New report explores the impact of sand and dust storms
On the launch of the report, Impacts of Sand and Dust Storms on Oceans: A Scientific Environmental Assessment for Policy Makers, author and University of Oxford lecturer, Nick Middleton discusses how the dust cycle affects and interacts with other global-scale biogeochemical cycles.
What exactly are we talking about when we refer to the “dust cycle”?
The dust cycle describes the movement of trillions of tiny particles through the Earth System. Sand and dust is raised by strong winds from areas of bare or sparsely vegetated ground. While some of this material falls back to the surface near the source, the smaller dust particles are carried further in the wind – sometimes thousands of kilometres – before being deposited.
Each year, an estimated two billion tonnes of dust is raised into the atmosphere; and one-quarter of this reaches the oceans.
Is this movement regular and predictable?
These long-distance dust flows are highly seasonal and can vary significantly from year to year. But most dust comes from deserts and semi-deserts, and a particularly dusty area known as the Dust Belt stretches from the Sahara across the Middle East to the deserts of Central and Northeast Asia.
The planet’s largest sources are in the Sahara. Much Saharan dust is transported south-westward by the Harmattan wind that prevails between November and April. This dust has marked effects on the North Atlantic and the Caribbean Sea, but Saharan dust also impacts the Mediterranean Sea and the Red Sea.
What role do sand and dust storms play in a healthy ecosystem?
Desert dust particles consist of minerals, nutrients, and organic and inorganic matter. Dust plays a role in a range of Earth’s physical, chemical and bio-geological processes, and interacts with the cycles of energy, nitrogen, carbon, and water. All are necessary for Earth system functions.
How do they affect ocean ecosystems?
Dust carries nutrients such as phosphorus, and trace metals—including iron, manganese, titanium, aluminium—to oceanic ecosystems, elements that are essential for all life forms. In this way, desert dust is a principal driver of oceanic primary productivity, which forms the base of the marine food web.
Marine primary production also fuels the global carbon cycle via the exchange of CO2 between ocean and atmosphere, so desert dust has impacts on our climate system. Dust also provides some of the building blocks for coral reefs: dust particles are incorporated into coral skeletons as they grow.
Desert dust also provides the primary external source of iron to offshore waters, but controls on iron aerosol solubility are poorly understood. Iron is required for phytoplankton growth, but the iron must be in a form that can be used by living organisms, which is dependent partly on its solubility. What are some of the negative effects of sand and dust storms?
The fertilizing effect of desert dust is thought to have an impact on algal blooms, some of which can be harmful, and may contribute to Sargassum seaweed mats. Unusually large blooms of floating Sargassum seaweed have been noted since 2011 in parts of the Caribbean Sea and along the Atlantic coastlines of West Africa and Brazil. These drifting seaweed mats provide important habitat for many species in the open ocean, but close to shore, they can disrupt shipping, fishing and tourism.
Potential links have also been identified between microorganisms, trace metals and organic contaminants carried in desert dust and some of the complex changes on coral reefs observed in numerous parts of the world. Disease has undoubtedly been an important factor in recent coral reef declines worldwide and several of the diseases that affect corals are associated with microorganisms carried in desert dust.
A wide variety of microorganisms—including fungi, bacteria and viruses—has been found in desert dust. Most of these pathogens come from dryland soils and are highly resistant to desiccation, temperature extremes, conditions of high salinity and exposure to ultraviolet radiation. They are therefore typically able to survive in the atmosphere for many days.
Do sand and dust storms play a role in transporting diseases like COVID-19?
We still have numerous basic questions to answer regarding these desert-derived bioaerosols. It is thought that many of the microorganisms transported in desert dust are capable of causing disease outbreaks in a wide range of organisms, both terrestrial and marine, but we have little data on specific microbes found in dust storms known to cause disease in people and animals.
How does this report contribute to existing knowledge about sand and dust storms?
While our understanding of the dust cycle has improved greatly in recent decades, large uncertainties and knowledge gaps remain. Nonetheless, this knowledge has significant implications for a number of Sustainable Development Goals – particularly Goal 14 on Life Below Water and Goal 15 on Life on Land.
Marking the start of the United Nations Decade of Ocean Science for Sustainable Development (2021–2030), this report explores the impacts of sand and dust storms on oceans—their ecosystem functions, goods and services—which are potentially numerous and wide-ranging. Sand and dust storms thus warrant continued careful monitoring and research.
Mighty oceans and humble ponds play key roles in biodiversity
By monitoring oceans and peering into ponds, European projects seek to protect an array of animal and plant life.
By SOFIA STRODT
In January, word emerged that scientists had discovered a new colony of penguins in Antarctica using images from Europe’s flagship Copernicus satellite network. By coincidence, the same month marked the start of an initiative that will rely on the same Earth-observation system for different purposes.
