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Tag Archive: ocean

  1. Hotter, longer, more frequent — marine heatwaves on the rise

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    • From 1925-2016, the study found the frequency of marine heatwaves had increased on average by 34% and the length of each heatwave had increased by 17%. Together this led to a 54% increase in the number of marine heatwave days every year.

    April 10, 2018 University of New South Wales

    We know heatwaves over land have been increasing, but now new research reveals globally marine heatwaves have also been increasing in length, number and intensity over the past century. More intriguing still, this trend has accelerated markedly since 1982.

    …Persistent warm water in the north Pacific from 2014-2016 led to fishery closures, mass strandings of marine mammals and harmful algal blooms along coastlines. That heatwave even changed large-scale weather patterns in the Pacific Northwest.

    More recently still, Tasmania’s intense marine heatwave in 2016 led to disease outbreaks and slowing in growth rates across aquaculture industries….

    ….”With more than 90% of the heat from human caused global warming going into our oceans, it is likely marine heatwaves will continue to increase. The next key stage for our research is to quantify exactly how much they may change.

    “The results of these projections are likely to have significant implications for how our environment and economies adapt to this changing world.”…

    Eric C. J. Oliver, Markus G. Donat, Michael T. Burrows, Pippa J. Moore, Dan A. Smale, Lisa V. Alexander, Jessica A. Benthuysen, Ming Feng, Alex Sen Gupta, Alistair J. Hobday, Neil J. Holbrook, Sarah E. Perkins-Kirkpatrick, Hillary A. Scannell, Sandra C. Straub, Thomas Wernberg. Longer and more frequent marine heatwaves over the past century. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03732-9

  2. Atlantic Ocean circulation at weakest point in more than 1,500 years; that’s bad news

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    • The oceans’ circulation hasn’t been this sluggish in 1,600 years. That’s bad news.

    • The research suggests that the Atlantic Meridional Overturning Circulation (AMOC) has weakened over the past 150 years by approximately 15 to 20 percent.

    • The present-day AMOC is exceptionally weak

    April 11, 2018 Woods Hole Oceanographic Institution  Read full ScienceDaily article here and Washington Post coverage here

    New research provides evidence that a key cog in the global ocean circulation system hasn’t been running at peak strength since the mid-1800s and is currently at its weakest point in the past 1,600 years. If the system continues to weaken, it could disrupt weather patterns from the United States and Europe to the African Sahel, and cause more rapid increase in sea level on the US East Coast.

    ….Another study in the same issue of Nature, led by Levke Ceasar and Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research, looked at climate model data and past sea-surface temperatures to reveal that AMOC has been weakening more rapidly since 1950 in response to recent global warming. Together, the two new studies provide complementary evidence that the present-day AMOC is exceptionally weak, offering both a longer-term perspective as well as detailed insight into recent decadal changes….

    When it comes to regulating global climate, the circulation of the Atlantic Ocean plays a key role. The constantly moving system of deep-water circulation, sometimes referred to as the Global Ocean Conveyor Belt, sends warm, salty Gulf Stream water to the North Atlantic where it releases heat to the atmosphere and warms Western Europe. The cooler water then sinks to great depths and travels all the way to Antarctica and eventually circulates back up to the Gulf Stream.
    Credit: Intergovernmental Panel on Climate Change

    David J. R. Thornalley, Delia W. Oppo, Pablo Ortega, Jon I. Robson, Chris M. Brierley, Renee Davis, Ian R. Hall, Paola Moffa-Sanchez, Neil L. Rose, Peter T. Spooner, Igor Yashayaev, Lloyd D. Keigwin. Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature, 2018; 556 (7700): 227 DOI: 10.1038/s41586-018-0007-4

    L. Caesar, S. Rahmstorf, A. Robinson, G. Feulner & V. Saba. Observed fingerprint of a weakening Atlantic Ocean overturning circulationNature Volume 556pages191–196 (April 2018) doi:10.1038/s41586-018-0006-5

     

     


  3. Great Pacific Garbage Patch: Sixteen times more plastic than previously estimated

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    • 1.8 trillion pieces of plastic weighing 80,000 metric tons are currently afloat in an area known as the Great Pacific Garbage Patch — and it is rapidly getting worse.

