We will face a string of terrible catastrophes unless we act

Two thousand scientists, in a hundred countries, engaged in the most elaborate, well organized scientific collaboration in the history of humankind, have produced long-since a consensus that we will face a string of terrible catastrophes unless we act to prepare ourselves and deal with the underlying causes of global warming.

Al Gore

Examination of tree rings in Europe indicates a 2,000 year cooling trend.  It was warmer in the Roman era.  Oops.

Professor Dr. Jan Esper's group at the Institute of Geography at JGU used tree-ring density measurements from sub-fossil pine trees originating from Finnish Lapland to produce a reconstruction reaching back to 138 BC.

In so doing, the researchers have been able for the first time to precisely demonstrate that the long-term trend over the past two millennia has been towards climatic cooling.

Daily Mail

Daily Mail

First, the science. After many years in this line of work, I’ve come to the firm conclusion that global warming is one of those research areas where scientists think they know much more than they really do. In many ways, putting a man on the Moon was far easier than understanding the climate system. Yes, carbon dioxide is a greenhouse gas — a minor one. And, yes, humans burning fossil fuels produces carbon dioxide: one molecule of CO2 for every 100,000 molecules of atmosphere, every five years.

...Compared to the carbon dioxide that humans produce, Mother Nature routinely transfers 40 times as much CO2, and 24,000 times as much water vapor (Earth’s primary greenhouse gas), back and forth between the atmosphere and the Earth’s surface, every day.

Roy Spencer