The two degree temperature target (beyond which we will face an existential climate crisis) is inaccurate, irrelevant, and vague. It appears to be based on the claim that modern humans (Homo sapiens) never existed when the average global temperature was two degrees above the mid-nineteenth century, and therefor, since this is an "unprecedented" state of affairs, must lead to catastrophe.
But, first, it is incorrect, as shown below. Modern humans evolved before the last interglacial period, the Eemian, which was at least a degree warmer than the present at times, and perhaps more. Second, it is a non sequitur, for two reasons: one, that an unprecedented global climate condition does not logically or scientifically predict catastrophe; second, that human beings do not live in an average global climate but a local one -- there is little doubt, for example, that Europe and the North Atlantic climate region has undergone temperature swings of two and more degrees during the Holocene, yet the millions who have lived there during this period survived and even thrived -- despite possessing little more than Stone Age technology for much of this time, while being subject to famines, droughts, contagions, warfare, and invasions -- conditions which no longer prevail even today, let alone 50 or 100 years from now.
That the claim is vague, and lacking in any scientific specificity, I hope is clear.
But, first, it is incorrect, as shown below. Modern humans evolved before the last interglacial period, the Eemian, which was at least a degree warmer than the present at times, and perhaps more. Second, it is a non sequitur, for two reasons: one, that an unprecedented global climate condition does not logically or scientifically predict catastrophe; second, that human beings do not live in an average global climate but a local one -- there is little doubt, for example, that Europe and the North Atlantic climate region has undergone temperature swings of two and more degrees during the Holocene, yet the millions who have lived there during this period survived and even thrived -- despite possessing little more than Stone Age technology for much of this time, while being subject to famines, droughts, contagions, warfare, and invasions -- conditions which no longer prevail even today, let alone 50 or 100 years from now.
That the claim is vague, and lacking in any scientific specificity, I hope is clear.
Prof. Roger Pielke Jr. on origins of 2 degree temp target: ‘Has little scientific basis’
Via: Roger Pielke Jr.’s The Climate Fix website: https://theclimatefix.wordpress.com/2017/09/18/pielke-on-climate-5/
Do you want to know the origins of the 2 degree temperature target that underpins much of climate policy discussions and action?
- As is often the case, it is an arbitrary round number that was politically convenient. So it became a sort of scientific truth. However, it has little scientific basis but is a hard political reality.
- Jaeger and Jaeger (2011) explain that it came from “a marginal remark in an early paper about climate policy”
- That “marginal paper” was a 1975 working paper by economist William Nordhaus (here in PDF and
a second version is from 1977, with the figure shown below). At p. 23,
“If there were global temperatures of more than 2 or 3 C. above the
current average temperature, this would take the climate outside of the
range of observations which have been made over the last several hundred
thousand years.”
- Nordhaus’ claim was sourced to climatologist Hubert Lamb (1972) who in turn calculated long-term variations in temperature based on record kept in Central England.
- So: The 2 degree temperature target that sits at the center of current climate policy discussions originated in a local, long-term record of temperature variation in England, which was adapted by an economist in a “what if?” exercise.
- The 2 degree target is today far more politically “real” than its grounding in science or policy. That won’t change, but it is nonetheless a fascinating look at the arbitrariness of policy and how it is that issues are framed shapes what options are deemed relevant and appropriate.
- As an example, check out this paper just out today in Nature — it argues that we can emit more than we thought and still hit a 1.5 degree temperature target. People will argue about the results, many because of its perceived political implications. But this argument is only tenuously related to actual energy policies, instead it is related to how we should think about arguments that might be used to motivate people to think about energy policies and thus demand action and so on. Tenuous, like I said.
Flashback Climategate emails: Phil Jones says critical 2-degree C limit was ‘plucked out of thin air’
Via: https://junkscience.com/2011/11/climategate-2-0-jones-says-2o-limit-plucked-out-of-thin-air/
From the Climategate 2.0 collection, to a European Peoples Party officials who is trying to eliminate skepticism from the EPP’s position paper on climate, Phil Jones describes the origin of the 2o limit:
“The 2 deg C limit is talked about by a lot within Europe. It is never defined though what it means. Is it 2 deg C for the globe or for Europe? Also when is/was the base against which the 2 deg C is calculated from? I know you don’t know the answer, but I don’t either! I think it is plucked out of thin air. I think it is too high as well. If it is 2 deg C globally, this could be more in Europe – especially the northern part. A better limit might be maintaining some summer Arctic sea ice!”
Warmist father Hans Joachim Schellnhuber of 2C temperature limit admits it’s ‘a political goal’– Hans Joachim Schellnhuber, a top German climate scientist who helped establish the 2-degree threshold, stressed it was a policy marker: “Two degrees is not a magical limit — it’s clearly a political goal,” says Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK). “The world will not come to an end right away in the event of stronger warming, nor are we definitely saved if warming is not as significant. The reality, of course, is much more complicated.” Schellnhuber ought to know. He is the father of the two-degree target. “Yes, I plead guilty,” he says, smiling. The idea didn’t hurt his career. In fact, it made him Germany’s most influential climatologist. Schellnhuber, a theoretical physicist, became Chancellor Angela Merkel’s chief scientific adviser — a position any researcher would envy.
Out of Africa: When Did Prehistoric Humans Actually Leave—and Where Did They Go?
Scientists have discovered the oldest human fossil ever found outside of Africa in Misliya Cave, Israel. The find means our current timing for human migration—and evolution—could be off by at least 50,000 years.
So when did humans really start exploring the rest of the world?
Where humans went next, however, is still a big mystery.
Out of Africa
The traditional “Out of Africa” model holds that humans first traveled from the continent between 130,000 and 115,000 years ago, toward the Middle East.The newly discovered fossil is estimated to be between 170,000 and 190,000 years old. Before now, the earliest remains found in Israel were dated between 90,000 and 120,000 years old. This means humans reached the region at least 50,000 years earlier than expected.
Chris Stringer of London’s Natural History Museum, who was not involved in the latest discovery, told the BBC: “The find breaks the long-established 130,000-year-old limit on modern humans outside of Africa.... The new dating hints that there could be even older Homo sapien finds to come from the region of western Asia.”
Moving back the date of that first migration has big consequences for our understanding of human evolution. “The entire narrative of the evolution of Homo sapiens must be pushed back by at least 100,000 to 200,000 years,” study author Israel Hershkovitz from Tel Aviv University explained in a statement. “In other words, if modern humans started traveling out of Africa some 200,000 years ago, it follows that they must have originated in Africa at least 300,000 to 500,000 years ago.”
What path did early humans take?
The early excursions into Eurasia responsible for the Misliya fossil likely ended in extinction. Scientists had believed a second exodus occurred about 60,000 years ago.This idea was brought under scrutiny last year, when a team of scientists reviewed human bones from China. The bones were estimated to be up to 120,000 years old. The team argued that multiple dispersals might explain a growing body of evidence finding humans in the wrong place, at the wrong time.
They produced a map (below) describing the human journey from Africa as a series of smaller migrations around the globe.
The question of when humans left Africa is far from solved. The Misliya jawbone has once again thrown the question of human origins wide open.
Hershkovitz explains: “This finding—that early modern humans were present outside of Africa earlier than commonly believed—completely changes our view on modern human dispersal and the history of modern human evolution.”
