Tag archive

increased

Octopuses May Be Adapting to The Rising Acidity of Our Oceans, Study Suggests

in Science News by


We know that all the excess CO2 we’re pumping into the air – alongside a host of other damaging effects – is driving up the acidity of the oceans as it sinks and dissolves into the water, but it seems as though the hardy octopus can find ways to adapt to its rapidly changing environment.

 

Previous research into the impact of ocean acidification on cephalopods such as octopuses, cuttlefish, and squid has shown some indication increased carbon dioxide in the water could negatively impact this type of marine life.

However, in a new study, a group of Octopus rubescens – a species of octopus common to the west coast of North America – were observed adjusting their routine metabolic rate (RMR) over a series of weeks in response to lowering pH levels in the surrounding water.

“Challenges to an organism’s physiology are often reflected in changes in energy use and therefore can be observed as changes in aerobic metabolic rate,” write the researchers in their paper.

A total of 10 octopuses were studied under controlled lab conditions, with RMR measured immediately after exposure to acidic water, after one week, and after five weeks. Critical oxygen pressure – a measure of whether not not animals are getting enough oxygen – was monitored at the same time.

To begin with, high levels of metabolic change were detected in the creatures – a sort of shock reaction that actually conflicts with earlier research into cephalopods, which had recorded a reduction in metabolic change in similar scenarios.

 

However, RMR had returned to normal after one week, and remained the same five weeks later, suggesting some adaptation had occurred. The increased acidity did have an impact on the ability of the octopuses to function at low oxygen levels, however.

“This response in RMR suggests that O. rubescens is able to acclimate to elevated CO2 over time,” write the researchers. “The observed increase in RMR may be the result of multiple acute responses to hypercapnia [increased CO2 in the blood], possibly including both behavioural and physiological strategies.”

Those strategies could include preparing to move to find a new stretch of water to inhabit, for example, the researchers suggest (something that wasn’t possible here). The short RMR boost might also reflect the octopuses making quick adjustments to their biological processes to suit the new acid level.

The study is the first to look at both short-term (one week) and longer-term (five week) changes in metabolism rates in cephalopods in response to ocean acidification. We know these creatures are tough, and it seems they even have coping strategies that might allow them to adapt to humans destroying the natural environment all around them.

None of this means that we should be okay with the current climate crisis though, or not be trying to make major changes to reverse it. When we don’t take proper care of the planet, it’s not just ourselves that we’re potentially dooming to extinction.

Also, these tests were done in controlled laboratory conditions that don’t take into account many other interlinking factors in the animals’ natural environment. For instance, even if the octopus themselves are able to adjust, what about their food supply?

“While this species may be able to acclimate to near-term ocean acidification, compounding environmental effects of acidification and hypoxia may present a physiological challenge for this species,” write the researchers.

The research has been published in Physiological and Biochemical Zoology.

 



Source link

Here’s What We Know About The New COVID-19 Mutations So Far

in Science News by


The emergence in Britain and South Africa of two new variants of Sars-CoV-2, which are potentially far more infectious versions of the virus, has prompted widespread concern. Here is what we know – and what we don’t – about the mutations.

 

What are they?

All viruses mutate when they replicate in order to adapt to their environment.

Scientists have tracked multiple mutations of Sars-CoV-2, the virus that causes COVID-19, since it appeared in China in late 2019.

The vast majority of mutations did not materially alter either the virus’s virulence or transmissibility.​

However, one mutation – variant B117, which likely emerged in southeastern England in September, according to Imperial College London – has now been detected in countries across the world, including the United States, France, and India.​

Another variant, 501.V2, was detected in South Africa in October, and has since spread to several nations, including Britain and France.​

Both have multiple mutations to the virus, most notably on its spike protein – the part of the virus that latches on to human cells and helps it spread.

Specifically, the mutated versions have an altered receptor binding domain known as N501Y, which is situated on the virus’ protein spike and which allows easier access to the ACE2 receptor in human cells.

This makes the mutated versions potentially more infectious than other strains.

The European Centre for Disease Control (ECDC) says that while there is “no clear relationship” between enhanced ACE2 binding and increased transmissibility, “it is plausible that such a relationship exists”.

 

Are they more contagious?

Indeed, several recent studies – yet to be peer-reviewed – have concluded that the British variant of Sars-CoV-2 is likely to be far more transmissible than other strains.

​The NERVTAG expert committee which advises the British government on disease control has estimated the new mutation is between 50 percent and 70 percent more transmissible.​

A team at the London School of Hygiene and Tropical Medicine (LSHTM) concurs, with experts putting increased transmissibility in the 50-74 percent range.

