The global scope of this phenomenon makes it particularly challenging because efforts to address the problem require cooperation between many different nations and international corporations. Add to this the disagreements over the veracity of the problem and the mechanisms causing our planet to warm, and what you will find is a very dangerous situation with no easy remedies. Earth’s climate is a changeable climate. We know through studying dendrochronology, ice core samples, mud core samples and historical records that the earth has gone through many cyclical changes in climate over the millennia. As little as 1000 years ago, the earth experienced a period of rapid warming known as the Medieval Warming Period. Northern locations, such as the southern regions of Greenland became inhabitable and were colonized by Viking settlers. A mere 200 years ago saw the northern hemisphere experience a climate anomaly known as the Little Ice Age. European glacial ice advanced down mountainsides, growing seasons shortened and crops failed. What caused these most recent episodes of climate change? That question is an important one because its answer is at the heart of the current debate surrounding the veracity of our current heating. Many complex systems help to regulate earth’s temperature. The circulation of warm waters from the equator towards the pole and cold water from cold to warm helps to evenly distribute heat in the northern and southern hemispheres. Changes in this thermohaline circulation have been linked to periods of cooling on earth. The amount of aerosols emitted from volcanic activity is also a factor that determines world climate. Other determinants involve the changing degree of axial tilt of the earth and the variable distance between the earth and the sun caused by an ever-changing (albeit slowly) orbit around the sun.