Early migrations of Siberians to America tracked using bacterial population structures

Early migrations of humans to the Americas from Siberia around 12,000 years ago have been traced using the bacteria they carried by an international team including scientists at the University of Warwick

UNIVERSITY OF WARWICK

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• International team used the stomach bacteria Helicobacter pylori as a biomarker for ancient human migrations
• DNA sequences catalogued at University of Warwick in EnteroBase, a public genomes database, demonstrate that a migration of Siberians to the Americas occurred approximately 12,000 years ago
• Project began in 2000s but new statistical techniques allowed researchers to reconstruct and date the migrations of Siberian Helicobacter pylori

Early migrations of humans to the Americas from Siberia around 12,000 years ago have been traced using the bacteria they carried by an international team including scientists at the University of Warwick.

Using samples of a stomach bacteria called Helicobacter pylori, which has shared a tight co-evolutionary relationship with humans for at least the past 100,000 years, analyses using new statistical techniques provide evidence that humans colonised the Americas through a pre-Holocene migration of evolutionarily ancient northern Eurasians across the Bering land bridge.

The study entitled "Helicobacter pylori's historical journey through Siberia and the Americas" is published this week (14 June) in the prestigious international journal Proceedings of the National Academy of Sciences of the USA (PNAS) by a team of researchers led by Professor Yoshan Moodley at the University of Venda, South Africa.

The research used genetic information on H. pylori catalogued in EnteroBase at the University of Warwick to trace the evolutionary history of the bacteria. H. pylori is a stomach bacteria that infects approximately half of individuals worldwide, but scientists have found that its genetic sequence also varies with the region that it is identified in.

Previous analyses had identified three populations of H. pylori from individuals in Eurasia and the Americas, and current data demonstrates that H. pylori from Siberia define additional previously unknown subpopulations of those groupings. The data also indicated one of these bacterial populations, which includes H. pylori from indigenous Americans, was distributed over the breadth of Siberia, suggesting that this population may have travelled with humans to the Americas at some point.

However, classical statistical analyses of the sequences were partially inconsistent with each other. To reconstruct the most likely evolutionary history for H. pylori in Siberia, researchers compared the most likely evolutionary models and timings using a technique called approximate Bayesian computation (ABC). The results showed that a tiny population of H. pylori colonised the Americas in a single migration event approximately 12,000 years ago.

Professor Mark Achtman of Warwick Medical School at the University of Warwick, senior co-author on the paper, said: "This project began in the early 2000s, when nothing was known about the genetic diversity of Helicobacter pylori in central Asia. By 2007, hundreds of Siberian H. pylori strains had been cultivated and selected genes had been sequenced. But repeated attempts by multiple talented population geneticists failed to shed light on their evolutionary history.

"This study now uses the powerful approach of ABC statistics to reconstruct and date the migrations of Siberian H. pylori (and their human hosts) across Siberia and to the Americas."

Originally, all modern humans came from Africa. About 60,000 years ago small groups of hunter-gatherers left Africa on foot and made their way into Eurasia where they settled. These were the world's first human immigrants. Astonishingly, by the end of the ice age some 50,000 years later, modern humans had already reached the American continent which, if travelling over land, is almost as far away from Africa as it is possible to get.

These ancient human migrations took place during the last glacial period, or ice age, which lasted from 115,000 to 11,700 years ago. At that time, most of northern Eurasia, also known as Siberia, would have been a frozen wasteland, and presumably inhospitable to long-term human settlement. So how then, did humans manage to migrate across this vast region and find their way to North America? This is one of the most important, and as yet unanswered, questions in human prehistory, because it would explain how humans were able to colonise the whole world from an African origin, in such a short space of time.

The team took the unusual approach of using the DNA of a human stomach bacterium named Helicobacter pylori as a biomarker for ancient human migrations. They successfully collected, sequenced and analysed bacterial strains from indigenous people across Siberia and the Americas. The bacterial DNA sequence database they generated suggested that, remarkably, some groups of humans, known as ancient northern Eurasians, did manage to reside in Siberia throughout the bitter ice age. Yet, other human groups who originally inhabited warmer latitudes in Asia, colonised Siberia after the end of the ice age, leading to the complex mix of human populations we see in that region today.

The team also used their bacterial data set to model human migration into the Americas. It is important to remember that during the ice age, much more water was frozen at the earth's poles, making the sea level at that time over 100 metres lower than the present-day sea level, thus exposing a land bridge between Eurasia and North America and allowing human migration. The team showed that one small group of ancient northern Eurasians managed to successfully cross this land bridge about 12,000 years ago, and this population subsequently expanded to give rise to the indigenous Americans we see today.

