Posted on

Polluted oceans:
Let the trash take itself out

Up to 12.7 million tons of waste makes its way into the world’s oceans each year, forming massive “plastic islands” in oceanic gyres and devastating birds and marine life in the process.

Cleanup, in which plastics are currently collected at sea, stored and shipped to shore for disposal, is estimated to take from 50 to 130 years with annual costs expected by some at nearly US $37 million. In the meantime, the trash is degrading faster than it can be gathered, disintegrating into harmful and even more difficult to mitigate microscopic forms.

Listen to the Deep Dive

Now a team of researchers from Massachusetts in the United States is suggesting a new approach: self-powered cleanup vessels that turn the trash they harvest from the seas into the fuel they use for the job.

RELATED: Microplastics: The invisible threat

The “blue diesel”-powered ships could reduce the amount of fuel and roundtrips needed to remove ocean waste, the researchers write in a paper published in the Proceedings of the National Academy of Sciences of the United States of America.

The researchers, representing Harvard University, the Woods Hole Oceanographic Institution and the Worcester Polytechnic Institute, suggest using high temperatures and high pressure in a process called hydrothermal liquefaction to depolymerize the plastics into a harnessable energy, creating self-powered cleanup that eliminates the need to refuel or unload plastic waste and potentially reduces total cleanup times.

Of course, it isn’t enough to clean up the oceans faster and with less fuel waste. The world needs to address the amount of garbage that makes it into the oceans in the first place, the researchers write. “Reducing or eliminating the amount of plastic waste generated is critically important, especially when the current loading may persist for years to even decades,” they say.

 COVID’s toll on the oceans 

Meanwhile, researchers from China’s School of Atmospheric Sciences at Nanjing University and the Scripps Institute of Oceanography at the University of California-San Diego say the COVID-19 pandemic is making an already bad situation in the oceans even worse.

Also writing in the Proceedings of the National Academy of Sciences of the United States of America, the scientists say that of the 8 million tons of plastic waste generated until recently in the fight against the virus, about 25,000 tons of medical waste, mostly from hospitals, has entered the world’s oceans. And more is expected to come, not only damaging marine species but potentially spreading contaminants including the COVID-19 virus.

The hospital trash, they say, dwarfs the amount of waste from discarded personal-protective equipment (PPEs) and plastic packaging produced by a surge of online shopping in the wake of the pandemic. For a little perspective, the authors cite another study estimating that 1.56 million face masks made it to the oceans in 2020.

Plastics that wash into the oceans are endangering wildlife. IMAGE: Shutterstock

Five of the top six rivers associated with medical-waste discharge are in Asia (Shatt al Arab, Indus, Yangtze,Ganges Brahmaputra and Amur). The other, the Danube, is in Europe.

The authors call for increased public awareness of plastics’ environmental impacts; better collection, treatment and recycling of plastic waste; and improved waste-management practices at pandemic epicenters, particularly in developing countries.

 Microbots to the rescue? 

A solution to microplastics in water might come in an equally small package: microbots.

The bacterium-size bots when added to water with a little hydrogen peroxide attach to microscopic bits of plastic and begin to break them down. The research was recently published in ACS Applied Materials & Interfaces.

“They can sweep a much larger area than you would be able to touch with stationary technology,” says study co-author Martin Pumera, a researcher at the University of Chemistry and Technology, Prague.

Pumera envisions setting the microbots loose in the oceans to collect microplastics, but Win Cowger, an expert in plastic pollution at the University of California, Riverside, who was not involved with the study, tells Scientific American that closed systems such as those for drinking-water or wastewater treatment would probably be better potential targets.

Posted on

AI app can diagnose plant disease
and recommend treatment

The United Nations Food and Agriculture Organization estimates that almost U.S.$300 billion is lost globally to pests and disease every year, but the solution may lie in an artificial intelligence application you can download to your smartphone.

The International Center for Biosaline Agriculture in Dubai, in collaboration with the University of Barcelona, in 2022 launched an AI application that can help smallholder farmers detect crop disorders.

The application, called Dr. Nabat (the Arabic word for plant), aims to reduce crop loss in Tunisia, Egypt and the UAE. The app can diagnose 18 diseases commonly found in cucumbers, tomatoes and capsicum peppers. The developers plan to roll it out to other countries and eventually include other crops in the Middle East and North Africa such as quinoa.

