The dominant hypothesis for this trend is that large volcanic eruptions have subsided while increasing amounts of carbon dioxide have been absorbed out of the atmosphere due to interactions between monsoon rains and ground-up rock exposed by India pushing into Asia and creating the Himalayas.

Additionally, it is believed that the melting ice that produced higher sea levels resulted in the ocean absorbing more carbon dioxide out of the atmosphere.

Ruddiman primarily relies on the groundwork by Milutin Milankovitch to explain the effects of solar radiation and Earth's orbit on the climate.

By examining ice cores from around the world scientists have been able to link levels of greenhouse gases such as carbon dioxide and methane to the various cycles of Earth's climate history.

Approximately 10,000 years ago the ice that once covered large portions of the northern hemisphere began to recede and gave rise to a new way of life for early humans.

However, about 8,000 years ago humans first developed agriculture and a domesticated lifestyle that allowed them to continually inhabit regions and build large civilizations.

According to Ruddiman farming and related activities resulted in large amounts of greenhouse gases (carbon dioxide and methane) being released into the atmosphere at a time when natural cycles of the Earth indicated they should have been falling.

[4] Ruddiman goes as far as to say that if these gases had not been released into the atmosphere, areas in northern Canada such as Hudson Bay and Baffin Island would currently be covered in ice today.

This, according to Ruddiman, will result in a continued warming trend that will only stop when technology either produces a new source of fuel or figures out a way to separate the carbon dioxide emissions prior to being released into the atmosphere.

Eventually, carbon and methane emissions will be controlled and lowered a great deal and Ruddiman asserts when this happens the Earth will most likely begin an era of cooling temperatures.