a Scientific American article with the secondary headline-
full article here- How to Misinterpret Climate Change Research - Scientific American
I encourage everyone to read it, and parse it for information that supports the headline. if anything it buttresses the 'contrarian' case.
I get it that Stevens doesnt want to say that his work has added another coupla slashes to the 'Death of a Thousand Cuts' that is happening to CAGW and the IPCC. probably for political reasons as well as scientific uncertainty. but what does Stevens think about that evil denier Nic Lewis?
part of the message Stevens was responding to (read more at - Bishop Hill blog - Lewis on the SciAm article )
Scientific American is shrunken, twisted shadow of its former self.
ps. I hope everyone caught the reference to low climate sensitivity when using real(ish) temperature data, and high climate sensitivity using proxy estimates of temperature.
Research into the cooling impact of aerosols sends climate contrarians into a tailspin
full article here- How to Misinterpret Climate Change Research - Scientific American
I encourage everyone to read it, and parse it for information that supports the headline. if anything it buttresses the 'contrarian' case.
Stevens narrowed the range in his study, cutting the cooling effect to about half of IPCC's suggestion of 1.9 Wm2...It's a tiny tweak with grand implications. If the maximum cooling ability of aerosols is only 1.0 Wm2, as Stevens suggests, the particles would offset only a third of warming caused by greenhouse gases. In comparison, at the IPCC's maximum cooling value, aerosols would offset two-thirds of the warming.
The misinterpretation of Stevens' paper began with Nic Lewis, an independent climate scientist. In a blog post for Climate Audit, a prominent climate skeptic blog, he used Stevens' study to suggest that as CO2 levels double in the atmosphere, global temperatures would rise by only 1.2 to 1.8 degrees Celsius. The measure is called "climate sensitivity."....That's less than the assumed 2 C threshold for catastrophic climatic change in parts of the world. It's also lower than an IPCC estimate that a doubling of CO2 will raise global temperatures by 1.5 to 4.5 C.
When scientists use temperature records from the 20th century to constrain sensitivity, they get low values. When they use records stretching many millenia, painstakingly assembled from trees and other proxies that contain imprints of past climates, they get values toward the higher end of the IPCC range of 1.5 to 4.5 C.
I get it that Stevens doesnt want to say that his work has added another coupla slashes to the 'Death of a Thousand Cuts' that is happening to CAGW and the IPCC. probably for political reasons as well as scientific uncertainty. but what does Stevens think about that evil denier Nic Lewis?
“Dear Nic,
because I have reservations about estimates of ocean heat uptake used in the ‘energy-balance approaches’, and because of a number of issues (which you allude to) regarding differences between effective climate sensitivity estimates from the historical record and ECS, I am not ready to draw the inference from my study that ECS is low. That said, I do think what you write in the two paragraphs above is a fair characterization of the situation and of your important contributions to the scientific debate. The Ringberg meeting also made me confident that the open issues are ones we can resolve in the next few years.
Feel free to quote me on this.
Best wishes, Bjorn”
part of the message Stevens was responding to (read more at - Bishop Hill blog - Lewis on the SciAm article )
The article also states, paraphrasing rather than quoting, “Lewis had used an extremely rudimentary, some would even say flawed, climate model to derive his estimates, Stevens said.” LC14 used a simple energy budget climate model, described in AR5 WG1, to estimate equilibrium climate sensitivity (ECS) from estimates of climate system changes over the last 150 years or so. An essentially identical method was used to estimate ECS in Otto et al (2013), a paper of which Bjorn Stevens was an author, along with thirteen other AR5 WG1 lead authors (and myself). Energy budget models actually estimate an approximation to ECS, effective climate sensitivity, not ECS itself, which some people may regard as a flaw. AR5 WG1 states that “In some climate models ECS tends to be higher than the effective climate sensitivity”; this is certainly true. Since the climate system takes many centuries to equilibrate, it is not known whether or not this is the case in the real climate system. LC14 discussed the issues involved in some detail, and my Climate Audit blog post referred to estimating “equilibrium/effective climate sensitivity”.
Scientific American is shrunken, twisted shadow of its former self.
ps. I hope everyone caught the reference to low climate sensitivity when using real(ish) temperature data, and high climate sensitivity using proxy estimates of temperature.