Global warming

Tag: Global warming

Warm-water ‘blobs’ significantly diminish salmon, other fish populations, study says

It’s no secret that salmon and other Northwest fish populations are expected to shrink as a result of a warming Pacific Ocean. But a new study suggests that the resulting decline in commercial fishing by 2050 could be twice as great as previously estimated by climate scientists.
The higher estimates of population declines were calculated by researchers at the University of British Columbia, who took into account occasional “marine heat waves” that can play havoc with the ecosystem. A recent example is the warm-water event known as the “blob,” which included ocean temperatures up to 7 degrees above average (Fahrenheit) during a two-year period beginning in 2014.

Current sea surface temperature anomalies (variations from average) for the Pacific Coast off North and South America. The temperature scale is different from the maps above.
Map: NOAA Coral Reef Watch, April 23, 2020

William Cheung, who led the new study, told me that previous estimates of declines in fish populations assumed that the waters would warm at a steady rate as a result of climate change. But the impacts are much greater, he said, when one considers the occasional shocks to the system caused by rapid warming. Climate-change models predict at least four additional “blobs” before the end of the century, although nobody can predict when exactly they will occur.
Cold-water fish subjected to warm water face a disruption in their normal body functions, reducing the size of the fish and increasing the risk of death. Warm water also can reduce the overall production in the food web, making it more difficult for fish to find suitable prey.
For the fishing industry, marine heat waves are not unlike a sudden pandemic such as COVID-19, William said. Fishing crews can adjust to normal fluctuations in fish populations, just as health-care providers adjust to flu seasons, but sudden and stronger disruptions can lead to more serious consequences.
“Last year, management agencies closed the Alaska Pacific cod fisheries (for 2020), because they had a suspicion that the blob was returning,” said Cheung, a professor at the UBC Institute for the Oceans and Fisheries. “There was concern that the already low Pacific cod population could be hit by a heat wave that could drive the fish stocks to very low levels.”
The 2019 “return of the blob” was not as long-lasting as the 2014-16 event, but waters off the coast are still warmer than normal.
The new study, published online in the journal “Scientific Reports,” combined climate and fish models to estimate the impacts of future “blobs” from Alaska to the Gulf of California. Findings suggest that the total biomass of fish will decline, and fish will move around to establish new distribution patterns. That will decrease the amount of fish available for harvest as well as changing the location where the fish can be caught.
William Cheung

While many studies have talked about fish stocks moving around in response to changing ocean temperatures, William said biomass decreases could be a more consistent indicator for assessing the impacts of marine heat waves on various species.
During a heat wave, the average biomass of sockeye salmon in the ocean off Alaska and British Columbia is expected to decline by more than 10 percent — in addition to a biomass decrease of 10 to 20 percent by 2050 under long-term climate projections.
Of 22 fisheries included in the study, only Alaskan Pollock in the Eastern Bering Sea is expected to increase significantly in biomass during marine heat waves. Pacific sardine and Japanese mackerel may show little change.
Because sardines do better in warmer waters, long-term models tend to project increases in sardine biomass along the West Coast over time, while anchovies, which prefer cooler waters, are projected to decrease. At the same time, such models predict that both species will expand their ranges northward, producing greater numbers in the Gulf of Alaska.
But the story is different when marine heat waves are added into the picture, according to the new study. Rapid warming can push temperatures to the limit for both sardines and anchovies, decreasing their total biomass in the Gulf of Alaska as well as along the West Coast.
The study found that the fish most impacted by a combination of long-term climate change and future “blobs” were pelagic (open water) species, followed by salmon and then bottom fish. Among the five species of Pacific salmon, the biomass of sockeye salmon is expected to decrease the most — 40 percent by 2100 throughout the study area. Coho are next on the list of affected salmon.
Pacific cod, sablefish and Pacific Ocean perch were the bottom fish projected to sustain the most losses throughout the area.
Worldwide, the frequency of marine heat waves has doubled since 1982, and climate models predict they will become more frequent and last longer in the coming years.
William noted that the study was based on a climate model that uses a high rate of greenhouse gas emissions (RCP 8.5). While recent temperatures seem to be following that high-emissions trend, emission reductions would have benefits for almost all fish populations. Still, any improvements in ocean-temperature trends will lag behind improvements in atmospheric conditions because of the heat-retention properties of water.
“Our results underscore the need for a reduction of anthropogenic greenhouse gas emissions – the fundamental driver of ocean
warming — to limit challenges from marine heat waves on fish stocks and fisheries,” William said.
The fact that marine heat waves can develop rapidly demands that scientists become better at short-term predictions, he said. Meanwhile, fisheries managers are challenged to develop plans that can respond quickly to changing conditions by reducing fishing seasons or moving fishing areas.
William plans further analysis of “blobs” across the globe, with a goal of developing projections of worldwide fishery impacts. That could lead to an economic analysis of future financial repercussions expected to result from sudden warming events in many locations.
NOAA stories for further reading:

