Constantine Alexander's Journal

Older and larger trees enhance woodland bird biodiversity in cities

The Big Oak, located in Thomasville, Georgia is a 329 year old Live Oak, and is one of the largest of its kind East of the Mississippi River. This photo was taken by Carla Finley (CC).

By Science for Environment Policy

Managing urban green spaces to ensure that they have a good mix of tree species, including some older and larger trees, can enhance species diversity of woodland birds, a new study has shown. The study, carried out in Prague, Czech Republic, also showed that the presence of water bodies increased the number of species of woodland birds.

Urban green spaces provide numerous important ecosystem services. Not only can they enhance human health and well-being and alleviate city heat waves, they also provide habitat for a range of wildlife. As people continue to migrate from rural areas into the cities and urban sprawl extends into natural habitats, the careful management of these areas becomes increasingly important.

In this study researchers set out to identify factors that enhance the diversity of woodland bird species in urban green spaces. They surveyed 290 green spaces around the city of Prague, Czech Republic, counting the number of woodland bird species they saw over three visits to the sites. They also recorded a number of habitat characteristics such as the trunk diameter of the trees (an indication of age), number of tree species, density of shrubs and whether there was a water body at the site.

The results showed that the number of woodland bird species increased with the number of tree species. This may reflect the fact that different tree species provide different types of nesting and foraging opportunities, say the researchers. On average, the sites contained just over 12 species, with a minimum of 3 and a maximum of 19.

Bird species richness also increased with the presence of older trees. Coverage of just 12% of the area by trees that had a trunk diameter of 50 cm or more increased the number of bird species by an average of two. In other words, say the researchers, even a very few old trees can enhance biodiversity of birds in urban green spaces. This effect might be because older trees provide holes for species such as woodpeckers to nest in; they may also harbour more insects for foraging.

The results also reveal that the presence of water bodies such as small ponds, rivers or streams increased the number of species of woodland birds, on average, by two. This is somewhat surprising, say the researchers, as they did not include any wetland birds in their counts. This might reflect the fact that riverside areas provide a greater diversity of foraging habitats.

Finally, the researchers investigated the effects of the surrounding habitats, within 500 m of the study sites. This showed that bird diversity at the sites increased with the amount of continuous tree cover nearby and also with the scattered trees that are found in residential areas of the city.

Overall, the researchers recommend that urban green spaces should be managed to ensure a range of tree species and that the greater value of older, larger trees and water bodies should also be taken into account.

Citation: Ferenc, M., Sedláček, O. & Fuchs, R. (2014). How to improve urban greenspace for woodland birds: site and local-scale determinants of bird species richness. Urban Ecosystems. 17: 625–640. DOI: 10.1007/s11252-013-0328-x.

Contact: M. Ferenc

Conservation scientists asking wrong questions on climate change impacts on wildlife

Wildlife Conservation Society, University of Queensland, and others urge more focus on more imminent threats

Walruses. Photo by: Magnus Elander (CC).

Scientists studying the potential effects of climate change on the world's animal and plant species are focusing on the wrong factors, according to a new paper by a research team from the Wildlife Conservation Society, University of Queensland, and other organizations. The authors claim that most of the conservation science is missing the point when it comes to climate change.

While the majority of climate change scientists focus on the "direct" threats of changing temperatures and precipitation after 2031, far fewer researchers are studying how short-term human adaptation responses to seasonal changes and extreme weather events may threaten the survival of wildlife and ecosystems much sooner. These indirect effects are far more likely to cause extinctions, especially in the near term.

The review appears online in the international journal Diversity and Distributions.

"A review of the literature exploring the effects of climate change on biodiversity has revealed a gap in what may be the main challenge to the world's fauna and flora," said the senior author Dr. James Watson, Climate Change Program Director and a Principle Research Fellow at the University of Queensland.

The research team conducted a review of all available literature published over the past twelve years on the impacts of climate change on species and ecosystems. In their review, the authors classified studies examining the projected changes in temperature and precipitation as "direct threat" research. Direct threats also included changes such as coral bleaching, shifting animal and plant life cycles and distributions, and habitat loss from sea level rise. Human responses to climate change—including everything from shifting agriculture patterns, the construction of sea walls to protect cities from sea level rise, changes in human fishing intensity, diversion of water, and other factors—were classified as "indirect threats."

The authors found that the vast majority of studies (approximately 89 percent of the research included in the review) focused exclusively on the direct impacts of climate change. Only 11 percent included both direct and indirect threats, and the authors found no studies focusing only on indirect threats.