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* 'Helicobacter pylori's historical journey through Siberia and the Americas' will be published in Proceedings of the National Academy of Sciences, Link: https://www.pnas.org/cgi/doi/10.1073/pnas.2015523118

* This research involved an international team of researchers from the University of Venda, University of Ferrara, Research Institute for Physical-Chemical Medicine (Moscow), Pirogov National Medical and Surgical Center (Moscow), University of Warwick, Instituto Politécnico Nacional (Mexico City), University of Cambridge and Friedrich Alexander University Erlangen-Nuremberg

Study finds lightning impacts edge of space in ways not previously observed

Solar flares jetting out from the sun and thunderstorms generated on Earth impact the planet's ionosphere in different ways, which have implications for the ability to conduct long range communications

UNIVERSITY OF CENTRAL FLORIDA

Research News

 

Solar flares jetting out from the sun and thunderstorms generated on Earth impact the planet's ionosphere in different ways, which have implications for the ability to conduct long range communications.

A team of researchers working with data collected by the Incoherent Scatter Radar (ISR) at the Arecibo Observatory, satellites, and lightning detectors in Puerto Rico have for the first time examined the simultaneous impacts of thunderstorms and solar flares on the ionospheric D-region (often referred to as the edge of space).

In the first of its kind analysis, the team determined that solar flares and lightning from thunderstorms trigger unique changes to that edge of space, which is used for long-range communications such the GPS found in vehicles and airplanes.

The work, led by New Mexico Tech assistant professor of physics Caitano L. da Silva was published recently in the journal Scientific Reports, a journal of the Nature Publishing Group.

"These are really exciting results," says da Silva. "One of the key things we showed in the paper is that lightning- and solar flare-driven signatures are completely different. The first tends to create electron density depletions, while the second enhancements (or ionization)."

While the AO radar used in the study is no longer available because of the collapse of AO's telescope in December of 2020, scientists believe that the data they collected and other AO historical data will be instrumental in advancing this work.

"This study helps emphasize that, in order to fully understand the coupling of atmospheric regions, energy input from below (from thunderstorms) into the lower ionosphere needs to be properly accounted for," da Silva says. "The wealth of data collected at AO over the years will be a transformative tool to quantify the effects of lightning in the lower ionosphere."

Better understanding the impact on the Earth's ionosphere will help improve communications.

da Silva worked with a team of researchers at the Arecibo Observatory (AO) in Puerto Rico, a National Science Foundation facility managed by the University of Central Florida under a cooperative agreement. The co-authors are AO Senior Scientist Pedrina Terra, Assistant Director of Science Operations Christiano G. M. Brum and Sophia D. Salazar a student at NMT who spent her 2019 summer at the AO as part of the NSF- supported Research Undergraduate Experience. Salazar completed the initial analysis of the data as part of her internship with the senior scientists' supervision.

"The Arecibo Observatory REU is hands down one of the best experiences I've had so far," says the 21-year-old. "The support and encouragement provided by the AO staff and REU students made the research experience everything that it was. There were many opportunities to network with scientists at AO from all over the world, many of which I would likely never have met without the AO REU."

AO's Terra and Brum worked with Salazar taking her initial data analysis, refining it and providing interpretation for the study.

"Sophia's dedication and her ability to solve problems grabbed our attention from the very first day of the REU program," Brum says. "Her efforts in developing this project resulted in publication in one of the most prestigious journals in our field."

"Another remarkable result of this work is that for the first time, a mapping of the spatial and seasonal occurrence of lightning strike over the region of the Puerto Rico archipelago is presented," Brum says. "Intriguing was also the detection of a lighting activity hotspot concentrated in the western part of La Cordillera Central mountain range of Puerto Rico."

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About the authors:

da Silva conducts research in the area of atmospheric sciences, geophysics, and plasma physics. He's intrigued by space electricity; thunderstorms and their effects in the near-Earth space environment; lightning physics; modeling of electrical discharge plasmas; and development of computer-based tools for analysis of atmospheric and geophysical phenomena. He holds multiple degrees including a doctorate in electrical engineering from Penn State University and a master's degree in geophysics and space physics from the National Institute for Space Research (INPE) in Brazil, which is the same alma mater of Brum and Terra. The three INPE alumni had a brief brainstorming session over coffee about this project in the AGU 2018 Fall Meeting, in San Francisco, CA.

Terra who worked at AO since 2006, was a post-doctoral scholar at Cornell University. She has multiple degrees including an electrical engineering degree and both master's and doctorate in space physics from the INPE Research in Brazil. Terra is a UCF's graduate faculty member and is the responsible for the passive optical laboratories at AO, including the remote facility at the island of Culebra.

Brum has been working at AO since 2007 and was a post-doctoral scholar at INPE, Utah State University, and Cornell University. He holds multiple degrees including a master's and a doctorate degree in space geophysics from the INPE. Brum is the head of the AO Space and Atmospheric department, Deputy Director of Science Operations, and a UCF graduate faculty member.

Eco-friendly smart farms based on nutrient solution recirculation

UV sterilization and microbial stability analysis used to recycle nutrient solution; proposed method minimizes the use fertilizers and water by hydroponic farms

NATIONAL RESEARCH COUNCIL OF SCIENCE & TECHNOLOGY

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IMAGE: THE INTEGRATED MODEL DESCRIPTION. view more 

CREDIT: KOREA INSTITUTE OF SCIENCE AND TECHNOLOGY(KIST)

The development of new urban agriculture technologies, such as vertical and smart farms, has accelerated rapidly in recent years. These technologies are based on hydroponic cultivation in which plants are grown using nutrient-rich solutions rather than soil. Approximately 20-30% of the nutrient solutions used during hydroponic cultivation are discharged without being absorbed by the crops, and because most farmers in South Korea do not treat the discharged solutions, hydroponic farms contribute significantly to environmental pollution.

