By 2300, climate change may cause fishery yields to decline by as much as 20% around the globe, and by as much as 60% in the North Atlantic, a new modeling study suggests.
The study primarily attributes this decline to a lack of ocean mixing, such that nutrients sink into the deep ocean instead of staying at the ocean surface; such alterations to ocean mixing would ultimately drive a decline in fish populations near the surface, the authors say. Climate change models consistently estimate that fisheries will decline by the end of this century, yet there have been few efforts to explore what changes might occur beyond 2100. Here, J. Keith Moore and colleagues used modeling to explore the effects of climate change on fisheries under a "business-as-usual" scenario whereby carbon emissions continue apace, at the same level as they are now.
The Southern Ocean currently experiences mixing between the bottom and top oceanic layers, delivering such a substantial amount of nutrients to the surface that an abundance flows into other oceans. However, simulations by Moore et al. suggest that a combination of changing winds and warmer upper oceanic layers, plus a poleward shift of nutrient upwelling in the Antarctic, will cause an increased portion of nutrients to sink into the deeper layer of the ocean and become trapped there (for example, the amount of phosphate being upwelled will be reduced by 41%, the model estimates). This will reduce the delivery of nutrients to other oceanic areas, they note. While ocean warming and stratification will increase globally, deep mixing in the North Atlantic will be particularly reduced, the authors find. They note that the long-term effects of these changes mean that fisheries will be reduced for a thousand years or more.
Conservation of shoreline plants and seaweeds could, in turn, help preserve shellfish habitats.
Study authors Nyssa Silbiger, then a UCI postdoctoral researcher, and UCI graduate student Laura Elsberry (standing) survey tide-pool communities at Corona del Mar State Beach. Credit: Cascade Sorte / UCI.
Marine plants and seaweeds in shallow coastal ecosystems can play a key role in alleviating the effects of ocean acidification, and their robust population in shoreline environments could help preserve declining shellfish life, according to a study by University of California, Irvine ecologists.
In a new study on the Pacific Coast, Nyssa Silbiger, former UCI postdoctoral researcher, and Cascade Sorte, assistant professor of ecology & evolutionary biology, determined that marine plants and seaweeds decrease the acidity of their surroundings through photosynthesis. Their findings suggest that maintaining native seawater vegetation could locally lessen the acidifying effects of rising CO2 levels on marine animals who are sensitive to ocean pH, which has declined since preindustrial times.
The study results appear online in the open-access Scientific Reports. "Our findings from sites spanning some 1,000 miles of coastline show that marine life plays a leading role in driving local pH conditions," Sorte said.
About 90 percent of fishery catch comes from coastal ecosystems. Any coastal pH decrease has a major impact on animals such as corals, oysters and mussels, whose shells and skeletons can become more brittle in low-pH environments.
This is a major concern for shellfish fisheries, which contribute over $1 billion annually to the U.S. economy while providing more than 100,000 jobs.
Due to their findings, the authors recommend efforts to conserve marine plants and seaweeds in shoreline habitats, including where commercial seafood is harvested.
"The environmental and economic consequences resulting from ocean acidification are dire," said Silbiger, now an assistant professor of biology at California State University, Northridge. "Decreasing CO2 emissions is still the No. 1 most important way to protect our marine ecosystems, but our research indicates that marine life also has substantial control over coastal pH."
The study received UCI seed funding for single- and multi-investigator research projects and support from the UCI OCEANS Initiative; research travel was sponsored by GoWesty.
In a new commentary in the journal Nature Climate Change, IIASA researchers argue that a broader range of scenarios is needed to support international policymakers in the target of limiting climate change to under 2°C above pre-industrial levels, and to avoid potential negative environmental and social consequences of carbon dioxide removal on a massive scale.
"Many currently used emissions pathways assume that we can slowly decrease fossil fuel emissions today and make up for it later with heavy implementation of negative emissions technologies," says IIASA Ecosystems Services and Management Program Director Michael Obersteiner, lead author of the article. "This is a problem because it assumes we can put the burden on future generations--which is neither a realistic assumption nor is it morally acceptable from an intergenerational equity point of view."