New report describes anticipated climate-change effects in Washington state

Early effects of a warming Earth have reached Washington state, as we can see from actual measurements. Annual snowpack is declining in the mountains; ancient glaciers are shrinking; sea levels are rising; and coastal waters are becoming less hospitable to sea life.
These are some of the changes outlined in a new easy-to-read briefing report titled “Shifting Snowlines and Shorelines” by the Climate Impacts Group at the University of Washington. The report is designed to bring a clear message to leaders and citizens of Washington state regarding where we have come with respect to climate change and where we may be going.
“We are seeing the consequences (of warming), even at the local level,” said Amy Snover, director of the Climate Impacts Group. “The impacts are only expected to worsen over time.”

Amy stressed the “urgent need” to do what we can to reduce the amount of warming caused by greenhouse gas emissions. At the same time, she said, people must address the problems being seen now and prepare for worse conditions in the future.
The new briefing report is a localized summary of the “Special Report on the Ocean and Cryosphere in a Changing Climate,” a 755-page report issued in September by the Intergovernmental Panel on Climate Change (IPCC). The target audience of the new brief, Amy told me, is primarily decision makers, including officials at all levels of government.
Among the findings listed in the brief for Washington state:

  • On average, spring snowpack has declined about 30 percent from 1955 to 2016.
  • In the North Cascades, the total area occupied by glaciers has decreased more than 56 percent since 1900.
  • At Friday Harbor in northern Puget Sound, sea level has risen more than 4 inches since 1934, with other amounts at other locations.
  • Peak streamflow is coming earlier in the year — up to 20 days earlier in 2002 compared to 1948 in the most snow-dominated watersheds of Puget Sound.
  • Coastal waters are warming — between 0.9 and 1.8 degrees Fahrenheit from 1990 to 2012 — while the Pacific Ocean and Puget Sound are shifting toward more acidic conditions with effects on a variety of species.

The decision to write a localized brief about sea levels and the cryosphere (frozen parts of the Earth) resulted from acclaim for the Climate Impact Group’s previous briefing, called “No Time to Waste,” which followed the IPCC special report on what people will be facing if global warming reaches 1.5 degrees C (2.7 degrees F) above pre-industrial levels. See the 616-page document “Global Warming of 1.5° C.”

