Earth used to be cooler than we thought, which changes our math on global warming

Earth was cooler than we thought 6,000 years ago.Gerd Altmann/Pixabay

A long-standing mystery about the Holocene has a potential solution.

The last 12,000 years have been much cooler than previously thought, according to research published Wednesday in the journal Nature. And in contrast, human-caused warming of the atmosphere is even more anomalous than we’d realized. That’s because the study’s authors have found a new way to estimate historical temperatures which they say filters out seasonal shifts that had made past millennia seem warmer than they really were.

The findings offer a possible solution to an outstanding riddle about the recent history of climate change. The problem, called the Holocene warming conundrum, is that previous reconstructions of the historical climate showed a warm period from 6,000 to 10,000 years ago, followed by a period of cooling. Climate models of the same period, however, suggest that the planet would have been warming steadily.

By fine-tuning how we interpret the physical evidence of the changing climate, explains Samantha Bova, a paleoclimate researcher at Rutgers University and one of the study authors, “[the data] do show a warming that’s highly consistent with what is predicted by climate models.”

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Climate change in antiquity: mass emigration due to water scarcity

 The absence of monsoon rains at the source of the Nile was the cause of migrations and the demise of entire settlements in the late Roman province of Egypt. This demographic development has been compared with environmental data for the first time by professor of ancient history, Sabine Huebner of the University of Basel - leading to a discovery of climate change and its consequences.

The oasis-like Faiyum region, roughly 130 km south-west of Cairo, was the breadbasket of the Roman Empire. Yet at the end of the third century CE, numerous formerly thriving settlements there declined and were ultimately abandoned by their inhabitants. Previous excavations and contemporary papyri have shown that problems with field irrigation were the cause. Attempts by local farmers to adapt to the dryness and desertification of the farmland - for example, by changing their agricultural practices - are also documented.

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A New Archaeology For The Anthropocene Era

Archaeological studies of low-density, agrarian-based cities such as ancient Angkor Wat

in Cambodia are increasingly being used to inform the development of more

sustainable urban centres in the future [Credit: Alison Crowther]

A paper published in Nature Ecology and Evolution aims to give pause to an audience that has been largely prepared to take such out-of-touch depictions at face value. It reveals an archaeology practiced by scientists in white lab coats, using multi-million-euro instrumentation and state-of-the-art computers.

It also reveals an archaeology poised to contribute in major ways to addressing such thoroughly modern challenges as biodiversity conservation, food security and climate change.

"Archaeology today is a dramatically different discipline to what it was a century ago," observes Nicole Boivin, lead author of the study and Director of the Institute's Department of Archaeology. "While the tomb raiding we see portrayed in movies is over the top, the archaeology of the past was probably closer to this than to present-day archaeology. Much archaeology today is in contrast highly scientific in orientation, and aimed at addressing modern-day issues."

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Jahrhundertdürre im Mittelalter – mit Parallelen zum Klimawandel heute?

 

Leipziger Forschende identifizieren aus historischen Quellen bisher unbekannte Dürreperiode

Der Übergang von der mittelalterlichen Warmzeit zur Kleinen Eiszeit wurde offenbar von starken Dürren zwischen 1302 und 1307 in Europa begleitet, die der feucht-kalten Phase der 1310er Jahre und der damit verbundenen großen Hungersnot von 1315-21 vorausgingen. Die Wetterlagen 1302-07 seien vergleichbar mit der Wetteranomalie 2018, als in Kontinentaleuropa eine außergewöhnliche Hitze und Dürre herrschte, schreiben die Forschenden der Leibniz-Institute für Geschichte und Kultur des östlichen Europa (GWZO) und für Troposphärenforschung (TROPOS) im Fachjournal Climate of the Past.

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Searching for the people of Doggerland

 

This hammerstone was recently found off the coast of Norfolk. CREDIT: University of Bradford

Around 8,150 years ago, a sudden shift in the seabed created the Storegga tsunami in the North Sea. With all known evidence pointing towards this event greatly affecting, but not completely inundating, Doggerland (the strip of land that once connected Britain to continental Europe – see CA 367), the search is now on for evidence of human occupation. While it is thought that there must have been significant Mesolithic groups living here during the period, without knowing just how populated the area was likely to be it cannot be determined how catastrophic the tsunami may have been. 

As part of the ‘Europe’s Lost Frontiers’ project, researchers from the University of Bradford have been analysing the evolution of Doggerland, tracing its gradual inundation. At the end of the last Ice Age, c.11,700 years ago, Doggerland probably stretched all the way from Yorkshire to Denmark, but by 9000 cal BC the North Sea had begun to flood in, creating an archipelago that predominately included ‘Dogger Island’ (an upland area in the northern reaches of Doggerland) and Dogger Bank off the eastern coast of Great Britain. By the time of the Storegga tsunami, this landmass had shrunk even more, greatly reducing the size of both areas to shallow sandbanks. (More information on this process, along with the full impact of the tsunami, was recently published in Antiquity journal: https://doi.org/10.15184/aqy.2020.49)

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Mysterious Cornwall shipwrecks re-emerge for first time in decades

 

Many locals cannot remember ever seeing the wrecks at Porth Kidney Sands near St Ives (Picture: Cornwall Live/BPM Media) 

New pictures show wooden structures that are barely intact visible on the beach. 

Elsewhere, there are other remains of ships nearby that are more familiar to locals, including the jagged fragments of the steam collier Bessie, one mile away at Carbis Bay. 

That was wrecked along with various other ships during a raging storm named Cintra, in November 1893. 

Those wrecks also occasionally reveal themselves after winter storms when there are low tides.

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