This problem can be reduced if hydroponic farms use a recirculating hydroponic cultivation method that reuses the nutrient solutions after sterilizing them with ultraviolet (UV) light, instead of discharging them. However, two main issues complicate the implantation of such recirculation systems. First, the potential for diseases and nutrient imbalances to develop owing to microbial growth in the recycled nutrient solutions must be eliminated. Second, the initial investment required to set up a recirculating hydroponic cultivation system is often prohibitive, costing hundreds of millions of Korean won per hectare.

However, a new study conducted by researchers at the Korea Institute of Science and Technology (KIST)proposes a method that can stably manage the microbial population in recirculating hydroponic cultivation systems. The research team, led by Drs. Ju Young Lee and Tae In Ahn of the Smart Farm Research Center, KIST Gangneung Institute of Natural Products, conducted an integrated analysis of the microbial growth characteristics by constructing a model that simulates the flow of water and nutrients, and the inflow, growth, and discharge of microorganisms in recirculating and non-circulating hydroponic cultivation systems. Their simulations revealed that the microbial population in recirculating hydroponic cultivation systems can be controlled by adjusting the UV output and the water supply. On the contrary, in non-circulating hydroponic cultivation, the microbial population fluctuates considerably depending on the amount of water used, increasingly sharply if there is too little water.

High cost has restricted the use of UV sterilization systems in hydroponic farming in Korea And prompted the research team to develop their own UV sterilization system, with further studies underway to commercialize this system as an economical alternative to imported systems.

The results of the study have already received strong interest: the rights to the operation and management software technology for recirculating hydroponic cultivation has been acquired by Dooinbiotech Co., Ltd. for an advance fee of 80 million won (8.5% of the operating revenue), while an agreement is in place with Shinhan A-Tec Co., Ltd. for the advanced recirculating hydroponic cultivation technology for an advance fee of 200 million won (1.5% of the operating revenue). Commercializing the recirculating hydroponic cultivation system is expected to reduce fertilizer costs by approximately 30~40%, which equates to 30 million won per year based on a 1-hectare farm.

Commenting on the envisaged impacts of the study, Dr. Ju Young Lee said, "The developed system makes the transition to eco-friendly recirculating hydroponic cultivation systems an affordable option for many more farmers." Dr. Tae In Ahn added, "We are also developing software and operation manuals to guide farmers in managing the nutrient balance in the solutions to increase the number of farms using the recirculating hydroponic cultivation system."

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The study was supported by the Ministry of Agriculture, Food, and Rural Affairs (Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry) and the Innovative Smart Farm Technology Development Program of Multi-agency Package. The research results are published in the latest issue of the Journal of Cleaner Production (IF: 7.24, ranked in the top 6.9% by JCR), a highly respected international journal in the field of environmental science.

 

Human-driven climate change only half the picture for krill

UNIVERSITY OF COLORADO AT BOULDER

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IMAGE: ANTARCTIC KRILL, EUPHAUSIA SUPERBA. view more 

CREDIT: UWE KILS / WIKIPEDIA

In the heart of their Antarctic habitat, krill populations are projected to decline about 30% this century due to widespread negative effects from human-driven climate change. However, these effects on this small but significant species will be largely indistinguishable from natural variability in the region's climate until late in the 21st century, finds new University of Colorado Boulder research.

Published today in Frontiers in Marine Science, the study has important implications for not only the local food web, but for the largest commercial fishery in the Southern Ocean: A booming $2 billion fish oil industry, sold as Omega-3 supplements in retail giants like Costco.

"Krill are what links the ecosystem together," said Zephyr Sylvester, lead author on the paper and graduate student in environmental studies. "They're really important to the Southern Ocean for pretty much every predator species."

Because these tiny animals live in one of the most sensitive areas in the world to climate change, explicitly separating trends associated with human-driven warming from those arising naturally in krill habitat is a crucial step for planning and mapping harvest limits.

This study is also the first of its kind to use a group of climate models to demonstrate that climate change has the potential to dramatically alter Antarctic marine ecosystems, but that natural climate variability can obscure human-driven trends.

Small but significant

Krill are about 2.5 inches (6 cm) long, fast swimming zooplankton that live in large groups. They're key to the region's food chain, eaten by just about everything that lives in the waters surrounding Antarctica: Penguins, seals, fish and whales, some of which are still recovering from overharvesting in previous centuries.

But while they are one of the most abundant species on Earth--their total biomass estimated at 300 to 500 million tons--krill can only survive in a narrow temperature range and are strongly affected by variables in their underwater environment.

