The soil beneath our feet is not as biologically diverse as scientists previously thought, according to a research team that includes a Virginia Tech soil microbial ecologist.
Leftover DNA from dead organisms — known as “relic DNA” — has historically thrown a wrench into estimates, causing scientists to overestimate microbial diversity by as much as 55 percent. Understanding microbial diversity in soil is crucial for understanding how environmental processes like atmospheric nitrogen fixation and climate change occur.
But a team that includes Michael Strickland, an assistant professor of biological sciences in the College of Science, used a high throughput sequencing technique to determine the exact make-up of 31 soil samples from varying climates and ecosystems.
“When we started to realize that our numbers could be off, we knew we had to find a way to take a closer look at how many species are actually there,” said Strickland, who is also affiliated with the university’s Global Change Center and the Fralin Life Science Institute.
Information about populations of microbes in soil is important because these organisms play critical roles in the terrestrial ecosystem and they help maintain soil fertility.
But linking the activities of microbes to soil processes is difficult. Scientists need to measure living microbes — a challenging task because DNA from dead microbes can persist in soil for years, obscuring the analysis of microbial diversity.
“This research suggests that a significant proportion of the microorganisms detected in soil using DNA based techniques are no longer living,” said Ember Morrissey, an assistant professor of plant and soil sciences at West Virginia University who was not involved in the research project. “As a consequence we may need to use tools that distinguish the genetic material of living cells from the relic DNA of dead microbes in order to understand the influence of microbial ‘species’ on important ecosystem processes.”
Paul Carini, a microbial ecophysiologist at the University of Colorado Boulder and first author of the paper, used PMA, a photoreactive dye that binds to relic DNA but does not adhere well to living cells, to distinguish viable cells from DNA debris in soil.
“Accounting for relic DNA in our analyses will help us understand the important ebb and flow of the soil microbiome and help us better understand how microbes help regulate soil fertility and make earth habitable in the face of a changing climate,” said Carini.
Although soil microbial communities were found to be less diverse than previously thought, they are still pretty diverse, according to Strickland. In one gram of soil, thousands of species of microbes live, causing Strickland to deem soil as “the poor man’s rainforest.”
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Story by Lindsay Key, Fralin Life Science Institute
The extinction crisis is far worse than you think. In all of Earth’s history, there have been five mass extinction events. You can see them charted here. Now, we’re on the verge of the sixth extinction. And three-quarters of all species could vanish. Imagine three out of four species that were common are gone. This is the first time humans have caused anything like this.
In a world characterized by rising temperatures, deforestation and other human influences on the environment, the spread of infectious disease is a hot topic. Many recent studies suggest that environmental changes can affect the transmission of everything from malaria to the Zika virus — and it’s increasingly important to understand these links, scientists say.
This week, a new study has provided new evidence that environmental changes can increase the threat of disease. It concludes that unusually warm temperatures caused by 2015’s severe El Niño event — probably compounded by ongoing climate change — may have aided in the rapid spread of the Zika virus in South America that year. And while there are many complex factors at play in the spread of mosquito-borne diseases, the study may help scientists better prepare for the kinds of future effects we might see in our warming world.
“The start of the mission was simple — trying to address where the risk will be, where is it going to move next, where could Zika happen on the planet on a global scale,” said Cyril Caminade, a research fellow at the University of Liverpool and the new study’s lead author. To that end, the authors designed a study that would help them determine how climatic changes have impacted the mosquito-borne transmission of Zika.
There are two main species of mosquito known to carry the Zika virus — Aedes aegypti, or the yellow fever mosquito, which is widespread in the tropics; and Aedes albopictus, or the Asian tiger mosquito, which lives in both tropical and temperate regions of the world. Scientists also believe Zika can be sexually transmitted, but the new study focused only on mosquito transmission.
For the study, the researchers collected published information on the distribution of these two mosquito species and how temperature variations can affect them. Studies suggest, for instance, that up to a certain point, rising temperatures can cause mosquitoes to bite more frequently. The researchers also collected global historical climate data from the past few decades and used all the information to build a model of Zika transmission worldwide.
The model produced an unusually high disease transmission potential in the tropics for the year 2015, including in Colombia and Brazil, the countries hit hardest by Zika. Similar results occurred between 1997 and 1998, one of the only other times on record to experience such a brutal El Niño event.
“Our model indicates that the 2015 El Niño event, superimposed on the long-term global warming trend, has had an important amplification effect,” the researchers note in the paper.