The researchers point out that 87% of the scenarios in the IPCC 5th Assessment Report that limit climate change to less than 2°C rely heavily on negative emissions in the second half of the century, with most of the carbon dioxide removal coming from a suite of technologies known as Bioenergy with Carbon Capture and Storage (BECCS). Assuming that it's even possible to deploy BECCS on the scale required (a big question for a technology that has not yet been widely tested or implemented), massive implementation of land-based carbon dioxide removal strategies would have impacts on both the environment and the food system, with previous research showing trade-offs for food security and environmental conservation.
At the same time, reliance on future negative emissions to achieve climate goals may also fail to account for feedbacks in the climate system such as methane release from thawing permafrost, which are not yet fully understood.
"Many of our scenarios do not account for the uncertainties related to the climate mitigation process. Are our carbon budget estimates reasonable? Are the technologies going to develop the way we need them to be? Are natural carbon sinks reliable, or might they turn around?" says IIASA researcher Johannes Bednar, a coauthor.
In the article, the researchers present four archetype scenarios that incorporate a broader range of potential mitigation options. These include:
Major reliance on carbon dioxide removal in the future, the current archetype of many existing scenarios for achieving the 2°C or more stringent 1.5°C target.
Rapid decarbonization starting immediately, and halving every decade as proposed in a recent Science commentary coauthored by IIASA researchers.
Earlier implementation of carbon dioxide removal technologies, and phasing out by the end of the century
Consistent implementation of carbon dioxide removal from now until the end of the century.
Under all these scenarios, current country commitments under the Paris Agreement would not be sufficient to achieve the required cuts, the researchers say.
The article adds to a large body of significant IIASA research on pathways and scenarios for climate mitigation, as well as integrated research on climate and other sustainable development goals. It also provides a critical look at the current outlook for reaching climate targets.
IIASA researcher Fabian Wagner, another study coauthor adds, "In this paper we have shown that negative emission technologies may not only be an asset but also an economic burden if not deployed with care. We as scientists need to be careful when we communicate to policymakers about how realistic different scenarios might be. When we present scenarios that require the world to convert an amount of land equivalent to all today's cropland to energy plantations, alarm bells should go off."
Increased fluctuations in the path of the North Atlantic jet stream since the 1960s coincide with more extreme weather events in Europe such as heat waves, droughts, wildfires and flooding, reports a University of Arizona-led team. The research is the first reconstruction of historical changes in the North Atlantic jet stream prior to the 20th century. By studying tree rings from trees in the British Isles and the northeastern Mediterranean, the team teased out those regions' late summer weather going back almost 300 years -- to 1725.
"We find that the position of the North Atlantic Jet in summer has been a strong driver of climate extremes in Europe for the last 300 years," said Valerie Trouet, an associate professor of dendrochronology at the University of Arizona Laboratory of Tree-Ring Research.
Having a 290-year record of the position of the jet stream let Trouet and her colleagues determine that swings between northern and southern positions of the jet became more frequent in the second half of the 20th century, she said.
"Since 1960 we get more years when the jet is in an extreme position." Trouet said, adding that the increase is unprecedented.
When the North Atlantic Jet is in the extreme northern position, the British Isles and western Europe have a summer heat wave while southeastern Europe has heavy rains and flooding, she said. When the jet is in the extreme southern position, the situation flips: Western Europe has heavy rains and flooding while southeastern Europe has extreme high temperatures, drought and wildfires.
"Heat waves, droughts and floods affect people," Trouet said. "The heat waves and drought that are related to such jet stream extremes happen on top of already increasing temperatures and global warming -- it's a double whammy."
Extreme summer weather events in the American Midwest are also associated with extreme northward or southward movements of the jet stream, the authors write.
"We studied the summer position of the North Atlantic jet. What we're experiencing now in North America is part of the same jet stream system," Trouet said.
This winter's extreme cold and snow in the North American Northeast and extreme warmth and dryness in California and the American Southwest are related to the winter position of the North Pacific Jet, she said.
The paper, "Recent enhanced high-summer North Atlantic Jet variability emerges from three-century context," by Trouet and her co-authors Flurin Babst of the Swiss Federal Research Institute WSL in Birmensdorf and Matthew Meko of the UA is scheduled for publication in Nature Communications on Jan. 12. The U.S. National Science Foundation and the Swiss National Science Foundation funded the research.
"I remember quite vividly when I got the idea," Trouet said. "I was sitting in my mom's house in Belgium."
While visiting her family in Belgium during the very rainy summer of 2012, Trouet looked at the newspaper weather map that showed heavy rain in northwestern Europe and extreme heat and drought in the northeastern Mediterranean.