Currently, fishing in the Southern Ocean is managed by the Convention on the Conservation of Antarctic Marine Living Resources, known as CCAMLR (pronounced "cam-ah-lar"), an international body established as part of the Antarctic Treaty System.

The first item on their agenda? Krill. Yet 40 years after their founding, their catch limits on this creature are still only set using a stock assessment that does not account for natural environmental variability or climate change impacts.

While today there is widespread international recognition of the importance of understanding the impacts of climate change on this marine ecosystem, knowing how the climate naturally varies is an important prerequisite, according to Sylvester.

"The thing that we really have to understand is: Is there enough krill to feed everything that needs to eat it in the Southern Ocean, as well as humans?" said Cassandra Brooks, co-author on the paper and assistant professor of environmental studies. "My hope is that we can take this as a first step to understanding how to manage krill better."

What is natural variability?

Every environment on Earth naturally varies a bit each year in its weather, temperature and precipitation. For example, some winters in Colorado have more snowfall, some have less. Some will be a bit warmer, some colder. Human-driven climate change aside, each year in the state has a unique pattern of precipitation and temperature due to natural variability.

But separating the effects of human-driven climate change from natural changes in a region is no easy task. To be able to pull apart the variables affecting the Southern Ocean over this century, the researchers ran a larger group of models many times, known as a large ensemble earth system model. It's the first time this has been done for the Southern Ocean and for krill.

"Then we were able to look at the different trends and quantify how much the natural variability was masking the signal for climate change," said Sylvester.

This research addresses one of the biggest disconnects between scientists and fishery managers: understanding and communicating uncertainty. By being able to quantify how much change is likely to occur from natural variability, and separately from climate change, it allows everyone involved to plan better for the future and sustain krill for those who depend on it, according to Brooks.

"Even if we won't see this really strong signal from climate change until later, what's important for us to understand is that the Southern Ocean is a very dynamic system and we absolutely have to be managing for natural variability," said Brooks. "And we should be ready to manage for the broader impacts of climate change."

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Matthew Long at the National Center for Atmospheric Research is a co-author on this publication.

Microbes in ocean play important role in moderating Earth's temperature

Methane-eating microbes help regulate Earth's temperatures with remarkably high metabolic rates within seafloor carbonate rocks

HARVARD UNIVERSITY, DEPARTMENT OF ORGANISMIC AND EVOLUTIONARY BIOLOGY

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IMAGE: TWO VIEWS OF THE CARBONATE CHIMNEYS AT THE POINT DUME METHANE SEEP OFF SOUTHERN CALIFORNIA ARE COVERED WITH COLORFUL MICROBIAL MATS AND PERMEATED BY METHANE-EATING MICROBES. view more 

CREDIT: COURTESY OF COURTESY OF THE SCHMIDT OCEAN INSTITUTE (PERMISSION TO USE WITH PROPER CITATION)

Methane is a strong greenhouse gas that plays a key role in Earth's climate. Anytime we use natural gas, whether we light up our kitchen stove or barbeque, we are using methane.

Only three sources on Earth produce methane naturally: volcanoes, subsurface water-rock interactions, and microbes. Between these three sources, most is generated by microbes, which have deposited hundreds of gigatons of methane into the deep seafloor. At seafloor methane seeps, it percolates upwards toward the open ocean, and microbial communities consume the majority of this methane before it reaches the atmosphere. Over the years, researchers are finding more and more methane beneath the seafloor, yet very little ever leaves the oceans and gets into the atmosphere. Where is the rest going?

A team of researchers led by Jeffrey J. Marlow, former postdoctoral researcher in Organismic and Evolutionary Biology at Harvard University, discovered microbial communities that rapidly consume the methane, preventing its escape into Earth's atmosphere. The study published in Proceedings of the National Academy of Sciences collected and examined methane-eating microbes from seven geologically diverse seafloor seeps and found, most surprisingly, that the carbonate rocks from one site in particular hosts methane-oxidizing microbial communities with the highest rates of methane consumption measured to date.

"The microbes in these carbonate rocks are acting like a methane bio filter consuming it all before it leaves the ocean," said senior author Peter Girguis, Professor of Organismic and Evolutionary Biology, Harvard University. Researchers have studied microbes living in seafloor sediment for decades and know these microbes are consuming methane. This study, however, examined microbes that thrive in the carbonate rocks in great detail.

Seafloor carbonate rocks are common, but in select locations, they form unusual chimney-like structures. These chimneys reach 12 to 60 inches in height and are found in groups along the seafloor resembling a stand of trees. Unlike many other types of rocks, these carbonate rocks are porous, creating channels that are home to a very dense community of methane-consuming microbes. In some cases, these microbes are found in much higher densities within the rocks than in the sediment.

During a 2015 expedition funded by the Ocean Exploration Trust, Girguis discovered a carbonate chimney reef off the coast of southern California at the deep sea site Point Dume. Girguis returned in 2017 with funding from NASA to build a sea floor observatory. Upon joining Girguis's lab, Marlow, currently Assistant Professor of Biology at Boston University, was studying microbes in carbonates. The two decided to conduct a community study and gather samples from the site.

