1. Global Warming: Did it Start in the Stone Age?
Presented by:
Loren Berman, Dana Kresel,
Shayna Sehayik, and Sam Shaffer

2. William Ruddiman’s Theory
The combined effects of deforestation and agricultural practices in the early Holocene period led to increased levels of CO2 and CH4 about 8000 years ago.
This stands in contrast to the idea that it was the Industrial Revolution that started global warming.
These increased GHG emissions staved off an ice age.

3. Rice Paddies Rice paddies release methane into the atmosphere.
Ruddiman notes an upward trend of atmospheric methane, at a time when it should have decreased, corresponding to the new rice irrigation techniques used by farmers in Asia about 5000 yrs ago.

4. Deforestation Deforestation leads to CO2 emissions.
Based on historical documents from the Middle Ages, Ruddiman argues that a significant portion of Eurasia was already deforested.
Right as deforestation practices spread across Eurasia, CO2 levels rose rapidly, against a natural declining trend.

5. Staving Off an Ice Age
Anomalies amounting to 250 ppb of CH4 and 40 ppm of CO2 would cause an increase of 0.8 degrees Celsius.
Without this addition, the global temperature would have been degrees cooler.
This drop in temperature would have allowed for ice sheets to form as far south as northern Canada

6. Criticisms Methane Emissions Deforestation Coral Reef Calcification
Role of anthropogenic forces alone
Provides ‘evidence’ for skeptics
He offers no solution for GW today
Current Implications
Water management and rice cultivation practices
Deforestation vs. forest conservation