"I had seen the exact same map in my tree-ring data," she said. The tree rings showed that hot temperatures in the Mediterranean occurred the same years that it was cool in the British Isles -- and vice versa.
The part of an annual tree ring that forms in the latter part of the growing season is called latewood. The density of the latewood in a particular tree ring reflects the August temperature that year. Other investigators had measured the annual latewood density for trees from the British Isles and the northeastern Mediterranean for rings formed from 1978 back to 1725. Because August temperatures in those two regions reflect the summer position of the North Atlantic jet stream, Trouet and her colleagues used those tree-ring readings to determine the historical position of the jet stream from 1725 to 1978. For the position of the jet stream from 1979 to 2015, the researchers relied on data from meteorological observations.
"There's a debate about whether the increased variability of the jet stream is linked to man-made global warming and the faster warming of the Arctic compared to the tropics," Trouet said.
"Part of the reason for the debate is that the data sets used to study this are quite short -- 1979 to present. If you want to see if this variability is unprecedented, you need to go farther back in time -- and that's where our study comes in."
With the discovery of much older trees in the Balkans and in the British Isles, Trouet hopes to reconstruct the path of the North Atlantic jet stream as much as 1,000 years into the past. She is also interested in reconstructing the path of the North Pacific jet stream, which influences the climate and weather over North America.
Oscillations of water temperature in the tropical Pacific Ocean can induce rapid melting of Antarctic ice shelves.
Front of the Getz Ice Shelf. Credit: Jeremy Harbeck/NASA.
A new study published Jan. 8 in the journal Nature Geoscience reveals that strong El Nino events can cause significant ice loss in some Antarctic ice shelves while the opposite may occur during strong La Nina events.
El Niño and La Niña are two distinct phases of the El Niño/Southern Oscillation (ENSO), a naturally occurring phenomenon characterized by how water temperatures in the tropical Pacific periodically oscillate between warmer than average during El Niños and cooler during La Niñas.
The research, funded by NASA and the NASA Earth and Space Science Fellowship, provides new insights into how Antarctic ice shelves respond to variability in global ocean and atmospheric conditions.
The study was led by Fernando Paolo while a PhD graduate student and postdoc at Scripps Institution of Oceanography at the University of California San Diego. Paolo is now a postdoctoral scholar at NASA's Jet Propulsion Laboratory. Paolo and his colleagues, including Scripps glaciologist Helen Fricker, discovered that a strong El Niño event causes ice shelves in the Amundsen Sea sector of West Antarctica to gain mass at the surface and melt from below at the same time, losing up to five times more ice from basal melting than they gain from increased snowfall. The study used satellite observations of the height of the ice shelves from 1994 to 2017.
"We've described for the first time the effect of El Niño/Southern Oscillation on the West Antarctic ice shelves," Paolo said. "There have been some idealized studies using models, and even some indirect observations off the ice shelves, suggesting that El Niño might significantly affect some of these shelves, but we had no actual ice-shelf observations. Now we have presented a record of 23 years of satellite data on the West Antarctic ice shelves, confirming not only that ENSO affects them at a yearly basis, but also showing how."
The opposing effects of El Niño on ice shelves - adding mass from snowfall but taking it away through basal melt - were at first difficult to untangle from the satellite data. "The satellites measure the height of the ice shelves, not the mass, and what we saw at first is that during strong El Niños the height of the ice shelves actually increased," Paolo said. "I was expecting to see an overall reduction in height as a consequence of mass loss, but it turns out that height increases."
After further analysis of the data, the scientists found that although a strong El Niño changes wind patterns in West Antarctica in a way that promotes flow of warm ocean waters towards the ice shelves to increase melting from below, it also increases snowfall particularly along the Amundsen Sea sector. The team then needed to determine the contribution of the two effects. Is the atmosphere adding more mass than the ocean is taking away or is it the other way around?
"We found out that the ocean ends up winning in terms of mass. Changes in mass, rather than height, control how the ice shelves and associated glaciers flow into the ocean," Paolo said. While mass loss by basal melting exceeds mass gain from snowfall during strong El Niño events, the opposite appears to be true during La Niña events.