Last week, researchers at Imperial College London released the results of a study into thousands of genetic sequences of Sars-CoV-2 found in Britain between October and December.

They found that the new variant had a “substantial transmission advantage”, with a reproduction rate between 0.4 and 0.7 higher than the unmutated virus.​

Preliminary studies on the South African variant have also concluded it is more contagious than regular Sars-CoV-2.

Although initial data seems to confirm that the two new versions are more contagious, experts have urged caution.

Bruno Coignard, head of infectious diseases at France’s health authority Sante Publique France, told AFP that the British variant’s spread was due to “a combination of factors”.

“These concern the virus’ characteristics but also prevention and control measures put in place,” he said.

 

Are they more dangerous?

There is currently no evidence to suggest that the mutated viruses are any stronger than normal.

But increased transmissibility alone poses an enormous problem, given that a small but consistent percentage of COVID-19 patients require hospital care.

“Increased transmissibility eventually translates to a far higher incidence rate, and even with the same mortality, this means significant pressure on health systems,” said Coignard.

Adam Kucharski, an epidemiologist at LSHTM, said that a virus that is 50 percent more contagious would be a “much bigger problem” than one that is 50 percent more deadly.

​In a Twitter thread, he explained how a disease such as COVID-19, with a reproduction (R) rate of 1.1 – where each patient on average infects 1.1 others – and a mortality rate of 0.8 percent would be expected to produce 129 deaths within a month.​

If the mortality rate increased 50 percent, the number of deaths would rise to 193.

But due to the exponential growth in cases with a more contagious variant, a disease with a 50 percent higher transmission rate would see the death toll hit 978.​

Arnaud Fontanet, an epidemiologist with France’s science council, admitted on Monday that the new British variant was “extremely concerning right now”.

 

Initial studies also concluded that the British variant was significantly more contagious among young people, which raises the issue of whether or not to keep schools open.​

The LSHTM study concluded that lockdowns similar to those seen across Britain in November would be insufficient to stem the new variant’s spread “unless primary schools, secondary schools, and universities are also closed”.

Will vaccines still work?

As vaccination campaigns get underway across the world, is there any reason to fear that the new mutations may not respond to the host of vaccines already on the market?​

After all, the messenger RNA vaccines developed by Pfizer and Moderna trick the body into reproducing the virus’s spike protein – the precise part of the pathogen that has mutated in the new versions.​

The ECDC said it was too soon to know if the mutations will impact vaccine efficacy.

Last week, Henry Walke from the American Centers for Disease Control told reporters that “experts believe our current vaccines will be effective against these strains”.

On Monday however, Francois Balloux, professor of Computational Systems Biology and Director at University College London’s Genetics Institute said that the South African variant’s spike protein mutation “helps the virus to bypass immune protection provided by prior infection or vaccination”.

German vaccine developer BioNTech said Friday its vaccine appeared to be effective at neutralising a variant of the coronavirus that shared a key spike protein mutation with the British variant.​

In unreviewed research, scientists in the US took blood samples from 20 people who had received two doses of the Pfizer/BioNTech vaccine and exposed them to virus molecules with the N501Y mutation.

They found “no reduction in neutralisation activity against the virus bearing the (mutated) spike”.

What can we do about them?

Coignard said it was impossible to eradicate the new viral variants entirely, although the goal from policymakers should be “maximum delay” of their spread.

The ECDC says that in countries currently unaffected by the new mutations, “efforts to delay the spread should mirror those made during the earlier stage of the pandemic“.

These include tests and quarantining of new arrivals, contact tracing, and limited travel, it said.

By sheer luck, certain existing PCR tests can detect the British variant.

Fontanet, therefore, advocated “extremely aggressive surveillance” through widespread testing.

“We need to be even more vigilant in our prevention measures to slow the spread of COVID-19 by wearing masks, staying at least six feet apart from people we don’t live with, avoiding crowds, ventilating indoor spaces, and washing our hands,” said Walke.​

© Agence France-Presse

 





Source link

60% of Americans Agree That Rising Coronavirus Cases Are Due to New Infections

in Science News by


Sixty percent of Americans agree that newly confirmed coronavirus cases are primarily caused by new infections, according to a new survey – but most Republicans blame increased testing instead.

 

The survey, conducted by Pew Research Centre, found that 62 percent of Republicans and Republican-leaning independents said that rises in coronavirus case numbers are primarily because of increased testing.

