Neanderthal Tartar and the Anthropocene
Cooking with firewood and domesticating plants and animals changed Earth’s climate
Humans have biological and cultural inertia that keeps them from making quick changes that might upset gains from the past. That is entirely understandable and there is a genetic wisdom in that. Trouble is, genetic wisdom is garnered in thousand-year and ten-thousand-year adjustments, —the normal time it took climate change to unfold before the Anthropocene. Homo is adapted to that slow process. Consider this chart of the Vostok cores:
At the left end of the chart, 800,000 years ago, atmospheric CO2 was below 200 ppm and Earth’s average temperature was 9 degrees colder than today. Over about 20,000 years, CO2 rose, primarily by volcanic activity, to 250 ppm and that warmed Earth to approximately the same climate we have today. Both CO2 and temperature then declined for 40 to 50,000 years and bottomed out in another ice age, which we emerged from 700,000 years ago. That process was repeated about ten times before the present era. All the while, humans were evolving.
It is difficult to provide a detailed description of the humans that existed 800,000 years ago because the fossil record from that time period is limited. It is generally thought that they had similar physiology to modern humans. There were a few more species within the genus. They occupied a range of habitats, including grasslands, forests, and coastal areas, and relied upon a variety of wild sources for their food, some of it now extinct. The oldest known evidence of the controlled use of fire comes from sites in Israel and Georgia that are approximately 1 million years old. When it got very, very cold, fire would have been our ancestors’ most important tool.
Archaeological evidence from South Africa 100,000 years ago indicates Homo sapiens ate crushed wild grass seeds. In Shanidar Cave (Zagros, Iraqi Kurdistan), occupied by Neanderthals around 70,000 years ago and early modern humans around 40,000 years ago, wild mustard and pistachio were garnishes on salads of wild grass seeds mixed with pulses such as bitter vetch (Vicia ervilia), grass pea (Lathyrus spp) and wild pea (Pisum spp). There are traces of these grass seeds in the tartar on Neanderthal teeth.
The people who lived in these caves during the ice ages ground, pounded and mashed the seeds into a mixture that was heated up with water to make a porridge. Using fire changed things. These humans were no longer just living alongside nature. Now they were actively altering the landscape, a little at first, but then more and more. Soaking, heating and de-hulling reduced the seeds’ bitterness and toxins, but because seed coats weren’t completely removed, researchers think that these people wanted to retain a little of the bitter flavor. Cooking was a bittersweet gift.
Foraging for plants does not change the climate. Subsistence fishing and hunting when clan numbers are small does not change the climate. Cooking and heating with firewood or charcoal and domesticating plants and animals does. We know humans have been doing this for tens of thousands of years.
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On December 13, 2022, James Hansen and Makiko Sato with 14 co-authors submitted “Global Warming in the Pipeline” to Oxford Open Climate and invited criticism. The paper was science-shattering in its findings. Going on Twitter, I gushed it was like watching James T. Kirk beat the Kobayashi Maru simulation--Hansen and team validated both the Ruddiman Apostasy and the McPherson Paradox.
The Ruddiman Apostasy
In Copenhagen during UN COP15, I asked Stephen Schneider, IPCC’s Lead Author in Working Group II, if he was willing to concede that Ruddiman and others were correct in believing that human influence on climate extended back to the last Ice Age. He was not. I pushed. He dug in his heels. Founder and editor of the journal Climatic Change, he had authored or co-authored over 450 scientific papers and other publications. He stood for the IPCC and mainstream climate science.
Some background: this was not our first rodeo. Schneider’s 1989 book, Global Warming, came out within a few months of my own book, Climate in Crisis. Schneider’s book, while getting favorable reviews, read a little like a ChatGPT transcript—very middle of the road. Nonetheless, it was the first book on climate science written for the general public (nine months before McKibben’s End of Nature). Two years later Schneider received the prestigious MacArthur "Genius Award.”
In 1971, while a post-doc fellow with Hansen at GISS, Schneider had been second author on a Science paper that concluded:
[I]t is projected that man's potential to pollute will increase six-to eightfold in the next 50 years. If this increased rate of injection of particulate matter in the atmosphere should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 °K. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is believed to be sufficient to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production.
While Schneider’s analysis of the exponential increase in greenhouse pollution was spot on, and prescient for 1971, his prediction of a coming ice age in 50 years (2021) was laughable. He retracted the paper in 1974 and got the part about aerosol/emission balancing right in a subsequent book, The Genesis Strategy, in 1976. Hansen has now weighed in (at last!) and solved the equation definitively.
Hansen shared Schneider’s qualms about unexplained imbalances but was not willing to predict a coming ice age. He thought the aerosol data was wrong, and it has taken him nearly 50 years to prove it. The new paper says:
A warm LGM [Last Glacial Maximum] suggested by CLIMAP and MARGO [climate model] data (~3°C cooler than the Holocene) can be firmly rejected, because it is now certain that their SST data (sea surface temperature) yield a planet out of energy balance by more than 2 W/m2, as discussed above. An energy imbalance of +2 W/m2 is enough to raise the temperature of the upper kilometer of the ocean 2.2°C or melt ice to raise sea level 22 m [72.2 feet] in a century - and 10 times those amounts in a millennium. Such change rates did not occur, so the LGM was more than 3°C cooler than today. As discussed above, we accept the recent paleo analyses concluding that the LGM was at least ~6°C cooler than the Holocene.
