Stoaty said:
"It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century." (summary for policy makers from the latest IPCC report):
http://www.ipcc.ch/report/ar5/wg1/docs/WGIAR5_SPM_brochure_en.pdf" onclick="window.open(this.href);return false;
Just another inaccurate statement in a long line from those on the government payroll promoting climate alarmism.
Back in 1988, James Hansen predicted we would experience a temperature rise of 0.5 degrees Celsius per decade in the business-as-usual scenario. Well, we have now lived the business-as-usual scenario. Temperatures are currently below the "best-case" curve he predicted for the situation in which CO2 emissions had magically completely stopped by 2000. You can only come to such absurd conclusions as Hansen did when you believe that CO2 is the dominant actor in a world in which it only plays a bit part.
The global temperature trend has now been completely flat for the past decade or two, depending upon which global dataset is used. If the IPCC were really trying to get the science correct instead of just promoting panic, they would realize that CO2 CANNOT be the dominant cause of the rise in the latter half of the 20th century. If that assertion were true, then the current temperature trend would be even steeper today than it was back then, given that the forcing from CO2 is now higher than it was back then.
Simply put, for global temperatures to be completely flat while CO2 is at it's recent maximum and the Sun is in a fairly neutral condition means that another weak forcing is completely offsetting the CO2 forcing. The negative side of the PDO is likely that forcing.
No, if the PDO can singlehandedly offset the increasing forcing from CO2, then it is clear that CO2 was not the major driver behind the rise in the second half of the 20th century. As I have presented previously, that honor falls squarely with the Sun. Plus PDO was also forcing in the positive direction during that time. CO2 likely played a very minor role in the whole thing.
True climate denialism is the denial that the changes in the Sun are the primary driver of the global temperature on Earth. At the end of the 20th century, the influence of cosmic rays on the climate were not known and only postulated. But we now have the empirical evidence both
from the lab and
from observation from satellites that show a 5% reduction in global cloudiness results directly from a 20% reduction in cosmic ray influx.
As can be seen in Figure 3D of this paper, during the Maunder Minimum, cosmic ray flux was about 60% higher than it was for the latter half of the 20th century. That means the world likely had over 10% more cloudiness during the Maunder Minimum. And it was very cold. That period is known as the Little Ice Age. We are all about to receive a spectacular demonstration of the effects of a quiet Sun as solar activity comes down from the current peak of solar cycle 24 and produces few, if any sunspots in solar cycle 25.
The mitigating factor is that we now have elevated CO2 levels to partially offset the effects that we will all begin to feel due to the quiet Sun. The small warming effect and enhanced plant growth that CO2 affords should help us survive the coming cold period.
But will any of these changes in our climate affect the drought situation in CA? Will increases in aerosol production from increased cosmic ray influx result in more rain in CA? Not if there is no water vapor in the air. Weatherman has indicated that rain is somewhat unlikely in the climate of CA. And the article I linked previously says that CA has been developed during a particularly wet period. If it now reverts back to its "normal" dry condition, it's possible it could stay that way for a very long time.