While the app might solve complicated problems for smallholder farmers, it’s easy to use, the developers say. The farmer aims the Android phone camera at the crop, snaps a photo and instantly receives a diagnosis and recommendation for treatment.

The launch comes after a two-year beta trial in which 414 smallholder farmers and extension specialists fed data into the application.

Tarifa Alzaabi, director general of the International Center for Biosaline Agriculture, says providing this kind of information to smallholder farmers is important to the world’s food security.

“(The farmers) are the backbone of many agricultural economies, yet they often lack access to information about pests and diseases. We have developed this mobile application to help bridge this gap and put knowledge in their hands,” she says.

The World Economic Forum estimates smallholder farmers are responsible for one-third of global food supply.

Posted on

Ask the experts: What’s the future of hydrocarbons in an increasingly green world?

Behaviors must start changing now

Michael Jefferson

From the supply side there are a few problems facing us as we (or some of us) endeavor to move to “an increasingly green world.” For example, the UK is Europe’s windiest country, yet in the first 11  months of 2021 there were at least 85 days when wind energy failed to provide even 10 percent of the country’s electricity grid load, leaving gas (and sometimes even coal) to come to the rescue.

Things are not helped by the fact that this sector has only just begun to invest in significant volumes of back-up storage, and wind energy producers who look as if they may produce electricity when not required are paid to shut down temporarily.

Michael Jefferson

Michael Jefferson is a professor at ESCP Europe Business School (London campus). Read more›››

Formerly Group Chief Economist, Shell International (1974-1979), and other planning and oil supply and trading posts (1979-1990); deputy secretary general, World Energy Council (1990-1999); lead author, contributing author, IPCC reports; recipient of the IPCC’s certificate for contributing to their award of the Nobel Peace Prize, 2007.

Chairman, Policies Committee, World Renewable Energy Network, 1991-2007; senior editor Energy Policy journal 2013-2019.‹‹‹ Read less

On the demand side there are serious issues arising about how societies will be able to cope as demand for electricity rises concurrently with pressure to reduce reliance on hydrocarbons. The demands of re-charging electric vehicles is but one of these. There is also the rising opposition to plastics. We should all abhor plastic waste. But there are estimated to be up to 9,000 plastics products, all reliant on hydrocarbons (petro-chemicals is perhaps a more relevant term here).

You may gather that I believe we are still only in the early stages of realizing how great the challenges are of seeking to move forward along an increasingly green path.

Hopefully a greater effort will be taken in using solar power, wind towers, learning from traditional architectural layouts to reduce dependence on hydrocarbons. But we all need to be aware of the many basic needs provided for by petro-chemicals, realistic time horizons for moving off petroleum in the transportation sector, and the key contribution which gas will make to the needed energy transition. In many countries, the general population remains concerned about the safety of nuclear power, and perhaps insufficiently aware of the current constraints or challenges to wind and wave power, and modern biomass.

Readers of this may find me unduly pessimistic, so I had better point out that I believe human activities have raised near surface global temperature by just over 1 degree Celsius over the past 140 years, and I fear they could raise it by nearer 3 degrees (rather than 1.5 or 2.0) over the remainder of this century.

I have worked with climate research scientists for over 40 years, with the Intergovernmental Panel on Climate Change (IPCC) between 1991 and 2015 in various roles, and believe strongly in the need for sound precautionary policies and investments — as well as behavioral changes — now to counter climate change, even if the start of a new global solar minimum happened to be just round the corner.

 

Hydrocarbons will continue to have a significant role

Mai Bui

Hydrocarbons have provided the majority of the world’s energy needs for centuries. Employed in many areas of society, hydrocarbons have played an important role in the power, industry, transport, commercial and residential sectors, with 84 percent of the global primary energy consumption currently coming from fossil fuels. At a global scale, total anthropogenic CO2 emissions reached 36.4 Gt/year in 2019, which reduced to 34.07 Gt/year in 2020 due to the Covid-19 pandemic.

Subsequently, a growing number of countries and companies have recognized the need to commit to a target of net-zero emissions by 2050 (or 2060 as in China’s case).

