Tree-ring records reveal Asian monsoon variability
2021-07-20
(Press-News.org) Chinese researchers along with international colleagues recently reported a 6,700-year-long, precisely dated and well-calibrated tree-ring stable isotope chronology from the Northeastern Tibetan Plateau. It reveals full-frequency precipitation variability in the Asian Summer Monsoon (ASM) from interannual to multimillennial timescales with a long-term decreasing trend and several abrupt climate change events.
The international research team comprised 20 scientists from research groups based in China, Norway, Germany, United Kingdom, USA, Sweden, Canada, and Switzerland and was jointly led by Prof. Nils Christian Stenseth from the University of Oslo and Prof. YANG Bao from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences. The team studied more than 9,500 individual oxygen isotope measurements from juniper tree rings to reconstruct ASM variability over the past 6,700 years.
The researchers extracted and analyzed the oxygen isotopes from each ring in each tree independently, enabling them to build the most detailed dataset ever for the period from the mid-Holocene to the present.
These tree-ring stable isotopes offer a far more accurate archive for reconstructing full-frequency precipitation variability in North China than conventional tree-ring studies, which often fail.
By comparing this ASM precipitation reconstruction with another tree-ring oxygen record from the Animaqing Mountains, the researchers inferred that during the mid-Holocene, the ASM limit extended at least 300 km further northwest compared to its present day limit.
This allows direct comparison between the ASM's northern boundary 5,000 years ago and in the current era.
This precipitation reconstruction also provides a valuable opportunity to determine the societal and ecological responses to rapid climatic change in the past.
The reconstruction suggests that a rapid decrease in moisture availability from ~2,000-1,500 BCE caused a drought regime from ~1,675-1,185 BCE, which might have played an important role in regional forest deterioration and enhanced aeolian activity during that time.
In addition, the data also suggest that abrupt aridification starting about 2,000 BCE might have contributed to the shift of Neolithic cultures in northern China and likely triggered human migration and societal transformation during that time.
INFORMATION:
The results were published in PNAS in an article entitled "Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years."
This research was financially supported by the National Natural Science Foundation of China, the Belmont Forum and the Joint Programming Initiative-Climate, Collaborative Research Action.
ELSE PRESS RELEASES FROM THIS DATE:
2021-07-20
Tokyo, Japan - While researchers have known for years that immunoglobulin A (IgA) is important for gut health, it has remained unclear exactly what role it plays in preventing infection and disease. But now, researchers from Japan have found that eliminating IgA disrupts the balance of the intestinal ecosystem, making it susceptible to disease.
In a study published online in May in Gut, researchers from Tokyo Medical and Dental University (TMDU) have revealed that IgA deficiency results in substantial inflammation of the ileum, a specific part of the small intestine.
IgA is present in large quantities in the small intestine, where it helps protect the body against microorganisms that could potentially cross the lining of the gut to cause ...
2021-07-20
A new study by a team of researchers has found that the consolidation of traditional smallholder farms in China has a devastating effect on the biodiversity of wild pollinators in the area.
Pollinators play an essential role when it comes to supporting global food production.
However, wild pollinators are on the decline for several reasons, including the loss of floral resources and nesting sites. This loss of biodiversity could have far-reaching consequences for global food production in future.
"Biodiversity is essential for all life, with pollinators being one of the most important groups," says Dr Yi Zou from Xi'an Jiaotong-Liverpool ...
2021-07-20
CORVALLIS, Ore. - A 17-year study in Oregon, Washington and California found that removal of invasive barred owls arrested the population decline of the northern spotted owl, a native species threatened by invading barred owls and the loss of old-forest habitats.
The conservation and management of northern spotted owls became one of the largest and most visible wildlife conservation issues in United States history after the U.S. Fish and Wildlife Service listed the spotted owl as threatened under the Endangered Species Act in 1990 because of rapid declines in the owl's old-forest habitats. Four years later, the Northwest Forest Plan was adopted and reduced the rate of logging of old-growth forests on federal lands.