The EU-funded NECCTON project is gearing up to help Europe protect endangered fish and whales. It will harness the European Copernicus Marine Service – or CMEMS – to collect more detailed data on species threatened by habitat loss, unsustainable fishing and industrial pollution.
From satellites to seabeds
‘This is going to be particularly helpful for policymakers, marine managers and fisheries,’ said Stefano Ciavatta, coordinator of the project running through 2026. ‘We want to provide better simulations and projections of the state of marine ecosystems and of their ability to support diverse fish communities.’
While earth-observation satellites including Europe’s flagship Copernicus number in the many hundreds, it’s often claimed that we know less about the ocean floor than we do about the surface of the moon.
Biodiversity protection has received fresh impetus as a result of a United Nations summit in Canada in December 2022 and a landmark UN agreement in March this year on a High Seas Treaty to protect oceans. And with 68 000 kilometres of coastline – more than the US and Russia combined –the EU is stepping up efforts to improve marine health.
CMEMS, one of six Copernicus services, provides analyses and forecasts of marine environments for all kinds of users ranging from fishing hobbyists to the navies of EU Member States. It is run by France-based Mercator Ocean International, a non-profit entity in the process of becoming an intergovernmental organisation.
The Copernicus marine service monitors all the European regional seas and the world’s oceans. Its models forecast things like sea temperatures, tides and currents, making it easier to anticipate developments such as fish migration patterns.
NECCTON plans to provide a more complete picture of the environmental state of these waters by gathering data on fish, pollution and the seabed conditions for marine life.
‘We will develop new tools to share the modelling capabilities of the Copernicus Marine Service across the different centres in Europe, optimise scientific efforts and boost collaboration,’ said Ciavatta, an oceanographer at Mercator Ocean International.
The ultimate aim is to help users of the service make better-informed decisions about the sustainable use of marine resources.
The Copernicus marine service could, for instance, deliver information on where tuna populations are located or whether marine habitats have the right conditions for dolphins.
To make sound policy decisions, scientists and authorities need projections on how changes that result from global warming, pollution and overfishing could affect the marine system as a whole.
NECCTON plans to simulate changes in organisms within the food web using climate scenarios. This activity could, for example, enable researchers to get a clearer picture of the impact of declining fish stocks on the marine system over the coming decades.
When it comes to protecting biodiversity, it’s not just the mighty oceans that have researchers’ attention. So do humble duck ponds.
The EU-funded PONDERFUL project is examining the relationship between ponds and their surrounding environment. The initiative is focusing on the wide range of living organisms to which ponds are home.
Fish, toads, snails, dragonflies and leeches are just some of the creatures making up a vast, balanced web that, if disrupted, could result in the ecosystem’s collapse.
‘Collectively, ponds are the richest freshwater habitats,’ said project coordinator Sandra Brucet, a biologist and researcher on aquatic ecology at the University of Vic in Spain. ‘They are more abundant than lakes, rivers and wetlands.’
Research suggests that ponds make a greater contribution to biodiversity than many larger bodies of water by supporting more plants and animals, many of which are endangered.
Nonetheless, ponds so far have been largely neglected by policymakers. For example, a major piece of EU legislation in 2000 on cleaning up water bodies excludes for the most part those smaller than 50 hectares. Also, research on ponds has long been overlooked.
‘Two decades ago, researchers mainly focused on lakes and rivers,’ said Brucet, who came up with the idea of PONDERFUL.
Now things are changing as the project, which began in late 2020, enters its final two years.
With more than 80 researchers from 11 countries – Belgium, Denmark, France, Germany, Portugal, Spain, Sweden, Switzerland, Turkey, the UK and Uruguay – the initiative is deepening knowledge about how best to manage and restore ponds in a changing climate.
PONDERFUL is evaluating future “pondscapes” at eight demonstration sites that include a total of more than 500 ponds. Testing will help develop a guide for reducing pollution in ponds, creating new ones and helping them serve broader environmental goals such as the preservation of biodiversity.
Runoff from agricultural fields is one of the main threats to the health of ponds. Nutrients in such runoff can cause harmful algal blooms, a lack of oxygen and dead zones as fish die off.
Brucet and her team have already drawn some important lessons.
An accumulation of debris and an increase in sediment loads, which result mainly from agricultural-field erosion and are usually rich in nutrients from fertiliser runoff, can have a harmful effect on the overall state of ponds.
Sediment increases are accelerated by erosion of ponds’ edges and seasonal buildup of organic material such as dead plants and tree leaves, for instance. The nutrients in this material in turn often feed algal blooms that can produce toxins and kill fish, mammals and birds.
Dredging and removing sediments help prevent such buildup.
Separately, reshaping the edges of ponds that are artificially drained for agriculture can prevent too much water from escaping.
