THIS POST IS A CRITICAL REVIEW OF A CLIMATE CRISIS CLAIM BY THE GUARDIAN ON 1/28/2021. IT IS A RECITATION OF THE OFT REPEATED CLAIM BY CLIMATE SCIENTISTS AND ACTIVISTS THAT THE CURRENT WARM PERIOD IS UNPRECEDENTED AND THEREFORE HUMAN CAUSED AND THAT THEREFORE IT IS A CLIMATE CRISIS THAT MUST BE CHECKED WITH CLIMATE ACTION CONSISTING OF A COMPLETE CESSATION OF THE USE OF FOSSIL FUELS. LINK TO THE GUARDIAN ARTICLE: https://www.theguardian.com/environment/2021/jan/27/climate-crisis-world-now-at-its-hottest-for-12000-years

PART-1: WHAT THE GUARDIAN ARTICLE SAYS

Climate crisis: world is at its hottest for at least 12,000 years – study: Scientists say temperatures globally at highest level since start of human civilisation: Damian Carrington Environment editor

The world’s continuously warming climate is revealed also in contemporary ice melt at glaciers, such as with this one in the Kenai mountains, Alaska The world’s continuously warming climate is revealed also in contemporary ice melt at glaciers, such as with this one in the Kenai mountains, Alaska (seen September 2019). Photograph: Joe Raedle/Getty Images The planet is hotter now than it has been for at least 12,000 years, a period spanning the entire development of human civilisation, according to research. Analysis of ocean surface temperatures shows human-driven climate change has put the world in “uncharted territory”, the scientists say. The planet may even be at its warmest for 125,000 years, although data on that far back is less certain. The research, published in the journal Nature, reached these conclusions by solving a longstanding puzzle known as the “Holocene temperature conundrum”. Climate models have indicated continuous warming since the last ice age ended 12,000 years ago and the Holocene period began. But temperature estimates derived from fossil shells showed a peak of warming 6,000 years ago and then a cooling, until the industrial revolution sent carbon emissions soaring. This conflict undermined confidence in the climate models and the shell data. But it was found that the shell data reflected only hotter summers and missed colder winters, and so was giving misleadingly high annual temperatures. “We demonstrate that global average annual temperature has been rising over the last 12,000 years, contrary to previous results,” said Samantha Bova, at Rutgers University–New Brunswick in the US, who led the research. “This means that the modern, human-caused global warming period is accelerating a long-term increase in global temperatures, making today completely uncharted territory. It changes the baseline and emphasises just how critical it is to take our situation seriously. The world may be hotter now than any time since about 125,000 years ago, which was the last warm period between ice ages. However, scientists cannot be certain as there is less data relating to that time. One study, published in 2017, suggested that global temperatures were last as high as today 115,000 years ago, but that was based on less data. The new research examined temperature measurements derived from the chemistry of tiny shells and algal compounds found in cores of ocean sediments, and solved the conundrum by taking account of two factors. First, the shells and organic materials had been assumed to represent the entire year but in fact were most likely to have formed during summer when the organisms bloomed. Second, there are well-known predictable natural cycles in the heating of the Earth caused by eccentricities in the orbit of the planet. Changes in these cycles can lead to summers becoming hotter and winters colder while average annual temperatures change only a little. Combining these insights showed that the apparent cooling after the warm peak 6,000 years ago, revealed by shell data, was misleading. The shells were in fact only recording a decline in summer temperatures, but the average annual temperatures were still rising slowly, as indicated by the models. “Now they actually match incredibly well and it gives us a lot of confidence that our climate models are doing a really good job,” said Bova. The study looked only at ocean temperature records, but Bova said: “The temperature of the sea surface has a really controlling impact on the climate of the Earth. If we know that, it is the best indicator of what global climate is doing.” She led a research voyage off the coast of Chile in 2020 to take more ocean sediment cores and add to the available data. Jennifer Hertzberg, of Texas A&M University in the US, said: By solving a conundrum that has puzzled climate scientists for years, Bova and colleagues’ study is a major step forward. Understanding past climate change is crucial for putting modern global warming in context. Lijing Cheng, at the International Centre for Climate and Environment Sciences in Beijing, China, recently led a study that showed that in 2020 the world’s oceans reached their hottest level yet in instrumental records dating back to the 1940s. More than 90% of global heating is taken up by the seas. Cheng said the new research was useful and intriguing. It provided a method to correct temperature data from shells and could also enable scientists to work out how much heat the ocean absorbed before the industrial revolution, a factor little understood. The level of carbon dioxide today is at its highest for about 4m years and is rising at the fastest rate for 66m years. Further rises in temperature and sea level are inevitable until greenhouse gas emissions are cut to net zero.

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PART-2: CRITICAL COMMENTARY

HUMAN CAUSE: THE REAL ISSUE HERE IS HUMAN CAUSE BECAUSE WITHOUT EVIDENCE OF HUMAN CAUSE OF THE WARMING TREND, WHATEVER IMPACTS THE WARMING MAY HAVE ARE ALL NATURAL.

LINK: https://tambonthongchai.com/2021/11/09/the-issue-is-human-cause/

(ITEM#1) That the current Holocene warm period is “Unprcedented” in the Holocene does not serve as empirical evidence that establishes either human cause or cataclysmic consequences in the absence of the proposed climate action by humans. Multiple “unprecendented” claims of this nature are made in this Guardian artcle.