"We measured the rate at which the microbes from the carbonates eat methane compared to microbes in sediment," said Girguis. "We discovered the microbes living in the carbonates consume methane 50 times faster than microbes in the sediment. We often see that some sediment microbes from methane-rich mud volcanoes, for example, may be five to ten times faster at eating methane, but 50 times faster is a whole new thing. Moreover, these rates are among the highest, if not the highest, we've measured anywhere."

"These rates of methane oxidation, or consumption, are really extraordinary, and we set out to understand why," said Marlow.

The team found that the carbonate chimney sets up an ideal home for the microbes to eat a lot of methane really fast. "These chimneys exists because some methane in fluid flowing out from the subsurface is transformed by the microbes into bicarbonate, which can then precipitate out of the seawater as carbonate rock," said Marlow. "We're still trying to figure out where that fluid - and its methane - is coming from."

The micro-environments within the carbonates may contain more methane than the sediment due to its porous nature. Carbonates have channels that are constantly irrigating the microbes with fresh methane and other nutrients allowing them to consume methane faster. In sediment, the supply of methane is often limited because it diffuses through smaller, winding channels between mineral grains.

A startling find was that, in some cases, these microbes are surrounded by pyrite, which is electrically conductive. One possible explanation for the high rates of methane consumption is that the pyrite provides an electrical conduit that passes electrons back and forth, allowing the microbes to have higher metabolic rates and consume methane quickly.

"These very high rates are facilitated by these carbonates which provide a framework for the microbes to grow," said Girguis. "The system resembles a marketplace where carbonates allow a bunch of microbes to aggregate in one place and grow and exchange - in this case, exchange electrons - which allows for more methane consumption."

Marlow agreed, "When microbes work together they're either exchanging building blocks like carbon or nitrogen, or they're exchanging energy. And one kind of way to do that is through electrons, like an energy currency. The pyrite interspersed throughout these carbonate rocks could help that electron exchange happen more swiftly and broadly."

In the lab, the researchers put the collected carbonates into high pressure reactors and recreated conditions on the sea floor. They gave them isotopically labeled methane with added Carbon-14 or Deuterium (Hydrogen-2) in order to track methane production and consumption. The team next compared the data from Point Dume to six additional sites, from the Gulf of Mexico to the coast of New England. In all locations, carbonate rocks at methane seeps contained methane-eating microbes.

"Next we plan to disentangle how each of these different parts of the carbonates - the structure, electrical conductivity, fluid flow, and dense microbial community - make this possible. As of now, we don't know the exact contribution of each," said Girguis.

"First, we need to understand how these microbes sustain their metabolic rate, whether they're in a chimney or in the sediment. And we need to know this in our changing world in order to build our predictive power," said Marlow. "Once we clarify how these many interconnected factors come together to turn methane to rock, we can then ask how we might apply these anaerobic methane-eating microbes to other situations, like landfills with methane leaks."

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New health benefits of red seaweeds unveiled

CARL R. WOESE INSTITUTE FOR GENOMIC BIOLOGY, UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN

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IMAGE: RED SEAWEEDS CONTAIN SUGARS, SUCH AS AGAROTRIOSE (AGADP3) AND 3,6-ANHYDRO-L-GALACTOSE (AHP), THAT STIMULATE THE GROWTH OF PREBIOTIC BACTERIA AND CAUSE APOPTOSIS IN HUMAN COLON CANCER CELLS. view more 

CREDIT: EUN JU YUN

Red seaweeds have been prevalent in the diets of Asian communities for thousands of years. In a new study, published in Marine Drugs, researchers have shown how these algae confer health benefits.

"In the past, people have wondered why the number of colon cancer patients in Japan is the lowest in the world," said Yong-Su Jin (CABBI/BSD/MME), a professor of food microbiology. "Many assumed that it was due to some aspect of the Japanese diet or lifestyle. We wanted to ask whether their seaweed diet was connected to the lower frequency of colon cancer."

Although several studies have shown that Asians who eat seaweed regularly have lower risk of colon, colorectal, and breast cancer, it was unclear which component was responsible for the anti-cancer effects.

In the study, the researchers broke down the structure of different types of red seaweed using enzymes and tested the sugars that were produced to see which one of them caused health benefits. Among the six different sugars produced, agarotriose and 3,6-anhydro-L-galactose, or AHG, showed the most promise.

"After we produced these sugars, we tested their prebiotic activity using the bacteria Bifidobacterium longum ssp. infantis," said Eun Ju Yun, a former postdoctoral researcher at the Carl R. Woese Institute for Genomic Biology. B. infantis is a probiotic bacterium; it colonizes the gut of infants and provides health benefits. Among the seaweed-derived sugars, the bacteria could only consume agarotriose, indicating that it works as a prebiotic i.e., it improves the growth of probiotic bacteria.

"We also tested another strain, B. kashiwanohense, and found that it also consumed agarotriose," Jin said. "These results show us that when we eat red seaweed, it gets broken down in the gut and releases these sugars which serve as food for the probiotic bacteria. It could help explain why Japanese populations are healthier compared to others."

