Archive for September, 2019

Sep 25 2019

The Intergovernmental Panel on Climate Change (IPCC) releases its Special Report on the Ocean and the Cryosphere in a Changing Climate

The new IPCC Special Report, released today,  is the first IPCC Report to focus on the role of the ocean in the global climate and the effects of climate change on the ocean. Ocean acidification is extensively covered throughout the report. A few OA-relevant excerpts from the Summary for Policymakers are cited below:

OBSERVED CHANGES AND IMPACTS

Observed Physical Changes

A2.5 The ocean has taken up between 20–30% (very likely) of total anthropogenic CO2 emissions since the 1980s causing further ocean acidification. Open ocean surface pH has declined by a very likely range of 0.017–0.027 pH units per decade since the late 1980s, with the decline in surface ocean pH very likely to have already emerged from background natural variability for more than 95% of the ocean surface area. {3.2.1; 5.2.2; Box 5.1; Figures SPM.1, SPM.2}

Observed Impacts on Ecosystems

A5.3 Eastern Boundary Upwelling Systems (EBUS) are amongst the most productive ocean ecosystems. Increasing ocean acidification and oxygen loss are negatively impacting two of the four major upwelling systems: the California Current and Humboldt Current (high confidence). Ocean acidification and decrease in oxygen level in the California Current upwelling system have altered ecosystem structure, with direct negative impacts on biomass production and species composition (medium confidence). {Box 5.3, Figure SPM.2}

A6.4 Warm-water coral reefs and rocky shores dominated by immobile, calcifying (e.g., shell and skeleton producing) organisms such as corals, barnacles and mussels, are currently impacted by extreme temperatures and ocean acidification (high confidence). Marine heatwaves have already resulted in large-scale coral bleaching events at increasing frequency (very high confidence) causing worldwide reef degradation since 1997, and recovery is slow (more than 15 years) if it occurs (high confidence). Prolonged periods of high environmental temperature and dehydration of the organisms pose high risk to rocky shore ecosystems (high confidence). {SR1.5; 5.3.4, 5.3.5, 6.4.2.1, Figure SPM.2}

PROJECTED CHANGES AND RISKS

Projected Physical Changes

B2.3 Continued carbon uptake by the ocean by 2100 is virtually certain to exacerbate ocean acidification. Open ocean surface pH is projected to decrease by around 0.3 pH units by 2081–2100, relative to 2006– 2015, under RCP8.5 (virtually certain). For RCP8.5, there are elevated risks for keystone aragonite shell-forming species due to crossing an aragonite stability threshold year-round in the Polar and sub-Polar Oceans by 2081–2100 (very likely). For RCP2.6, these conditions will be avoided this century (very likely), but some eastern boundary upwelling systems are projected to remain vulnerable (high confidence). {3.2.3, 5.2.2, Box 5.1, Box 5.3, Figure SPM.1}

B2.4 Climate conditions, unprecedented since the preindustrial period, are developing in the ocean, elevating risks for open ocean ecosystems. Surface acidification and warming have already emerged in the historical period (very likely). Oxygen loss between 100 and 600 m depth is projected to emerge over 59–80% of the ocean area by 2031– 2050 under RCP8.5 (very likely). The projected time of emergence for five primary drivers of marine ecosystem change (surface warming and acidification, oxygen loss, nitrate content and net primary production change) are all prior to 2100 for over 60% of the ocean area under RCP8.5 and over 30% under RCP2.6 (very likely). {Annex I: Glossary, Box 5.1, Box 5.1 Figure 1}

Projected Risks for Ecosystems

B5.3 Warming, ocean acidification, reduced seasonal sea ice extent and continued loss of multi-year sea ice are projected to impact polar marine ecosystems through direct and indirect effects on habitats, populations and their viability (medium confidence). The geographical range of Arctic marine species, including marine mammals, birds and fish is projected to contract, while the range of some sub-Arctic fish communities is projected to expand, further increasing pressure on high-Arctic species (medium confidence). In the Southern Ocean, the habitat of Antarctic krill, a key prey species for penguins, seals and whales, is projected to contract southwards under both RCP2.6 and RCP8.5 (medium confidence). {3.2.2, 3.2.3, 5.2.3}

B5.4 Ocean warming, oxygen loss, acidification and a decrease in flux of organic carbon from the surface to the deep ocean are projected to harm habitat-forming cold-water corals, which support high biodiversity, partly through decreased calcification, increased dissolution of skeletons, and bioerosion (medium confidence). Vulnerability and risks are highest where and when temperature and oxygen conditions both reach values outside species’ tolerance ranges (medium confidence). {Box 5.2, Figure SPM.3}

