#California; #IslandBuilding; #GreenlandIceSheet; #SouthEastAsia
California (US), Sep 24 (Canadian-Media): The Greenland ice sheet owes its existence to the growth of an arc of islands in Southeast Asia—stretching from Sumatra to New Guinea—over the last 15 million years, a new study claims, phys.org/news reports said.
Mt. Sumbing, an arc volcano in Central Java, in 2016. The uplift of volcanic rock in the entire Southeast Asian island arc, starting 15 million years ago, triggered global cooling and eventually ice sheets that covered much of North America and Northern Europe 18,000 years ago, according to UC Berkeley scientists and their colleagues. Credit: UC Berkeley photo by Yuem Park
According to an analysis by researchers at the University of California, Berkeley, UC Santa Barbara and a research institute in Toulouse, France, as the Australian continent pushed these volcanic islands out of the ocean, the rocks were exposed to rain mixed with carbon dioxide, which is acidic. Minerals within the rocks dissolved and washed with the carbon into the ocean, consuming enough carbon dioxide to cool the planet and allow for large ice sheets to form over North America and Northern Europe.
"You have the continental crust of Australia bulldozing into these volcanic islands, giving you really high mountains just south of the equator," said Nicholas Swanson-Hysell, associate professor of earth and planetary science at UC Berkeley and senior author of the study. "So, you have this big increase of land area that is quite steep, in a region where it's warm and wet and a lot of rock types that have the ability to naturally sequester carbon."
Starting about 15 million years ago, this tropical mountain-building drew down carbon dioxide in the atmosphere, decreasing the strength of the greenhouse effect and cooling the planet. By about 3 million years ago, Earth's temperature was cool enough to allow snow and ice to remain through the summer and grow into huge ice sheets over the Northern Hemisphere, like that covering Greenland today.
Once Northern Hemisphere ice sheets grew, other climate dynamics led to a cycle of glacial maxima and minima every 40,000 to 100,000 years. At the most recent glacial maximum, about 15,000 years ago, massive ice sheets covered most of Canada, the northern portions of the U.S., as well as Scandinavia and much of the British Isles.
"If it wasn't for the carbon sequestration that's happening in the Southeast Asian islands, we wouldn't have ended up with the climate that includes a Greenland ice sheet and these glacial and interglacial cycles," Swanson-Hysell said. "We wouldn't have crossed this atmospheric CO2 threshold to initiate Northern Hemisphere ice sheets."
The periodic growth and decline of the northern ice sheets—the cycle of glacial maxima and minima—is likely postponed, due to human emissions that have increased carbon dioxide concentrations in the atmosphere.
"A process that took millions of years we have reversed in 100 years," Swanson-Hysell said. "Over the next tens to hundreds of thousands of years, geological processes in places like Southeast Asia will once again decrease CO2 levels in the atmosphere—a pace that is frustratingly slow when humanity is facing the impact of current global warming."
UC Berkeley doctoral student Yuem Park, Swanson-Hysell and their colleagues, including Francis Macdonald of UC Santa Barbara and Yves Goddéris of Géosciences Environnement Toulouse, will publish their findings this week in the journal Proceedings of the National Academy of Sciences.
Geologists have long speculated about the processes that periodically warm and cool the planet, occasionally covering the entire globe with ice and turning it into a so-called snowball Earth.
Once scientists realized that, over the course of millions of years, tectonic processes move land masses around the planet like massive jigsaw puzzle pieces, they sought a connection between continental movements—and collisions—and ice ages. Cycles of Earth's orbit are responsible for the 40,000- or 100,000-year fluctuations in temperature that overlay the long-term warming and cooling.
The rise of the Himalayas in Asia in the mid-latitudes over the past 50 million years has been a prime candidate for cooling and the start of a glacial climate after an extended geologic interval without ice sheets. A few years ago, however, Swanson-Hysell and Macdonald saw a correlation between mountain-building in tropical areas and the onset of time intervals with ice ages over the past 500 million years.
In 2017, they proposed that a major ice age 445 million years ago was triggered by mountain- building in the tropics, and they followed that in 2019 with a more complete correlation of the last four time intervals of glacial climate and collisions between continents and tropical island arcs. They argue that the combination of increased exposure of rock with minerals that can sequester carbon and a plenitude of warm tropical rain is particularly effective in pulling carbon dioxide from the atmosphere.
The process involves chemical dissolution of the rocks that consume carbon dioxide, which is then locked in carbonate minerals that form limestone rock in the ocean. The calcium within seashells that you find on the beach may have come out of a tropical mountain on the other side of the world, Swanson-Hysell said.