Eighty percent of their Democratic counterparts said that more infections – not tests – led to more cases. Overall, 60 percent mostly blamed infections, while 39 percent mostly blamed tests.

According to a July analysis from STAT, most of the new cases in the US are, in fact, because of rising case counts and not because of increased testing. The analysis looked at data from The COVID Tracking Project to calculate the number of cases per 1,000 tests. Since the number of tests was fixed, the number of cases per thousand tests is independent of increased testing.

STAT found that in Florida, the number of cases between May to July per 1,000 tests jumped from 32 to 193, showing that the increase in cases was because the disease was more widespread, not because more people were getting tested.

For some states like New York, even with expanded testing, the number of cases dropped, according to STAT’s analysis. New York doubled testing from May to July, but the number of cases dropped. This was true for 16 states and Washington, DC, which reported fewer cases per 1,000 tests, and overall, STAT reported.

Meanwhile, Trump has for long blamed testing for the increase in the number of cases, and last month called to pull out federal funding from 13 testing sites in 5 states.

To Trump’s credit, STAT found that 7 states saw an increased number of cases that was partially associated with more testing.

Testing remains viral to prevent the spread of the virus, and Trump’s call to cut federal testing contradicts the advice of public health experts.

 

Dr. David Persse, public health authority for the Houston Health Department, told the US Surgeon General in an email obtained by Business Insider that losing federal funding would cause “catastrophic cascading consequences in the region’s ability to adequately test, quarantine, and isolate.” 

The Harvard Global Health Initiative says that only 18 states meet the “minimum targets” for testing aimed to reduce spread of the virus by testing those who are symptomatic.

The US has had more than 5.4 million confirmed cases of coronavirus as of Monday, according to Johns Hopkins University.

This article was originally published by Business Insider.

More from Business Insider:

 





Source link

Doctors Warn COVID-19 May Trigger Diabetes in Otherwise Healthy People

in Science News by


Recent studies from England and other countries have suggested that adults with both types 1 and 2 diabetes have an increased risk of death if they catch COVID-19, especially if they have poor glucose control.

 

The weight of evidence is building up to support this theory. And when the dust settles, a more critical analysis of the data will probably confirm this increased risk.

But in early June, several well respected academics from around the world wrote a letter to the New England Journal of Medicine (NEJM) suggesting that COVID-19 is not just a risk for people with diabetes – it may actually cause diabetes.

There are two main types of diabetes. Type 1, caused by the body’s own immune system attacking the islet cells in the pancreas that produce insulin, a so-called autoimmune disease.

Eventually, there are no islets left and hence no insulin can be made to control blood glucose levels. We don’t know what starts this autoimmunity, but viral infections have been suggested as a possible trigger.

Type 2 diabetes happens when the islet cells have to produce vast amounts of insulin because the main target organs (liver, muscle, fat) do not respond as well as they should to insulin’s message. Finally, the islet cells become exhausted and die.

We have known for many years that viral infections may be linked to the first time a patient has diabetes symptoms. (Type 1 diabetes presents in a seasonal fashion, a fact often seen with viral infections.) And viral infections may also trigger the destruction of the insulin-producing islet cell “factories” in the pancreas, setting up a chronic autoimmune response.

 

There are recorded cases of acute diabetes developing during mumps and enterovirus infections. And there is significant evidence linking one particular enterovirus, Coxsackie-B1, with classical autoimmune type 1 diabetes.

In addition, The Environmental Determinants of Diabetes in the Young (TEDDY) study from the US and Europe documented an increased risk of developing signs of islet cell autoimmunity after respiratory infections caught in the winter months.

There’s something about coronaviruses

What about COVID-19? There has been a case report from China of a young man of previous good health presenting with new-onset, severe diabetes, termed keto-acidosis, after contracting COVID-19.

Before the COVID-19 pandemic, east Asia experienced the SARS outbreak (2002-04), which was also caused by a coronavirus. There were documented cases of acute onset diabetes in people with SARS pneumonia, which was not seen in those with pneumonia of other causes.

In most cases, the diabetes resolved after three years, but it persisted in 10 percent of patients.

The coronaviruses responsible for the current and previous outbreaks share a similar way of getting into cells. The now-familiar protein spikes on the surface of the virus attach to ACE2 receptors that are abundant in lung, kidney and islet cells in the pancreas.

