Roy Spencer is one of the less than 3% of climate scientists whose research suggests that humans are playing a relatively minimal role in global warming. As one of those rare contrarian climate experts, he's often asked to testify before US Congress and interviewed by media outlets that want to present a 'skeptical' or false balance climate narrative. He's also a rather controversial figure, having made remarks about "global warming Nazis" and said,
"I view my job a little like a legislator, supported by the taxpayer, to protect the interests of the taxpayer and to minimize the role of government."
In any case, as one of those rare contrarian climate scientists, Spencer is in a good position to present the best arguments against the global warming consensus. Conveniently, he recently did just that on his blog, listing what he considers the "Top Ten Good Skeptical Arguments," throwing in an 11th for good measure. He also conveniently posed each of these arguments as questions; it turns out they're all easy to answer.
1) No Recent Warming. If global warming science is so "settled", why did global warming stop 15 years ago, contrary to all "consensus" predictions?
Quite simply, it hasn't. Even global surface temperatures (which is how Spencer is likely measuring 'global warming', although they only account for about 2% of the Earth's warming), have warmed about 0.2°C over the past 15 years, according to the best available measurements. More importantly, the planet has continued to accumulate heat at a rate equivalent to 4 Hiroshima atomic bomb detonations per second over the past 15 years.
2) Natural or Manmade? If we don't know how much of recent warming is natural, then how can we know how much is manmade?
We do.
Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, light green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), Wigley and Santer 2012 (WS12, dark green), and Jones et al. 2013 (J13, pink).
The IPCC stated with 95% confidence that most of the global warming since 1950 is human-caused, with a best estimate that 100% is due to humans over the past 60 years. The IPCC was able to draw this conclusion with such high confidence because that's what the scientific evidence and research clearly and consistently concludes.
3) IPCC Politics and Beliefs. Why does it take a political body (the IPCC) to tell us what scientists "believe"? And when did scientists' "beliefs" translate into proof? And when was scientific truth determined by a vote…especially when those allowed to vote are from the Global Warming Believers Party?
The IPCC merely brings the world's top climate scientists together every 5 to 7 years. It's those scientists who summarize the up-to-date status of the scientific research in their respective fields of expertise. The IPCC report and the 97% expert consensus on human-caused global warming are themselves not proof of anything. They summarize and reflect the scientific evidence – that vast body of evidence is the reason the consensus exists.
4) Climate Models Can't Even Hindcast. How did climate modelers, who already knew the answer, still fail to explain the lack of a significant temperature rise over the last 30+ years? In other words, how to you botch a hindcast?
Global surface temperatures have risen more than 0.5°C over the past 30 years. That rise is significant, both in the statistical sense and the subjective sense. Climate models have accurately reproduced that rise.
5) …But We Should Believe Model Forecasts? Why should we believe model predictions of the future, when they can't even explain the past?
Climate models have accurately reproduced the past, but let's put them aside for a moment. We don't need climate models to project future global warming. We know the planet will warm between about 1.5 and 4.5°C in response to the increased greenhouse effect from a doubling of atmospheric carbon dioxide (the 'climate sensitivity').
In a business-as-usual scenario, atmospheric carbon dioxide levels are expected to surpass 900 ppm by 2100 – that's close to two doublings from the pre-industrial level of 280 ppm. Hence we know that business-as-usual will cause between 2.5 and 7.5°C (most likely 5°C) warming if we stop carbon dioxide levels from rising beyond about 900 ppm. This is based on simple math and what we know about the physics of the climate – no fancy models needed.
6) Modelers Lie About Their "Physics". Why do modelers insist their models are based upon established physics, but then hide the fact that the strong warming their models produce is actually based upon very uncertain "fudge factor" tuning?
Putting aside the accusation that hundreds of climate modelers are all liars – the answer is that their models are indeed based upon well-established physics. Spencer's question likely refers to the uncertain size of the cooling influence of aerosols. However, that is a physical uncertainty. We don't have very good measurements of this effect; unfortunately the rocket carrying NASA's Glory satellite that had instruments to measure the climate effect of aerosols crashed two years ago. Nevertheless, climate models use the available data to account for their influence, and their projections include the associated uncertainties.
7) Is Warming Even Bad? Who decided that a small amount of warming is necessarily a bad thing?
We're headed for about 5°C global surface warming above pre-industrial temperatures by 2100 if we continue on a business-as-usual path. 5°C is the difference between average temperatures now and those during the last ice age. That's not "small" by any stretch of the imagination. As for who decided that amount warming is a bad thing – climate scientists researching the impacts of climate change.
Posted by dana1981 on Tuesday, 6 May, 2014
 |
The Skeptical Science website by Skeptical Science is licensed under a Creative Commons Attribution 3.0 Unported License. |