Over the entire 23-year observation period, the ice shelves in the Amundsen Sea sector of Antarctica had their height reduced by 20 centimeters (8 inches) a year, for a total of 5 meters (16 feet), mostly due to ocean melting. The intense 1997-98 El Nino increased the height of these ice shelves by more than 25 centimeters (10 inches). However, the much lighter snow contains far less water than solid ice does. When the researchers took density of snow into account, they found that ice shelves lost about five times more ice by submarine melting than they gained from new surface snowpack.
"Many people look at this ice-shelf data and will fit a straight line to the data, but we're looking at all the wiggles that go into that linear fit, and trying to understand the processes causing them," said Fricker, who was Paolo's PhD adviser at the time the study was conceived. "These longer satellite records are allowing us to study processes that are driving changes in the ice shelves, improving our understanding on how the grounded ice will change," Fricker said.
"The ice shelf response to ENSO climate variability can be used as a guide to how longer-term changes in global climate might affect ice shelves around Antarctica," said co-author Laurie Padman, an oceanographer with Earth & Space Research, a nonprofit research company based in Seattle. "The new data set will allow us to check if our ocean models can correctly represent changes in the flow of warm water under ice shelves," he added.
Melting of the ice shelves doesn't directly affect sea level rise, because they're already floating. What matters for sea-level rise is the addition of ice from land into the ocean, however it's the ice shelves that hold off the flow of grounded ice toward the ocean.
Understanding what's causing the changes in the ice shelves "puts us a little bit closer to knowing what's going to happen to the grounded ice, which is what will ultimately affect sea-level rise," Fricker said. "The holy grail of all of this work is improving sea-level rise projections," she added.
In broadest view yet of world's low oxygen, scientists reveal dangers and solutions.
Low oxygen caused the death of these corals and others in Bocas del Toro, Panama. The dead crabs pictured also succumbed to the loss of dissolved oxygen. Credit: Arcadio Castillo/Smithsonian.
In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold. In coastal water bodies, including estuaries and seas, low-oxygen sites have increased more than 10-fold since 1950. Scientists expect oxygen to continue dropping even outside these zones as Earth warms.
"Oxygen is fundamental to life in the oceans," said Denise Breitburg, lead author and marine ecologist with the Smithsonian Environmental Research Center. "The decline in ocean oxygen ranks among the most serious effects of human activities on the Earth's environment."
"It's a tremendous loss to all the support services that rely on recreation and tourism, hotels and restaurants and taxi drivers and everything else," said Levin. "The reverberations of unhealthy ecosystems in the ocean can be extensive."
The study came from a team of scientists from GO2NE (Global Ocean Oxygen Network), a new working group created in 2016 by the United Nation's Intergovernmental Oceanographic Commission. The review paper is the first to take such a sweeping look at the causes, consequences and solutions to low oxygen worldwide, in both the open ocean and coastal waters. The article highlights the biggest dangers to the ocean and society, and what it will take to keep Earth's waters healthy and productive.
The Stakes
"Approximately half of the oxygen on Earth comes from the ocean," said Vladimir Ryabinin, executive secretary of the International Oceanographic Commission that formed the GO2NE group. "However, combined effects of nutrient loading and climate change are greatly increasing the number and size of 'dead zones' in the open ocean and coastal waters, where oxygen is too low to support most marine life."
In areas traditionally called "dead zones," like those in Chesapeake Bay and the Gulf of Mexico, oxygen plummets to levels so low many animals suffocate and die. As fish avoid these zones, their habitats shrink and they become more vulnerable to predators or fishing. But the problem goes far beyond "dead zones," the authors point out. Even smaller oxygen declines can stunt growth in animals, hinder reproduction and lead to disease or even death. It also can trigger the release of dangerous chemicals such as nitrous oxide, a greenhouse gas up to 300 times more powerful than carbon dioxide, and toxic hydrogen sulfide. While some animals can thrive in dead zones, overall biodiversity falls.
Climate change is the key culprit in the open ocean. Warming surface waters make it harder for oxygen to reach the ocean interior. Furthermore, as the ocean as a whole gets warmer, it holds less oxygen. In coastal waters, excess nutrient pollution from land creates algal blooms, which drain oxygen as they die and decompose. In an unfortunate twist, animals also need more oxygen in warmer waters, even as it is disappearing.
