Unusual and unprecedented warming? What do geologic and human history tell us?
The key pillar in the argument that man-made increases in greenhouse gases are causing harmful warming of the planet is the supposition that recent temperature increases are unusual and unprecedented. If that is the case, then it would provide strong support for human influences to be the primary driver of modern warming. On the other hand, if modern temperature changes are similar to previous cycles of warming and cooling, it would indicate that the more than 300-year general warming trend we are experiencing is a normal continuation of planetary and geologic cycles. Geologic data confirm that the nine previous warming trends, dating back to the end of the last ice age are remarkably similar to the current warming period (CWP) and all had higher temperatures. Five of the nine also had higher rates of warming than the CWP. Additionally, vast numbers of historic records document that the Medieval, Roman and Minoan warm periods were warmer than we find in the 21st century. The data support the contention that our current warming is neither unusual nor unprecedented and that the previous warming periods ushered in eras of great prosperity, bountiful harvests and the blossoming of great civilizations.
AAPG Datapages/Search and Discovery Article #90373 © 2019 AAPG Eastern Section Meeting, Energy from the Heartland, Columbus, Ohio, October 12-16, 2019