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Heatwaves sweeping oceans 'like wildfires', scientists reveal

Ocean heatwaves have become far more frequent

The average number of marine heat wave days for the period 1987-2016, compared to the average for 1925-1954.
Source: Nature Climate Change | by The New York Times 

From The Guardian by Damian Carrington

Extreme temperatures destroy kelp, seagrass and corals – with alarming impacts for humanity

The number of heatwaves affecting the planet’s oceans has increased sharply, scientists have revealed, killing swathes of sea-life like “wildfires that take out huge areas of forest”.

The damage caused in these hotspots is also harmful for humanity, which relies on the oceans for oxygen, food, storm protection and the removal of climate-warming carbon dioxide the atmosphere, they say.

Global warming is gradually increasing the average temperature of the oceans, but the new research is the first systematic global analysis of ocean heatwaves, when temperatures reach extremes for five days or more.

The research found heatwaves are becoming more frequent, prolonged and severe, with the number of heatwave days tripling in the last couple of years studied.
In the longer term, the number of heatwave days jumped by more than 50% in the 30 years to 2016, compared with the period of 1925 to 1954.

As heatwaves have increased, kelp forests, seagrass meadows and coral reefs have been lost.
These foundation species are critical to life in the ocean.
They provide shelter and food to many others, but have been hit on coasts from California to Australia to Spain.

“You have heatwave-induced wildfires that take out huge areas of forest, but this is happening underwater as well,” said Dan Smale at the Marine Biological Association in Plymouth, UK, who led the research published in Nature Climate Change.
“You see the kelp and seagrasses dying in front of you.
Within weeks or months they are just gone, along hundreds of kilometres of coastline.”

As well as quantifying the increase in heatwaves, the team analysed 116 research papers on eight well-studied marine heatwaves, such as the record-breaking “Ningaloo Niño” that hit Australia in 2011 and the hot “blob” that persisted in the north-east Pacific from 2013 to 2016.
“They have adverse impacts on a wide range of organisms, from plankton to invertebrates, to fish, mammals and seabirds,” Smale said.

Bleached coral in New Caledonia in the southern Pacific. Photograph: AP

The scientists compared the areas where heatwaves have increased most with those areas harbouring rich biodiversity or species already near their temperature limit and those where additional stresses, such as pollution or overfishing, already occur.
This revealed hotspots of harm from the north-east Atlantic to the Caribbean to the western Pacific.
“A lot of ocean systems are being battered by multiple stresses,” Smale said.

The natural ocean cycle of El Niño is a key factor in pushing up temperatures in some parts of the ocean and the effect of global warming on the phenomenon remains uncertain, but the gradual overall heating of the oceans means heatwaves are worse when they strike.

Before and after the 2011 marine heatwave off the WA coast and its effects on kelp.

 credit : J. Costa, S. Bennett

“The starting temperature is much higher, so the absolute temperatures [in a heatwave] are that much higher and more stressful,” said Smale.
Some marine wildlife is mobile and could in theory swim to cooler waters, but ocean heatwaves often strike large areas more rapidly than fish move, he said.

The researchers said ocean heatwaves can have “major socioeconomic and political ramifications”, such as in the north-west Atlantic in 2012, when lobster stocks were dramatically affected, creating tensions across the US-Canada border.

“This [research] makes clear that heatwaves are hitting the ocean all over the world … The ocean, in effect, is spiking a fever,” said Prof Malin Pinsky, at Rutgers University, US, and not part of the team.
“These events are likely to become more extreme and more common in the future unless we can reduce greenhouse gas emissions.”

Dr Éva Plagányi at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia also likened ocean heatwaves to wildfires.
“Frequent big hits can have long-lasting effects,” she said.
“This study shows that record-breaking events are becoming the new normal.”

On a related note, the increase in ocean heat content in 2018 – about 9 zettajoules – is around 18 times more than the total energy used by everyone on Earth in 2018. 
ScienceMag : Improved estimates of ocean heat content from 1960 to 2015

NOAA Global Ocean Heat and Salt Content

The damage global warming is causing to the oceans has also been shown in a series of other scientific papers published in the last week.
Ocean warming has cut sustainable fish catches by 15% to 35% in five regions, including the North Sea and the East China Sea, and 4% globally, according to work published by Pinsky and colleagues.

“We were stunned to find that fisheries around the world have already responded to ocean warming,” he said.
Another study showed that achieving the 2C climate change target set out in the Paris agreement would protect almost 10m tonnes of fish catches each year, worth tens of billions of dollars.

Separate work by Plagányi’s team showed that climate change will reverse the recovery of whales in the Southern Ocean by damaging the krill on which they feed.
“Models predict concerning declines, and even local extinctions by 2100, for Pacific populations of blue and fin whales, and Atlantic and Indian Ocean fin and humpback whales,” they said.

“In the space of one week, scientific publications have underscored that unless we take evasive action, our future oceans will have fewer fish, fewer whales and frequent dramatic shifts in ecological structure will occur, with concerning implications for humans who depend on the ocean,” said Plagányi.