Mai Bui

Mai Bui is a research associate at the Centre for Environmental Policy at Imperial College London.

Even at a national scale, reaching net-zero will be a major challenge, requiring unprecedented levels of greenhouse gas emissions reduction and removal from the atmosphere. The net-zero transition will employ a portfolio of different technology options, including renewable energy, hydrogen and energy-efficiency improvements.

Carbon-capture and -storage (CCS) technologies will also play an important role in reducing emissions associated with hydrocarbons in the power and industrial sectors, as well as generating low-carbon hydrogen (e.g. from natural gas or biomass) to use for transport or residential heating. CCS can also be used for CO2 removal from the atmosphere, which can be used to offset any residual CO2 emissions that are not captured.

It is highly likely that hydrocarbons will continue to have a significant role for the upcoming decades, particularly in countries and sectors that currently rely on carbon-based fuels. Although 2050 seems far into the future, reducing emissions at a gigaton scale will require major infrastructure changes and large-scale deployment of low-carbon technologies.

Carbon capture and storage could be key to helping tackle global warming. CREDIT: Shutterstock

Furthermore, governments will have an essential role in developing policy that will support and facilitate the transition to net-zero. Although urgent action is needed immediately, it is crucial that the transition to a green-oriented future is affordable and socially equitable.

We need to strike the right balance between cost, energy security, meeting emissions-reduction targets, while also avoiding unintended negative impacts to society and the environment.

 

3 pathways to a net-zero future

Martin Haigh

In the long run, we need to get to net-zero CO2 emissions to stop the world’s temperature rising.

That means that we need to be on a pathway to reduce our use of fossil hydrocarbons. In turn, that boils down to three options:

  • fossil hydrocarbons are not burned but used to make products like plastics (in which case those need to be either recycled or disposed of responsibly);
  • fossil hydrocarbons are burned and the emissions are captured;
  • or fossil hydrocarbons are burned and the emissions are balanced by negative emissions elsewhere.

Then the debates start about how we achieve this. Because of the pervasive use of hydrocarbons across our economies and lives, the implications are profound: justice and equity. Which uses are seen as more legitimate? How much more time should developing countries have to decarbonize? Indeed, should developing countries’ emissions rise for a period in order to continue meeting human-development goals?

  • demand or supply of fossil hydrocarbons? Can you effect change by stifling production of fossil hydrocarbons, or do you need to address demand for any change to be lasting?
  • economics and practicalities. How much change is realistic by 2030? What are the knock-on consequences of changes? Which policies are most effective in driving change?
Martin Haigh

Martin Haigh looks after the long-term energy modelling behind the Shell scenarios.

These are just a few examples, but the “how” touches almost all areas of politics, economics, technology and society. We explored a range of alternatives in our scenarios: Waves, Islands and Sky 1.5, available here. These look at wider drivers of change and the implications for the whole energy system, hydrocarbon and non-hydrocarbon.

In the Sky 1.5 scenario, a stretching and rapid world of change across the energy system, we look at the most practical means of keeping the temperature rise to 1.5 degrees C above pre-industrial levels by 2100. All available options come into play, including negative emissions, and both technological (bioenergy with CCS) and natural (nature-based solutions).

In Waves, stronger demand combines with a widespread desire to drive the energy transition by focusing on elimination of fossil hydrocarbons as the root cause of climate change. In common with Sky 1.5 is strong growth in renewables and hydrogen, but in this scenario, CSS does not play a material role.

Going green means more than just reducing our energy consumption. IMAGE: Shutterstock

The result in Waves is that emissions take longer to peak and fall. In Islands, near-term energy (and hydrocarbon) demand grows more slowly than the other scenarios, as countries focus on trying to stimulate sluggish economies and address local concerns.

The flip side to factors leading to the slower growth in demand is that the pace of transition is slower and similar to historical norms. Here are our outlooks for the future of oil demand and supply.

In the long-term, demand moves away from oil. The timing of the peak of demand for oil is quite different, possibly even this decade (Sky 1.5). But there are very different trends underneath this, both regionally and across sectors. Some uses, notably the “non-energy use” sector (material products like plastics), continue to be robust throughout the century, while it moves away more rapidly in sectors like car travel. Our data set provides the figures behind this graph, together with outlooks for other hydrocarbons (natural gas, coal and bioenergy, the non-fossil hydrocarbon), alongside other energy sources, and then how the uses of these different energy forms evolve.