The researchers also tested the sugars to see if they had any anti-cancer activity. "We found that AHG specifically inhibits the growth of human colon cancer cells and does not affect the growth of normal cells," Yun said. The anti-cancer activity of AHG is due to its ability to trigger apoptosis or cell death.

"There is a lot of information on how red seaweeds are degraded by microorganisms in the ocean and in the human body," said Kyoung Heon Kim, a professor of biotechnology and the co-advisor on the paper. "Our work explains why red seaweeds are beneficial by providing the molecular mechanism. We will continue studying their function in animal models and hopefully we will be able to use them as a therapeutic agent in the future."

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The paper "In vitro prebiotic and anti-colon cancer activities of agar-derived sugars from red seaweeds" can be found at 10.3390/md19040213. The work was funded by the Mid-career Researcher Program through the National Research Foundation (NRF) of Korea; by the Ministry of Oceans and Fisheries, Korea; by the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry, and Fisheries (iPET); and by the Brain Pool Program through the Korean Federation of Science and Technology Societies.

New research finds 1M deaths in 2017 attributable to fossil fuel combustion

Contemporary and comprehensive evaluation of source sector and fuel contributions to the PM2.5 disease burden across over 200 countries

WASHINGTON UNIVERSITY IN ST. LOUIS

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IMAGE: MAP: NATIONALLEVEL OUTDOOR PM2.5 DISEASE BURDEN IN 2017 (FROM THE 2019 GLOBAL BURDEN OF DISEASE CONCENTRATION-RESPONSE RELATIONSHIPS). PANELS: ANNUAL AVERAGE POPULATION-WEIGHTED PM2.5 EXPOSURE LEVELS AND ATTRIBUTABLE MORTALITY (ROUNDED TO THE NEAREST... view more 

CREDIT: LAB OF RANDALL MARTIN

An interdisciplinary group of researchers from across the globe has comprehensively examined the sources and health effects of air pollution -- not just on a global scale, but also individually for more than 200 countries.

They found that worldwide, more than one million deaths were attributable to the burning of fossil fuels in 2017. More than half of those deaths were attributable to coal.

Findings and access to their data, which have been made public, were published today in the journal Nature Communications.

Pollution is at once a global crisis and a devastatingly personal problem. It is analyzed by satellites, but PM2.5 -- tiny particles that can infiltrate a person's lungs -- can also sicken a person who cooks dinner nightly on a cookstove.

"PM2.5 is the world's leading environmental risk factor for mortality. Our key objective is to understand its sources," said Randall Martin, the Raymond R. Tucker Distinguished Professor in the Department of Energy, Environmental & Chemical Engineering at Washington University in St. Louis.

Martin jointly led the study with Michael Brauer, a professor of public health at the University of British Columbia. They worked with specific datasets and tools from the Institute for Health Metrics and Evaluation at the University of Washington, the Joint Global Change Research Institute at the University of Maryland and Pacific Northwest National Laboratory, as well as other researchers from universities and organizations across the world, amassing a wealth of data, analytical tools and brainpower.

First author Erin McDuffie, a visiting research associate in Martin's lab, used various computational tools to weave the data together, while also enhancing them. She developed a new global dataset of air pollution emissions, making it the most comprehensive dataset of emissions at the time. McDuffie also brought advances to the GEOS-Chem model, an advanced computational tool used in the Martin lab to model specific aspects of atmospheric chemistry.

With this combination of emissions and modeling, the team was able to tease out different sources of air pollution -- everything from energy production to the burning of oil and gas to dust storms.

This study also used new techniques to remote sensing from satellites in order to assess PM2.5 exposure across the globe. The team then incorporated information about the relationship between PM2.5 and health outcomes from the Global Burden of Disease with these exposure estimates to determine the relationships between health and each of the more than 20 distinct pollution sources.

As McDuffie put it: "How many deaths are attributable to exposure to air pollution from specific sources?"

Ultimately, the data reinforced much of what researchers already suspected, particularly on a global scale. It did offer, however, quantitative information in different parts of the world, teasing out which sources are to blame for severe pollution in different areas.

For instance, cookstoves and home-heating are still responsible for the release of particulate matter in many regions throughout Asia and energy generation remains a large polluter on the global scale, McDuffie said.

Apples to apples One unique aspect of this research is its use of the same underlying datasets and methodology to analyze pollution on different spatial scales.

"Previous studies end up having to use different emissions data sets or models all together," said first author Erin McDuffie. In those instances, it is difficult to compare results in one place versus another.

"We can more directly compare results between countries," McDuffie said. "We can even look at pollution sources in places that have implemented some mitigation measures, versus others that haven't to get a more complete picture of what may or may not be working."

And natural sources play a role, as well. In West sub-Saharan Africa in 2017, for instance, windblown dust accounted for nearly three quarters of the particulate matter in the atmosphere, compared with the global rate of just 16 percent. The comparisons in this study are important when it comes to considering mitigation.