Despite more ...
2021-07-20
Tsukuba, Japan - Scientists from the department of Anatomy and Embryology at the Faculty of Medicine of the University of Tsukuba created a computer model to simulate the development of complex structures based on the Delta-Notch signaling pathway. This work may lead to a more comprehensive picture of the process that results in the formation of organs and other physiological systems.
The development of a tiny embryo consisting of undifferentiated cells into a healthy fetus with spatially defined organs depends on the complex interplay between genetic instructions and signaling molecules. For example, "Notch" genes are ...
2021-07-20
Berkeley -- More than 700 imaging satellites are orbiting the earth, and every day they beam vast oceans of information -- including data that reflects climate change, health and poverty -- to databases on the ground. There's just one problem: While the geospatial data could help researchers and policymakers address critical challenges, only those with considerable wealth and expertise can access it.
Now, a team based at the University of California, Berkeley, has devised a machine learning system to tap the problem-solving potential of satellite imaging, using low-cost, ...
2021-07-20
CATONSVILLE, MD, July 20, 2021 - Uber and Lyft are popular on-demand ways to travel, but does that mean trains and buses are a thing of the past? Travelers prefer different modes of transportation at different times. So how can all these modes co-exist and do so successfully? New research in the INFORMS Journal Transportation Science has created a model and an algorithm to redistribute transit resources based on commuter preferences resulting in millions in savings.
"Based on case study experiments in New York City, our optimized transit schedules consistently lead to 0.4%-3% system-wide cost reduction. This amounts to rush hour savings of millions of dollars per day, while simultaneously reducing costs to passengers and transportation service ...
2021-07-20
A team of chemists from the Croatian Ruđer Bošković Institute (RBI) described a new, easy-to-use method for uninterrupted monitoring of mechanochemical reactions. These reactions are conducted in closed milling devices, so in order to monitor the reaction one has to open the reaction vessel, thus interfering with the process. The new method uses Raman spectroscopy to get deeper insight into solid-state milling reactions, without the usual interruption of the chemical reaction process.
Mechanochemical synthesis by milling is used today to prepare all ...
2021-07-20
High school students who participated in summer programs about public health increased their interest in pursuing careers in science, technology, engineering and mathematics (STEM), according to a Rutgers study.
Published in the journalPedagogy in Health Promotion, the study explored whether increasing public health awareness would motivate high school students to pursue public health careers.
Researchers found that the summer program, Public Health: Outbreaks, Communities, and Urban Studies (PHocus) offered in 2018 and 2019 increased the students' knowledge in public health, epidemiology, urban public health and global public health.
"Including interdisciplinary, authentic ...
2021-07-20
ROCHESTER, Minn. ? Using data from 9,859 COVID-19 infections, Mayo Clinic researchers have new insights into risk factors for younger populations, some of which differ significantly from their older counterparts. People younger than 45 had a greater than threefold increased risk of severe infection if they had cancer or heart disease, or blood, neurologic or endocrine disorders, the research found. These associations were weaker in older age groups. The study was published in Mayo Clinic Proceedings.
The research team studied people living in a 27-county region of Southeast Minnesota and West Central Wisconsin surrounding Mayo Clinic in Rochester diagnosed with COVID-19 between March and ...
2021-07-20
In the largest study of its kind, an investigation by UC San Francisco has found no evidence that moderate coffee consumption can cause cardiac arrhythmia.
In fact, each additional daily cup of coffee consumed among several hundred thousand individuals was associated with a 3 percent lower risk of any arrhythmia occurring, including atrial fibrillation, premature ventricular contractions, or other common heart conditions, the researchers report. The study included a four-year follow up.
The paper is published July 19, 2021, in JAMA Internal Medicine.
"Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias," said senior and corresponding author Gregory Marcus, MD, professor ...
LAST 30 PRESS RELEASES:
[Press-News.org] Tree-ring records reveal Asian monsoon variability