"We built up a new database of these types of mountain-building events and then reconstructed the latitude at which they happened," Swanson-Hysell said. "Then we saw, hey, there is a lot of cooling when there is a lot of this type of mountain being built in the tropics, which is the Southeast Asian setting. The Southeast Asian islands are the best analog for processes that we also see further in the past."
For the current paper, Park, Swanson-Hysell and Macdonald teamed up with Goddéris to model more precisely what carbon dioxide levels would be with changes in the size of the Southeast Asian islands.
The researchers first recreated the sizes of the islands as they grew over the last 15 million years, focusing primarily on the largest: Java, Sumatra, the Philippines, Sulawesi and New Guinea. They calculated that the area of the islands increased from 0.3 million square kilometers 15 million years ago to 2 million square kilometers today. UC Santa Barbara graduate student Eliel Anttila, who was an undergraduate student in earth and planetary science at UC Berkeley and is a co-author of the paper, contributed to this aspect of the research.
They then used Godderis' GEOCLIM computer model to estimate how the growth of these islands altered carbon levels in the atmosphere. Together with UC Berkeley postdoctoral scholar Pierre Maffre, who recently obtained his Ph.D. in Godderis' lab, they updated the model to account for the variable effect of different rock types. The model is linked with a climate model in order to relate CO2 levels to global temperatures and precipitation.
They found that the increase of land area along the southeast edge of the Pacific corresponded with global cooling, as reconstructed from oxygen isotope compositions in ocean sediments. The carbon dioxide levels inferred from the model also match some measurement-based estimates, though Swanson-Hysell admits that estimating CO2 levels more than a million years ago is difficult and uncertain.
Based on their model, chemical weathering in the Southeast Asian islands alone diminished CO2 levels from more than 500 parts per million (ppm) 15 million years ago to approximately 400 ppm 5 million years ago and, finally, to pre-industrial levels of 280 ppm. Fossil fuel-burning has now raised the level of carbon dioxide in the atmosphere to 411 ppm—levels that haven't been seen on Earth for millions of years.
While the threshold for Arctic glaciation is estimated to be about 280 ppm of carbon dioxide, the threshold for ice sheet formation at the South Pole is much higher: about 750 ppm. That's why the Antarctic ice sheets began forming much earlier, about 34 million years ago, than those in the Arctic.
While the researchers' model doesn't allow them to isolate the climatic effects of the rise of the Himalayas, their Southeast Asian island scenario alone can account for the appearance of Northern Hemisphere ice sheets. They did explore the effect of volcanic events occurring around the same time, including massive lava flows, or flood basalts, such as those in Ethiopia and North America (Columbian traps). Though the weathering of such rocks has been proposed as an ice age trigger, the model shows that this activity played a minor role, compared to the rise of the Southeast Asian islands.
"These results highlight that the Earth's climate state is particularly sensitive to changes in tropical geography," the authors conclude.
Swanson-Hysell credits the campus's France-Berkeley Fund for providing resources for an initial collaboration with Goddéris that led to a large collaborative grant from the National Science Foundation's (NSF's) Frontier Research in Earth Science program to further pursue the research resulting in this paper.
The French-American team plans to model other past ice ages, including the one in the Ordovician period 445 million years ago that, in 2017, Swanson-Hysell and Macdonald proposed was triggered by a collision similar to that occurring today in the Southeast Asian islands. That collision took place during the first phase of Appalachian mountain-building, when the present-day eastern U.S. was located in the tropics.
#Bangkok, #FAO; #Covid19; #UN; #UNSDGs; #SDGs;
Bangkok, Sep 6 (Canadian-Media): Innovation, solidarity, coherence and strong partnership among and within countries of Asia and the Pacific are required for the region to rebound from the damage caused by COVID-19 and the ongoing effects of chronic undernourishment, FAO reports said.
Drones used in the Philippines to assess damages to agricultural land caused by severe weather events. Image credit: FAO
That was a call made by more than 40 member countries of the Food and Agriculture Organization of the United Nations concluding a four-day regional conference. About 750 participants, including representatives of the private sector and civil society, pledged to work to transform food systems, making them more sustainable, productive and resilient, and to feed a hungry world in a way that is profitable for farmers yet produces healthy food that is accessible to all.
"To transform food systems for sustainable healthy diets we must have coherence, partnerships and solidarity to reduce the costs of production," FAO Director-General QU Dongyu said on the final day of the 35th Regional Conference for Asia and the Pacific, hosted by the Government of Bhutan.
"Big data, a digital economy and mobile technology will help producers achieve that." Today, mobile technology is leading innovation "and a smartphone in the hands of a smallholder farmer is his new farming tool," the Director-General added.
The Conference also learned more about the establishment of a FAO Office of Innovation and the creation of an International Platform for Digital Food and Agriculture.