The structure of SARS-COV-2 with its spike protein (S). (PenWin/iStock/Getty Images Plus)(PenWin/iStock/Getty Images Plus)

It is proposed that once in islets, COVID-19 disrupts normal cell function leading to abnormalities in the pathways that maintain blood glucose through insulin secretion. It is also possible that cell invasion leads to acute inflammation that kills islet cells.

So does COVID-19 cause diabetes? The answer is, we don’t know, and the NEJM letter makes it clear that a lot of this is still conjecture. COVID-19 may trigger type 1 or type 2 diabetes. This might even be a new form of diabetes.

Unlike the wealth of data presented on the risk of death with known diabetes, severe obesity, high blood pressure and ethnicity, there is little data on COVID-19 and newly diagnosed diabetes. To address this, the authors of the NEJM letter have developed a register to record all COVID-related diabetes cases.

A register is essential to gather enough data to start unravelling the mystery of any direct link between COVID-19 and diabetes. And if such a link is found, it will be equally important to determine how COVID-19 causes the damage to best identify treatments, given that COVID-19 may be around for quite some time yet. The Conversation

Julian Hamilton-Shield, Professor in Diabetes and Metabolic Endocrinology, University of Bristol.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



Source link

Accidental Poisoning Is on The Rise in The US as People Try to Sanitise Their Homes

in Science News by


With so many people experiencing heartbreaking losses in this pandemic, it’s only natural we all want to do everything in our power to protect ourselves and those we love. Unfortunately, in some instances, our desire to defend against COVID-19 is creating even more health problems.

 

The US Centers for Disease Control and Prevention (CDC) has just released a report revealing a rise in calls to poison helplines. This rise coincides with increased media coverage of COVID-19, as the first case was reported in the US on 19 January 2020.

While the researchers stress they cannot yet demonstrate a direct link between these chemical exposures and efforts to prevent COVID-19, the CDC reports 20 percent more calls about concerning exposures to cleaning products and disinfectants, compared with calls made in early 2019.

They compared the number of calls to 55 poison control centres between January and March 2020 to the same periods in 2019 and 2018. By comparison, reports made in early 2018 were lower than this year’s, by around 16 percent.

The biggest surge in reports occurred at the beginning of March 2020. For the cleaning products, bleaches account for the largest percentage of the rise, while non-alcoholic disinfectants and hand sanitisers dominated the disinfectant category.

“The timing of these reported exposures corresponded to increased media coverage of the COVID-19 pandemic, reports of consumer shortages of cleaning and disinfection products, and the beginning of some local and state stay-at-home orders,” they wrote.

Rise in calls to poison helplines. (CDC)Rise in reported exposures to poisonous chemicals. (CDC)

Even before the current rises, concerns for children under the age of five represented the largest portion of calls. This continues to be true, as chemical exposure cases across all ages increased this year, with up to half of all calls concerning young children. The case study provided by the CDC report shows just how frightening such a situation can be.

After eating an unknown amount of an ethanol-based hand sanitiser, a preschool child became dizzy and hit her head in a fall. Paramedics found her unresponsive when they responded to her parents’ 911 call and rushed her to hospital.

 

There, staff found her blood alcohol level to be 273 milligrams per decilitre, over triple the legal driving limit for adults in most US states, which is 80 milligrams per decilitre. Luckily, after overnight admission to the paediatric intensive care unit, the young patient recovered.

Earlier in March, Rutgers University microbiologist and food safety expert Donald Schaffner warned how dangerous washing food with soap could be.

“There’s a bunch of people out there recommending you wash your fresh produce with soap. This is not a good idea. Soap is known to cause vomiting and or diarrhoea,” he explained on Metafact.

And in their other case example, the CDC report illustrates just how perilous fears of contracting COVID-19 through groceries can become.

After hearing on the news that groceries should be cleaned before eating, an adult woman tried to clean her produce with diluted bleach and hot water; unfortunately, heat increases the release of chlorine fumes. She experienced coughing, wheezing and trouble breathing, ending up requiring oxygen and bronchodilators in hospital to restore her blood oxygen levels back to normal.

 

These inadvertent poisonings highlight the dangers of unclear advice and the need for us all to be cautious about who we choose to listen to. As we’ve all witnessed, the rapidly shifting nature of this emergency can make this challenging, as even political leaders and medical experts can provide conflicting and even dangerous advice.

So it pays to be highly sceptical about the information you see on the internet, and even in the news. When in any doubt, the safest bet is always to check directly with leading world health authorities such as the CDC and World Health Organization.