For Washington state, “No Time to Waste” provides some numerical forecasts for hotter days, reduced snowpack, higher winter streamflows, lower summer streamflows and sea level rise. Predictions were derived from years of research in the Northwest along with relevant research from other regions.
“By mid-century, if greenhouse gas emissions continue on their current pathway, the average year in Washington will be warmer than the hottest year of the 20th century,” the brief states.
If greenhouse gas emissions stopped today, the 1.5-degree limit set by the Paris Agreement would not be exceeded. However, an immediate halt to emissions is impossible, of course. We are, in fact, getting close to locking in at least a 1.5-degree rise along with drastic consequences.
“Limiting warming to 1.5°C can only be achieved if action is taken to reduce global CO2 emissions by about 45% from 2010 levels by 2030 and to ‘net zero’ by around 2050,” the brief states.
Amy Snover sees a growing recognition of the climate-change problem as well as growing support for action. In fact, actions have begun in Washington state to reduce greenhouse gases and to address the anticipated problems, she said.
“That’s the happy secret of climate change,” Amy told me. “There is more happening than most people know. That being said, it isn’t really enough. It’s just the beginning, and a lot more needs to be done.”
Local governments are beginning to plan for higher water levels, as I described in a 2017 story for the Encyclopedia of Puget Sound. Many waterfront property owners also are beginning to consider their options, as I reported in a separate story.
Sea-level rise depends on two factors: how fast the oceans rise and the rate of vertical land shifts. A sophisticated analysis of these two factors in Puget Sound and along the Washington Coast give us a good idea of what we are facing under various climate-change scenarios. Check out “Projected Sea Level Rise for Washington State” (PDF 10.4 mb).
One of the great values of this analysis is that we can look at the probabilities that certain sea levels will be reached at certain times under various climate-change scenarios. We can choose just about any location by pointing to a map of Washington state, as I explained in a Water Ways blog post in August 2018. For example, I listed the projected sea-level rise in 2050 for various locations, using a 50 percent probability and a high greenhouse gas scenario:

  • Neah Bay, 0.1 foot;
  • Sekiu, 0.3 foot;
  • Ocean Shores, Ozette, 0.4 foot;
  • Aberdeen, Point Roberts, Port Angeles, 0.5 foot;
  • Bellingham, La Push, Queets, San Juan Island, 0.6 foot;
  • Anacortes, Hoodsport, La Conner, Sequim, 0.7 foot;
  • Bremerton-Port Orchard-Silverdale, Everett, Gig Harbor, Hansville, Port Townsend, Poulsbo-Suquamish-Bainbridge, Seattle, Shelton, Tacoma, Vashon Island (most), Whidbey Island, 0.8 foot;
  • Ballard, Edmonds, East Vashon-Des Moines, Federal Way, Port Ludlow, Shelton, 0.9 foot; and
  • Kingston, Olympia, 1.0 foot.

For other stories about the local impacts of climate change, please check out the Encyclopedia of Puget Sound’s sections on:

Changes were made to an earlier version of this blog post to clarify the opening sentence, the first quote by Amy Snover and the effect of an immediate halt to greenhouse gas emissions.

New report describes anticipated climate-change effects in Washington state

Early effects of a warming Earth have reached Washington state, as we can see from actual measurements. Annual snowpack is declining in the mountains; ancient glaciers are shrinking; sea levels are rising; and coastal waters are becoming less hospitable to sea life.
These are some of the changes outlined in a new easy-to-read briefing report titled “Shifting Snowlines and Shorelines” by the Climate Impacts Group at the University of Washington. The report is designed to bring a clear message to leaders and citizens of Washington state regarding where we have come with respect to climate change and where we may be going.
“We are seeing the consequences (of warming), even at the local level,” said Amy Snover, director of the Climate Impacts Group. “The impacts are only expected to worsen over time.”

Amy stressed the “urgent need” to do what we can to reduce the amount of warming caused by greenhouse gas emissions. At the same time, she said, people must address the problems being seen now and prepare for worse conditions in the future.
The new briefing report is a localized summary of the “Special Report on the Ocean and Cryosphere in a Changing Climate,” a 755-page report issued in September by the Intergovernmental Panel on Climate Change (IPCC). The target audience of the new brief, Amy told me, is primarily decision makers, including officials at all levels of government.
Among the findings listed in the brief for Washington state:

  • On average, spring snowpack has declined about 30 percent from 1955 to 2016.
  • In the North Cascades, the total area occupied by glaciers has decreased more than 56 percent since 1900.
  • At Friday Harbor in northern Puget Sound, sea level has risen more than 4 inches since 1934, with other amounts at other locations.
  • Peak streamflow is coming earlier in the year — up to 20 days earlier in 2002 compared to 1948 in the most snow-dominated watersheds of Puget Sound.
  • Coastal waters are warming — between 0.9 and 1.8 degrees Fahrenheit from 1990 to 2012 — while the Pacific Ocean and Puget Sound are shifting toward more acidic conditions with effects on a variety of species.