    March 22, 2018 The Ocean Cleanup  see ScienceDaily article here

    Video explanation: https://www.youtube.com/watch?time_continue=67&v=0EyaTqezSzs

    Video: https://www.youtube.com/watch?v=VxMATP5oRx4

    ….The Great Pacific Garbage Patch (GPGP), located halfway between Hawaii and California, is the largest accumulation zone for ocean plastics on Earth. Conventionally, researchers have used single, fine-meshed nets, typically less than a meter in size, in an attempt to quantify the problem. However, this method yields high uncertainty because of the small surface area that is covered.

    …The results, published today in Scientific Reports, reveal that the GPGP, defined as the area with more than 10 kg of plastic per km2, measures 1.6 million square kilometers, three times the size of continental France. Accumulated in this area are 1.8 trillion pieces of plastic, weighing 80,000 metric tons, the equivalent of 500 Jumbo Jets. These figures are four to sixteen times higher than previous estimates. 92% of the mass is represented by larger objects; while only 8% of the mass is contained in microplastics, defined as pieces smaller than 5 mm in size.

    “We were surprised by the amount of large plastic objects we encountered,” said Dr. Julia Reisser, Chief Scientist of the expeditions. “We used to think most of the debris consists of small fragments, but this new analysis shines a new light on the scope of the debris.”…

    L. Lebreton, B. Slat, F. Ferrari, B. Sainte-Rose, J. Aitken, R. Marthouse, S. Hajbane, S. Cunsolo, A. Schwarz, A. Levivier, K. Noble, P. Debeljak, H. Maral, R. Schoeneich-Argent, R. Brambini, J. Reisser. Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-22939-w


    New analysis reveals the Great Pacific Garbage Patch contains as much as sixteen times more plastic than previously estimated, with pollution levels increasing exponentially.
    Credit: Image courtesy of The Ocean Cleanup
  4. Pacific Heat Wave Known As ‘The Blob’ Appears To Be In Retreat

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    • The transition from “the Blob” to cooler water was observed for 2 months but the deep water is still very warm.

    by March 15, 2018  Read OPB/EarthFix article here

    ….A report from the National Oceanic and Atmospheric Administration (NOAA) outlined the latest ocean observations for the organization that sets salmon catch limits off the West Coast. The Pacific Fishery Management Council will set those limits in early April.

    The extended marine heatwave of the past few years has been nicknamed “the Blob.”

    ….Within the past year, the El Niño effect has dissipated, and other longer-term climate cycles are shifting back toward a more average level.

    “We finally saw some of those northern, fat copepods off the coast of Oregon, which was a very good signal,” said Jennifer Fisher, a researcher with NOAA and Oregon State University. “But the caveat to that is that we saw that transition for only a couple months.”

    Fisher says they will test again this coming summer to see if the trend holds.

    Fisher’s tempered optimism is not unique. Elsewhere scientists are still finding lingering effects of the Blob.

    “If you look in the North Pacific, the deep water is still very warm,” Toby Garfield said. “Which means there’s still a lot of heat being stored.”

    In addition, last summer, there was a major low-oxygen event that caused crab die-offs….

  5. In 2017, the oceans were by far the hottest ever recorded

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    • Researcher found that the upper 2000 meters (more than 6000 feet) of ocean waters were far warmer in 2017 than the previous hottest years 2013-2016.
    • It turns out that 2017 was a record-breaking year, 1.51 × 1022 Joules hotter than any other year. For comparison, the annual electrical generation in China is 600 times smaller than the heat increase in the ocean.

    by John Abraham 26 January 2018 read full Skeptical Science post here

    Among scientists who work on climate change, perhaps the most anticipated information each year is how much the Earth has warmed. That information can only come from the oceans, because almost all heat is stored there. If you want to understand global warming, you need to first understand ocean warming.

    This isn’t to say other measurements are not also important. For instance, measurements of the air temperature just above the Earth are really important. We live in this air; it affects us directly. A great commentary on 2017 air temperatures is provided by my colleague Dana Nuccitelli. Another measurement that is important is sea level rise; so too is ocean acidification. We could go on and on identifying the markers of climate change. But in terms of understanding how fast the Earth is warming, the key is the oceans.

    This important ocean information was just released today by a world-class team of researchers from China. The researchers (Lijing Cheng and Jiang Zhu) found that the upper 2000 meters (more than 6000 feet) of ocean waters were far warmer in 2017 than the previous hottest year. We measure heat energy in Joules. It turns out that 2017 was a record-breaking year, 1.51 × 1022 Joules hotter than any other year. For comparison, the annual electrical generation in China is 600 times smaller than the heat increase in the ocean.