When efforts are made to enhance pond wildlife as a whole, the researchers found that not only do populations of endangered frogs, toads and newts increase but also flora benefits.
‘Biodiversity of aquatic plants increases significantly after cleaning up ponds,’ Brucet said.
Healthy ponds even play a role on another important environmental front: fighting climate change. That’s because they act as “carbon sinks” that store greenhouse gases including carbon dioxide.
Brucet’s project runs through November 2024 and signals that ponds, after long being disregarded by researchers and policymakers, are finally joining oceans and seas as a focus of Europe’s green ambitions.
Research in this article was funded via the EU. The article was originally published in Horizon, the EU Research and Innovation Magazine.
Largest river and wetland restoration initiative in history launched at UN Water Conference
A coalition of governments today launched the Freshwater Challenge – the largest ever initiative to restore degraded rivers, lakes and wetlands, which are central to tackling the world’s worsening water, climate and nature crises.
Announced at the UN Water Conference in New York, the Freshwater Challenge aims to restore 300,000km of rivers – equivalent to more than 7 times around the Earth – and 350 million hectares of wetlands – an area larger than India – by 2030.
Along with water supplies, healthy freshwater ecosystems provide a wealth of benefits to people and nature, and are critical to mitigating and adapting to climate change, and achieving the Sustainable Development Goals (SDGs). Yet one-third of the world’s wetlands have been lost over the past 50 years, and we are still losing them faster than forests. Rivers and lakes are the most degraded ecosystems in the world, with fish populations, many of which are vital for community food security, pushed to the brink.
Released this week, the IPCC’s sixth assessment report outlines the serious impacts of climate change on freshwater ecosystems, highlighting the need to protect and restore them to enhance adaptation and build resilient societies, economies and ecosystems.
Championed by the governments of Colombia, the Democratic Republic of Congo, Ecuador, Gabon, Mexico and Zambia, the Freshwater Challenge calls on all governments to commit to clear targets in their updated National Biodiversity Strategies and Action Plans, National Determined Contributions and National Implementation Plan for the SDGs to urgently restore healthy freshwater ecosystems.
Susana Muhamad, Minister of Environment and Sustainable Development, Colombia: said”This initiative is in line with the priorities of the National Development Plan 2022-2026, which will allow the country to strengthen Territorial Planning around Water by protecting all water systems from a perspective of water as a common resource and fundamental right. This implies the participation of communities to resolve socio-environmental conflicts, respecting cultural diversity and guaranteeing the conservation of biodiversity”.
The Freshwater Challenge is a country-driven initiative with an inclusive, collaborative approach to implementation, where governments and their partners will co-create freshwater solutions with indigenous people, local communities, and other stakeholders.
Building on the Global Biodiversity Framework agreed in Montreal in December 2022, which included the restoration of 30% of the world’s degraded ‘inland waters’, the Challenge will contribute to the UN Decade on Ecosystem Restoration. The UN Decade is a drive to revive our planet, co-led by the United Nations Environment Programme (UNEP) and the UN Food and Agriculture Organization (FAO).
Inger Andersen, UNEP Executive Director said, “Healthy rivers, lakes and wetlands underpin our societies and economies, yet they are routinely undervalued and overlooked. That is what makes the commitment by the governments of Colombia, DR Congo, Ecuador, Gabon, Mexico and Zambia so commendable. While countries have pledged to restore one billion hectares of land, the Freshwater Challenge is a critical first step in bringing a much-needed focus on freshwater ecosystems.”
Stuart Orr, Freshwater Lead at WWF International said, “The clearest sign of the damage we have done – and are still doing – to our rivers, lakes and wetlands is the staggering 83% collapse in freshwater species populations since 1970. The Freshwater Challenge puts the right goals and frameworks in place to turn this around – benefiting not only nature but also people across the world. We need governments and partners to commit to this urgently as part of the Water Action Agenda coming out of this UN conference.”
The Freshwater Challenge will focus on providing the evidence needed at country level to effectively design and implement restoration measures, identify priority areas for restoration, update relevant national strategies and plans, and mobilise resources and set up financial mechanisms to implement the targets.
Championed by the coalition of countries, the Freshwater Challenge is supported by the UN Decade on Ecosystem Restoration, the Secretariat of the Convention on Wetlands, WWF, IUCN, The Nature Conservancy, Wetlands International and ABinBev.
Clouds in the sky provide new clues to predicting climate change
While barely being given a second thought by most people, the masses of condensed water vapour floating in the atmosphere play a big role in global warming.
By MICHAEL ALLEN
Predicting how much Earth’s climate will warm is vital to helping humankind prepare for the future. That in turn requires tackling a prime source of uncertainty in forecasting global warming: clouds.
Some clouds contribute to cooling by reflecting part of the Sun’s energy back into space. Others contribute to warming by acting like a blanket and trapping some of the energy of Earth’s surface, amplifying the greenhouse effect.