The model also helped the researchers identify the ideal seasonal climate conditions for Zika transmission around the world. In South America, for instance, the model suggests that the potential for transmission should peak in the winter and spring.
In the southeastern U.S., on the other hand, summer is ideal. In fact, the model suggests this region has a high potential for disease transmission during this time, due partly to the high temperatures and partly to the fact that both mosquito species are found there.
That said, reports of Zika have been limited in the U.S. so far — and this speaks to the complexity of vector-borne disease transmission, Caminade said. Climate can certainly play a significant role in setting up the right conditions for an outbreak, but epidemics also depend on many other factors, including population density, access to healthcare and the use of pesticides and other anti-mosquito interventions in any given location. Some of these factors — which were not accounted for in the new study — can probably explain why there hasn’t been much Zika transmission in the U.S. so far.
Caminade also pointed out that after a population has been exposed to a mosquito-borne disease like Zika, a phenomenon called “herd immunity” often occurs — this happens when so many people have already been exposed, and developed an immunity, that there aren’t enough new people left to infect to continue the epidemic. This is the probably part of the reason we didn’t see Zika epidemics in other tropical parts of the world in 2015, despite the new study’s results. And some experts have suggested that herd immunity will likely cause the current situation in South America to burn itself out within a few more years.
Virginia Tech’s new Global Systems Science Destination Area grows from roots that extend back to the university’s founding as a land-grant college, to branches that include the globe’s most urgent and complicated challenges.
One of five new Destination Areas — sites of interdisciplinary collaboration where experts are positioned to address the full complexities of pressing problems worldwide — Global Systems Science targets the interface between society and the environment.
“The heart of the Global Systems Science Destination Area is the intimate and complex relationship that we have with the environment,” said William Hopkins, director of the Global Change Center at Virginia Tech and professor in the Department of Fish and Wildlife Conservation. “For example, as the need to provide food, energy, and water to a growing human population continues to escalate, how do we prevent, halt, or reverse undesirable side effects like pollution and climate change?”
Global Systems Science targets what are known as “wicked problems,” challenges considered difficult, if not impossible, to solve because of their complexity, size, economic effects, or continuously changing nature.
“They cannot be solved with our traditional research and training models,” Hopkins said. “They require new science and technologies, advanced computational methods, and highly transdisciplinary approaches, to include an integrated combination of collaborating scientists, engineers, and social scientists, as well as diverse non-academic stakeholders.”
Fortunately, the same complexity that makes wicked problems so tough to tackle plays to Virginia Tech’s strengths. Students, faculty, and staff from a variety of backgrounds and academic pursuits collaborate daily to tackle challenges in the spirit of Virginia Tech’s land-grant mission and its motto of Ut Prosim(That I May Serve).
Take, for instance, the groundbreaking work by the Flint Water Study research team led by Marc Edwards, the Charles Lunsford Professor of Civil and Environmental Engineering, which exposed a public health crisis in the industrial Michigan city.
From the forest to the faucet, securing clean water is crucial to the future of the global population, and Virginia Tech is poised to play a key role in that endeavor.
“The demand and need for water are definitely expanding rapidly, but it’s a finite resource,” said Stephen Schoenholtz (pictured above), director of the Virginia Water Resources Research Center and professor in the Department of Forest Resources and Environmental Conservation. “Fresh water is essential in every person’s life every day. It’s essential for energy and food, and there are no replacements. It’s a major issue that affects everything.”
Amy Pruden, the Thomas Rice Professor of Civil and Environmental Engineering and a member of the Flint Water Study team, has conducted important water-related research into the growing problem of antibiotic resistance. Pathogenic bacteria have evolved so that traditional antibiotics no longer control them. One study found that, by 2050, infections resistant to drugs — infections that now kill about 700,000 people a year — will grow to kill 10 million people annually, more than the current number killed by cancer.
“Antibiotic resistance is a major public health threat,” Pruden said. “It’s become apparent that we need an interdisciplinary approach to understand this growing resistance and to develop strategies to stop it. It’s such an urgent problem; we need our antibiotics to keep working. When you have an urgent, interdisciplinary problem, you need people of different backgrounds to come together and work to find solutions.”
Global Systems Science, along with the four other Destination Areas — Adaptive Brain and Behavior, Intelligent Infrastructure for Human-centered Communities, Data Analytics and Decision Sciences, and Integrated Security — aim to bring Hokies together in interdisciplinary collaborations to tackle these and other broad, societal-scale problems facing the world.