 

Gulf countries need to take the lead

Adnan Shihab-Eldin

With increasing momentum in favor of switching to global clean-energy sources (net-zero emissions) by around 2050, the United Nations Climate Change Conference of the Parties (COP26) in November adopted a series of decisions embodied in the Glasgow Climate Act (GCA), which aims to achieve the Paris Agreement’s climate-change goal of keeping the projected rise in global average temperature below 1.5 degrees C.

Renewable technologies, solar and wind in particular, are at the forefront of the clean-energy mix. Nuclear energy and clean, carbon-neutral fossil-energy fuels could competitively be part of the mix, but their roles and shares are uncertain due to multiple, and sometimes contradictory, views about the optimal path of the transition, its component technologies and who will bear investment costs estimated at about $5 trillion annually by 2030, according to the NZE2050 scenario from the International Energy Agency (IEA).

There remain significant differences among industrial countries over how to proceed with emissions reductions: Some vehemently oppose expanding nuclear energy and clean fossil-energy technologies and some European countries are against including such technologies in the list of clean-energy sources and products eligible for global trade, raising obstacles to plans to export and import fossil-based clean (blue) hydrogen and ammonia.

Adnan Shihab-Eldin

Dr. Adnan Shihab-Eldin is a senior visiting research fellow at the Oxford Institute for Energy Studies and a board member of both the Kearney Energy Transition Institute, Amsterdam, and Gulf Bank of Kuwait.

Those countries, and most environmental activists, are betting that renewable energy could provide most if not all of the clean-energy supply, despite technical and economic obstacles that prevent their share in electrical grids from exceeding, on average, about 30 percent. A number of extreme energy-transition scenarios predict a sharp decline in the contribution of fossil energy to total demand, from the current 80 percent to about 20 percent by 2050 (e.g. IEA’s NZE2050). However, such scenarios are idealistic, costly and difficult to realize.

Among a wide range of other scenarios, OPEC’s latest annual World Oil Outlook report projects oil and gas demand to grow, albeit at a slower pace, until at least 2045, with the share of fossil sources falling to about 70 percent.

Regardless of the degree of optimism or pessimism of these scenarios, the goal and trajectory of all energy-transition pathways are unequivocal: a rapid transition to a clean-energy mix, with a wide range of component technologies. The growing enthusiasm for protecting the environment is sometimes shrouded in an increasingly negative outlook toward fossil sources, irrespective of how clean some can be.

This will no doubt drive an accelerating shift in policies, unless countries with large reserves of fossil sources, combined with low production costs, such as the Gulf states, start immediately making strategic investments to develop CO2 capture, use and storage technologies (CCUS, or CCS), including direct capture of CO2 from air (DAC). The investments are huge but worth it, for they will help to maintain a robust role for fossil-energy sources. Although many CCS projects are being implemented by oil- and gas-producing countries, most of them are still of small capacity and their number is growing slowly due to their high cost.

In line with the GCA call to member states to make more ambitious and concrete pledges to reduce carbon emissions, the Gulf states should embrace an ambitious initiative: pledging to equip all fossil-based power plants with (CCS) systems by 2035. Such an initiative would be welcomed worldwide. Furthermore, it will reduce Gulf countries’ CO2 emissions by approximately 25 percent, or about 1 percent of total global emissions — a significant decrease given the size of their economies is about 1.8 percent of the global economy.

Individual countries have their own views on how to go green in a post-carbon future. CREDIT: Shutterstock

Most importantly, implementing this initiative will significantly reduce the cost of CCS technologies, increase their reliability and global acceptance and ensure a continued robust role for oil and gas well into the second half of this century, while providing clean energy sources (electricity and fuel) to the world’s poor. Recently, the Gulf countries have taken encouraging steps in this direction. The Kingdom of Saudi Arabia (KSA) and the United Arab Emirates (UAE) have adopted clear and well-considered energy-transition strategies.

As part of its Vision 2030, the KSA implemented major environmental initiatives and emission-reduction programs such as the “Green Saudi Arabia” and announced its commitment to becoming carbon neutral by 2060 and producing 50 percent of its electricity from renewable-energy sources by 2030.

