Airguns and ship sounds dangerously disrupt the natural behaviour of the "unicorn of the sea." Study

The Royal Society - Biology Letters

A pod of narwhals in the Arctic.

Manmade noise is increasing in the Arctic, posing a threat to narwhals. To study this, narwhals were fitted with tags and exposed to ship and airgun noise. The whales showed clear reactions to sound disturbance by first reducing and then ceasing foraging. Reactions could be detected as far as 40 km from the ship, where the signals were embedded in the natural background noise. The reactions of the whales demonstrate their sensitivity and emphasize that - "if healthy narwhal populations are to be maintained," humans need to "manage" activities that make such noise.

The findings have just been published by the Royal Society.

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RAPIDLY WARMING OCEANS HAVE LEFT MANY NORTHERN MARINE MAMMALS SWIMMING IN TROUBLED WATERS. BUT PERHAPS NONE MORE SO THAN THAT STRANGE AND MYSTERIOUS "UNICORN OF THE SEA," THE NARWHAL.

Baleens - beneficial gluttons of the high seas

Scientists believe the ravenous appetites of baleen whales - Earth's largest creatures - and their prodigious waste - hold clues to the very health and productivity of our oceans.

by Larry Powell

A blue whale (Balaenoptera musculus) defecates. Photo credit-Ryan Lavery (Smithsonian)

Baleens include humpbacks, fins, minkes and blue whales, the latter being the largest creatures ever to live on Earth. The carnivorous marine mammals catch and consume vast amounts of prey. And they recycle ocean nutrients by excreting undigested food in what have been described as "volcano-like" movements.

A minke whale tagged by the research team off the coast of Antarctica in 2019. Credit: Ari Friedlaender under NOAA/NMFS permit 23095.

By attaching tags to the backs of 321 whales from seven baleen species, the researchers now reckon that - before the onset of whaling in the twentieth century - and in the Southern Ocean alone - baleens were, amazingly, consuming more than twice what the world's entire marine fisheries catch today. 

A humpback whale feeds on sand lance in the Stellwagen Bank National Marine Sanctuary. Credit: Elliott Hazen

Yearly, they probably ate 430 million tonnes of Antarctic krill (small crustaceans found in all the world's oceans) before whaling ramped up in the 19 hundreds in the Atlantic, Pacific, and Southern Oceans. That's up to thirty percent of their entire body mass, on average, and, in some areas of the ocean at least, triple the volume previously thought. And, incredibly, it's twice the total biomass of this entire species of krill thought to exist today. 

The scientists hope, if baleen numbers could somehow recover to what they were before that twentieth century whaling, their "nutrient recycling services" could not only help boost ocean productivity but restore ecosystem functions to their previous glory.

According to the Smithsonian Institute, heavily involved in the study, whales both eat and excrete immense amounts of iron. It is an important nutrient which spurs the growth of phytoplankton blooms. If it weren't for the whales, this valuable commodity would sink from near the surface, where the whales live (and where the iron is needed), to the bottom where it would be lost. 

These findings have just been published in the journal, Nature.

Declining Arctic sea ice may increase wildfires in the western US - & Canada?

Nature

Declining sea ice in the Arctic may contribute to increased wildfire activity in the western United States, suggests a modelling study published in Nature Communications. The finding demonstrates the influence that human-induced climate change can have on extreme weather events in the region.

Wildfires in the western US (& Canada) have become more frequent and severe in recent years. Although there is some evidence that Arctic sea ice declines can influence extreme weather conditions in temperate and subtropical regions, the impact on wildfires has been unclear.

Yufei Zou, Hailong Wang and colleagues combined data on wildfire incidence, sea ice concentrations and weather conditions over the past 40 years and conducted model simulations to investigate the relationship between these factors. 

The authors identified an association between declining Arctic sea ice concentrations from July to October and the increasing probability of large wildfires in the western US during the following September to December. The model simulations indicate that declines in Arctic sea ice are linked to air circulation changes that cause hotter and dryer weather conditions, which increase the likelihood of wildfires.

The authors conclude that the influence of Arctic sea ice concentrations on wildfires is of similar magnitude to that of the tropical El Niño Southern Oscillation, which can also modulate regional wildfire conditions. As Arctic sea ice is projected to continuously decline, this could further increase the susceptibility of the western US to wildfires in the future, they suggest.

Major toilet paper brands are flushing our forests down the drain

The National Observer

What runs through your mind when you’re deciding which toilet paper to buy? Sale price, roll size, pitiful single-ply or luxurious triple? Climate change might not make your list of considerations, but it should. Story here.