"Ultimately, it will be important to consider sources at the subnational scale when developing mitigation strategies for reducing air pollution," McDuffie said.

Martin and McDuffie agreed that, while a takeaway from this work is, simply put, air pollution continues to sicken and kill people, the project also has positive implications.

Although pollution monitoring has been increasing, there are still many areas that do not have the capability. Those that do may not have the tools needed to determine, for instance, how much pollution is a product of local traffic, versus agricultural practices, versus wildfires.

"The good news is that we may be providing some of the first information that these places have about their major sources of pollution," McDuffie said. They may otherwise not have this information readily available to them. "This provides them with a start."

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Rocky Mountain subalpine wildfires higher now than past 2,000 years

By Rachel Ramirez 

CNN


Following a devastating wildfire season in 2020, new research shows that high-elevation forests in the Rocky Mountains are burning more now than any time in the past 2,000 years amid extreme, climate change-induced drought.

© Canyon Lakes Ranger RD Canyon Lakes Ranger RD shared photos from one of their firefighters of the Cameron Peak fire taken on August 13.

The study, published Monday in the Proceedings of the National Academy of Sciences, concluded that fire activity in subalpine forests of northern Colorado and southern Wyoming is unprecedented in the last several millennia -- a clear signal that the climate crisis is increasing the severity and extent of wildfires in the West.

Rising temperatures and prolonged drought in the West will continue to exacerbate and accelerate wildfire activity for at least several decades, scientists say. Philip Higuera, lead author of the study and fire ecology professor at the University of Montana, told CNN last year's wildfire season was a game changer.

"After 2020, it's clear we're in uncharted territory," Higuera said. "People are being negatively impacted by these wildfires either directly or indirectly. Climate models suggest that this trend is only set to continue."

The current drought sets the stage for another brutal fire season in 2021, particularly in California where rainfall deficits and dead vegetation are already breaking records that scientists didn't expect until August, Higuera said.

The 2020 wildfire season pushed Higuera and his colleagues to analyze historical fire records to understand how 21st century activity differs from the past. In addition to historical records, they also used charcoal found in lake sediments around the subalpine forests -- or high-elevation forests -- to compare how often fires have occurred in the area on average in the last two millennia.

Higuera's team found that last year's wildfires accounted for 72 percent of the total charred area in the subalpine forests since 1984. They also found the current rate of burning is 22 percent higher than the maximum average rate over the past 2,000 years -- a period of time the temperature in the Northern Hemisphere was actually slightly higher than it was during the 20th century.

The study's authors say the increase is a particularly significant climate impact, since subalpine forests typically burn less frequently than lower elevation forests.

Higuera called the results "sobering."

"Understanding how ecosystems have changed in the past is one of our best ways to learn more about how our forests change as climate changes," Higuera said. "Studying the past is so important because it really helps highlight the degree to which we are changing the landscapes that we live in now."

Jennifer Marlon, a climate scientist at the Yale School of the Environment who was not involved with the study, said these results suggest the seasons are shifting.

"When you get extreme heat and drought together, that's a recipe for really severe wildfires," Marlon told CNN. "The fingerprints of global warming are all over this kind of fire behavior."

Concerningly, Higuera said, what has worked to prevent wildfires at low elevations -- controlled burns -- is not an easy solution for subalpine forests.

"In lower elevation forests, it's an easier proposition to say we need to return prescribed fire to these forests to help get them back to conditions similar to how they were before fire suppression," Higuera said. "It's not as feasible in high elevation forests."

"Fire managers are faced with challenging decisions," he added, "whether having to modify the way that fire exists in these systems versus accepting these high severity fires, which is hard when they burn close to human communities."

Forests are vital to addressing the most dire effects of the climate crisis. They not only protect biodiversity, but also absorb and store carbon dioxide emitted from human activities. But as wildfires worsen, the carbon stored in these forests is increasingly released back into the atmosphere, an impact compounded by bad air quality.

Scientists say that forest ecosystems including the subalpine in the Rocky Mountains could soon reach a tipping point unless climate change is addressed. But Higuera warns that the solution isn't to eliminate fire from management systems because it has historically been part of the life cycle of forests.

"One of the challenges of living in the West is that we know that fire is an important component on these landscapes," he said. "If we remove it, that will take away a lot of the things we've come to expect such as species composition. The challenge for us is to be able to learn how to live with fire on the landscapes in ways that do not turn into human disasters."

Climate change leads to unprecedented Rocky Mountain wildfires

UNIVERSITY OF WYOMING

Research News

 

IMAGE: THE MULLEN FIRE LOOMS NEAR A PROPERTY IN CENTENNIAL, WYO., LAST FALL. BRYAN SHUMAN, A PROFESSOR IN UW'S DEPARTMENT OF GEOLOGY AND GEOPHYSICS, WAS A MAIN CO-AUTHOR OF A PAPER,... view more 

CREDIT: JASON SHOGREN

June 14, 2021 - Last fall, the Mullen fire west of Laramie raged for the better part of two months, burning more than 176,000 acres and 70 structures in Wyoming's Carbon and Albany counties, and in Jackson County, Colo.