On a similar path, the UAE nearly 15 years ago launched pioneering initiatives and implemented the construction of Masdar Clean Energy City, four nuclear power plants and several large solar power plants with total capacities of more than 2 GW. But more investments and innovations are needed to make CCS and clean fossil fuel an important component of the future global clean-energy mix.

The GCC countries and other low-cost oil producers have the most to gain if they do and the most to lose if they don’t.

Posted on

Lessons from the desert beetle

Could a desert beetle be the key to pulling water from the air?

Residents of the world’s most arid regions might someday raise a glass of water to the Namib desert beetle, which is giving up secrets to harvesting water from the air.

Several species of Namib desert beetles are native to an area of southwestern Africa without much ground water and rainfall averages of about 1.3 to 5 centimeters a year. To compensate, the beetles  “fog bask,” leaning into the fog that rolls in several times a week to collect the water they need to stay alive. Water from the air collects on the beetles’ abdomens, then rolls into their mouths.

Researchers have studied the beetles for decades, but several teams have peeled back more of their mysteries in recent years.

The desert beetle inspired researchers, who found that bumpy surfaces caught water droplets with more efficiency than did a smooth sphere. IMAGE: Anas Albounni, KUST Review

Hunter King, a physicist at the University of Akron in Ohio, USA, and his team took their cues from the bumps on the beetle’s back and found that shape and texture could become a “fog magnet,” with 1-millimeter bumps catching water with 2.5 times more efficiency than a smooth sphere with the same surface area.

“We think the real take-away message is one of enhanced filtration of hard-to-catch, low inertia particles/droplets,” King says.

In 2021, researchers from Fuzhou and Soochow universities in China and Nanyang Technological University in Singapore reported on how they mimicked the beetle’s exoskeleton, weaving superhydrophilic and superhydrophobic materials with copper particles to increase the water-harvesting rate of conventional fog harvesters. The researchers say their biomimetic material would be well-suited to large-scale production.

Posted on

A river runs over it

Think the Amazon River is the largest river on Earth? Technically, you’d be right but the river with twice the amount of water than the Amazon can be found in the sky.

Atmospheric rivers are long, narrow bands of concentrated water vapor that produce major amounts of rainfall. They exist on a global scale, transporting moisture from the tropics to the higher latitudes.

And they can have a huge effect on the way you live. “Atmospheric rivers are responsible for important impacts throughout the Earth’s middle and polar latitudes, such as flooding, influence on water resources, and melting of polar ice sheets,” explains Kyle Mattingly of the University of Wisconsin.

IMAGE: Unsplash
Like a hurricane
but not

Atmospheric rivers are not big hurricanes. Read more›››

Although they share many features (high winds and lots of rain originating from the tropics), atmospheric rivers are sustained, moving bands of moisture with wide-spread impact. Think a jet stream, but wet, and closer to the ground.

Hurricanes, on the other hand, are rapidly rotating storm systems that concentrate their water content into precipitation over a much smaller area. Hurricanes take heat from the tropics to the poles, which plays an important role in regulating global climate; atmospheric rivers take moisture out of the tropics and spread it around the world.‹‹‹ Read less

A 1998 paper from Yong Zhu and Reginald Newell, the researchers who coined the term, says on any given day, atmospheric rivers account for over 90 percent of the global north-south water-vapor transport.

There are typically three to five rivers present within a hemisphere at any given time, and any single one can carry a greater flux of water than the Amazon River. For context, that’s about 6,592 cubic kilometers of water every year, or more water than the next seven largest independent rivers combined. It’s just water vapor instead of liquid water.

These rivers in the sky help replenish reservoirs and redistribute water in the Earth system, but they can also be detrimental to the places they deposit water.

Extreme weather events such as severe flooding and high winds are now found to be associated with atmospheric rivers. These elongated tendrils of moisture stretching from the tropics poleward act as conveyor belts, feeding huge amounts of tropical moisture into existing weather systems, intensifying the rainfall. Record-breaking rainfall is often associated with an atmospheric river making landfall.