(ITEM#2): The planet is hotter now than it has been for at least 12,000 years, a period spanning the entire development of human civilisation. In a related post we described the the paleo history of Holocene temperature cycles as alternating periods of warming and cooling at centennial and millennial time scales: LINK: https://tambonthongchai.com/2019/06/11/chaoticholocene/ . At least nine such periods are identified including the current warm period that began when the most recent cold period known as the Little Ice Age ended. The warming trend that ensued is with us today and in the science of anthropogenic global warming and climate change it is understood as human caused by way of the fossil fuel emissions of the industrial economy because the end of the Little Ice Age coincides with the Industrial Revolution. We note here that human civilization actually started 8,000 years ago in period known as the “Holocene Climate Optimum” described in a related post LINK: https://tambonthongchai.com/2018/08/20/the-holocene-optimum-period-a-bibliography/ . The 12,000-year time span described here takes us back to the beginning of the Holocene interglacial following its recovery from the Younger Dryas cold period to include a 4,000-year period when the earth was cooler than the Holocene Climate Optimum 8,000 years ago. The motivation for that appears to be that a claim to 12,000 years of unprecedentedness provides stronger evidence of human cause that the usual claim to 8,000 years of unprecedentedness. The truth is that unprecedentedness is not evidence of human cause no matter how long it can be strtched by including known cold periods.

(ITEM#3): {note: YBP=years before present}. In yet another related post at this site LINK: https://tambonthongchai.com/2019/06/11/chaoticholocene/ we show that so far, the Holocene interglacial has, since the Younger Dryas re-glaciation, gone through multiple warming and cooling cycles at centennial and millennial time scales. Shortly after the Younger Dryas cooling, about 11,700YBP, a strong warming trend set in and persisted with a steady warming of 17C that rescued the Holocene from the YDE but two more glacial interruptions were still to come. The first of these two cooling events is called the 8.2K cooling because it ends 8200YBP. The Holocene interglacial recovered from the 8.2K mini glacial event and warmed to the so called “Holocene Climate Optimum” (HCO) ≈7000YBP, credited with the Neolithic Revolution that is thought to have created human civilization. Four other Holocene temperature excursions since the HCO are recognized as the Bronze Age or Minoan warm period ≈3000YBP, the Roman warm period (RWP)≈2000YBP, the Medieval warm period (MWP) ≈1100YBP, and the Little Ice Age (LIA) ≈500YBP-100YBP. The current warm period, described as Anthropogenic Global Warming (AGW) is thought to be caused by the Industrial Economy. The timing of the Industrial Revolution appears to mark the change from the cold of the Little Ice Age to the warmth of the current warm period.

These cyclical temperature dynamics, seen both in glaciation and in interglacial periods, exhibit chaotic behavior at centennial and millennial time scales as noted in the literature. For example, Gerard Bond, in the 1997 paper “A pervasive millennial-scale cycle, writes that “pacings of the Holocene events and of and those in the last glaciation are statistically the same. Together, they make up a series of climate shifts with a period close to 1470 ± 500 years“. That is, although glaciation and interglacials are entirely different climate states, both are subject to the same underlying chaotic volatility at the same time scale such as the random and chaotic climate cycles of the Holocene that don’t appear to follow a pattern other than that warming and cooling cycles alternate. In this context, our post Little Ice Age warming cycle is best understood as the latest such temperature cycle of the Holocene where no role of the Industrial Revolution is needed to explain this cyclical behavior of the interglacial. Therefore, the “unprecedented” comparison as an argument for the exceptionalism of the current warm period, in and of itself, does not prove human cause.

(ITEM#4): An unusual claim made in this Guardian document is that the “unprecedented” argument for the current warm period can be extended beyond the Holocene to the prior interglacial, the Eemian. The Eemian interglacial is presented in a related post on this site with an extensive bibliography on the topic: LINK: https://tambonthongchai.com/2018/12/21/eemian/ . No indication is found in the climate science literature in the study of the relevant paleo climatology that the current warm period is warmer than the Eemian. However, going back to our primary observation in the unprecedented argument, that “unprecedented does not prove human cause since many natural unprecented warming cycles have come and gone, even if the current warm period were warmer than the Eemian, it would not prove human cause.

SUMMARY AND CONCLUSIONS: To summarize, (a) uprecendented does not prove human cause and (b) the comparison is renderered all the more mysterious in what appears to be a desperate search to extend the usual climate science comparison with “the last 2,000 years” with the supersitious and mysterious idea that the human cause idea can be made stronger by going farther and farther back in time. Such an unscientific and invalid argument for the human cause that would validate the need for human intervention to “save the planet” does not support or strengthen the climate science case for human cause but rather exposes the underlying methodological weaknesses and a desperate need for human cause to support the anti fossil fuel activism of this enterprise. RELATED POST ON ANTI FOSSIL FUEL ACTIVISM: https://tambonthongchai.com/2020/03/23/anti-fossil-fuel-activism-disguised-as-climate-science/

The case for human cause can be made only by providing the empirical evidence that relates rising atmospheric CO2 concentration to fossil fuel emissions at an annual time scale as claimed in the “Airborne Fraction” argument of climate science. The need for the “unprecedented” deception is best understood in terms of the inability of climate science to provide that evidence.

The “Airborne Fraction” issue in climate science is discussed in a related post in the context of a lecture on that topic by climate scientist and carbon budget giant of our time, Professor Glen Peters: LINK: https://tambonthongchai.com/2020/12/29/climate-scientist-explains-the-carbon-budget/

CONCLUSION: WE CONCLUDE FROM THIS ANALYSIS THAT THE SERIES OF ARGUMENTS PRESENTED BY THE GUARDIAN THAT THE CURRENT WARM PERIOD IS UNPRECEDENTED DOES NOT PROVE HUMAN CAUSE EVEN IF THESE UNPRECEDENTED ARGUMENTS COULD BE VALIDATED WITH EMPIRICAL EVIDENCE.