‘Clouds interact very strongly with climate,’ said Dr Sandrine Bony, a climatologist and director of research at the French National Centre for Scientific Research (CNRS) in Paris.
They influence the structure of the atmosphere, impacting everything from temperature and humidity to atmospheric circulations.
And in turn the climate influences where and what types of clouds form, according to Bony, a lead author of the Nobel Peace Prize-winning assessment report in 2007 by the United Nations Intergovernmental Panel on Climate Change.
So many processes and feedback loops can affect climate change that it’s helpful to break down the issue into smaller parts.
‘Every time we manage to better understand one of the pieces, we decrease the uncertainty of the whole problem,’ said Bony, who coordinated the EU-funded EUREC4A project that ended last year.
A number of years ago, Bony and her colleagues discovered that small, fluffy clouds common in trade wind regions cause some of the largest levels of uncertainty in climate models. These clouds are known as trade cumulus.
While trade cumulus clouds are small and relatively unspectacular, they are numerous and very widely found in the tropics, according to Bony. Because there are so many of these clouds, what happens to them potentially has a huge impact on climate.
EUREC4A used drones, aircraft and satellites to observe trade cumulus clouds and their interactions with the atmosphere over the western Atlantic Ocean, near Barbados.
Many models assume that the structure and number of these clouds will change significantly as the global temperature warms, leading to possible feedback loops that amplify or dampen climate change. The models that project a strong reduction in such clouds as temperatures rise tend to predict a higher degree of global warming.
But Bony and her colleagues discovered that trade cumulus clouds change much less than expected as the atmosphere warms.
‘In a way, it is good news because a process that we thought could be responsible for a large amplification of global warming does not seem to exist,’ she said. More importantly, it means that climatologists can now use models that more accurately represent the behaviour of these clouds when predicting the effect of climate change.
Reducing this element of uncertainty in forecasts of the global extent of warming will make predictions of local impacts such as heatwaves in Europe more precise, according to Bony.
‘The increase in the frequency of heatwaves very much depends on the magnitude of global warming,’ she said. ‘And the magnitude of global warming depends very much on the response of clouds.’
Water and ice
Meanwhile, Professor Trude Storelvmo, an atmospheric scientist at the University of Oslo in Norway, has been exploring the processes inside a different type of cloud – mixed-phased clouds – to help improve climate models.
She is fascinated by how processes in clouds that occur on a tiny, micrometre scale can have such a big influence on global-scale atmospheric and climate processes.
Mixed-phase clouds contain both liquid water and ice and are responsible for the majority of rainfall across the globe. In recent years, it has become clear that they also play an important role in climate change.
Storelvmo coordinated the EU-funded MC2 project, which ran for five years until last month and unearthed new details about how mixed-phase clouds react to higher temperatures. The results highlight the urgency of transitioning to a low-carbon society.
The more liquid water that mixed-phased clouds contain, the more reflective they are. And by reflecting more radiation from the sun away from the Earth, they cool the atmosphere.
‘As the atmosphere warms, these clouds tend to shift away from ice and towards liquid,’ said Storelvmo. ‘What happens then is the clouds also become more reflective and they have a stronger cooling effect.’
But some years ago, Storelvmo and colleagues discovered that most global climate models overestimate this effect. MC2 flew balloons into mixed-phase clouds and used remote sensing data from satellites to probe their structure and composition.
The researchers discovered that current climate models tend to make the mix of water and ice in mixed-phase clouds more uniform and less complex than in real clouds, leading to overestimations of the amount of ice in the clouds.
Because these model clouds have more ice to lose, when simulations warm them the shift in reflectiveness is greater than in real clouds, according to Storelvmo. This means the models overestimate the dampening effect that mixed-phase clouds have on climate change.
When the team plugged the more realistic cloud data into climate models and subjected it to simulated warming, they made another important finding: the increase in the reflectiveness of mixed-phased clouds weakens with warming.
While with moderate warming the dampening effect on higher temperatures is quite strong, this is no longer the case as warming intensifies.
There comes a point when the ice in the cloud has all melted and the cooling effect weakens – and then completely vanishes. Exactly when this starts to happen is a question for future research.
But, according to Storelvmo, this reinforces the need for urgent reductions in greenhouse-gas emissions.
‘Our findings suggest that if we just let greenhouse-gas emissions continue, it won’t just be a linear and gradual warming – there could be a rapidly accelerating warming when you get to a certain point,’ she said. ‘We really need to avoid reaching that point at all costs.’
As new findings on clouds such as these are integrated into models, climate predictions used by policymakers will become more refined.
Research in this article was funded via the EU’s European Research Council (ERC). The article was originally published in Horizon, the EU Research and Innovation Magazine.
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