For now, when it comes to clearing and disinfectant products, the CDC advises the following:

  • always read and follow directions on the label;
  • only use water at room temperature for dilution (unless stated otherwise on the label);
  • avoid mixing chemical products;
  • wear eye and skin protection;
  • ensure adequate ventilation;
  • store chemicals out of the reach of children.

It is also important to be aware that there is no evidence of anyone contracting COVID-19 through food. And, as Schaffner advises, only use cold water to wash your fruit and vegetables. Take care out there.

These findings were published in the CDC’s Morbidity and Mortality Weekly Report.

 



Source link

Accidental Poisoning Is on The Rise in The US as People Try to Sanitise Their Homes

in Science News by


With so many people experiencing heartbreaking losses in this pandemic, it’s only natural we all want to do everything in our power to protect ourselves and those we love. Unfortunately, in some instances, our desire to defend against COVID-19 is creating even more health problems.

 

The US Centers for Disease Control and Prevention (CDC) has just released a report revealing a rise in calls to poison helplines. This rise coincides with increased media coverage of COVID-19, as the first case was reported in the US on 19 January 2020.

While the researchers stress they cannot yet demonstrate a direct link between these chemical exposures and efforts to prevent COVID-19, the CDC reports 20 percent more calls about concerning exposures to cleaning products and disinfectants, compared with calls made in early 2019.

They compared the number of calls to 55 poison control centres between January and March 2020 to the same periods in 2019 and 2018. By comparison, reports made in early 2018 were lower than this year’s, by around 16 percent.

The biggest surge in reports occurred at the beginning of March 2020. For the cleaning products, bleaches account for the largest percentage of the rise, while non-alcoholic disinfectants and hand sanitisers dominated the disinfectant category.

“The timing of these reported exposures corresponded to increased media coverage of the COVID-19 pandemic, reports of consumer shortages of cleaning and disinfection products, and the beginning of some local and state stay-at-home orders,” they wrote.

Rise in calls to poison helplines. (CDC)Rise in reported exposures to poisonous chemicals. (CDC)

Even before the current rises, concerns for children under the age of five represented the largest portion of calls. This continues to be true, as chemical exposure cases across all ages increased this year, with up to half of all calls concerning young children. The case study provided by the CDC report shows just how frightening such a situation can be.

After eating an unknown amount of an ethanol-based hand sanitiser, a preschool child became dizzy and hit her head in a fall. Paramedics found her unresponsive when they responded to her parents’ 911 call and rushed her to hospital.

 

There, staff found her blood alcohol level to be 273 milligrams per decilitre, over triple the legal driving limit for adults in most US states, which is 80 milligrams per decilitre. Luckily, after overnight admission to the paediatric intensive care unit, the young patient recovered.

Earlier in March, Rutgers University microbiologist and food safety expert Donald Schaffner warned how dangerous washing food with soap could be.

“There’s a bunch of people out there recommending you wash your fresh produce with soap. This is not a good idea. Soap is known to cause vomiting and or diarrhoea,” he explained on Metafact.

And in their other case example, the CDC report illustrates just how perilous fears of contracting COVID-19 through groceries can become.

After hearing on the news that groceries should be cleaned before eating, an adult woman tried to clean her produce with diluted bleach and hot water; unfortunately, heat increases the release of chlorine fumes. She experienced coughing, wheezing and trouble breathing, ending up requiring oxygen and bronchodilators in hospital to restore her blood oxygen levels back to normal.

 

These inadvertent poisonings highlight the dangers of unclear advice and the need for us all to be cautious about who we choose to listen to. As we’ve all witnessed, the rapidly shifting nature of this emergency can make this challenging, as even political leaders and medical experts can provide conflicting and even dangerous advice.

So it pays to be highly sceptical about the information you see on the internet, and even in the news. When in any doubt, the safest bet is always to check directly with leading world health authorities such as the CDC and World Health Organization.

For now, when it comes to clearing and disinfectant products, the CDC advises the following:

  • always read and follow directions on the label;
  • only use water at room temperature for dilution (unless stated otherwise on the label);
  • avoid mixing chemical products;
  • wear eye and skin protection;
  • ensure adequate ventilation;
  • store chemicals out of the reach of children.

It is also important to be aware that there is no evidence of anyone contracting COVID-19 through food. And, as Schaffner advises, only use cold water to wash your fruit and vegetables. Take care out there.

These findings were published in the CDC’s Morbidity and Mortality Weekly Report.

 



Source link

Giant Ocean Heatwave Called ‘The Blob’ Has Caused The Biggest Seabird Die-Off on Record

in Science News by


Scientists have reported on another devastating biological disaster, caused by a patch of abnormally warm water in the Pacific Ocean known as ‘the Blob’.