However, this water content doesn’t just fall out of the sky on a whim. The rivers pass through various atmospheric conditions on their journey, and where conditions are right for precipitation, water is released as rain or snow. Mountainous regions are particularly effective at squeezing moisture out of these sky rivers as wind travels up their sides.

A NEW ANCIENT PHENOMENON

Despite earning a name only in 1998, atmospheric rivers have been meandering through the skies for millions of years — they’re not new. So why are atmospheric rivers making a splash in the current zeitgeist?

Climate change, of course.

Plus, it’s a useful and versatile term, says Mattingly. “The ‘rivers in the sky’ metaphor helps to vividly communicate these scientific ideas to the public. In places such as California, where they have major impact, the concept helps people connect weather they experience personally with processes operating at much larger scales in the climate system.”

Understanding atmospheric rivers is key to improving weather forecasts for better managing water resources and predicting flood risk. However, atmospheric rivers are also influenced by climate change.

Previous work has examined the relationship between weather patterns and atmospheric-river development, but with climate change, these features may become more variable — and therefore harder to predict. This could mean a less reliable source of precipitation for those areas depending on the water redistribution, but could also mean extreme flooding in other places.

To those living in the Middle East, huge amounts of rainfall are pretty rare and would likely be welcomed to recharge oases, water crops and wash away the dust that accumulates in cities. The reality can be much more detrimental than beneficial, unfortunately.

A global phenomenon, atmospheric rivers have far-reaching influences on weather patterns and natural disasters. IMAGES: Unsplash and Pexels

Although a large body of research has shown the impacts of atmospheric rivers on weather-related natural disasters over the western United States and Europe, little is known about their mechanisms and contribution to flooding in the Middle East.

However, a rare atmospheric river was found responsible for the record floods of March 2019 in Iran that damaged one-third of the country’s infrastructure and saw the death of 76 people. This river started its 9,000-kilometer journey in the Atlantic Ocean before making landfall over the Zagros Mountains. It needed special conditions to make this trek across North Africa, including anomalously warm sea-surface temperatures.

What do we know is a symptom of global warming? Rising sea temperatures. The moisture transported by this rare atmospheric river was equivalent to more than 150 times the accumulated flow of the four major rivers in the region: the Tigris, Euphrates, Karun and Karkheh. Even now, people are still wrestling with the aftermath.

It was a rare atmospheric river for 2019. But like hurricanes, atmospheric rivers are projected to grow longer, wider and wetter in a warming climate. Several recent studies have modelled how atmospheric rivers will change in the coming decades: The planet warms, more water evaporates and a wetter atmosphere makes for stronger storms.

BLOWING HOT AND COLD

Challenging our understanding of atmospheric-river genesis is the increasing activity in the polar regions. Atmospheric rivers developing near the poles transport large amounts of moisture and heat and have been playing a significant role in short-duration but high-volume melt events over the Arctic and Antarctic in recent years.

There are several reasons for this, explains Mattingly. “Research to date has shown that atmospheric rivers can increase ice melt by enhancing the water-vapor greenhouse effect, releasing condensational latent heat into the air over the ice, forming bands of cloud that reflect heat back to the surface, and providing more water to the cyclones ahead of which they develop. In addition, atmospheric rivers are closely related to the atmospheric fronts over the Southern Ocean, which, in turn, reinforce subantarctic cyclone dynamics.”

The number and intensity of cyclones around Antarctica over the past few decades have increased as the storm tracks shift toward the pole under enhanced greenhouse-gas concentrations.

In the largest calving event from the Amery Ice Shelf since 1963, an iceberg 1,636 square kilometers with an estimated weight of 315 billion tons broke away from its glacier in September 2019.

Melting polar ice is concerning enough, but global warming and atmospheric changes could lead to more such calving events.

Atmospheric rivers can increase ice melt by enhancing the water-vapor greenhouse effect.

– Kyle Mattingly, University of Wisconsin

Cyclogenesis, the formation of cyclones, is a major factor in this, and an increase in the frequency and intensity of atmospheric rivers in the region will only exacerbate the problem. It’s not just calving events we need to be worried about.