"The reactions of human communities to these changes should be treated as a top priority by the research community," said Dr. Watson. "The short-term, indirect threats are not merely 'bumps in the road'—they are serious problems that require a greater analysis of social, economic, and political issues stemming from changes already occurring."

Citation: Chapman, S., Mustin, K., Renwick, A. R., Segan, D. B., Hole, D. G., Pearson, R. G., Watson, J. E. M. (2014), Publishing trends on climate change vulnerability in the conservation literature reveal a predominant focus on direct impacts and long time-scales. Diversity and Distributions. DOI: 10.1111/ddi.12234. 

Contact: John Delaney
718-220-3275
Wildlife Conservation Society

Related articles

Paper predicts a future without carnivores would be truly scary

Study provides insights on protecting world's poor from climate change

Europe's habitat and wildlife is vulnerable to climate change

Offshore renewable energy sites provide new habitat for marine species

Deep-sea octopus broods eggs for over 4 years

This deep-sea octopus (Graneledone boreopacifica) spent four and one half years brooding her eggs on a ledge near the bottom of Monterey Canyon, about 1,400 meters (4,600 feet) below the ocean surface. Credit: MBARI.

Researchers at the Monterey Bay Aquarium Research Institute (MBARI) have observed a deep-sea octopus brooding its eggs for four and one half years—longer than any other known animal. Throughout this time, the female kept the eggs clean and guarded them from predators. This amazing feat represents an evolutionary balancing act between the benefits to the young octopuses of having plenty of time to develop within their eggs, and their mother's ability to survive for years with little or no food.

Every few months for the last 25 years, a team of MBARI researchers led by Bruce Robison has performed surveys of deep-sea animals at a research site in the depths of Monterey Canyon that they call "Midwater 1." In May 2007, during one of these surveys, the researchers discovered a female octopus clinging to a rocky ledge just above the floor of the canyon, about 1,400 meters (4,600 feet) below the ocean surface. The octopus, a species known as Graneledone boreopacifica, had not been in this location during their previous dive at this site in April.

Over the next four and one-half years, the researchers dove at this same site 18 times. Each time, they found the same octopus, which they could identify by her distinctive scars, in the same place. As the years passed, her translucent eggs grew larger and the researchers could see young octopuses developing inside. Over the same period, the female gradually lost weight and her skin became loose and pale.

The researchers never saw the female leave her eggs or eat anything. She did not even show interest in small crabs and shrimp that crawled or swam by, as long as they did not bother her eggs.

The last time the researchers saw the brooding octopus was in September 2011. When they returned one month later, they found that the female was gone. As the researchers wrote in a recent paper in the Public Library of Science (PLOS ONE), "the rock face she had occupied held the tattered remnants of empty egg capsules."

After counting the remnants of the egg capsules, the researchers estimated that the female octopus had been brooding about 160 eggs.

Most female octopuses lay only one set of eggs and die about the time that their eggs hatch. The eggs of Graneledone boreopacifica are tear-drop-shaped capsules the size of small olives. As the young develop inside the eggs, they require plenty of oxygen. This means that the female octopus must continuously bathe the eggs in fresh, oxygenated seawater and keep them from being covered with silt or debris. The female must also guard her eggs vigilantly to prevent them from being eaten by predators.

Because the young octopus spend so much time in their eggs, by the time they hatch they are fully capable of surviving on their own and hunting for small prey. In fact, the newborns of G. boreopacifica are larger and better developed than the hatchlings of any other octopus or squid.

In their recent paper, the researchers point out that octopus eggs, like those of other invertebrates, develop more slowly in cold water. The seawater near the ocean floor at the Midwater 1 site is about three degrees Celsius (37 degrees Fahrenheit), which is typical for the depths of Monterey Canyon.

Given this chilly environment, it's not surprising that octopuses are not the only deep-sea animals to brood their young for long periods of time. One type of mysid (a shrimp relative that is abundant in depths of Monterey Canyon) carries its eggs for 20 months and goes without food the whole time. Like octopus hatchlings, the young of this shrimp also emerge from their eggs as fully developed miniature adults.

Such long brooding times present an evolutionary challenge, especially for animals such as octopus, which do not live very long. As the authors noted in their paper, "The trade-off within the reproductive strategy of deep-living octopods is between the mother's ability to endure a long brooding period and the competitiveness of her hatchlings. Graneledone boreopacifica produces hatchlings that are very highly developed, which gives them the advantage of a high potential for survival."