This concentrated marine heatwave lingered in the northeast Pacific between 2013 and 2016, and researchers now think it was largely responsible for the death of almost a million common murres (Uria aalge), amongst other wildlife. This makes it the largest seabird die-off in recorded history.

 

The estimate is based on some 62,000 murres that washed ashore on the west coast of the US during 2015 and 2016, covering an area stretching from California to Alaska. Only a fraction of birds that die at sea typically wash ashore, indicating the scale of the mass dying was much larger than the number of bodies we’ve found.

The emaciated birds were left starved by a lack of food, caused by increased competition in the warmer waters, according to the scientists – and numerous other species may have been hit by the same confluence of factors.

“Think of it as a run on the grocery stores at the same time that the delivery trucks to the stores stopped coming so often,” says biologist Julia Parrish, from the University of Washington.

“We believe that the smoking gun for common murres – beyond the marine heat wave itself – was an ecosystem squeeze: fewer forage fish and smaller prey in general, at the same time that competition from big fish predators like walleye, pollock and Pacific cod greatly increased.”

The team reviewed studies of fish and plankton collected by fisheries during the time the blob was at its peak, as well as other field studies and reports, and concluded that the warmer temperatures in the water had increased the metabolism of these cold-blooded ocean dwellers.

 

That meant predatory fish would have been eating more than usual, and that’s likely to have caused pressure on the top of the food chain. In the end, the schools of forage fish that murres rely on would’ve become very hard to find.

While the common murre is one of the most resilient birds around – feeding on small ‘forage fish’ like herring, sardines, anchovies and young salmon – it was unable to cope with the effects of the blob.

blob boost 2The common murre. (Jane Dolliver)

“Food demands of large commercial ground fish like cod, pollock, halibut and hake were predicted to increase dramatically with the level of warming observed with the blob,” says biologist John Piatt, from the US Geological Survey’s Alaska Science Center.

“Since they eat many of the same prey as murres, this competition likely compounded the food supply problem for murres, leading to mass mortality events from starvation.”

Mass die-offs seen in Cassin’s auklets and puffins can most probably be attributed to warming events as well, the scientists say. They describe seabirds like the murres as “bellwethers” of warming oceans and the ecological change they bring.

 

Localised ocean heatwave blobs have become more common over the last century, and are expected to further increase in frequency as the planet warms up. This particular one was exacerbated with warming winds from El Niño during 2015 and 2016.

Similar blobs of heated ocean water are now forming across the globe, threatening to impact marine wildlife further. As far as the researchers behind this latest study are concerned, the toll taken on the murre population is a warning of what’s to come as climate change takes hold – in other words, the next die-off could be even worse.

“The magnitude and scale of this failure has no precedent,” says Piatt. “It was astonishing and alarming, and a red-flag warning about the tremendous impact sustained ocean warming can have on the ecosystem.”

The research has been published in PLOS One.

 



Source link

Scientists Have Detected a Rapid Spike of a Widely Overlooked Greenhouse Gas

in Science News by


Carbon dioxide and methane aren’t the only greenhouse gases the world needs to worry about. The rapid rise of nitrous oxide (N2O), colloquially known as ‘laughing gas’, is no joke either.

 

This little-known greenhouse gas may not be as prevalent nor as long-lasting as carbon dioxide, but it is hundreds of times more potent and can stick around in the atmosphere for more than a century.

Today, it’s released mainly through human agricultural practices, such as using cheap nitrogen fertiliser. And, as you’ve no doubt guessed, it’s also a main contributor to ozone depletion and global warming.

To make matters worse, we’ve seriously underestimated its use. Since the turn of the century, new measurements reveal atmospheric N2O has risen much faster than experts at the United Nations once predicted.

“We see that the N2O emissions have increased considerably during the past two decades, but especially from 2009 onwards,” says climate scientist Rona Thompson from the Norwegian Institute for Air Research (NILU).

“Our estimates show that the emission of N2O has increased faster over the last decade than estimated by the Intergovernmental Panel on Climate Change (IPCC) emission factor approach.”

Instead of basing their calculations on human emissions, which are usually gathered from indirect sources, the researchers used a ‘top-down’ approach, based on dozens of atmospheric measurements from around the world. These data were then used to predict N2O dynamics on land and in the ocean between 1998 and 2016.

 

Unlike the simple model put forward by the IPCC in 2006, which assumed a linear relationship between N2O emissions and nitrogen use, the new findings suggest the issue could escalate quickly – more than it already has.