The decision to write a localized brief about sea levels and the cryosphere (frozen parts of the Earth) resulted from acclaim for the Climate Impact Group’s previous briefing, called “No Time to Waste,” which followed the IPCC special report on what people will be facing if global warming reaches 1.5 degrees C (2.7 degrees F) above pre-industrial levels. See the 616-page document “Global Warming of 1.5° C.”

For Washington state, “No Time to Waste” provides some numerical forecasts for hotter days, reduced snowpack, higher winter streamflows, lower summer streamflows and sea level rise. Predictions were derived from years of research in the Northwest along with relevant research from other regions.
“By mid-century, if greenhouse gas emissions continue on their current pathway, the average year in Washington will be warmer than the hottest year of the 20th century,” the brief states.
If greenhouse gas emissions stopped today, the 1.5-degree limit set by the Paris Agreement would not be exceeded. However, an immediate halt to emissions is impossible, of course. We are, in fact, getting close to locking in at least a 1.5-degree rise along with drastic consequences.
“Limiting warming to 1.5°C can only be achieved if action is taken to reduce global CO2 emissions by about 45% from 2010 levels by 2030 and to ‘net zero’ by around 2050,” the brief states.
Amy Snover sees a growing recognition of the climate-change problem as well as growing support for action. In fact, actions have begun in Washington state to reduce greenhouse gases and to address the anticipated problems, she said.
“That’s the happy secret of climate change,” Amy told me. “There is more happening than most people know. That being said, it isn’t really enough. It’s just the beginning, and a lot more needs to be done.”
Local governments are beginning to plan for higher water levels, as I described in a 2017 story for the Encyclopedia of Puget Sound. Many waterfront property owners also are beginning to consider their options, as I reported in a separate story.
Sea-level rise depends on two factors: how fast the oceans rise and the rate of vertical land shifts. A sophisticated analysis of these two factors in Puget Sound and along the Washington Coast give us a good idea of what we are facing under various climate-change scenarios. Check out “Projected Sea Level Rise for Washington State” (PDF 10.4 mb).
One of the great values of this analysis is that we can look at the probabilities that certain sea levels will be reached at certain times under various climate-change scenarios. We can choose just about any location by pointing to a map of Washington state, as I explained in a Water Ways blog post in August 2018. For example, I listed the projected sea-level rise in 2050 for various locations, using a 50 percent probability and a high greenhouse gas scenario:

  • Neah Bay, 0.1 foot;
  • Sekiu, 0.3 foot;
  • Ocean Shores, Ozette, 0.4 foot;
  • Aberdeen, Point Roberts, Port Angeles, 0.5 foot;
  • Bellingham, La Push, Queets, San Juan Island, 0.6 foot;
  • Anacortes, Hoodsport, La Conner, Sequim, 0.7 foot;
  • Bremerton-Port Orchard-Silverdale, Everett, Gig Harbor, Hansville, Port Townsend, Poulsbo-Suquamish-Bainbridge, Seattle, Shelton, Tacoma, Vashon Island (most), Whidbey Island, 0.8 foot;
  • Ballard, Edmonds, East Vashon-Des Moines, Federal Way, Port Ludlow, Shelton, 0.9 foot; and
  • Kingston, Olympia, 1.0 foot.

For other stories about the local impacts of climate change, please check out the Encyclopedia of Puget Sound’s sections on:

Changes were made to an earlier version of this blog post to clarify the opening sentence, the first quote by Amy Snover and the effect of an immediate halt to greenhouse gas emissions.