Unfortunately, this scenario was typical during the intense 2020 fire season in the Rocky Mountain region, an area of Colorado and southern Wyoming where high-elevation forests are burning more than at any point in the past 2,000 years, according to a study in which a University of Wyoming faculty member was instrumental.

"Global warming is causing larger fires in Rocky Mountain forests than have burned for thousands of years," says Bryan Shuman, a professor in the UW Department of Geology and Geophysics. "The last time anything similar may have occurred was during a warm portion of the medieval era."

Shuman was the main co-author of a paper, titled "Rocky Mountain Subalpine Forests Now Burning More Than Any Time in Recent Millennia," that was published today (June 14) in the Proceedings of the National Academy of Sciences (PNAS). The journal is one of the world's most prestigious multidisciplinary scientific serials, with coverage spanning the biological, physical and social sciences.

Philip Higuera, a professor of fire ecology in the W.A. Franke College of Forestry and Conservation at the University of Montana, was the paper's lead author. Kyra Wolf, a Ph.D. candidate in paleoecology and forest ecology at the University of Montana, also contributed to the paper.

Higuera and Shuman conceived and designed the study, while Higuera and Wolf analyzed the data, a unique network of fire-history records, to understand how current fire activity compared to wildfires of the past. The 2020 fire season marks the emergence of 21st century fire regimes with distinctly higher rates of burning, not only from the late 20th century but relative to the past two millennia.

By November 2020, wildfires in southern Wyoming and northern Colorado were responsible for 72 percent of the total area burned in high-elevation, subalpine forests since 1984. During 2020, Colorado had experienced three of its largest fires on record.

"As the 2020 fire season unfolded, we realized we already had a well-defined understanding of the fire history of many of the places burning, based on over 20 lake sediment records our teams had collected over the past 15 years," Higuera says. "When the smoke settled, we thought 'Wow, we may have witnessed something truly unprecedented here.' So, we combined the existing records for the first time and compared them to recent fire activity. To our surprise, 2020 indeed pushed fire activity outside the range of variability these forests have experienced over at least the past two millennia."

Researchers used charcoal found in lake sediment records to assemble the fire history across the Rocky Mountains. They discovered that, since 2000, wildfires are burning nearly twice as much area, on average, compared to the last 2,000 years.

Over that 2,000-year period, fires in high-elevation, subalpine forest historically burned, on average, once every 230 years. In the 21st century, those fires now occur, on average, every 117 years. This is 22 percent higher than the maximum rate -- which took place during the Medieval Climate Anomaly (770-870) -- reconstructed over the past two millennia. During the Medieval Climate Anomaly, Northern Hemisphere temperatures were 0.3 degrees Celsius above the average in the 20th century.

"The results indicate that, if fires continue to burn as often as they do now, every forest in the region could be burned by the beginning of the next century," Shuman explains. "In the past, it would have taken 200 to 300 years, if not longer, for fires to affect that much area."

In the Rocky Mountains of northern Colorado and southern Wyoming, 840,000 acres burned between 1984 and 2019, Shuman says. Another 660,000 acres burned in 2020 alone. Approximately 1.1 million acres burned in the past decade in the Colorado-Wyoming study area, even though only 400,000 acres -- less than half as much -- burned in the previous 25 years, Shuman says.

Subalpine forests are becoming less resilient and more susceptible to fires because the climate is warming. Because humidity was extremely low, temperatures were high, and storm events produced high winds, forest management had little impact on the 2020 fires. They burned designated wilderness and national parks with limited fuel management; heavily managed areas with substantial timber removal; and intact forest and areas with extensive beetle kill. The extreme climate completely overrode all types of forest management, according to Shuman.

"Snowfall in our high-elevation forests is lower now than in past decades, and summers are hotter. The changes convert trees into dry fuel, primed and ready to burn," Shuman says. "With less snow now, the fire season lasts longer than before. When areas burn, the fires are bigger. They can burn longer.

"Then, after the fires, big areas with few live trees mean few seeds to help forests regrow and, even when seeds are plentiful, seedlings can often die from drought and heat," he continues. "Some forests may never grow back."

"It isn't unexpected to have more fires as temperatures rise. Our records show that fire tracked past variations in climate just as it does today," Wolf adds. "What's striking is that temperatures and, correspondingly, fire are now exceeding the range that these forests have coped with for thousands of years -- largely as a result of human-caused climate change."

Continual warming will reinforce newly emerging fire activity in these high-elevation forests, with significant implications for ecosystems and society, according to the paper.

"It may sound dire, but it's critical to remember that we have ample opportunities to limit or reverse climate warming, while still working to adapt to the increasing fire activity expected in upcoming decades," Higuera says.

Shuman helped plan the study, which came about because of more than $600,000 in grants he was able to obtain from the National Science Foundation to support undergraduate and graduate student research at UW.

"We were able to examine the 2020 fire season because of a decade of student projects at UW that revealed how often our forests have burned in the past few thousand years," Shuman says.

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