Between 2000 and 2005, and 2010 and 2015, N2O emissions were found to increase by roughly 10 percent. This is more than twice the rate estimated from fertiliser use, which was reported to the United Nations.

And this isn’t due to natural changes, the authors say, but rather our growing reliance on nitrogen fertilisers for agricultural crops. Producing nitric acid and burning fossil fuels and biomass certainly doesn’t help.

“This increase is significantly larger than prior estimates,” the authors write, adding that “a change of this magnitude cannot be explained by any known mechanism through the [N2O] sink, as it would require an increase in atmospheric lifetime of ~20 years, and such a change is unrealistic over this timescale.”

Screen Shot 2019 11 18 at 4.37.25 pm(Thompson et al., Nature Climate Change, 2019)

The vast majority of the excess nitrogen is coming from the land, and while emissions in the United States and Europe have remained fairly stable, N2O has shot up in China and to a lesser extent in India, Nepal, Bangladesh, Pakistan and Brazil.

The authors found these regions are responsible for roughly half the increase in global emissions over the past two decades, with Africa contributing a further 20 percent. For both China and Brazil, the IPCC projections were way off.

 

“This mismatch seems to arise from the fact that emissions in those regions are proportionally higher than the use of nitrogen fertilisers and manure,” explain the authors in a recent piece for The Conversation.

After a certain point, they explain, it appears as though plants can no longer fix nitrogen as effectively and this causes emissions to increase exponentially.

The idea is hardly new, but agricultural researcher Richard Eckard, who was not involved in the study, told ABC News Australia it’s never been studied at this global level before.

“When you exceed the [plant] system’s capacity to use that nitrogen fertiliser, the efficiency goes out the window, and the nitrogen can leak out of the cycle,” he told the ABC.

“That plays out in some industries where the recommended amount of fertiliser is exceeded, and you get exponential loss of nitrogen.”

In a Nature review of the study, environmental agronomist David Makowski agrees. He writes that the steady rise of nitrogen fertilisers in developing countries is most likely to blame for the recent spike in global emissions.

 

“This result reinforces the hypothesis of a nonlinear relationship between N2O emission and Nitrogen inputs and thus of a non-constant emission factor, as previously suggested by several experimental field studies and meta-analyses,” he writes.

“This implies that the IPCC’s default Tier 1 approach of a constant emission factor may both overestimate emissions when excess nitrogen is low and underestimate them when it is high.”

IPCC reports have been critiqued in the past for underestimating carbon emissions from thawing permafrost, tipping points and positive feedback loops. Now, it’s starting to look as though the same has occurred with N2O emissions.

Earlier this year, a study found that thawing permafrost in the Arctic may be releasing 12 times as much nitrous oxide as we previously thought. Even more recently, it’s been suggested that global warming and ocean acidification may simply make emissions of this potent gas worse.

“We will have to adjust our emission inventories in light of these results,” says Wilfried Winiwarter, a researcher at the IIASA Air Quality and Greenhouse Gases Program.

But more than that, the authors say we must reduce our emissions. In the USA and Europe, strong regulations have stopped nitrogen from building up in soils and in waterways, and more sustainable farming techniques in other parts of the world may help as well.

The authors suggest reducing the amount of soil tillage and waterlogging that occurs on farmed land – none of which come at the cost of agricultural output if done correctly.

“It’s not that they shouldn’t be using nitrogen fertiliser,” Eckard told the ABC, “but if we all used the right amount we’d have significantly less nitrous oxide going into the atmosphere.”

The study was published in Nature Climate Change

 



Source link

Extreme Hurricanes Are 3 Times More Likely Now Than 100 Years Ago, Scientists Warn

in Science News by


Hurricanes are the costliest natural disasters in the United States.

Hurricane Harvey, which ravaged parts of Texas in August 2017, cost the US US$125 billion (yes, billion with a ‘b’). Harvey’s total came second only to that of Hurricane Katrina, which hit Louisiana in 2005 and cost approximately US$161 billion, according to the National Oceanic and Atmospheric Administration (NOAA).

 

Economic losses from Katrina exceeded 1 percent of the US’s gross domestic product that year.

According to a study published today in the journal Proceedings of the National Academy of Sciences, extremely destructive storms like Harvey and Katrina – hurricanes that decimate large coastal areas to the tune of billions of dollars – have gotten far more common in the US relative to their less damaging counterparts.