This research suggests that, in addition to setting records for the longest brooding time of any animal, Graneledone boreopacifica may be one of the longest lived cephalopods (a group that includes octopuses, squids, and their relatives). Most shallow-water octopuses and squids live just a year or two.

"The ultimate fate of a brooding female octopus is inevitably death," the researchers wrote, "but in this first example from the deep sea, brooding also confers an extension of adult life that greatly exceeds most projections of cephalopod longevity."

Although long-term observations of deep-sea animals are rare, the researchers propose that extended brooding periods may be common in the deep sea. Such extended life stages would need to be taken into account in assessing the effects of human activities on deep-sea animals. In any case, this strategy has apparently worked for Graneledone boreopacifica—it is one of the most common deep-sea octopuses in the Northeastern Pacific.

Citation: Robison B, Seibel B, Drazen J (2014) Deep-Sea Octopus (Graneledone boreopacifica) Conducts the Longest-Known Egg-Brooding Period of Any Animal. PLoS ONE 9(7): e103437. doi:10.1371/journal.pone.0103437. 

Contact: Meilina Dalit
831-775-1716
Monterey Bay Aquarium Research Institute

Related articles

Turtle migration directly influenced by ocean drift experiences as hatchlings

Deep-sea squid can 'jettison arms' as defensive tactic

Scientists caution against exploitation of deep ocean

A new OSU study looks at how exploiting the ocean's vast resources have put it in peril. Credit: Oregon State University

The world's oceans are vast and deep, yet rapidly advancing technology and the quest for extracting resources from previously unreachable depths is beginning to put the deep seas on the cusp of peril, an international team of scientists warned this week.

In an analysis in Biogeosciences, which is published by the European Geosciences Union, the researchers outline "services" or benefits provided by the deep ocean to society. Yet using these services, now and in the future, is likely to make a significant impact on that habitat and what it ultimately does for society, they point out in their analysis.

"The deep sea is the largest habitat on Earth, it is incredibly important to humans and it is facing a variety of stressors from increased human exploitation to impacts from climate change," said Andrew Thurber, an Oregon State University marine scientist and lead author on the study. "As we embark upon greater exploitation of this vast environment and start thinking about conserving its resources, it is imperative to know what this habitat already does for us."

"Our analysis is an effort to begin to summarize what the deep sea provides to humans because we take it for granted or simply do not know that the deep sea does anything to shape our daily lives," he added. "The truth is that the deep sea affects us, whether we live on the coast or far from the ocean – and its impact on the globe is pervasive."

The deep sea is important to many critical processes that affect the Earth's climate, including acting as a "sink" for greenhouse gases – helping offset the growing amounts of carbon dioxide emitted into the atmosphere. It also regenerates nutrients through upwelling that fuel the marine food web in productive coastal systems such as the Pacific Northwest of the United States, Chile and others. Increasingly, fishing and mining industries are going deeper and deeper into the oceans to extract natural resources.

"One concern is that many of these areas are in international waters and outside of any national jurisdiction," noted Thurber, an assistant professor (senior research) in Oregon State's College of Earth, Ocean, and Atmospheric Sciences. "Yet the impacts are global, so we need a global effort to begin protecting and managing these key, albeit vast, habitats."

Fishing is an obvious concern, the scientists say. Advances in technology have enabled commercial fisheries to harvest fish at increasing depths – an average of 62.5 meters deeper every decade, according to fisheries scientists. This raises a variety of potential issues.

"The ability to fish deeper is shifting some fisheries to deeper stocks, and opening up harvests of new species," Thurber said. "In some local cases, individual fisheries are managed aggressively, but due to how slow the majority of the fish grow in the deep, some fish populations are still in decline – even with the best management practices."

The orange roughy off New Zealand, for instance, is both a model of effective and conservation-based management, yet its populations continue to decline, though at a slower rate than they would have experienced without careful management, Thurber noted.

"We also have to be concerned about pollution that makes its way from our continental shelves into the deep sea," he added. "Before it was 'out of sight, out of mind.' However, some of the pollution can either make it into the fish that we harvest, or harm the fishers that collect the fish for us. It is one of the reasons need to identify how uses of the deep sea in the short term can have long-term consequences. Few things happen fast down there."

Mining is a major threat to the deep sea, the researchers point out in their analysis. In particular, the quest for rare earth and metal resources, which began decades ago, has skyrocketed in recent years because of their increased use in electronics, and because of dwindling or limited distribution of supplies on land. Mining the deep ocean for manganese nodules, for example – which are rich in nickel – requires machines that may directly impact large swaths of the seafloor and send up a sediment plume that could potentially affect an even larger area, the scientists note.