At a meeting in San Francisco, thousands of researchers are pondering how they can influence President-elect Donald Trump’s thinking on climate change. Read the full story.[hr_shadow]
December 12, 2016 | The heads of Donald Trump’s transition teams for Nasa, the Environmental Protection Agency, the Department of the Interior and the Department of Energy, as well as his nominees to lead the EPA and the Department of the Interior, all question the science of human-caused climate change, in a signal of the president-elect’s determination to embark upon an aggressively pro-fossil fuels agenda.
Trump has assembled a transition team in which at least nine senior members deny basic scientific understanding that the planet is warming due to the burning of carbon and other human activity. These include the transition heads of all the key agencies responsible for either monitoring or dealing with climate change. None of these transition heads have any background in climate science.
Trump has also nominated Oklahoma attorney general Scott Pruitt to lead the EPA and is expected to pick congresswoman Cathy McMorris Rodgers to head the interior department. Pruitt has claimed that scientists “continue to disagree” about the causes and extent of global warming while McMorris Rodgers has said that former vice-president Al Gore, who has championed climate action, “deserves an ‘F’ in science.”
The president-elect has vowed to pursue an “America first” energy policy that will open up a new frontier in domestic coal, oil and gas extraction while eviscerating the effort to combat climate change, which Trump has previously called a “hoax”.
Trump is personally invested in this agenda. According to his latest financial disclosure records, Trump held investments in the fossil fuel companies Shell, Halliburton, Total and Chevron. His largest energy investment was in BHP Billiton, with the documents showing a stake worth up to $1.015m.
Trump also had interests in Energy Transfer Partners and Phillips 66, which are behind the controversial Dakota Access pipeline that Trump wants to see completed. Jason Miller, a Trump spokesman, has said that Trump sold all of his shares in June but has produced no evidence to prove this.
Michael Brune, executive director of the Sierra Club, said of Trump’s choices: “These are people that had slipped out of the conversation, we haven’t been even debating them in years because they were so out of step with where the American public and business is going on climate change.
“Now they’ve leapfrogged into the White House. The world has been turned upside down and it feels like basic science is up for debate. Will we now have to debate whether gravity exists too?”
EPA
Myron Ebell, head of the EPA transition team, is director of energy and environment at the libertarian thinktank the Competitive Enterprise Institute and chairman of the Cooler Heads Coalition, a group that opposes “global warming alarmism”.
Ebell has said that the scientific consensus on climate change is “phoney” and that scientists are part of an effort to spread falsehoods that will result in millions of people being “further impoverished by the higher energy prices resulting from the alarmists’ policy agenda”.
He has suggested that “alarmists could also be prosecuted for denying or grossly underestimating the deleterious effects of their energy-rationing policies on human flourishing”.
Other members of the EPA transition team have been plucked from rightwing thinktanks with fossil fuel funding. Amy Oliver Cooke, of the Independence Institute, has said she is an “energy feminist because I’m pro-choice in energy sources”. She has lashed out at “global warming alarmism” on Twitter and claimed falsely in 2014 that there had been 16 years without any global warming.
David Kruetzer, of the conservative Heritage Foundation, has erroneously claimed there has been “global cooling” in recent years while David Schnare, a former EPA lawyer, said last year that “for the last 18 years, the global temperature has been level”. Schnare’s statement is incorrect.
Department of the Interior
Doug Domenech, head of the interior department transition team, has said carbon dioxide is a “trace greenhouse gas” and has railed against “climate alarmists”.
Domenech is a former Virginia secretary of resources and is now part of the Texas Public Policy Foundation, which states the “forgotten moral case for fossil fuels” as its mission. Trump’s plan to open up more land for drilling will “reinvigorate communities across the nation, especially those most seriously impacted by the current restrictive energy policies”, Domenech wrote in November.
Nasa
Chris Shank, deputy chief of staff to the Republican congressman Lamar Smith, is leading Trump’s landing team at Nasa. Last year, Shank said: “The rhetoric that’s coming out, the hottest year in history, actually is not backed up by the science – or that the droughts, the fires, the hurricanes, etc, are caused by climate change, but it’s just weather.”
Nasa has an internationally venerated climate research operation that may be winnowed away under a Trump administration. Bob Walker, a Trump adviser and climate sceptic, has suggested completely removing Nasa’s $1.9bn Earth sciences budget and focusing instead on deep space exploration.
Global concentrations of methane, a powerful greenhouse gas and cause of climate change, are now growing faster in the atmosphere than at any other time in the past two decades.