Links :

• The Guardian : Our oceans broke heat records in 2018 and the consequences are catastrophic
• National Geographic : Ocean heat waves are killing underwater life, threatening biodiversity
• LiveScience : Could Earth's Oceans Ever Boil Away?
• NYTimes : Ocean Heat Waves Are Threatening Marine Life / Ocean Warming Is Accelerating Faster Than Thought, New Research Finds
• The Conversation : Suffering in the heat: the rise in marine heatwaves is harming ocean species
• ScienceNews : Oceans that are warming due to climate change yield fewer fish
• PSMag : The ocean gets heat waves too, and they are threatening marine ecosystems  
• CNN : What warmer oceans mean for the planet
• Univ. California : Warm seas scatter fish 

British nautical maps from century ago help B.C. researchers chart kelp beds

How a treasure of historical maps of kelp beds off the British Columbia coast, giving geographers a baseline in understanding the ocean's rainforests.

An example of a British chart from the 1850's showing the drawing of kelp blades to indicate kelp beds.

credit : The Canadian press / HO-Maycira Costa

From The Canadian Press by Hina Alam

A serendipitous meeting between a professor and a colleague last year led to a treasure trove of historical maps indicating kelp bed locations off British Columbia's coast, helping experts understand the changes in the ocean's rainforests.

University of Victoria geographer Maycira Costa is investigating B.C. kelp forests.

University of Victoria , The Canadian Press

University of Victoria geography Prof. Maycira Costa saw the squiggly lines on the yellowed, hand-drawn map in a picture frame above her colleague's desk.
The wall art was from 1903 and Costa said her co-worker had found it amongst a pile of old maps in someone's office.
"I started to look at the details and then I looked at the area that I know of kelp distribution because we are working there with the modern satellite," she said.
"And I looked at that and said, 'this is kelp distribution.' "

Using those British admiralty charts from 1858 to 1956, Costa and her research team have now created the first historical digital map of B.C.'s coastal kelp forests.
They'll use the maps to further investigate the loss of the kelp beds in research supported by Fisheries and Oceans Canada, Canadian Hydrographic Service and the Pacific Salmon Foundation, she said.
"Kelp was considered a navigational hazard so the British carefully annotated all kelp forests on their charts," Costa said.
"And the historical charts increase our understanding of kelp distribution over time."

The kelp forests are known to be an important habitat for several species along the B.C. coast.
Herring use the kelp beds as a deposit for their eggs, crabs, starfish and juvenile salmon also live in the forests, she said.
Kelp also works as a physical barrier to reduce wave action and cut coastal erosion.
"Kelp are the rainforests of the ocean. And they uptake a lot of carbon from the atmosphere of the ocean," she said.

Ross Bay with the GeoGarage platform (CHS nautical chart)

The province has two types of kelp forests, bull and giant.
They grow from shallow areas to depths of about 20 to 25 metres, Costa said.
One of the growing concerns for kelp is warmer water temperatures but it's unclear if that equates to loss of the forests.
"That's the golden question, right?"
Kelp beds are also vulnerable to coastal pollution and increased turbidity from shoreline development, she said.

Communities monitoring the kelp beds along the B.C. coast have indicated loss, and now with the help of the British maps the team will work to compare the ocean forests, she said.
They'll compare the historical maps with the satellite images from 2002 until 2017, she said.
"A lot of environmental conditions play a role in how successful kelp beds are in specific year. Some areas in the United States documented loss of kelp beds especially when the ocean gets warmer," Costa said.
The next step is to study kelp beds along the entire B.C. coast to better understand how much was lost, she said.
"We now know where they existed about 100 years ago. So what happened recently?"

Links

• The Sqamish Chief : More than 100 years later, naval charts reveal B.C. kelp beds
• SookeNewsMirror : 1858 Naval maps combined with satellite data helps researchers map kelp bed health
• UVIC : Spatial temporal distribution of Nereocyctis Luetkeana (Bull Kelp) and use by juvenile salmonids in the Salish Sea
• Hakai : Mapping Kelp from Space
• GeoGarage blog :The coral reef loss data hidden in old navigational charts 

Are ghost ships real ?

Please note: we are currently working on a fix for an error spotted in the video.

The error relates to the behavior of the water filling the hole in the Mary Celeste's hull.

The water would reach equilibrium with the outside water level, not cease filling at the hole.

We thank you for your patience as we work on a fix.

In 1884, the British steamer “Rumney” crashed into the French ship “Frigorifique.”

Seeing their ship filling with water, the French crew climbed aboard the “Rumney.”

But as they sailed towards port, a silent form emerged from the fog – the abandoned “Frigorifique,” seemingly back for revenge.

So what happened?

Peter B. Campbell investigates the fascinating phenomenon of ghost ships.

Lesson by Peter B. Campbell, animation by Zedem Media.

What happened to this ship still sailing without captain or crew?

How it's made : mapmaking

The creation of nautical maps explained.