“We estimate that there has been a tripling in the rate of the most damaging storms over the last century,” Aslak Grinsted, the lead author of the study, told Business Insider.

Aftermath of Hurricane Katrina in September, 2005. (Barbara Ambrose/NOAA)Aftermath of Hurricane Katrina in September 2005. (Barbara Ambrose/NOAA)

Hurricanes in the US are becoming more damaging

A large body of research has shown links between higher temperatures and stronger, wetter hurricanes that can cause more damage. But calculating the cost of those worsening storms is tricky.

Analyses have to factor in inflation and fluctuations in property costs, as well as the fact that more people live in vulnerable coastal areas than they did a century ago. So if the same storm were to hit an urban area today versus 100 years ago, the resulting damages are likely to be higher.

 

In their new study, Grinsted and his team found a new way to compare hurricane impacts across centuries. They elected to compare storms by the amount of impacted land area, rather than economic losses.

Using an insurance-industry database, the researchers calculated how much land was destroyed by more than 240 tropical storms and hurricanes that made landfall in the US between 1900 and 2018.

“We cannot directly compare the damage from the 1926 Great Miami hurricane with that from Hurricane Irma in 2017 without considering the increased amount of valuable property exposed,” the authors wrote.

So Grinsted coined a new metric: “area of total destruction,” or ATD. It’s a measurement of how big an area a given hurricane would have to destroy to equal the associated economic losses.

The study authors concluded that the frequency of the most damaging hurricanes (defined as ATDs exceeding 467 square miles; 1,200 square kilometres) increased 330 percent century-over-century.

Moderate storms with an ATD of 50 square miles (130 square kilometres) or less, by comparison, increased at a rate of 140 percent per century.

(Shayanne Gal/Business Insider)(Shayanne Gal/Business Insider)

The data revealed that the worst hurricanes were Katrina and Harvey, which both exceeded an ATD of 1,930 square miles (4,990 square kilometres).

According to Grinsted, the 2000s was the decade with the greatest aggregate ATD thus far.

That trend holds true regardless of whether the data set includes tropical storms and hurricanes, or just hurricanes. (A tropical storm becomes a hurricane after wind speeds top 74 mph; 119 km/h.)

 

Why hurricanes are getting stronger

Scientists can’t definitely say whether individual storms are directly caused by climate change, but warming overall makes hurricanes more frequent and devastating than they would otherwise be.

That’s because oceans absorb 93 percent of the extra heat that greenhouse gases trap in the atmosphere, and hurricanes use warm water as fuel. So a 1-degree Fahrenheit rise in ocean temperature can increase a storm’s wind speed by 15 to 20 miles per hour (24 to 32 km/h), according to Yale Climate Connections.

Plus, rising water temperatures lead to sea-level rise, which increases the risk of flooding during high tides and in the event of storms surges. Warmer air also holds more atmospheric water vapour, which enables tropical storms to strengthen and unleash more precipitation.

Interstate 69 inundated by Tropical Storm Harvey floodwaters in 2017. (AP/David J. Phillip)Interstate 69 inundated by Tropical Storm Harvey floodwaters in 2017. (AP/David J. Phillip)

Hurricanes also appear to be getting more sluggish – a slower pace of movement gives a storm more time to lash an area with powerful winds and dump rain, so its effects can wind up feeling more intense.

Over the past 70 years or so, the speed of hurricanes and tropical storms has slowed about 10 percent on average, according to a 2018 study.

 

“Nothing good comes out of a slowing storm,” James Kossin, a NOAA scientist, told National Geographic. “It can increase the amount of time that structures are subjected to strong wind. And it increases rainfall.”

Hurricane Harvey was a prime example of this. After it made landfall, Harvey stalled for days and dumped more than 51 inches (130 centimetres) of rain on the Houston area. Climate scientist Tom Di Liberto described it at the time as the “storm that refused to leave.”

To make matters worse, a warmer atmosphere can hold more moisture, so a 10 percent slowdown in a storm’s pace could double the amount of rainfall and flooding that an area experiences. The peak rain rates of storms have increased by 30 percent over the past 60 years.

Both predictive climate models and Grinsted’s new data suggest that more destructive hurricanes will continue to increase in frequency unless greenhouse gas emissions are curbed. But until that happens, Grinsted said, we have to prepare for what scientists know is coming.

“In the short term, we cannot hope to combat storms. So the risk has to be reduced in other ways: adapting, and reducing exposure,” he said. “It is also important to keep improving forecasting.”

This article was originally published by Business Insider.

More from Business Insider:

 



Source link

Go to Top