These mining resources are not limited to muddy habitats, Thurber pointed out. Massive sulfides present at hydrothermal vents are another resource targeted by mining interests.

"The deep sea has been an active area for oil and gas harvesting for many years," he said, "yet large reservoirs of methane and other potential energy sources remain unexploited. In addition to new energy sources, the potential for novel pharmaceuticals is also vast.

"There are additional threats to these unique habitats, including ocean acidification, warming temperatures and possible changes to ocean circulation through climate change."

The next step, the researchers say, is to attach an economic value to both the services provided by the deep sea – and the activities that may threaten those services.

"What became clear as we put together this synopsis is that there is vast potential for future resources but we already benefit greatly through this environment," Thurber said. ""What this means is that while the choices to harvest or mine will be decided over the coming decades, it is important to note that the stakeholders of this environment represent the entire world's population."

"The Bible, the Koran, the Torah, and early Greek texts all reference the deep sea," he added. "Maybe it's time for all of us to take a closer look at what it it has to offer and decide if and how we protect it."

Contact: Andrew Thurber
541-737-4500
Oregon State University

Related articles

Scientists call for new stewardship of the deep ocean: Earth's last frontier

Better science for better fisheries management

From 'Finding Nemo' to minerals -- what riches lie in the deep sea?

Worldwide water shortage by 2040

Krasnoyarsk hydroelectric plant spillway. Credit: Alex Polezhaev (CC).

By Winnie Axelse

In most countries, electricity is the biggest source of water consumption because the power plants need cooling cycles in order to function. The only energy systems that do not require cooling cycles are wind and solar systems, and therefore one of the primary recommendations issued by these researchers is to replace old power systems with more sustainable wind and solar systems.

The research has also yielded the surprising finding that most power systems do not even register how much water is being used to keep the systems going.

By 2020 the water issue affects 30-40% of the world

"It's a huge problem that the electricity sector do not even realise how much water they actually consume. And together with the fact that we do not have unlimited water resources, it could lead to a serious crisis if nobody acts on it soon", says Professor Benjamin Sovacool from Aarhus University.

Combining the new research results with projections about water shortage and the world population, it shows that by 2020 many areas of the world will no longer have access to clean drinking water. In fact, the results predict that by 2020 about 30-40% of the world will have water scarcity, and according to the researchers, climate change can make this even worse.

"This means that we'll have to decide where we spend our water in the future. Do we want to spend it on keeping the power plants going or as drinking water? We don't have enough water to do both", says Professor Benjamin Sovacool.

How to solve the problem?

In the reports, the researchers emphasise six general recommendations for decision-makers to follow in order to stop this development and handle the crisis around the world:

• Improve energy efficiency
• Better research on alternative cooling cycles
• Registering how much water power plants use
• Massive investments in wind energy
• Massive investments in solar energy
• Abandon fossil fuel facilities in all water stressed places (which means half the planet)

Close up on France, the US, China and India

The team of researchers conducted their research focusing on four different case studies in France, the United States, China and India respectively. Rather than reviewing the situation on a national level, the team narrowed in and focused on specific utilities and energy suppliers. The first step was identifying the current energy needs, and then the researchers made projections as far as 2040, and most of the results were surprising. All four case studies project that it will be impossible to continue to produce electricity in this way and meet the water demand by 2040.

"If we keep doing business as usual, we are facing an insurmountable water shortage – even if water was free, because it's not a matter of the price. There will no water by 2040 if we keep doing what we're doing today. There's no time to waste. We need to act now", concludes Professor Benjamin Sovacool.

Citation: Paul Faeth, Benjamin K. Sovacool, Zoë Thorkildsen, Ajith Rao, David Purcell, Jay Eidsness, Katie Johnson, Brian Thompson, Sara Imperiale, Alex Gilbert; A Clash of Competing Necessities, Water Adequacy and Electric Reliability in China, India, France and Texas; CNA Research Memorandum; IRM-2014-U-007191.

Contact: Benjamin Sovacool
45-87-16-69-15
Aarhus University

Related articles

EU could cut emissions by 40 percent at moderate cost

Denmark can triple its biomass production and improve the environment

NOAA: Alaska fisheries and communities at risk from ocean acidification

Individual components of the final ocean acidification risk index for each census area showing the communities with the highest risk are in the Southeast and Southwest of the state. Credit: NOAA

Ocean acidification is driving changes in waters vital to Alaska's valuable commercial fisheries and subsistence way of life, according to new NOAA-led research that will be published online in Progress in Oceanography.