That is the message of a team of international scientists in an editorial to be published 12 December in the journal Environmental Research Letters. The group reports that methane concentrations in the air began to surge around 2007 and grew precipitously in 2014 and 2015. In that two-year period, concentrations shot up by 10 or more parts per billion annually. It’s a stark contrast from the early 2000s when methane concentrations crept up by just 0.5 parts per billion on average each year. The reason for the spike is unclear but may come from emissions from agricultural sources and mainly around the tropics – potentially from farm sites like rice paddies and cattle pastures.
Scientists involved in the editorial will discuss these trends at a session during the fall meeting of the American Geophysical Union (AGU) in San Francisco on Tuesday, 13 December.
The findings could give new global attention to methane – which is much less prevalent in the atmosphere than carbon dioxide but is a more potent greenhouse gas, trapping 28 times more heat. And while research shows that the growth of carbon dioxide emissions has flattened out in recent years, methane emissions seem to be soaring.
“The leveling off we’ve seen in the last three years for carbon dioxide emissions is strikingly different from the recent rapid increase in methane,” says Robert Jackson, a co-author of the paper and a Professor in Earth System Science at Stanford University. The results for methane “are worrisome but provide an immediate opportunity for mitigation that complements efforts for carbon dioxide.”
Methane emissions by source. Credit: Global Charbon Project of Future Earth.
The authors of the new editorial previously helped to produce the 2016 Global Methane Budget. This report provided a comprehensive look at how methane had flowed in and out of the atmosphere from 2000 to 2012 because of human activities and other sources. It found, for example, that human emissions of the gas seemed to have increased after 2007, although it’s not clear by how much. The methane budget is published every two to three years by the Global Carbon Project, a research project of Future Earth.
Methane, Jackson says, is a difficult gas to track. In part, that’s because it can come from many different sources. Those include natural sources like marshes and other wetlands. But the bulk, or about 60 percent, of methane added to the atmosphere every year comes from human activities. They include farming sources like cattle operations – cows expel large quantities of methane from their specialised digestive tracks – and rice paddies – the flooded soils make good homes for microbes that produce the gas. A smaller portion of the human budget, about a third, comes from fossil fuel exploration, where methane can leak from oil and gas wells during drilling.
“Unlike carbon dioxide, where we have well described power plants, almost everything in the global methane budget is diffuse,” Jackson says. “From cows to wetlands to rice paddies, the methane cycle is harder.”
But a range of information – such as from large-scale inventories of methane emissions, measurements of methane in the air and computer models – suggests that this cycle has shifted a lot in the last two decades. Jackson and his colleagues, for instance, report that the growth of methane in the atmosphere was mostly stagnant in 2000 to 2006. But that changed after 2007.
“Why this change happened is still not well understood,” says Marielle Saunois, lead author of the new paper and an assistant professor of Université de Versailles Saint Quentin and researcher at Laboratoire des Sciences du Climat et de l’Environnement in France. “For the last two years especially, the growth rate has been faster than for the years before. It’s really intriguing.”
Saunois adds that this runaway pace could threaten international efforts to limit warming from climate change to 2 degrees Celsius. The research provides a strong argument that “we should do more about methane emissions,” Saunois says. “If we want to stay below 2 degrees temperature increase, we should not follow this track and need to make a rapid turn-around.”
Pinpointing where those methane emissions are coming from, however, isn’t easy. Many environmental advocates in North America have raised concerns that expanded drilling for natural gas in recent years could lead to a surge in methane emissions. But Saunois says that based on available data, the more likely source, at least for now, is agriculture. She and her colleagues aren’t sure what may be driving this increase. According to the Food and Agriculture Organization of the United Nations, livestock operations around the world expanded from producing 1,300 million head of cattle in 1994 to nearly 1,500 million in 2014 – with a similar increase in rice cultivation in many Asian countries.
Saunois and Jackson argue, however, that the story isn’t all bad news. A number of researchers have experimented with different ways of reducing methane emissions from farms. Feeding cows a diet supplemented with linseed oil, for example, seems to reduce the amount of methane they belch out. “When it comes to methane, there has been a lot of focus on the fossil fuel industry, but we need to look just as hard if not harder at agriculture,” Jackson says. “The situation certainly isn’t hopeless. It’s a real opportunity.”
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About the study:
The article “The growing role of methane in Anthropogenic Climate Change” will be published in Environmental Research Letters on 12 December at http://iopscience.iop.org/article/10.1088/1748-9326/11/12/120207
Authors: Saunois, M., Jackson, R.B., Bousquet, P., Poulter, B., Canadell, J.G.
