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.

Puzzle pieces

‘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.

Good news

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.’

Rude awakening

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. 

Today the Ministry of Ecology and Natural Resources and the Ministry of National Economy of the Republic of Kazakhstan jointly with the World Bank and Kazakhstan Association “ECOJER” launched a series of policy dialogues to support Kazakhstan in implementing its critical climate and environmental strategies, including the transition to a low-carbon economy, air quality management, and resilience to climate change. The first of the workshop series held today focused on supporting Kazakhstan’s transition to carbon neutrality by 2060.

Kazakhstan made a bold leap forward on a newly charted course for the country’s development by adopting The Strategy on Achieving Carbon Neutrality by 2060. Approved by the President of the Republic of Kazakhstan on February 2, 2023, the strategy sets ambitious net-zero carbon goals for climate action and identifies key technological transformations needed for the country’s decarbonization. To achieve these transformations, the country will require determining and implementing effective and targeted policies and programs across the whole of the country’s economy.

“Our goal is to reduce our carbon footprint and use the benefits of sustainable economic growth, improved public health and reduced climate risks. Net investment in low-carbon technologies is estimated at $610 billion. This will certainly lead to the emergence of new and expanding existing markets and niches for domestic manufacturers, and stimulate the creation of high-skilled jobs,” said Alibek Kuantyrov, Minister of National Economy of the Republic of Kazakhstan.

Participants of the first policy dialogue discussed a roadmap for the implementation of the government policies, measures, and investments in support of the approved strategy. The event also provided a forum for the experts to share best practices and experience in low-carbon policy implementation in the Czech Republic, Germany, and Poland.

“The recently adopted strategy for Kazakhstan’s transition to carbon neutrality attests to the government’s resolve to pivot towards a growth model that is driven less by fossil fuels and more by investments in climate-smart industries  in water, agriculture, and rangelands management. This broad economic transformation will require an enabling environment centered on policies, investments, and ensuring a just transition for people and communities,” says Andrei Mikhnev, World Bank Country Manager for Kazakhstan.

To help Kazakhstan prioritize the most impactful actions that can reduce greenhouse gas emissions and boost climate change adaptation while delivering on broader development goals and carbon-neutral future, the World Bank recently published Kazakhstan Country Climate and Development Report. The report suggests main pathways to support Kazakhstan’s low-carbon, resilient transition.

“Reduction of greenhouse emissions is a non-alternative course for Kazakhstan and there is an obvious need for legislative instruments. Today, government agencies need to develop the implementation roadmap, and the industry needs to get clear messages – in which direction they will move in the coming decades and what kind of support from the government they can count on. Such dialogues needed to ensure a balance of interests of state bodies and institutions, to identify business opportunities, and get knowledge of the best world experience, so that we can achieve our goals and improve the environmental situation in the country,”said Lazzat Ramazanova, Chairman of the Council of the Kazakhstan Association “ECOJER”.

The policy dialogues series aims to provide a robust platform for multi-stakeholder and multi-sectoral engagement. By bringing together Kazakhstan’s government agencies, the private sector, civil society, academia, international development organizations, and the world’s leading experts, the dialogues aim to foster collaboration and action to accelerate the implementation of Kazakhstan’s carbon neutrality targets as well as low-emission development strategy, international climate action commitments, and adaptation measures. The focus of the series’ next policy dialogues scheduled in April and June 2023 will be on air pollution reduction and climate change adaptation in support of Kazakhstan’s climate and development goals.

The World Economic Forum’s Blue Food Partnership launched today a Global Sustainable Aquaculture Roadmap at the Our Ocean Conference in Panama, in collaboration with FUTUREFISH and the Aquaculture Stewardship Council and in consultation with the Partnership’s Sustainable Aquaculture Working Group, to strengthen sustainable growth in aquaculture.

Blue foods – from the ocean, rivers and lakes – are the most highly traded food products in the world and provide livelihoods for millions of people as well as healthy and nutritious food for billions. Many types of blue foods also have lower carbon footprints than terrestrial food production and are critical to ensuring climate resilience as well as global food and nutrition security. Demand for these foods is expected to double by 2050 and much of this demand will be met through aquaculture production.

The roadmap is an important guide for transformative action in aquaculture value chains and the sector overall.

Like all food systems, aquaculture presents both opportunities and challenges. Some current aquaculture practices have a negative impact on habitats and communities, and significant progress is needed to realize sustainable growth while also making a broad contribution on the 2030 UN Sustainable Development Goals. Increased production must be undertaken from a nature-positive perspective to preserve critical habitats and biodiversity.

“Meeting our increasing demand for healthy and nutritious food in more sustainable ways is a monumental challenge, yet great potential lies in the water,” said Kristian Teleki, Director, Ocean Action Agenda and Friends of Ocean Action, World Economic Forum. “Blue foods from our ocean, rivers and lakes are the most highly traded food products in the world and already provide livelihoods for many millions as well as healthy and nutritious food for billions. This roadmap will ensure we are on a sustainable and ethical pathway to producing more food for an increasingly hungry planet.”

Informed by a systems-change approach, the roadmap see aquaculture as being fundamentally connected to nature, climate, nutrition and equitable livelihoods. Based on this approach, it provides four pathways – responsible production, better livelihoods, healthy consumption, and an enabling environment – to accelerate action towards the greater social, economic and environmental benefits that the sustainable growth of aquaculture can offer.

“It is increasingly recognized that the aquaculture industry must play a more active, leading and collaborative role in addressing challenges in the aquaculture sector,” said Chris Ninnes, CEO, Aquaculture Stewardship Council and Co-Chair, Blue Food Partnership’s Sustainable Aquaculture Working Group. “Some progress has been made by the collective efforts of various committed industry associations but more needs to be done across the wide spectrum of aquaculture systems to make them as sustainable as possible for the long term.”

The Sustainable Aquaculture Working Group is a pre-competitive initiative of the Blue Food Partnership, supported by the UK government’s Blue Planet Fund. Bringing together stakeholders from the private sector, non-governmental and intergovernmental organizations, scientists and governments, the partnership aims to catalyse science-based actions towards healthy and sustainable blue food value chains.

The Blue Food Partnership will share key findings from the roadmap and spark discussion among representatives across geographies, sectors and production systems at an official side event at the Our Ocean Conference in Panama City on Friday 3 March.

“We invite all relevant stakeholders engaged in aquaculture to view this roadmap as a community resource to be shared and applied to their own efforts. From there, we can collectively build momentum towards the sustainable growth of aquaculture that is good for people, nature and climate,” Teleki said.