Despite their distance, the sand dunes of the Sahara and the ice caps of the Antarctic are linked by global atmospheric phenomena. CREDIT: Anas Albounni, KUST Review

“Our analysis of the polynya event in September 2017, where a body of unfrozen ocean appeared within a thick body of ice during Antarctica’s winter, shows that the atmospheric rivers that initiated this were the most intense on record,” Mattingly says. “Surprisingly, these atmospheric rivers resulted in the highest amount of snowfall on record over the study area, but because of the warm temperatures, it was this warm snow that enhanced the ice melt and inhibited refreezing.”

It may be rare now, but under a warmer climate, atmospheric-river activity is expected to intensify considerably: a scary thought when we now know it can melt the sea ice in the middle of the Antarctic winter.

It’s not all bad, though. Within the sea-ice zones of both hemispheres these polynyas act as oases, enabling marine mammals such as walruses, narwhals and belugas to overwinter.

Some polynyas, such as the North Water Polynya between Canada and Greenland, occur at the same time and place each year. Animals can adapt their life strategies to this regularity, with polynyas in McMurdo Sound in the Antarctic providing a vital winter feeding place for the Cape Royds penguin colony.

IMAGE: Unsplash
A bad year for oysters

Aside from crazy weather, atmospheric rivers can have unexpected secondary consequences. Read more›››

In 2011, there was a massive wild Olympia oyster die-off in Northern California. These oysters were sensitive to the low salinity levels caused by excess freshwater dropped into the ocean from the sky by the 20 atmospheric rivers that passed through the region between October 2010 and September 2011.

It is yet to be seen what other marine life may be affected by an increased frequency in atmospheric rivers. ‹‹‹ Read less

The problem arises in the intensification of the atmospheric rivers affecting a larger area than that of the natural polynya, which may prevent sea-ice growth around the polynya and contribute to keeping it open even after the river moves on.

Jonathon Wille, postdoctoral researcher at the Université Grenoble Alpes, is also investigating the impacts of atmospheric rivers on Antarctica.

“The Antarctic continent, like many deserts in the world, receives a large percentage of its yearly precipitation from just a few intense events,” Wille explains. “They may be rarer here, but they still have a major influence on the surface-mass balance of the ice sheet and are responsible for 10 to 20 percent of the total snowfall across East Antarctica.

“This may seem a modest percentage, but this contribution to the snowfall budget has been driving parts of the positive annual snowfall trends in some areas and the negative trends in others. Atmospheric rivers also control the year-to-year variability of precipitation across most of the ice sheet.”

Given this link, increased future atmospheric river activity would result in higher snowfall accumulation on the Antarctic continent. Combine this with Mattingly’s results showing it was snow that melted the sea ice, and we have a problem.

CLOSER TO HOME

If Antarctica feels too far flung to worry about, you can always turn your attention to the European Alps.

Over the past four decades, there has been a pronounced reduction in the snow depth in the Alps, says Diana Francis, senior research scientist at Khalifa University, and, for once, it’s not a warming planet that is directly to blame. A new atmospheric river route has appeared, originating in the eastern Atlantic Ocean and drifting over the Sahara Desert on its way to Europe, bringing desert dust with it.

“Dust may actually play a bigger role in melting snow than ambient air temperature,” Francis explains. “It’s estimated that a single dust event in March 2018, where Saharan sand blew in over the Caucasus Mountains, may have shortened the snow-cover duration by up to 30 days, with this effect even more pronounced at higher elevations.”

Cryoconite is dust made up of microscopic mineral and organic particles that are carried by the winds and fall on the ice. IMAGE: Shutterstock

The dust magnifies the snowmelt in a number of ways.

Dust may actually play a bigger role in melting snow than ambient air temperature.

– Diana Francis, senior research scientist at Khalifa University

For starters, airborne dust enhances the radiative effects of the water vapor in the atmospheric river, meaning the air can hold higher amounts of moisture, and the dust particles can act as cloud-condensation nuclei, promoting the development of clouds that then rain on the mountain snow.

Then, there’s the dust that is deposited on the snow. Dust on the snow impedes the albedo effect, where the white snow reflects the UV radiation back, reducing the heat and keeping things cool.

Dust-covered snow can’t do this, with the darker surface absorbing a larger fraction of the incoming solar radiation, causing it to melt. Drastically, in fact, as Francis confirms the snow-albedo feedback in response to Saharan dust can lead to the snow melting up to 38 days earlier than normal.

