They say that parts of the southern Indian Ocean, the eastern tropical Pacific and the Atlantic are already less oxygen-rich because of global warming. And oxygen deprivation could become increasingly widespread across large regions of ocean between 2030 and 2040.
Anyone who has ever kept a home aquarium knows that, in the summer, the fish in the tank are more likely to be seen gasping nearer the surface. That is because the colder the water, the greater its capacity for dissolved oxygen.
Growing concentrations in the atmosphere of the greenhouse gas carbon dioxide have begun to change the ocean chemistry, making sea water gradually and alarmingly more acidic and less hospitable to many of the species adapted to ocean life.
Now Matthew Long, an oceanographer at the U.S. National Centre for Atmospheric Research in Boulder, Colorado and colleagues report in Global Biogeochemical Cycles journal that they repeatedly modeled changes in the ocean’s oxygen content over the years 1920 to 2100.
Oxygen from the atmosphere gets into the sea only when it dissolves directly or is released by photosynthesizing marine plants and phytoplankton. The warmer the water, the harder life is for the creatures nearer the surface.
To make things more difficult, warmer waters are less dense, making them less likely to sink and bring the colder, more oxygen-rich waters to the surface. In unusually hot weather, “dead zones” appear in the seas, where fish and shellfish cannot survive.
The researchers warn that there will be more of these as global temperatures continue to rise. “Loss of oxygen in the ocean is one of the serious side-effects of a warming atmosphere and a major threat to marine life,” Dr. Long said.
“Since oxygen concentrations in the ocean naturally vary, depending on variations in winds and temperature at the surface, it’s been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability.”
The new map suggests that even by 2100, some waters—off the east coasts of Africa and Australia and Southeast Asia and parts of the South Atlantic, for instance—will remain oxygen-rich. But oxygen loss due to climate change will become detectable much more swiftly in northern waters in the Pacific and parts of the Atlantic.
There are uncertainties. Oxygen measurements in the world’s oceans—and 70 percent of the planet is covered by blue water—are relatively sparse.
“We need comprehensive and sustained observations of what’s going on in the oceans to compare with what we’re learning from our models and to understand the full impact of a changing climate,” Dr. Long said.
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EcoWatch Daily Newsletter
By David Reichmuth
Over the last month, I've seen a number of opinion articles attacking electric vehicles (EVs). Sadly, this comes as no surprise: now that the Biden administration is introducing federal policies to accelerate the roll out of electric vehicles, we were bound to see a reaction from those that oppose reducing climate changing emissions and petroleum use.
The majority of EVs sold in 2020 were models with a starting price (Manufacturers Suggested Retail Price) under $40,000 and only a fifth of models had a starting price over $60,000.
On Friday, China set out an economic blueprint for the next five years, which was expected to substantiate the goal set out last fall by President Xi Jinping for the country to reach net-zero emissions before 2060 and hit peak emissions by 2030.
The Great Trail in Canada is recognized as the world's longest recreational trail for hiking, biking, and cross-country skiing. Created by the Trans Canada Trail (TCT) and various partners, The Great Trail consists of a series of smaller, interconnected routes that stretch from St. John's to Vancouver and even into the Yukon and Northwest Territories. It took nearly 25 years to connect the 27,000 kilometers of greenway in ways that were safe and accessible to hikers. Now, thanks to a new partnership with the Canadian Paralympic Committee and AccessNow, the TCT is increasing accessibility throughout The Great Trail for people with disabilities.
Trans Canada Trail and AccessNow partnership for AccessOutdoors / Trails for All project. Mapping day at Stanley Park Seawall in Vancouver, British Columbia with Richard Peter. Alexa Fernando<p>This partnership also comes at a time when access to outdoor recreation is more important to Canadian citizens than ever. <a href="https://www150.statcan.gc.ca/n1/daily-quotidien/200527/dq200527b-eng.htm" target="_blank" rel="noopener noreferrer">Studies from the spring of 2020</a> indicate that Canadian's <a href="https://www.bnnbloomberg.ca/moneytalk-mental-health-during-covid-19-1.1567633" target="_blank" rel="noopener noreferrer">mental health has worsened</a> since the onset of social distancing protocols due to COVID-19. </p><p>The <a href="https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/safe-activities-during-covid19/art-20489385" target="_blank" rel="noopener noreferrer">Mayo Clinic</a> lists hiking, biking, and skiing as safe activities during COVID-19. Their website explains, "When you're outside, fresh air is constantly moving, dispersing these droplets. So you're less likely to breathe in enough of the respiratory droplets containing the virus that causes COVID-19 to become infected."</p><p>TCT leadership took this into consideration when embarking on the accessibility project. McMahon explains that there has never been a more important time to bring accessibility to the great outdoors: "Canadians have told us that during these difficult times, they value access to natural spaces to stay active, take care of their mental health, and socially connect with others while respecting physical distancing and public health directives. This partnership is incredibly important especially now as trails have become a lifeline for Canadians."</p><p>Together, these organizations are paving the way for better physical and mental health among all Canadians. To learn more about the TCT's mission and initiatives, check out their <a href="https://thegreattrail.ca/stories/" target="_blank">trail stories</a> and <a href="https://thegreattrail.ca/wp-content/uploads/2021/01/TCT_2020-Donor-Impact-Report_EN_8.5x14-web.pdf" target="_blank">2020 Impact Report</a>.</p>