Please also watch this video.

"Truth in Advertising - a TV commercial as it should be"

Australian bushfires triggered prolific phytoplankton blooms vast distances away

Nature

Bushfire East of Lake Dundas, Western Australia. Photo by Pierre Markuse

The 2019–2020 Australian wildfires released more than twice as much CO2 as previously reported on the basis of different fire inventories, reports a Nature paper. 

An independent study also published in Nature, suggests that aerosol emissions from these wildfires are likely to have fuelled vast plankton blooms thousands of kilometres away in the Southern Ocean. 

The findings highlight the complex links between wildfires, ecosystems and the climate. Climate-change-driven droughts and warming play a role in increasing the frequency and intensity of wildfires, which release CO2 into the atmosphere, potentially driving further climate change and increasing the risk of wildfires. 

In the summer season of 2019–2020, around 74,000 km2 — an area roughly equivalent to 2.5 times the area of Belgium — burned in the eucalyptus forests in the coastal regions of Victoria and New South Wales, Australia. These wildfires are known to have been extremely large in scale and intensity, and to have released large amounts of CO2 into the atmosphere, but emission estimates remain uncertain.

To gain insights into the amount of CO2 released by the Australia wildfires, Ivar Van der Velde and colleagues analysed new high-resolution satellite measurements of carbon monoxide concentration in the atmosphere, from which they infer fire-induced carbon emissions. They estimated that around 715 teragrams of CO2 were emitted between November 2019 and January 2020 — more than twice the amount previously estimated from five different fire inventories and comparable to a bottom-up bootstrap analysis of this fire episode, surpassing Australia’s normal annual fire and fossil fuel emissions by 80%. 

Gaining a stronger understanding of the atmospheric burden of CO2 caused by these fires, and what they will cause in the future, is critical for constructing future scenarios of the global carbon balance, the authors note.

In addition to carbon emissions, wildfires release aerosols that affect ecosystems; for example, transportation of nutrients such as nitrogen and iron can enhance plankton growth. Nicolas Cassar, Weiyi Tang and colleagues report the presence of extensive phytoplankton blooms from December 2019 to March 2020 in the Southern Ocean, downwind of the fires. Aerosol samples originating from the fires contained high levels of iron, which the authors suggest were transported vast distances and fertilized the blooms.

Together, these studies demonstrate that wildfires can have an important influence on atmospheric CO2 levels and ocean ecosystems.

Deforestation and fires are shrinking Amazonian habitats

Nature

 The Amazon - Manaus, Brazil. Photo by Bruno Kelly

The Amazon Basin has a vital role in regulating the Earth’s climate and is home to 10% of all known species. Degradation of the forest threatens the resilience of this ecosystem; around 21–40% of the forest cover is predicted to be lost by 2050, which will have large impacts on Amazonian biodiversity. 

To better understand these impacts, Xiao Feng and colleagues investigate how forest fires have been affecting the geographic range of 11,514 plant species and 3,079 animal species over the past two decades.Up to 85% of species listed as threatened in the Amazon may have lost a substantial portion of their habitat owing to deforestation and fires in the past two decades, a study in Nature indicates. It is estimated that for every 10,000 km2 of forest that is burned, about 27–37 additional plant species and about 2 or 3 more vertebrate species that have more than 10% of their range in the Amazon will be affected. As fires move closer to the heart of the Amazon Basin, which has greater levels of biodiversity, the impact of fires on biodiversity is expected to increase.

Since 2001, up to 189,755 km2 of Amazon rainforest have experienced fires - as much as four % of  the total area. This has impacted the ranges of as many as 85 % of species listed as threatened in this region. They note that periods of increased fires correlate with relaxation of policies designed to slow deforestation and forest burning. 

In Brazil, policies to reduce deforestation implemented in the mid-2000s were relaxed in 2019, which saw an increase of up to 28% in fire-impacted area, affecting the ranges of an estimated 12,064–12,801 plant and vertebrate species.

These findings demonstrate the connection between policy and forest fires and how these factors can impact biodiversity, the authors conclude.

Nearly Half the World's Children at 'Extremely High Risk' for Facing Effects of Climate Crisis, Report Finds

Common Dreams

 OCHA/Giles Clarke. Displaced children stand in the shredded remains of tents in Abs settlement, Yemen, for internally displaced persons. Located just 40 km from the frontlines, the settlement is regularly damaged by passing sandstorms.

"Virtually no child's life will be unaffected" by the climate emergency, said the director of UNICEF. Story here.