On the 33-acre Prairie Drifter Farm in central Minnesota, farmers Joan and Nick Olson are cultivating more than just organic vegetables. Alongside their seven acres of crops – including tomatoes, cucumbers and onions – they’ve also planted flowering plants, dogwood and elderberry hedgerows to accommodate species of bees and butterflies essential for the health of the crops.
The Olsons are not beekeepers, but they are part of a movement to reconnect sustainable farming to a healthy environment. As part of a 2013 project by Xerces Society, a nonprofit that specializes in wildlife preservation, the Olsons worked with a biologist to figure out what types of flowers and shrubs to plant to attract bees, butterflies and other insects that pollinate plants. With seeds and plants they received from Xerxes, and those bought with federal grants, the couple also planted strips of grasses and flowers to attract beetles, which help to defend the vegetables against pests.
“There’s now a ton of bees – bumblebees, honeybees, sweat bees – and predatory insects,” Joan Olson said, adding that the flowering plants also add beauty to the land. “It’s good for the habitat but it’s also lovely for us.”
The Olsons’ effort is one that General Mills, in partnership with Xerces and the US Department of Agriculture, hopes to replicate in other parts of the country in a new initiative. The company is contributing $2m to an ongoing project by Xerces to restore 100,000 acres of farmland in North America over the next five years. The project, which will receive an additional $2m from the agriculture department, will bring General Mills’ investment in pollinator habitat restoration to $6m since 2011.
“Most of our products contain honey, fruits, vegetables and other ingredients that require pollination,” said Jerry Lynch, chief sustainability officer at General Mills. “So healthy and abundant bee populations are a priority for us.”
Each year, pollinators contribute more than $24bn to the US economy. Honeybees alone are responsible for $15bn of it by boosting the production of fruits, nuts and vegetables. But bee and other pollinator populations such as butterflies have been in decline in recent years, which has made food giants sit up and take notice.
Nearly 30% of American honeybees were lost last winter, according to the department of agriculture. More than aquarter of the 46 bumblebee species in North America are considered at risk. Another study found that up to 40% of pollinators, including bees and butterflies, are in decline worldwid
“One in three bites of food that we eat comes from a pollinator, as well as nearly three-quarters of the crops that we eat,” said Scott Black, executive director of the Xerces Society.
Scientists are still investigating what is causing the mass die-off of bees, although they have reasons to believe that pesticides, fungicides, disease and a loss of habitat are all contributing factors. General Mills has been under pressure to protect the bees from exposure to pesticides.
Studies show that habitat restoration is an effective way to increase bee and other pollinator populations. Restoration work involves planting flowers and shrubs on marginal land, typically narrow strips and edges that border crop fields. President Obama established a 2014 task force that developed a plan to boost pollinator populations, which committed to restoring 7m acres of land for pollinators over the next five years.
“Restoration boils down to having the right kind of flowers in the places pollinators live, and having a lot of them,” said Andony Melathopoulos, assistant professor in pollinator health extension at Oregon State University.
Look out your window, and you may see people of all ages and sizes roaming the street: a 6-foot-5-inch man walking beside a 4-foot-6-inch boy, for example, or a sprouting teenager who is much taller than a full-grown adult.
Virginia Tech geoscientists Christopher Griffin and Sterling Nesbitt discovered that this sort of variation in growth patterns in people despite their ages also occurred among early dinosaurs, and may have provided an advantage in surviving the harsh environment at the end of the Triassic Period approximately 201 million to 210 million years ago.
The discovery was published Dec. 5 in the Proceedings of the National Academy of Sciences.
“We found that the earliest dinosaurs had a far higher level of variation in growth patterns between individuals than crocodiles and birds, their closest living relatives,” said Griffin, of Redding, California, the lead author and a first-year doctoral student in the department of geosciences in the College of Science. “Not only were there many different pathways to grow from hatchling to adult, but there was an incredible amount of variation in body size, with some small individuals far more mature than some larger individuals, and some large individuals more immature than we would guess based on size alone.”
The study focused on the skeletal changes that occurred during growth in the small carnivorous dinosaur Coelophysis (SEE-lo-FY-sis), one of the earliest dinosaurs.
Hundreds of these animals, ranging from young, immature individuals to older, mature individuals, were buried together by a flooded river about 208 million years ago in present-day New Mexico. Griffin examined 174 fossils from this site that are housed within natural history museum collections across North America.