    The authors provide a long history of ocean heat, going back to the late 1950s. By then there were enough ocean temperature sensors to get an accurate assessment of the oceans’ warmth. Their results are shown in the figure below. This graph shows ocean heat as an “anomaly,” which means a change from their baseline of 1981–2010. Columns in blue are cooler than the 1981-2010 period, while columns in red are warmer than that period. The best way to interpret this graph is to notice the steady rise in ocean heat over this long time period.

    OHC

    Ocean heat content change since 1958. Illustration: Cheng and Zhu (2018), Advances in Atmospheric Sciences

    ….It’s interesting to look at the top five years on record in terms of ocean heat; they are listed below.

      1. 2017: 19.19 × 1022 J
      2. 2015: 17.68 × 1022 J
      3. 2016: 17.18 × 1022 J
      4. 2014: 16.74 × 1022J
      5. 2013: 16.08 × 1022 J

    Note that these are the five hottest years ever recorded. Truly astonishing.

    Cheng, L. & Zhu, J. 2017 was the warmest year on record for the global ocean. Adv. Atmos. Sci. (2018) 35: 261. https://doi.org/10.1007/s00376-018-8011-z

  6. Coastal water absorbing more carbon dioxide

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    • Findings may help scientists understand how much carbon dioxide can be released while still limiting global warming

    • while the amount of carbon dioxide in the open ocean is increasing at the same rate as in the atmosphere, these same carbon dioxide concentrations are increasing slower in the coastal ocean because the coastal ocean is shallower than the open ocean and can quickly transfer sequestered carbon dioxide to the deep ocean…
    • nutrient pollution entering coastal waters from things like fertilizer on land stimulate the growth of algae within the continental shelves, which subsequently removes more carbon dioxide from the atmosphere
    • the continental shelves are becoming a crucial element in the global carbon cycle and for the climate system; scientists should take into account the contribution of continental shelves to calculate global carbon budgets

    January 31, 2018 University of Delaware read full ScienceDaily article here

    Oceanographers reveal that the water over the continental shelves is shouldering a larger than expected portion of atmospheric carbon dioxide. The findings may have important implications for scientists focused on understanding how much carbon dioxide can be released into the atmosphere while still keeping warming limited.

    As more carbon dioxide enters the atmosphere, the global ocean soaks up much of the excess, storing roughly 30 percent of the carbon dioxide emissions coming from human activities.

    In this sense, the ocean has acted as a buffer to slow down the greenhouse gas accumulation in the atmosphere and, thus, global warming. However, this process also increases the acidity of seawater and can affect the health of marine organisms and the ocean ecosystem.

    New research by University of Delaware oceanographer Wei-Jun Cai and colleagues at Université Libre de Bruxelles, Texas A&M University-Corpus Christi, University of Hawaii at Manoa and ETH Zurich, now reveals that the water over the continental shelves is shouldering a larger portion of the load, taking up more and more of this atmospheric carbon dioxide….

    Goulven G. Laruelle, Wei-Jun Cai, Xinping Hu, Nicolas Gruber, Fred T. Mackenzie, Pierre Regnier. Continental shelves as a variable but increasing global sink for atmospheric carbon dioxide. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-017-02738-z

  7. 11 Billion Pieces of Plastic Are Smothering Reefs, Infecting Corals

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    • When plastic debris meets coral the likelihood of disease increases from 4 to 89 percent — a 20-fold change.
    • About 11.1 billion plastic items are entangled on reefs across the Asia-Pacific region, and this will likely increase 40% over the next 7 years.
    • “While we can’t stop the huge impact of global warming on coral health in the short term, this new work should drive policy toward reducing plastic pollution.”

    January 25, 2018 Cornell University read full ScienceDaily article here

    For coral reefs, the threat of climate change and bleaching are bad enough. An international research group has now found that plastic trash — ubiquitous throughout the world’s oceans — intensifies disease for coral, adding to reef peril.

    Plastic pollution carries diseases to coral reefs. Credit: © whitcomberd / Fotolia

    “Plastic debris acts like a marine motorhome for microbes,” said the study’s lead author, Joleah Lamb, a postdoctoral research fellow at Cornell. She began collecting this data as a doctoral candidate at James Cook University in Australia.

    Plastics make ideal vessels for colonizing microscopic organisms that could trigger disease if they come into contact with corals,” Lamb said. “Plastic items — commonly made of polypropylene, such as bottle caps and toothbrushes — have been shown to become heavily inhabited by bacteria. This is associated with the globally devastating group of coral diseases known as white syndromes.”

