What’s the national priority du jour? Global warming. Sigh.
The majority of 20th century warming (0.7C) took place before 1940, i.e., before the post-war growth in human CO2 emissions. The 19th century was still in the depths of the Little Ice Age, and over the last 100 years the global climate rebounded from the LIA to the levels of warmth enjoyed during the preceding medieval warm period.
Virtually all scientists accept that the world has warmed since 1860. Most on both sides of the warmist/skeptic divide believe that humans have had some effect. The difference in position is to what degree is human and what degree is naturally caused; whether the warming will continue if additional CO2 is pumped into the atmosphere; and whether additional warming will be catastrophic. On human vs natural, there is no consensus, but the pendulum seems to be is swinging away from the notion that humans are solely responsible for the warming. Some believe that a hyperactive sun during the 20th century may in fact have been the culprit, (I think that the 1976 shift in the Pacific Decadal Oscillation to the warm phase is the main culprit of the late 20th century warming) and given the projected quiet sun for the next two solar cycles, we will be able to test that hypothesis empirically.
As for the continuation of warming, we are in a 18 year pause in warming (See here:http://www.woodfortrees.org/…/plot/rss/from:1996.5/trend — RSS is satellite derived temperature data) Climate scientists know that the reflective properties of CO2 diminish logarithmically, meaning that if humanity continues pumping out CO2, it will add little warming to the atmosphere. Both sides understand this scientific fact, it’s just that one side predicts that CO2 warming will “force” warming from other greenhouse gases such as water vapor. The forcings concept is highly debated but it seems to be called into question by the pause since 1996.
The final part is predictions of catastrophe, which IMO are risible. They are based on computer models that have been empirically proven incorrect. See here:http://www.drroyspencer.com/…/CMIP5-90-models-global…. The computer models have been not only invalidated by the current 18 year climate pause, but have proven incapable of what’s called hindcasting — recreating past climate shifts. It appears that climate is too complex to model so far.
Furthermore, the endless catastrophes have failed to materialize. More tornadoes? False. More hurricanes? False. Stronger hurricanes? False…in fact, global cyclonic activity is at all time low levels. Less snow? False. Ice-free arctic? False. Ice-free antarctic? False. In fact, polar ice is about normal for the period of satellite measurement. Polar bears heading to extinction? False. The global population is the highest in my lifetime. Coral reefs dying/disappearing? I don’t know, but it looks like the Australians are beginning to question those claims as well. http://www.heraldsun.com.au/…/story-fni0ffxg-1226849583753
So, why is this the new priority? Maybe because the administration knows that global warming legislation doesn’t stand a snowball’s chance in Hell in either the House or the Senate but Obama can pander resolutely to the left through executive orders.