People's livelihoods are also on the line, the scientists reported, especially in developing nations. Smaller, artisanal fisheries may be unable to relocate when low oxygen destroys their harvests or forces fish to move elsewhere. In the Philippines, fish kills in a single town's aquaculture pens cost more than $10 million. Coral reefs, a key tourism attraction in many countries, also can waste away without enough oxygen.
Some popular fisheries could benefit, at least in the short term. Nutrient pollution can stimulate production of food for fish. In addition, when fish are forced to crowd to escape low oxygen, they can become easier to catch. But in the long run, this could result in overfishing and damage to the economy.
Low-oxygen zones are spreading around the globe. Red dots mark places on the coast where oxygen has plummeted to 2 milligrams per liter or less, and blue areas mark zones with the same low-oxygen levels in the open ocean. Credit: GO2NE working group. Data from World Ocean Atlas 2013 and provided by R. J. Diaz.
Winning the War: A Three-Pronged Approach
To keep low oxygen in check, the scientists said the world needs to take on the issue from three angles:
Address the causes: nutrient pollution and climate change. While neither issue is simple or easy, the steps needed to win can benefit people as well as the environment. Better septic systems and sanitation can protect human health and keep pollution out of the water. Cutting fossil fuel emissions not only cuts greenhouse gases and fights climate change, but also slashes dangerous air pollutants like mercury.
Protect vulnerable marine life. With some low oxygen unavoidable, it is crucial to protect at-risk fisheries from further stress. According to the GO2NE team, this could mean creating marine protected areas or no-catch zones in areas animals use to escape low oxygen, or switching to fish that are not as threatened by falling oxygen levels. Improve low-oxygen tracking worldwide. Scientists have a decent grasp of how much oxygen the ocean could lose in the future, but they do not know exactly where those low-oxygen zones will be. Enhanced monitoring, especially in developing countries, and numerical models will help pinpoint which places are most at risk and determine the most effective solutions.
"This is a problem we can solve," Breitburg said. "Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline." As proof Breitburg points to the ongoing recovery of Chesapeake Bay, where nitrogen pollution has dropped 24 percent since its peak thanks to better sewage treatment, better farming practices and successful laws like the Clean Air Act. While some low-oxygen zones persist, the area of the Chesapeake with zero oxygen has almost disappeared. "Tackling climate change may seem more daunting," she added, "but doing it is critical for stemming the decline of oxygen in our oceans, and for nearly every aspect of life on our planet."
Diminishing sea ice near the Arctic coast leaves more open water near the coast for winds to create waves. The increased wave action reaches down and stirs up sediments on shallow continental shelves, releasing radium and other chemicals that are carried up to the surface and swept away into the open ocean by currents such as the Transpolar Drift. A new study found surprising evidence that climate change is rapidly causing coastal changes in the Arctic that could have significant impacts on Arctic food webs and animal populations. (Natalie Renier, Woods Hole Oceanographic Institution).
Scientists have found surprising evidence of rapid climate change in the Arctic: In the middle of the Arctic Ocean near the North Pole, they discovered that the levels of radium-228 have almost doubled over the last decade.
The finding indicates that large-scale changes are happening along the coast--because the source of the radium is the land and shallow continental shelves surrounding the ocean. These coastal changes, in turn, could also be delivering more nutrients, carbon, and other chemicals into the Arctic Ocean and lead to dramatic impacts on Arctic food webs and animal populations.
The research team, led by Woods Hole Oceanographic Institution (WHOI), suspects that melting sea ice has left more open water near the coast for winds to create waves. The wave action reaches down to the shallow shelves and stirs up sediments, releasing radium that is carried to the surface and away into the open ocean. The same mechanism would likely also mobilize and deliver more nutrients, carbon, and other chemicals into the Arctic Ocean, fueling the growth of plankton at the bottom of the food chain. That, in turn, could have significant impacts on fish and marine mammals and change the Arctic ecosystem.
The study was published Jan. 3, 2018, in the journal Science Advances. The research team included Lauren Kipp, Matthew Charette, and Paul Henderson (WHOI), Willard Moore (University of South Carolina), and Ignatius Rigor (University of Washington).
Scientists have long used radium-228 to track the flow of material from land and sediments into the ocean. It is a naturally occurring isotope produced by the radioactive decay of thorium in sediments. But unlike thorium, it dissolves into water, where scientists can track the sources, amounts, rates, and direction of its flow, said Kipp, who is lead author of the study and a graduate student in the MIT-WHOI Joint Program in Oceanography.