B6.1 All coastal ecosystems assessed are projected to face increasing risk level, from moderate to high risk under RCP2.6 to high to very high risk under RCP8.5 by 2100. Intertidal rocky shore ecosystems are projected to be at very high risk by 2100 under RCP8.5 (medium confidence) due to exposure to warming, especially during marine heatwaves, as well as to acidification, sea level rise, loss of calcifying species and biodiversity (high confidence). Ocean acidification challenges these ecosystems and further limits their habitat suitability (medium confidence) by inhibiting recovery through reduced calcification and enhanced bioerosion. The decline of kelp forests is projected to continue in temperate regions due to warming, particularly under the projected intensification of marine heatwaves, with high risk of local extinctions under RCP8.5 (medium confidence). {5.3, 5.3.5, 5.3.6, 5.3.7, 6.4.2, Figure SPM.3}

The full Report, as well as the Summary for Policymakers are available here.


Originally published: https://news-oceanacidification-icc.org/

Sep 5 2019

New Marine Heatwave Emerges off West Coast, Resembles “the Blob”

Researchers are monitoring a new marine heatwave off the West Coast for effects on the marine ecosystem.

Sea surface temperature anomaly maps show temperatures above normal in orange and red.

 

About five years ago “the Blob” of warm ocean water disrupted the West Coast marine ecosystem and depressed salmon returns. Now, a new expanse of unusually warm water has quickly grown in much the same way, in the same area, to almost the same size.

The warm expanse building off the West Coast stretches roughly from Alaska south to California. It ranks as the second largest marine heatwave in terms of area in the northern Pacific Ocean in the last 40 years, after “the Blob.”

“It’s on a trajectory to be as strong as the prior event,” said Andrew Leising, a research scientist at NOAA Fisheries’ Southwest Fisheries Science Center in La Jolla, California. He developed a system for tracking and measuring heatwaves in the Pacific Ocean using satellite data. “Already, on its own, it is one of the most significant events that we’ve seen.”

Cold water welling up from ocean depths along the coast has so far held the warm expanse offshore, he said. However, the upwelling, driven by coastal winds, usually wanes in the fall. The heatwave could then move onshore and affect coastal temperatures, he said. This already appears to have happened along the coast of Washington.

The new marine heatwave off the West Coast stands out in this map of sea surface temperature anomalies, with darker red denoting temperatures farther above average. The highest temperatures shown are more than 5 degrees Fahrenheit above average. Image from NOAA Coral Reef Watch, which corrects effectively for cloud cover.

NOAA Fisheries is focusing additional monitoring on the new heatwave, designated the Northeast Pacific Marine Heatwave of 2019. NOAA Fisheries’ Southwest and Northwest Fisheries Science Centers will provide fisheries managers and others with information on how the unusually warm conditions could affect the marine ecosystem and fish stocks.

“We learned with ‘the Blob’ and similar events worldwide that what used to be unexpected is becoming more common,” said Cisco Werner, NOAA Fisheries Director of Scientific Programs and Chief Science Advisor. “We will continue to inform the public about how the heatwave is evolving, and what we might anticipate based on experience.”

The new heatwave resembles the early stages of “the Blob.” This previous marine heat wave peaked through 2014 and 2015 with temperatures close to seven degrees Fahrenheit above average.

Blob Could Dissipate Quickly

Like “the Blob,” the new heatwave emerged over the past few months. A ridge of high pressure dampened the winds that otherwise mix and cool the ocean’s surface. The heatwave remains relatively new and is primarily affecting the upper layers of the ocean, it could break up rapidly.

“It looks bad, but it could also go away pretty quickly if the unusually persistent weather patterns that caused it change,” said Nate Mantua, a research scientist at the Southwest Fisheries Science Center.

Current forecasts show the heat wave moderating but continuing for months.

A key question is whether the new heatwave will last long enough to affect the marine ecosystem. Biologists say that its large size means it probably already has. For example, warmer conditions during “the Blob” left lesser-quality food available to young salmon entering the ocean. It also shifted predator distributions in ways that contributed to low returns of salmon.

Shifts in the marine food web during the evolution of the 2014-2015 marine heatwave called, “the Blob,” forced sea lion mothers to forage further from their rookeries in the Channel Islands off Southern California. Hungry pups set out on their own, but many became stranded on area beaches. 

