Dyson's Sphere of Influence, Part 3: The Garden of Eden

(This is part 3 in a series of posts Part 1, Part 2, Part 3, and Part 4)

One thing that scientists and conservative Christians may agree on is that there was a garden of Eden six thousand years ago; however, they may not agree on it's location nor its size. The garden I speak of is what is now the Sahara Desert. Ray Pierrehumbert describes the mid-holocene climatic optimum as a time in which forests extended farther north in Europe and rivers flowed in the Sahara (Principles of Planetary Climate, Chapter 1). The wet Sahara was probably a climate response to Earth's orbital precession, Earth's wobbling top-like motion that determines how the sun's energy is distributed globally.

Regarding the wet Sahara, Dyson said:

Six thousand years ago seems to have been the warmest and wettest period of the interglacial era that began twelve thousand years ago when the last Ice Age ended. I would like to ask two questions. First, if the increase of carbon dioxide in the atmosphere is allowed to continue, shall we arrive at a climate similar to the climate of six thousand years ago when the Sahara was wet? Second, if we could choose between the climate of today with a dry Sahara and the climate of six thousand years ago with a wet Sahara, should we prefer the climate of today? My second heresy answers yes to the first question and no to the second. It says that the warm climate of six thousand years ago with the wet Sahara is to be preferred, and that increasing carbon dioxide in the atmosphere may help to bring it back. I am not saying that this heresy is true. I am only saying that it will not do us any harm to think about it. (Dyson 2007, Heretical Thoughts about Science and Society)

The statements in this passage struck me as odd. I've perused many Holocene climate reconstructions and I didn't recall any prominent global spikes in temperature from this period, but my knowledge is incomplete. As a check on my memory, I consulted some graphs of ice core data plotted for Greenland and Antarctica and confirmed that nothing exceptional affected Greenland and Antarctica:

Interactive Paleoclimate Chart

Dyson's Sphere of Influence, Part 2

(This is part 2 in a series of posts. Part 1, Part 2,  Part 3)

I've been looking at climate modelling studies with a renewed vigor since reading Dyson's statement that projections of global warming are based on flawed climate models. It's not only Dyson's comment that provokes me. The climate models fallacy is promoted by many private interest groups trying to influence the COP21 climate talks in November. For example, the Cornwall Alliance is a group of faith-based, pro-fossil fuel, evangelicals:

Many fear that carbon dioxide emissions from fossil fuel use endanger humanity and the environment because they lead to historically unprecedented, dangerous global warming....
Computer climate models of the warming effect of enhanced atmospheric carbon dioxide are the basis for that fear. -- An Open Letter on Climate Change to the People, their Local Representatives, the State Legislatures and Governors, the Congress, and the President of the United States of America. Cornwall Alliance, 2015. 

This letter also cites a lot of inaccurate and outdated information on the instrumental record, and credits the Judeo-Christian Heritage with the rise of the modern scientific method and dismisses computer modelling as not a reliable avenue of research.

So, I want to share what fictions climate models help us to maintain, and I didn't have to dig deep for good example, rather, just open my mailbox. My most recent issue of Nature (15 Oct. 2015) reports on modelling the loss of continental ice from Antarctica:

• The multi-millennial Antarctic commitment to future sea-level rise, Golledge et. al, Nature 15 October 2015

Dyson's Sphere of Influence (Part 1)

(This is part 1 in a series of posts. Part 2, Part 2, Part 3)

I've been asked to comment on an essay by Freeman Dyson written in 2007 in which Dyson proposed some heresies about climate science. It seems unfair to criticize an essay from 8 years ago, but some of what he said was demonstrably wrong in 2007 and a recent interview from 2015 suggests his opinion hasn't evolved since then. A physicist with his reputation has the potential to influence a lot of people, so it's worthwhile to examine if his sphere of influence should extend to the realm of climate science. The recent interview with Dyson coincides with a release of a report by the special interest group The Global Warming Policy Foundation in which Freeman Dyson wrote the introduction. The latter two items appear to be in preparation for the upcoming climate talks in Paris, possibly with the goal of influencing public opinion.

• Dyson 2007, an essay for The Edge: Heretical Thoughts about Science and Society
• Dyson 2015, a recent interview: The Register, Oct 11, 2015 
• Oct 11, 2015: The Global Warming Policy Foundation report on the benefits of CO2.

Summary
This is part 1 of two or more posts in which I'm commenting on the following:
Part 1

• Dyson should acknowledge the entire scope of climate science before downplaying it's conclusions. 
• The greenhouse effect is often described inadequately, even by physicists.
• Ocean acidification, a result of our rate of CO2 emissions, is a well-acknowledged problem and missing from Dyson's commentary.

Part 2

• It's dangerous to use regional climate change to justify global climate change.
• What does land-use management and genetic engineering offer for mitigating our CO2 emissions?