Kipp led efforts to measure radium at 69 locations from the western edge of the Arctic Ocean to the Pole on a two-month voyage aboard the icebreaker Healy in the summer of 2015. The cruise was part of the international GEOTRACES program, which aims to measure chemical tracers in the world's ocean to understand ocean circulation and provide a baseline to assess future chemical changes in the oceans. The U.S. GEOTRACES program and this study are both funded by the National Science Foundation.
Scientists aboard the icebreaker Healy measured seawater chemistry across the Arctic Ocean and found that levels of radium-228 have almost doubled over the last decade in the middle of the ocean. The radium was transported from land and shallow continental shelves by currents such as the Transpolar Drift. The surprising finding is evidence that rapid climate change is causing large-scale changes along the Arctic coast, such as diminishing sea ice. These coastal changes, in turn, could also deliver more nutrients, carbon, and other chemicals into the Arctic Ocean and have significant impacts on the Arctic food web. (Natalie Renier, Woods Hole Oceanographic Institiution).
To their surprise, the research team found that radium-228 concentrations in the central Arctic Ocean had increased substantially since measurements had last been made in 2007. What was its source and why had it increased?
The team investigated the trajectories of sea ice drifting in the ocean and saw a pattern of ice--and hence water--flowing northward from the vast northern coast of Russia toward the middle of the Arctic Ocean, where the radium concentrations had increased. The pattern aligned with the Transpolar Drift, a powerful current flowing in same direction that could transport radium from coastal sources.
They concluded that the excess radium had to have come from sediments in the East Siberian Arctic Shelf off Russia, the largest continental shelf on Earth. It is relatively shallow, with an average depth of 170 feet, but it extends 930 miles off shore and contains a vast reservoir of radium and other chemical compounds.
Something had to have changed along the coast to explain the dramatic surge in radium in the middle of the Arctic Ocean. The scientists theorize that a warming Arctic environment has reduced sea ice cover, allowing for more wave action that stirs up sediments and mobilizes more radium.
But there are other possible contributing factors that are causing changes over the shelf, the scientists say. More wave action can also cause more coastline erosion, adding more terrestrial sediment into the ocean. Warming temperatures can thaw permafrost, liberating more material into the ocean, and increasing river and groundwater runoff can carry more radium, nutrients, carbon, and other material into the Arctic.
"Continued monitoring of shelf inputs to Arctic surface waters is therefore vital to understand how the changing climate will affect the chemistry, biology, and economic resources of the Arctic Ocean," the study's authors wrote.
Data coverage over the East Siberian Shelf is currently very limited, so it is important to conduct more studies in this region in order to pinpoint the direct causes of the increased shelf inputs and allow future monitoring. "Evidence from Kipp and co-workers for substantial ongoing change in the chemical environment of the Arctic Ocean emphasizes the need for sustained study of these changes and of the processes involved," said Bob Anderson, an Ewing-Lamont Research Professor at the Lamont-Doherty Earth Observatory of Columbia University and the director of the U.S. GEOTRACES Program Office. "It would be great if related efforts by marine geochemists in Russia could be integrated with future studies by other nations, for example under the auspices of the international GEOTRACES program."
Pacific Island nations are highly dependent on fisheries as a food source and for employment. Image by Quentin Hanich.
Many Pacific Island nations will lose 50 to 80 percent of marine species in their waters by the end of the 21st century if climate change continues unchecked, finds a new Nippon Foundation-Nereus Program study published in Marine Policy. This area of the ocean is projected to be the most severely impacted by aspects of climate change.
"Under climate change, the Pacific Islands region is projected to become warmer, less oxygenated, more acidic, and have lower production of plankton that form the base of oceanic food webs," said lead author Rebecca Asch, Nereus Program alumnus and Assistant Professor at East Carolina University. "We found that local extinction of marine species exceeded 50 percent of current biodiversity levels across many regions and at times reached levels over 80 percent."
The Pacific Islands region is the warmest of the global ocean. It's also an area where there is less seasonal variability -- it more or less feels like summer all year. Because there are no drastic seasons, the animals in the tropical Pacific may find changing conditions to be more of a shock.
"Additional warming will push ocean temperature beyond conditions that organisms have not experienced since geological time periods in this region," said co-author Gabriel Reygondeau, Nereus Fellow at UBC. "Since no organisms living in the ocean today would have time to adapt to these warmer conditions, many will either go extinct or migrate away from the western Pacific, leaving this area with much lower biodiversity."