Many of Alaska's nutritionally and economically valuable marine fisheries are located in waters that are already experiencing ocean acidification, and will see more in the near future, the study shows. Communities in southeast and southwest Alaska face the highest risk from ocean acidification because they rely heavily on fisheries that are expected to be most affected by ocean acidification, and have underlying factors that make those communities more vulnerable, such as lower incomes and fewer employment opportunities.

The term "ocean acidification" describes the process of ocean water becoming more acidic as a result of absorbing nearly a third of the carbon dioxide released into the atmosphere from human sources. This change in ocean chemistry is affecting marine life, particularly the ability of shellfish, corals and small creatures in the early stages of the food chain to build skeletons or shells.

Studies show that red king crab and tanner crab, two important Alaskan fisheries, grow more slowly and don't survive as well in more acidic waters. Alaska's coastal waters are particularly vulnerable to ocean acidification because of cold water that can absorb more carbon dioxide, and unique ocean circulation patterns which bring naturally acidic deep ocean waters to the surface.

"We went beyond the traditional approach of looking at dollars lost or species impacted; we know these fisheries are lifelines for native communities and what we've learned will help them adapt to a changing ocean environment," said Jeremy Mathis, Ph.D., co-lead author of the study, an oceanographer at NOAA's Pacific Marine Environmental Laboratory in Seattle, and the director of the University of Alaska Fairbanks School of Fisheries and Ocean Sciences Ocean Acidification Research Center.

The research presented in the new study examines the potential effects on a state where the fishing industry supports over 100,000 jobs and generates more than $5 billion in annual revenue and helps maintain the U.S. balance of trade in the global economy. Additionally, approximately 120,000 people or roughly 17 percent of Alaskans rely on subsistence fisheries for most, if not all of their dietary protein. Fishery-related tourism also brings in $300 million annually.

Fishermen from Homer, Alaska haul in tanner crabs, one of the fisheries that research is showing may be affected by ocean acidification. Credit: Mathis/ NOAA

"Ocean acidification is not just an ecological problem—it's an economic problem," said Steve Colt, Ph.D., co-author of the study and an economist at the University of Alaska Anchorage. "The people of coastal Alaska, who have always looked to the sea for sustenance and prosperity, will be most affected. But all Alaskans need to understand how and where ocean acidification threatens our marine resources so that we can work together to address the challenges and maintain healthy and productive coastal communities."

The study recommends that residents and stakeholders in vulnerable regions prepare for this environmental challenge and develop response strategies that incorporate community values and needs. "This research allows planners to think creatively about ways to help coastal communities withstand environmental change," said Sarah Cooley, Ph.D., co-lead author who was at the Woods Hole Oceanographic Institution while doing the research and is now science outreach manager at Ocean Conservancy, in Washington, D.C. "Adaptations can be tailored to address specific social and environmental weak points that exist in a community."

While acknowledging that the most important way to address ocean acidification is by reducing carbon dioxide emissions globally, the research shows that by examining all the factors that contribute to risk, more opportunities can be found to prevent harm to human communities at a local level. Decision-makers can address socioeconomic factors that lower the ability of people and communities to adapt to environmental change, such as low incomes, poor nutrition, lack of educational attainment and lack of diverse employment opportunities. NOAA's Ocean Acidification Program and the state of Alaska are also developing tools to help industry adapt to increasing acidity.

The new study is the first published research by the Synthesis of Arctic Research (SOAR) program, which is supported by an inter-agency agreement between NOAA’s Office of Oceanic and Atmospheric Research and the Bureau of Ocean Energy Management (BOEM) Alaska Region. 

Contact: John Ewald
240-429-6127
NOAA

Related articles

Palau's coral reefs surprisingly resistant to ocean acidification

Rising ocean acidification leads to anxiety in fish

From 'Finding Nemo' to minerals -- what riches lie in the deep sea?

Left: The first species ever recovered from the deep sea. Center: Rockfish use deep-sea carbonate formations at Hydrate Ridge, US, as a refuge. Right: Deep-sea corals such as the one pictured are a source of jewelery and other riches. Credit: SERPENT Project/D.O.B. Jones, L. Levin, UK's BIS Department.