Stated more simply, the modeling of the 1970s that put the last Ice Age 3 degrees colder than present was wrong, otherwise the greenhouse gases we’ve added would have raised sea level 700 feet per thousand years and that didn’t happen. Instead, the last Ice Age was twice as cold—6 to 7 degrees—and sea level has risen more slowly.
“Ruddiman’s thesis is more viable than it may have seemed.”
Hansen then went on to agree with what I have reported in several books over 30 years—that the comfortable Holocene in which civilization evolved is a human artifact.
The Holocene is an unusual interglacial. It began as expected: the maximum glacier melt rate was at 13.2 kyBP [kiloyears before present] and, after peaking early in the Holocene, GHG amounts began to decline as in most interglacials. However, several ky later, CO2 and CH4 began to increase, which raised a question of whether humans were beginning to affect GHG amounts. Ruddiman suggested that CO2 began to be affected by deforestation 8 ky [8000 years] ago and CH4 [methane] by rice irrigation 5 ky ago [5000 years].
One addition Ruddiman has made to his original 2003 work in recent years is to look at methane from cattle across Asia and Africa, announcing in 2016 “that the rising CH4 concentration after 5000 years ago was anomalous compared to previous interglaciations and likely anthropogenic.” Ruddiman concluded that when all sources were summed, human activity added 343 billion tons (equivalent to an anthropogenic CO2 input of ∼24 ppm) to the atmosphere before the industrial era. Hansen concluded that it began to change the climate about 8000 years ago.
According to Hansen’s paper, in the normal orbital cycle and oscillations of the tilt of the Earth we should have warmed an additional 1 degree and begun trending towards the next ice age 6000 years ago. Instead, both land and sea temperature stabilized and gave the second half of the Holocene such unusually stable weather that civilization could arise. Hansen’s team now agrees with Ruddiman—another climate-forcing factor was at work, beginning with the cooked seeds evidenced in the tartar of Neanderthal teeth.
Once you comprehend how elegantly and intricately humans are interconnected to Gaia, regulating surface temperature, precipitation and weather by our activities even when our population was one tenth or one hundredth of its present size, then you must appreciate how much greater our capacity to make profound disruptions has grown, while, at the same time, our ability to understand and modify our own behavior is unchanging.
That is the really scary part.
Meanwhile, let’s end this war. Towns, villages and cities in Ukraine are being bombed every day. Ecovillages and permaculture farms have organized something like an underground railroad to shelter families fleeing the cities, either on a long-term basis or temporarily, as people wait for the best moments to cross the border to a safer place, or to return to their homes if that becomes possible. There are still 70 sites in Ukraine and 300 around the region. They are calling their project “The Green Road.”
The Green Road is helping these places grow their own food, and raising money to acquire farm machinery and seed, and to erect greenhouses. The opportunity, however, is larger than that. The majority of the migrants are children. This will be the first experience in ecovillage living for most. They will directly experience its wonders, skills, and safety. They may never want to go back. Those that do will carry the seeds within them of the better world they glimpsed through the eyes of a child.
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The COVID-19 pandemic destroyed lives, livelihoods, and economies. But it has not slowed climate change, a juggernaut threat to all life, humans included. We had a trial run at emergency problem-solving on a global scale with COVID — and we failed. 6.6 million people, and counting, have died. We ignored well-laid plans to isolate and contact trace early cases; overloaded our ICUs; parked morgue trucks on the streets; incinerated bodies until the smoke obscured our cities as much as the raging wildfires. We set back our children’s education and mental health. We virtualized the work week until few wanted to return to their open-plan cubicle offices. We invented and produced tests and vaccines faster than anyone thought possible but then we hoarded them for the wealthy and denied them to two-thirds of the world, who became the Petri-plates for new variants. SARS jumped from people to dogs and cats to field mice. The modern world took a masterclass in how abysmally, unbelievably, shockingly bad we could fail, despite our amazing science, vast wealth, and singular talents as a species.
Having failed so dramatically, so convincingly, with such breathtaking ineptitude, do we imagine we will now do better with climate? Having demonstrated such extreme disorientation in the face of a few simple strands of RNA, do we imagine we can call upon some magic power that will change all that for planetary-ecosystem-destroying climate change?
As the world emerges into pandemic recovery (maybe), there is growing recognition that we must learn to do better. We must chart a pathway to a new carbon economy that goes beyond zero emissions and runs the industrial carbon cycle backward — taking CO2 from the atmosphere and ocean, turning it into coal and oil, and burying it in the ground. The triple bottom line of this new economy is antifragility, regeneration, and resilience. We must lead by good examples; carrots, not sticks; ecovillages, not carbon indulgences. We must attract a broad swath of people to this work by honoring it, rewarding it, and making it fun. That is our challenge now.
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“There are the good tipping points, the tipping points in public consciousness when it comes to addressing this crisis, and I think we are very close to that.”
— Climate Scientist Michael Mann, January 13, 2021.
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