That’s not all.

Mineral dust on snow and ice can provide nutrients to the microalgae that grow there. That might not sound so bad, but when microbes grow in abundance they can cause holes in the ice and snow cover, called cryoconite holes.

Among the 21 countries in the MENA region, Iran, Egypt and Saudi Arabia have benefited the most from this phenomenon.

– Mehry Akbary, assistant professor at the University of Tehran

The microalgae tend to concentrate at the bottom of these holes, creating a dark mass, which further reduces the albedo effect. As the snow melts, more of the darker material is exposed on the surface, creating a vicious circle.

The jet streams that zoom over the Earth often bring dust to northern latitudes, but with new atmospheric rivers lending a hand, alpine skiers won’t get much opportunity to enjoy the slopes.

But again, it’s not all bad. In a world without atmospheric rivers, drought would reign supreme. Atmospheric rivers are crucial to rebalancing water distribution around the planet, and while an increase in rain may be devastating, no rain at all would be just as bad. A better understanding of the future of rivers in the sky may also help water-resource managers on the ground.

THE GOOD NEWS

Mehry Akbary, assistant professor at the University of Tehran, thinks her findings on the development of atmospheric rivers in the Middle East and North Africa could be used to compensate for the shortage of water resources in this desert region.

The MENA region lies at the interface of the subtropics and mid-latitudes, and its geographical location means there is significant uncertainty about the magnitude of future changes to precipitation in much of the region.

However, because atmospheric water vapor will increase with increasing temperatures, researchers from Jet Propulsion Laboratory, University of Balamand Dubai, University of California and California State University say in their 2020 paper, confidence is high that precipitation extremes will increase in frequency and intensity throughout the MENA region.

Akbary thinks this could be more beneficial than detrimental, though. “As the most arid deserts of the world are located in the MENA region, atmospheric rivers can be counted as good sources of precipitation. Among the 21 countries in the MENA region, Iran, Egypt and Saudi Arabia have benefited the most from this phenomenon.”

Atmospheric rivers account for more than 30 percent of the total rainfall across the MENA region, with some areas seeing almost half their precipitation from rivers in the sky. “I believe if water storage systems are suitable, this huge amount of rainfall could be stored for coming droughts,” Akbary says.

Desertification may be kept at bay by the live-giving moisture in atmospheric rivers. CREDIT: Anas Albounni, KUST Review

In models simulating the year 2100, calibrated to represent a high-emissions future, we can see increases in atmospheric-river frequency in the North African coast, Turkey and Iran. This doesn’t mean the rest of the region will dry up: on the contrary, there is an expected increase in precipitation for the Arabian Peninsula.

From the Horn of Africa to the United Arab Emirates, more rain is coming. More water for a parched land can only be welcomed, but locals need to prepare for the accompanying high winds and flooding potential.

Mattingly thinks the largest impact from more frequent atmospheric rivers will be their effects on flooding and water resources. “More intense atmospheric rivers will lead directly to more intense floods in the future, and we are already seeing examples of extreme floods in recent years that were likely exacerbated by the fact a warmer atmosphere can hold more water vapor.

Although more rainfall might help replenish water resources in some areas, wetter and warmer atmospheric rivers will also present challenges to water managers in the future. For example, in areas such as the western U.S. that are heavily dependent on snow pack for their water resources, atmospheric rivers are expected to bring more rain to the region, rather than snow, which will likely result in depleted snow packs and stressed water resources during the dry summer months.”

In general, water managers are working to be more flexible in their approach to managing resources in the future.

– Kyle Mattingly, University of Wisconsin

It’s not all doom and gloom, though, Mattingly is keen to point out. “I do think that in general, water managers are working to be more flexible in their approach to managing resources in the future. California is, again, a good example, because in the past few years they have had to deal with a few wet seasons against the backdrop of a long-term drought and overall warming that has depleted reservoirs and snow packs. The challenge seems to be to develop approaches that conserve the water delivered quickly during more intense rain events to help ride out drought years.”

Models from around the world agree: Atmospheric rivers will become more frequent and intense as the planet warms. The researchers behind these models also agree: Knowing how atmospheric rivers develop and move – and what they may pick up along the way – is an important step toward accurately predicting them and their associated rainfall.