As fishing and the harvesting of metals, gas and oil have expanded deeper and deeper into the ocean, scientists are drawing attention to the services provided by the deep sea, the world's largest environment. "This is the time to discuss deep-sea stewardship before exploitation is too much farther underway," says lead-author Andrew Thurber. In a review published today in Biogeosciences, a journal of the European Geosciences Union (EGU), Thurber and colleagues summarise what this habitat provides to humans, and emphasise the need to protect it.

"The deep sea realm is so distant, but affects us in so many ways. That's where the passion lies: to tell everyone what's down there and that we still have a lot to explore," says co-author Jeroen Ingels of Plymouth Marine Laboratory in the UK.

"What we know highlights that it provides much directly to society," says Thurber, a researcher at the College of Earth, Ocean and Atmospheric Sciences at Oregon State University in the US. Yet, the deep sea is facing impacts from climate change and, as resources are depleted elsewhere, is being increasingly exploited by humans for food, energy and metals like gold and silver.

"We felt we had to do something," says Ingels. "We all felt passionate about placing the deep sea in a relevant context and found that there was little out there aimed at explaining what the deep sea does for us to a broad audience that includes scientists, the non-specialists and ultimately the policy makers. There was a gap to be filled. So we said: 'Let's just make this happen'."

In the review of over 200 scientific papers, the international team of researchers points out how vital the deep sea is to support our current way of life. It nurtures fish stocks, serves as a dumping ground for our waste, and is a massive reserve of oil, gas, precious metals and the rare minerals we use in modern electronics, such as cell phones and hybrid-car batteries. Further, hydrothermal vents and other deep-sea environments host life forms, from bacteria to sponges, that are a source of new antibiotics and anti-cancer chemicals. It also has a cultural value, with its strange species and untouched habitats inspiring books and films from 20,000 Leagues Under the Sea to Finding Nemo.

"From jewellery to oil and gas and future potential energy reserves as well as novel pharmaceuticals, deep-sea's worth should be recognised so that, as we decide how to use it more in the future, we do not inhibit or lose the services that it already provides," says Thurber.

The deep sea (ocean areas deeper than 200m) represents 98.5% of the volume of our planet that is hospitable to animals. It has received less attention than other environments because it is vast, dark and remote, and much of it is inaccessible to humans. But it has important global functions. In the Biogeosciences review the team shows that deep-sea marine life plays a crucial role in absorbing carbon dioxide from the atmosphere, as well as methane that occasionally leaks from under the seafloor. In doing so, the deep ocean has limited much of the effects of climate change.

This type of process occurs over a vast area and at a slow rate. Thurber gives other examples: manganese nodules, deep-sea sources of nickel, copper, cobalt and rare earth minerals, take centuries or longer to form and are not renewable. Likewise, slow-growing and long-lived species of fish and coral in the deep sea are more susceptible to overfishing. "This means that a different approach needs to be taken as we start harvesting the resources within it."

By highlighting the importance of the deep sea and identifying the traits that differentiate this environment from others, the researchers hope to provide the tools for effective and sustainable management of this habitat.

"This study is one of the steps in making sure that the benefits of the deep sea are understood by those who are trying to, or beginning to, regulate its resources," concludes Thurber. "We ultimately hope that it will be a useful tool for policy makers."

Citation: A. R. Thurber, A. K. Sweetman, B. E. Narayanaswamy, D. O. B. Jones, J. Ingels, R. L. Hansman; Ecosystem function and services provided by the deep sea; Biogeosciences Discussions, 2013; 10 (11): 18193 DOI: 10.5194/bgd-10-18193-2013. 

Contact: Barbara Ferreira
49-892-180-6703
European Geosciences Union

Related articles

Deep sea fish remove 1 million tonnes of CO2 every year from UK and Irish waters

Tiny plankton could have big impact on climate

Scientists call for new stewardship of the deep ocean: Earth's last frontier

Huge waves measured for first time in Arctic Ocean

As the climate warms and sea ice retreats, the North is changing. An ice-covered expanse now has a season of increasingly open water which is predicted to extend across the whole Arctic Ocean before the middle of this century. Storms thus have the potential to create Arctic swell – huge waves that could add a new and unpredictable element to the region. A University of Washington researcher made the first study of waves in the middle of the Arctic Ocean, and detected house-sized waves during a September 2012 storm. The results were recently published in Geophysical Research Letters.

"As the Arctic is melting, it's a pretty simple prediction that the additional open water should make waves," said lead author Jim Thomson, an oceanographer with the UW Applied Physics Laboratory.