Other impacts linked to the earlier heatwave include:

  • The largest harmful algal bloom recorded on the West Coast, which shut down crabbing and clamming for months.
  • Thousands of young California sea lions stranding on beaches.
  • Multiple declared fishery disasters.

NOAA Fisheries scientists recently convened a special meeting to discuss the emerging heatwave and how to anticipate and track its effects. They are now reviewing impacts documented during the “the Blob” to compare them against the effects of the emerging heatwave.

“Given the magnitude of what we saw last time, we want to know if this evolves on a similar path,” said Chris Harvey, a research scientist at the Northwest Fisheries Science Center.

Monitoring Framework in Place

NOAA Fisheries’ two West Coast laboratories collaborate on the California Current Integrated Ecosystem Assessment. This is a joint effort to track and interpret environmental change off the West Coast. That provides a framework to monitor shifting conditions, Harvey said.

One challenge will be applying lessons learned from the last heat wave to anticipate and mitigate potential impacts of the new one. For example, the warm water of “the Blob” led humpback and other whales to feed closer to shore. Record numbers became entangled in lines from crab traps and other fishing gear.

In response, fishermen, managers, and others have formed working groups in California, Oregon, and Washington. They hope to find ways of reducing the risk of entanglements.

The marine heatwave that has formed off the West Coast of North America is currently close to the warmest area in the Pacific Ocean. Map shows sea surface temperature anomalies, with darker orange representing temperatures farther above average. Image from NOAA National Environmental Satellite, Data, and Information Service.

 

Real-time research on environmental changes will give managers the details they need to respond, said Kristen Koch, Director of the Southwest Fisheries Science Center. “This is a time when we all need to know how our marine ecosystem is changing, and what that means for those of us who live along the West Coast.”

The new northeast Pacific heatwave reflects current weather patterns. This includes a band of high pressure stretching north to the Bering Sea and Alaska, which have been unusually warm in recent years, said Nick Bond, a research meteorologist with the Joint Institute for the study of the Atmosphere and Ocean in Seattle, a collaboration between NOAA and the University of Washington.

“There are definitely concerning implications for the ecosystem,” said Bond, who is credited with naming “the Blob.” “It’s all a matter of how long it lasts and how deep it goes.”


Original post: https://www.fisheries.noaa.gov/feature-story/new-marine-heatwave-emerges-west-coast-resembles-blob

Sep 5 2019

Marine Heat Wave Similar To ‘The Blob’ Returns To West Coast

The warm water stretches from Alaska to California, covering an area that’s almost as large as “the blob” and still growing.

“It’s on a trajectory to be as strong as the prior event,” said Andrew Leising, a research scientist at NOAA Fisheries’ Southwest Fisheries Science Center in La Jolla, California. “Already, on its own, it is one of the most significant events that we’ve seen.”

This map of sea surface temperatures illustrates the new marine heatwave off the West Coast as compared with “the blob” of 2014-15. Darker red denotes temperatures farther above average. The highest temperatures shown are more than 5 degrees Fahrenheit above average. NOAA Coral Reef Watch

The marine heat wave in 2014-15 sent water temperatures up to nearly 7 degrees Fahrenheit higher than normal. It caused massive harmful algae blooms that shut down crab and clam fisheries up and down the West Coast. It affected food availability in the ocean, which resulted in many young sea lions left stranded on beaches by parents searching for food. Warmer waters led humpback and other whales to feed closer to shore, which in turn caused record numbers of them to become entangled in lines from crab traps and other fishing gear. They also brought a baffling proliferation of an unfamiliar, pickle-shaped creature known as a pyrosome.

“We learned with ‘the Blob’ and similar events worldwide that what used to be unexpected is becoming more common,” said Cisco Werner, NOAA Fisheries director of scientific programs and chief science adviser. “We will continue to inform the public about how the heatwave is evolving, and what we might anticipate based on experience.”

Current forecasts show the heat wave moderating but continuing for months.

Nick Bond, a research meteorologist with the Joint Institute for the Study of the Atmosphere and Ocean in Seattle, said weather patterns in the region around Alaska and the Bering sea have been unusually warm in recent years. Scientists with NOAA are reviewing impacts documented during the “the blob” to compare them against the effects of the emerging heatwave.

“There are definitely concerning implications for the ecosystem,” said Bond, who is credited with naming “the Blob.” “It’s all a matter of how long it lasts and how deep it goes.”

This story will be updated.


Original post: https://www.opb.org/news/article/marine-heat-wave-blob-returns-west-coast/