Position 1: There is no evidence that Global Warming is happening.Position 2: Global Warming is happening but has natural rather than human causes.Position 3: Global Warming is happening and has human causes, but will not have catastrophic consequences.
William Ruddiman attributes the divergence to the early anthropogenic greenhouse gas emissions forcing of climate. This process, according to Ruddiman, dates back 8000 years. Ruddimamn points to forrest clearing and early agriculture as important components in global patterns of GHG emissions and atmospheric GHG concentration over the last 8000 years.
Atmospheric aerosols counteract the warming effects of anthropogenic greenhouse gases by an uncertain, but potentially large, amount.
this in turn suggests unintended consequences for global garbon controls.
Strong aerosol cooling in the past and present would then imply that future global warming may proceed at or even above the upper extreme of the range projected by the Intergovernmental Panel on Climate Change.
Once the reality of global warming has been established, the argument for AGW comes next. These arguments point to past examples of climate variation, the so called Medieval warm period, that was followed by the so called Little Ice Age. These episodes are not adiquately explained by AGW skeptics, and Ruddimamn explains them nicely from an AGW perspective. Of even greater difficulty to the anti-AGW cause is why the cold forcing mechanisms, the Milankovitch cycles
The recent announcement of the results of the Berkeley Earth Surface Temperature (BEST) Project by project chairman Richard Muller has caused quite a stir. True believers in catastrophic anthropogenic global warming (CAGW) have greeted it as the final nail in the coffin of dissent. Why? Because it concludes—take a deep breath, now—that “Global warming is real.”
As I have noted the reality of the Michael Mann’s hockey stick is also supported by the BEST data, and establishing global warming, places the onus on the Anti-AGW party to come up with a plausible explanation for why global climate is getting warmer, that excludes AGW. Needless to say, Beisner fails to do that. Instead he goes on the attack,
The only thing more stunning and frightening than the idiocy of equating “global warming” with “CAGW” is the failure of so much not only of the public, and not only of the media, but especially of the scientific community—well, okay, the already committed, true-believer “scientific community”—to recognize (admit? expose?) the rhetorical sleight of hand.
rhetorical sleight of hand.
We find that the number of record-breaking events increases approximately in proportion to the ratio of warming trend to short-term standard deviation. Short-term variability thus decreases the number of heat extremes, whereas a climatic warming increases it. For extremes exceeding a predefined threshold, the dependence on the warming trend is highly nonlinear. We further find that the sum of warm plus cold extremes increases with any climate change, whether warming or cooling. We estimate that climatic warming has increased the number of new global-mean temperature records expected in the last decade from 0.1 to 2.8. For July temperature in Moscow, we estimate that the local warming trend has increased the number of records expected in the past decade fivefold, which implies an approximate 80% probability that the 2010 July heat record would not have occurred without climate warming.
If Rahmstorf and Coumou are correct, catastrophic warming is upon us already.
Last year a catistrophic heatwave and drought struck Russia during the Summer. The record heat was so extreme that words like unprecedented and disastrous are appropriate.