His data show that winds in mid-September 2012 created waves of 5 meters (16 feet) high during the peak of the storm. The research also traces the sources of those big waves: high winds, which have always howled through the Arctic, combined with the new reality of open water in summer.

Arctic ice used to retreat less than 100 miles from the shore. In 2012, it retreated more than 1,000 miles. Wind blowing across an expanse of water for a long time creates whitecaps, then small waves, which then slowly consolidate into big swells that carry huge amounts of energy in a single punch.

The size of the waves increases with the fetch, or travel distance over open water. So more open water means bigger waves. As waves grow bigger they also catch more wind, driving them faster and with more energy.

Shipping and oil companies have been eyeing the opportunity of an ice-free season in the Arctic Ocean. The emergence of big waves in the Arctic could be bad news for operating in newly ice-free Northern waters.

"Almost all of the casualties and losses at sea are because of stormy conditions, and breaking waves are often the culprit," Thomson said. It also could be a new feedback loop leading to more open water as bigger waves break up the remaining summer ice floes.

"The melting has been going on for decades. What we're talking about with the waves is potentially a new process, a mechanical process, in which the waves can push and pull and crash to break up the ice," Thomson said.

Waves breaking on the shore could also affect the coastlines, where melting permafrost is already making shores more vulnerable to erosion.

The observations were made as part of a bigger project by a sensor anchored to the seafloor and sitting 50 meters (more than 150 feet) below the surface in the middle of the Beaufort Sea, about 350 miles off Alaska's north slope and at the middle of the ice-free summer water. It measured wave height from mid-August until late October 2012.

Satellites can give a rough estimate of wave heights, but they don't give precise numbers for storm events. They also don't do well for the sloppy, partially ice-covered waters that are common in the Arctic in summer.

Warming temperatures and bigger waves could act together on summer ice floes, Thomson said: "At this point, we don't really know relative importance of these processes in future scenarios."

Establishing that relationship could help to predict what will happen to the sea ice in the future and help forecast how long the ice-free channel will remain open each year.

The recent paper recorded waves at just one place. This summer Thomson is part of an international group led by the UW that is putting dozens of sensors in the Arctic Ocean to better understand the physics of the sea-ice retreat.

"There are several competing theories for what happens when the waves approach and get in to the ice," Thomson said. "A big part of what we're doing with this program is evaluating those models."

He will be out on Alaska's northern coast from late July until mid-August deploying sensors to track waves. He hopes to learn how wave heights are affected by the weather, ice conditions and amount of open water.

"It's going to be a quantum leap in terms of the number of observations, the level of detail and the level of precision" for measuring Arctic Ocean waves, Thomson said.

Citation: Jim Thomson, W. Erick Rogers; Swell and sea in the emerging Arctic Ocean; Geophysical Research Letters, 2014; 41 (9): 3136 DOI: 10.1002/2014GL059983. 

The research was funded by the U.S. Office of Naval Research.

Contact: Hannah Hickey
206-543-2580
University of Washington

Related articles

Arctic nearly free of summer sea ice during first half of 21st century

Arctic sea ice hits smallest extent in satellite era

Tracking the breakup of Arctic summer sea ice

Lead pollution beat explorers to South Pole, persists today

A member of the Norwegian-American Scientific Traverse of East Antarctica, which collected some of the ice cores used in a study that shows lead pollution reached Antarctica in the late 19th century, drills a shallow firn (compacted snow) core. Credit: Stein Tronstad/Norwegian Polar Institute.

By Maria-José Viñas, NASA.

Norwegian explorer Roald Amundsen reached the South Pole in 1911, but new research shows that industrial air pollution arrived long before any human.

Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada, created the most accurate and precise reconstruction to date of lead pollution over Earth's southernmost continent. The new record, described in an article published today in the online edition of the Nature Publishing Group's journal Scientific Reports, spans a 410-year period from 1600 to 2010.

"Our new record shows the dramatic impact of industrial activities such as smelting, mining and fossil fuel burning on even the most remote parts of the world," McConnell said.

"It is very clear that industrial lead contamination was pervasive throughout Antarctica by the late 19th century, more than two decades before the first explorers made it to the South Pole," he added. "The idea that Amundsen and Scott were traveling over snow that clearly was contaminated by lead from smelting and mining in Australia, and that lead pollution at that time was nearly as high as any time ever since, is surprising to say the least."

This study included ice cores collected as part of projects funded by the National Science Foundation. Additional ice cores were contributed to the study by international collaborators including the British Antarctic Survey, the Australian Antarctic Division and the Alfred Wegener Institute in Germany.