Climate change will be strongly felt in the Pacific Islands, including impacts on fisheries, sea level rise, and extreme weather events. Image by Quentin Hanich.
The authors examined the effects of climate change on more than a thousand species, including those that live on reefs and those that live in open-water habitats. Both groups underwent declines in local biodiversity, but the rates of decline were higher for the open-water species.
These changes would be detrimental to Pacific Islanders, who are highly dependent on marine species for food, economic opportunities, and cultural heritage. Additional threats come from sea level rise and increasing major storms. Also, these are often developing countries with less resources available for societal adaptations to climate change.
"One hopeful point is that the extent of these changes in biodiversity and fisheries was dramatically reduced under a climate change scenario where greenhouse gas emissions were close to what would be needed for achieving the Paris Climate Agreement" said co-author William Cheung, Nereus Director of Science. "As a result, these changes in oceanic conditions are not inevitable, but instead depend on the immediate actions of all countries to materialize their commitment to limit greenhouse gas emissions as is being discussed in COP23 in Bonn, Germany, this week."
The world's most prestigious award for pioneers in environmental science was given to Hans Joachim Schellnhuber this week in Tokyo.
Kazuhiko Ishimura, Chairman of the Asahi Glass Foundation, and Hans Joachim Schellnhuber. Photo: Asahi Glass Foundation
The world's most prestigious award for pioneers in environmental science was given to Hans Joachim Schellnhuber this week in Tokyo. He is Director of the Potsdam Institute for Climate Impact Research (PIK), a member of the Leibniz Association. The Blue Planet Prize, coming along with 50 million yen, honors outstanding thinkers who help to meet challenges of planetary dimensions. It is awarded by the Asahi Glass Foundation and handed over in presence of Japan's Imperial Prince and Princess. Schellnhuber received the prize for establishing a new field of science, Earth System Analysis, and introducing most influential concepts including the notion of tipping elements in the climate system. The second recipient is Gretchen Daily of Stanford University, USA, who was honored for her research about biodiversity and natural capital.
"Professor Schellnhuber pioneered a new field of climate science," said Yoshihiro Hayashi, Chairman of the Blue Planet Prize Selection Committee and Director General of the National Museum of Nature and Science in Tokyo. The Director of PIK provided "groundbreaking interdisciplinary science," Hayashi said. Furthermore, "one of his greatest successes was communicating the magnitude of the challenge of climate stabilization to a broad public as well as decision-makers," he added, calling Schellnhuber "the father of the 2 degrees limit for global warming". On the same note, the official declaration by the Blue Planet Prize organizers says: "His activities eventually created a torrent of measures against global warming worldwide, resulting in the 2-degree guardrail agreed upon by more than 190 countries at the UN climate summit COP21. Professor Schellnhuber and PIK have played a central role in this field for many years."
"I believe that the two recipients are leading us to a new era of tackling environmental issues," commented Hiroyuki Yoshikawa of the Blue Planet Prize Committee in his speech. He is a Special Counselor to the President of the Japan Science and Technology Agency, member of the Japan Academy, and a former President of both the Science Council of Japan and the University of Tokyo. The committee includes internationally renowned scientists such as Nobel Laureate Ryoji Noyori who met Schellnhuber on the eve of the prize ceremony.
Strong messages from Japan's Prime Minister Abe and the Imperial Prince Akishino
"This prize is said to be the Nobel Prize for environmental research," said Japan's minister of the Environment, Masaharu Nakagawa, in a personal meeting earlier this week. He thanked Schellnhuber "for helping with the long-term strategy of our country. We're in the midst of a broad change." Schellnhuber has visited Japan on a number of occasions for talks with high-ranking officials in the past years. Stabilizing the climate "is a global challenge which requires concerted action by all countries," Japans Prime Minister Shinzo Abe said in a message congratulating the awardees. "My government remains committed to climate action."
Marking the outstanding significance of the event for Japan, His Imperial Highness Prince Akishino attended the ceremony. "In recent years, we humans have pursued the progress of science and technology," - yet precisely by this way of economic development, "the ecosystems have been affected," said the Prince. He specifically mentioned the increase of dangerous weather extremes. "We need a correct understanding of the human effect on the environment - as well as actions. It is hence satisfying that the laureates have developed the science as well as they have sounded the alarm."