“As these animals grew, muscle attachment scars formed on the limb bones, and the bones of the ankle, hips, and shoulder fused together, similar to how the skull bones of a human baby fuse together during growth,” Griffin said. “Fossils of even a single partial skeleton of an early dinosaur are exceptionally rare, so to have an entire group of a single species that lived and died together provided an unparalleled opportunity to study early dinosaur growth like never before.”
Using a technique known as ontogenetic sequence analysis, Griffin was able to reconstruct the growth sequences of Coelophysis and compare them with two bird and one crocodylian species, ultimately demonstrating that the earliest dinosaurs developed differently than their living relatives.
“Studies like this are a perfect demonstration of how fossils can help us understand the evolution of peculiar features and behaviors of modern animals,” said Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the research. “How dinosaurs grew may have been both the key to their early success and the reason that one particular unique subgroup, the birds, survives today.”
This variation in early dinosaurs had been noticed for decades, but had usually been interpreted as a difference between males and females, with one sex identified by large muscle scars and fused bones.
However, statistical tests on the large Coelophysis sample showed no evidence that there were two groups in the sample, as would be expected given variation based on sex, said Griffin.
Instead, individuals were arranged on a spectrum ranging from completely lacking scars and fused bones to having all of them, which is what would be expected if these differences were based on growth.
Dr. Sterling Nesbitt works in the lab at Virginia Tech
“Large variation in early dinosaurs may have allowed them to survive harsh environmental challenges like dry climate and high levels of carbon dioxide,” said Nesbitt, an assistant professor of geosciences in the College of Science and affiliate with the university’s Global Change Center. “Understanding why dinosaurs were so successful has been a great mystery, and high variation may be one of the characteristics of dinosaurs that led to their success. However, it’s difficult to determine whether this trait evolved in response to the environment or was simply a stroke of luck that allowed these dinosaurs to survive and thrive and become the most dominate vertebrates on Earth for 150 million years.”
Griffin, who graduated with his master’s in geosciences from Virginia Tech in 2016, will continue his Ph.D. work with Nesbitt.
When the skies open up and deluge an area, the results can be catastrophic, with roads washed out and homes destroyed by the resulting flash floods. Such extreme downpours are already occurring more often across the US, but a new study finds that as global temperatures rise, storms could dump considerably more rain and skyrocket in frequency.
The study, in the journal Nature Climate Change, suggests that storms that now occur about once a season could happen five times a season by the century’s end, a 400% increase.
And when such storms do occur, they could produce up to 70% more rain. That means that an intense thunderstorm that would today drop about 5cm (2 inches) of rain would drop 9cm in the future.
Such massive amounts of rain occurring more often could put significant strain on infrastructure that already struggles to deal with heavy rainfall, as seen across the country this year in places from Louisiana to West Virginia.
“I think this is one of the most severe consequences of climate change, at least in the US,” said the study’s co-author, Andreas Prein, of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.
Heavy downpours have already increased across the entire continental US, according to the 2014 National Climate Assessment, mostly notably in the north-east, where they have risen by 71%.
Such an increase in extreme precipitation is expected as temperatures rise due to heat-trapping greenhouse gases accumulating in the atmosphere. One of the basic properties of the atmosphere is that moisture increases with temperature. That means when a storm forms, it has more moisture available to fuel rains.
Several extreme rainfall events have already been made more likely because of warming, analyses have shown.
“We see this in the real climate already. It will only intensify,” Prein said.
The most extreme rains happen in convective storms, or ones that feature rapidly rising air at their core. These storms happen on scales too small for global climate models to capture, though, meaning they can’t provide a detailed look at rainfall trends.
To get down to the level of those storms, the NCAR researchers used a higher-resolution model that captures finer details, but takes much longer to run – in this case, an entire year.
What they found was that if greenhouse gas emissions continue on their current path, the storms that produce the most intense rainfall will increase broadly across the Lower 48.
The Gulf and Atlantic coasts, where oceans provide abundant moisture, would see some of the biggest increases in frequency and rainfall amounts.
But even in the central portions of the country, which are expected to get drier overall as rising temperatures cause more soil evaporation, the most intense storms will drop more rain in the future. Essentially, the region will see fewer of the moderate storms that are a crucial source of water now and more of the intense storms.
That shift has serious implications for agriculture, one of the main economic drivers in the region, as heavy rains can be damaging to crops.
However, if the world, including the US, acts to limit emissions over the coming decades, these increases in rainfall won’t be as large.
“It’s really in our hands to change that if we want to,” Prein said.