"The ice cores obtained through international collaborations were critical to the success of this study in that they allowed us to develop records from parts of Antarctica not often visited by U.S.-based scientists," said co-author Tom Neumann of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who participated in a Norway-U.S. traverse that collected several of the cores used in this study. "This included the Law Dome region of East Antarctica and a big section of East Antarctica visited by the Norwegian-United States Scientific Traverse of East Antarctica."

Composite ice core records of lead in Antarctica from 1600 to 2010. The areas shaded in blue and red indicate when lead values were below or above the 410-year average, respectively, highlighting the dramatic change before and after industrialization in the Southern Hemisphere. Credit: Desert Research Institute.

All measurements of lead and other chemicals used in this study were made using DRI's continuous ice core analytical system. Low background atmospheric concentrations, together with well-known and often distinct isotopic characteristics (variants of lead with different atomic weights) of industrial sources make lead an ideal tracer of industrial pollution.

"Lead is a toxic heavy metal with strong potential to harm ecosystems," said co-author Paul Vallelonga of the University of Copenhagen. "While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby Port Pirie."

The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today, the authors report.

Data from the new ice core array illustrates that Antarctic lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the Great Depression and the end of World War II. Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.

Concentrations across the Antarctic continent have since declined, but still are about four-fold higher than before industrialization, despite the phase out of leaded gasoline and other mitigation efforts in many countries in the Southern Hemisphere, the report states.

"Our measurements indicate that approximately 660 tonnes [1.5 million pounds] of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years," McConnell said. "While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."

Contact: Maria-José Viñas
301-614-5883
NASA/Goddard Space Flight Center

Related articles

Antarctica's ice losses on the rise

Why Antarctic sea ice cover has increased under the effects of climate change

NOAA: 'Nuisance flooding' an increasing problem as coastal sea levels rise

Study looks at more than 60 years of coastal water level and local elevation data changes

Annapolis, Maryland, pictured here in 2012, saw the greatest increase in nuisance flooding in a recent NOAA study. Credit: With permission from Amy McGovern.

Eight of the top 10 U.S. cities that have seen an increase in so-called "nuisance flooding"--which causes such public inconveniences as frequent road closures, overwhelmed storm drains and compromised infrastructure--are on the East Coast, according to a new NOAA technical report.

This nuisance flooding, caused by rising sea levels, has increased on all three U.S. coasts, between 300 and 925 percent since the 1960s.

The report, Sea Level Rise and Nuisance Flood Frequency Changes around the United States, also finds Annapolis and Baltimore, Maryland, lead the list with an increase in number of flood days of more than 920 percent since 1960. Port Isabel, Texas, along the Gulf coast, showed an increase of 547 percent, and nuisance flood days in San Francisco, California increased 364 percent.

"Achieving resilience requires understanding environmental threats and vulnerabilities to combat issues like sea level rise," says Holly Bamford, Ph.D., NOAA assistant administrator of the National Ocean Service. "The nuisance flood study provides the kind of actionable environmental intelligence that can guide coastal resilience efforts."

"As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding," said William Sweet, Ph.D., oceanographer at NOAA's Center for Operational Oceanographic Products and Services (CO-OPS) and the report's lead author. "Flooding now occurs with high tides in many locations due to climate-related sea level rise, land subsidence and the loss of natural barriers. The effects of rising sea levels along most of the continental U.S. coastline are only going to become more noticeable and much more severe in the coming decades, probably more so than any other climate-change related factor."

The study was conducted by scientists at CO-OPS, who looked at data from 45 NOAA water level gauges with long data records around the country and compared that to reports of number of days of nuisance floods.

The extent of nuisance flooding depends on multiple factors, including topography and land cover. The study defines nuisance flooding as a daily rise in water level above the minor flooding threshold set locally by NOAA's National Weather Service, and focused on coastal areas at or below these levels that are especially susceptible to flooding.

The report concludes that any acceleration in sea level rise that is predicted to occur this century will further intensify nuisance flooding impacts over time, and will further reduce the time between flood events.

The report provides critical NOAA environmental data that can help coastal communities assess flooding risk, develop ways to mitigate and adapt to the effects of sea level rise, and improve coastal resiliency in the face of climate- and weather-induced changes.

Contact: Ben Sherman
301-713-3066
NOAA

Related articles

USGS-NOAA: Climate change impacts to US coasts threaten public health, safety and economy

Climate change impacts to US coasts threaten public health, safety and economy