The Conference heard that agricultural innovation can reduce back-breaking drudgery, and that food chains in the Asia-Pacific region are increasingly benefitting from technological innovation such as drones, satellite imagery, big data and block chains.
"Leveraging data, innovation and technology has shown that, here in Asia and the Pacific, we have brilliant minds, scientists and an entrepreneurial spirit that will lead us through the challenges presented by COVID-19 and help us conquer malnutrition and poverty," the Director-General said.
The Conference held a special session dedicated to the application of new technology and innovation in agriculture, which are wooing back young people and empowering women in the sector, according to participants. It was agreed that new and innovative food and agricultural policies, processes, investment and learning could get the region back on track to achieve Sustainable Development Goal 2 (ending hunger and promoting sustainable agriculture) by 2030.COVID-19 underscores the need to redouble efforts to end hunger and poverty.
The Asia-Pacific region is home to more than half of the world's undernourished people, and with the impacts of COVID-19 the number of hungry people in Southern Asia could rise by nearly a third to 330 million in the next ten years.
The participants heard how FAO's recently launched COVID-19 Response and Recovery Programme, would help countries mitigate the immediate impacts of the pandemic while build back better, accelerating global hunger-fighting efforts through a focus on innovation.
The Conference was chaired by the Minister for Agriculture and Forests of Bhutan, Yeshey Penjor, who called for strengthened collaboration: "While great strides had been made to reduce poverty and hunger by so many countries, COVID-19 has upended the momentum. We must prepare for higher risks ahead of us and make sure that there is sustainability in the food supply chain," he said.
The Conference also appreciated the FAO Hand in Hand Initiative that aims to enable matchmaking, bringing the right partners together at the right time, to help the region move forward and meet the needs of member countries. The Initiative has already seen the launch of state-of-the-art tools such as the Hand-in-Hand Geospatial Platform and the FAO Data Lab for statistical innovation.
"Ironically, the fact that COVID-19 has driven us to meet remotely has, in some ways, helped us to move away from formalities and get closer together," said Director-General QU, referring to the fact the Regional Conference was held entirely in virtual mode for the first time in FAO's history. "So while we are separated by some 11 time zones, we have still managed to come together, have thought-provoking discussions and reach consensus on a number of important issues."
There were a number of other firsts and achievements. The private sector joined for the first time a FAO Asia and the Pacific Regional Conference. Civil society organizations also continued to have an important voice. Prior to the conference, which is part of FAO's regional governance structure, national consultations were held in member nations across the region - another first.
#Northern England; #Archaeology; #LeadChristianCupUncovered; #Christianity
England, Sep 3 (Canadian-Media): Archaeologists have uncovered the fragments of a lead Christian cup, or chalice, lightly etched with symbols of early Christian iconography, at the archaeological site of Vindolanda, an ancient Roman military fort and settlement on Hadrian’s Wall in Northumberland, northern England, www.sci-news.com reports said.
A fragment of the 1,400-year-old Christian chalice found at Vindolanda in Northumberland, northern England. Image credit: Vindolanda Trust.
A total of 14 fragments from the ancient vessel were found hidden in the remains of a 6th century Christian church, inside the previously occupied Roman fort of Vindolanda.
“This is a really exciting find from a poorly understood period in the history of Britain,” said lead author Dr. David Petts, a researcher in the Department of Archaeology at Durham University.
“Its apparent connections with the early Christian church are incredibly important, and this curious vessel is unique in a British context.”
“It is clear that further work on this discovery will tell us much about the development of early Christianity in beginning of the medieval period.”
Each fragment of the ancient chalice was found to be covered by lightly etched symbols, each representing different forms of Christian iconography from the time.
The marks appear to have been added, both to the outside and the inside of this cup, by the same hand or artist and although they are now difficult to see with the naked eye, with the aid of specialist photography, the symbols have been carefully recorded and work has started on a new journey of discovery to unlock their meanings.
The etchings include some well-known symbols from the early church including ships, crosses and chi-rho, fish, a whale, a happy bishop, angels, members of a congregation, letters in Latin, Greek and potentially Ogam.
“We are used to first’s and the wow factor from our impressive Roman remains at Vindolanda with artifacts such as the ink tablets, boxing gloves, boots and shoes, but to have an object like the chalice survive into the post-Roman landscape is just as significant,” said Dr. Andrew Birley, director of excavations and CEO of the Vindolanda Trust.
“Its discovery helps us appreciate how the site of Vindolanda and its community survived beyond the fall of Rome and yet remained connected to a spiritual successor in the form of Christianity which in many ways was just as wide reaching and transformative as what had come before it.”
“I am delighted that we can now start to share our news about this discovery and shed some light on an often-overlooked period of our heritage and past.”