In a congratulatory message His Royal Highness The Prince of Wales, Charles, emphasized that Schellnhuber's work is important to persuade the world to counter climate change, and to save the planet for our children and grandchildren.
"Germany and Japan must take the lead in this race against global disaster"
Previous recipients of the prize include the godfather of climate modelling, Syukuro Manabe, from the US National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory, Norway's former Prime Minister Gro Harlem Brundtland, and Charles Keeling from the University of California at San Diego who gave his name to the famous Keeling curve of atmospheric CO2 concentration measurements.
"The sun first rises in the East," said Schellnhuber at the ceremony. "Philosophers in China and Japan have deliberated upon the harmony between nature and humanity for many centuries." Today, scientists around the world, including those at the Potsdam Institute for Climate Impact Research that Schellnhuber founded in 1992, are successfully investigating the nonlinear dynamics of the complex climate system, and religious leaders like Pope Francis - whose green Encyclical Schellnhuber had the honor to present to the world in 2015 - joined in the call for avoiding dangerous climate change. "Yet man-made climate change has roared on, since policy has largely failed us," said Schellnhuber. Now, on the basis of the Paris Agreement to limit temperature rise to well below 2 degrees Celsius, a great transformation of the global economy is required. "Germany and Japan must take the lead in this race against global disaster," Schellnhuber said. "They shall become closest partners in sustainable innovation - for the sake of our two nations and for the sake of our Blue Planet."
Environmental disturbances such as El Niño shake up the marine food web off Southern California, new research shows, countering conventional thinking that the hierarchy of who-eats-who in the ocean remains largely constant over time.
The new research published in the journal Science Advances examined the skin cells of common dolphins for chemical clues about the length of the marine food chain, which begins with tiny plankton and continues as species eat them, and other species eat those species. Large predators such as dolphins occupy the top of the food chain, their cells carrying chemical information from all the species beneath them.
Many scientists have long considered the length of the food chain in the open sea to be relatively stable, with roughly the same animal species feeding on each other through time. But the chemical signatures in the skin of Southern California dolphins collected over two decades now show otherwise, report scientists from NOAA Fisheries, Moss Landing Marine Laboratories and the Scripps Institution of Oceanography.
"We documented for first time marked changes in the pelagic food web length in response to various natural and anthropogenic related stressors," said lead author Rocio I. Ruiz-Cooley, formerly of NOAA Fisheries' Southwest Fisheries Science Center and now at Moss Landing Marine Laboratories. "This tells us that the food web is very dynamic, and reveals changes with the ecosystem around it."
The finding helps scientists understand the health and resilience of the ecosystem, she said. A longer food chain is more typical, and reflects a relatively diverse community, while shorter chains occur during extreme environmental conditions and suggest a decline in that diversity.
During strong climate perturbations such as the 1997-1999 El Niño Southern Oscillation that included the most intense El Niño event of the century, which brought unusual warming to the U.S. West Coast, the food chain in the California Current shortened sharply, the scientists found. That coincided with declines in ocean productivity such as reduced growth of plankton, declines of some fish and birds and expanded ranges of some species such as jumbo squid, perhaps as they searched for scarce food or followed favorable temperatures.
"These changes in life history traits and population dynamics likely reduced and/or removed populations of many species, including important components of the food web," in turn shrinking the food chain, scientists wrote in the new report. Predators may have exacerbated this impact as they fed on what was left and reduced the length of the food chain that supported them. Although some species such as jellyfish and tunicates such as salp may multiply quickly to fill such gaps, they provide so little nutrition that most predators do not pursue them and the food chain remains short.
The research demonstrates that top predators such as the common dolphin can serve as important indicators of the length of the food chain, which in turn provides insight into the ecosystem, Ruiz-Cooley said. The study drew upon the Southwest Fisheries Science Center's collection of skin tissue samples gathered from dolphins inadvertently entangled in gillnets off Southern California from 1991 to 2008, highlighting the value of that collection over time.
"This research, and the results it has produced, illustrate the great value of this time series reflected in the cell samples," said Lisa Ballance, director of the Science Center's Marine Mammal and Turtle Division, and coauthor on this paper. "As technology advances, we can extract even more information from the time series as a window into the past, and a baseline to address tomorrow's emerging issues."