    When plastic debris meets coral, the authors say, the likelihood of disease increases from 4 to 89 percent — a 20-fold change. The scientists estimate that about 11.1 billion plastic items are entangled on reefs across the Asia-Pacific region, and that this will likely increase 40 percent over the next seven years.

    Coral are tiny animals with living tissue that cling to and build upon one another to form “apartments,” or reefs. Bacterial pathogens ride aboard the plastics, disturbing delicate coral tissues and their microbiome…..

    Joleah B. Lamb, Bette L. Willis, Evan A. Fiorenza, Courtney S. Couch, Robert Howard, Douglas N. Rader, James D. True, Lisa A. Kelly, Awaludinnoer Ahmad, Jamaluddin Jompa, C. Drew Harvell. Plastic waste associated with disease on coral reefs. Science, 2018 DOI: 10.1126/science.aar3320

    ———

    Related story from News Deeply:

    11 Billion Pieces of Plastic Are Smothering Reefs, Infecting Corals

    Scientists surveyed nearly 125,000 coral reefs in the Asia-Pacific region, finding that 11.1 billion pieces of plastic debris are entangled in corals and are drastically increasing the likelihood that they will contract deadly diseases.

  8. Offshore Drilling Plan Under Fire: Law may have been violated, Senator says

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    • The administration plan calls for opening 90 percent of the U.S. coasts to oil and gas drilling, and scheduling 47 lease sales between 2019 and 2024. With states opposed and potential legal challenges, can it succeed?
  9. Climate change drives collapse in marine food webs

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    • Increased ocean temperatures reduce the vital flow of energy from the primary food producers at the bottom (e.g. algae), to intermediate consumers (herbivores), to predators at the top of marine food webs.

    January 9, 2018 University of Adelaide read full ScienceDaily article here

    A new study has found that levels of commercial fish stocks could be harmed as rising sea temperatures… drive the collapse of marine “food webs.” [The research shows] that increased temperatures reduce the vital flow of energy from the primary food producers at the bottom (e.g. algae), to intermediate consumers (herbivores), to predators at the top of marine food webs.

    Such disturbances in energy transfer can potentially lead to a decrease in food availability for top predators, which in turn, can lead to negative impacts for many marine species within these food webs.

    “Healthy food webs are important for maintenance of species diversity and provide a source of income and food for millions of people worldwide…

    …”Whilst climate change increased the productivity of plants, this was mainly due to an expansion of cyanobacteria (small blue-green algae),” said Mr Ullah. “This increased primary productivity does not support food webs, however, because these cyanobacteria are largely unpalatable and they are not consumed by herbivores.”

    ….Most research on ocean warming involves simplified, short-term experiments based on only one or a few species. “If we are to adequately forecast the impacts of climate change on ocean food webs and fisheries productivity, we need more complex and realistic approaches, that provide more reliable data for sophisticated food web models,” said project leader Professor Nagelkerken.

    Hadayet Ullah, Ivan Nagelkerken, Silvan U. Goldenberg, Damien A. Fordham. Climate change could drive marine food web collapse through altered trophic flows and cyanobacterial proliferation. PLOS Biology, 2018; 16 (1): e2003446 DOI: 10.1371/journal.pbio.2003446

  10. Strong support globally for ocean protection

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    January 10, 2018 University of California – San Diego read full ScienceDaily article

    People around the world strongly support ocean conservation measures, according to a new study of public perceptions of marine threats and protection.

    The public widely believes that the marine environment is under threat from human activities, and supports actions to protect the marine environment in their region, according to a new study to be published in the February issue of the journal Ocean and Coastal Management.

    The study, conducted by an international team of researchers, reviews a set of public perception surveys of marine issues that reached over 32,000 people in 21 countries. It provides one of the first systematic comparisons of the public perceptions of marine threats and protection around the world.

    The researchers found that 70% of respondents believe that the marine environment is under threat from human activities, and 45% believe the threat is high or very high. Survey respondents identified the greatest threats as pollution and fishing, followed by habitat alteration, climate change, and biodiversity loss….

    Heike K. Lotze, Haley Guest, Jennifer O’Leary, Arthur Tuda, Douglas Wallace. Public perceptions of marine threats and protection from around the world. Ocean & Coastal Management, 2018; 152: 14 DOI: 10.1016/j.ocecoaman.2017.11.004