Wildfire smoke in the northeast Pacific Ocean, September 2020.
| Photo Credit: NASA

Satyakam Arya, (2nd left) Managing Director and CEO of Daimler India Commercial Vehicles (DICV) presenting 31st edition of Dr. M.S. Swaminathan Environmental Protection 2025 award to N. Devakumar Sahala Samrudha from Mysuru and Veerappan from Cuddalore along RTN Dr. Soumya Swaminathan, Chairperson, MSSRF, C.K. Ranganathan, Founder of CavinKare group and RTN Balaji Sreenivasan, President Rotary Club of Madras East during the M.S. Swaminathan 100th year celebration in Chennai on Sunday.
| Photo Credit: B. JOTHI RAMALINGAM

Seven years before wildfires tore through opposite ends of the Los Angeles area, the Tubbs Fire in Northern California’s Sonoma County jumped a six-lane freeway and decimated Santa Rosa’s Coffey Park subdivision, a suburban enclave similar to Pacific Palisades and Altadena.

The fire destroyed about 5,000 homes in Santa Rosa and the surrounding area in October 2017, with about 1,500 of those in Coffey Park, making it California’s costliest wildfire disaster at the time. Within three years, 80% of Coffey Park’s destroyed homes were fully rebuilt and occupied, according to local officials.

The journey was long, uncertain and filled with detours, according to interviews with Coffey Park residents who rebuilt and local government officials. Debris removal was a lengthy, cumbersome process; there was contractor fraud, leading to criminal convictions; the minutiae of government approvals at every step caused frustration.

But the experiences of those who rebuilt in Coffey Park and Santa Rosa also showed the power of collective action by residents, and local government success streamlining construction, which offer a template for the Los Angeles-area communities of Pacific Palisades and Altadena, where more than 16,000 homes and other structures were destroyed by this month’s fires that also killed 28 people.

“Band together and have a group that you go through it with,” said Jeff Okrepkie, who started a nonprofit rebuilding group for Coffey Park, finished his rebuild in early 2020 and later became a Santa Rosa city council member. “It’s always easier to get your questions answered when you’re asking for 100 people, or 500 people.”

‘Not much you can do’

David Kovalevski wants to rebuild his century-old Altadena craftsman house that burned in the Eaton Fire northeast of Los Angeles, but the task looks daunting. “When can we even start?” he said. “It looks like a war zone.”

He is trying to understand what insurance will pay, and how that will compare to new, higher prices as thousands of homeowners in his area try to rebuild at the same time. “How will they even manage in a reasonable timeframe to rebuild so many houses at the same time?” Damian Clopton had many of the same questions in the weeks after he fled his burning Coffey Park home in October 2017 with his wife, Ashley Osbun, four cats and a laptop.

He remembered the “shell shock,” waking up each morning in an unfamiliar house, only to realize a few seconds later his predicament. “Everything just sucks in the beginning,” Clopton said. “You really want to move on and there’s not much you can do.”

That was because, like in Pacific Palisades and Altadena, residents were largely kept out as emergency crews sent cadaver dogs to search for missing people and Hazmat crews removed toxic waste.

Then came debris removal, which started about a month after the fire and took two-and-a-half months to complete. In Sonoma County in 2017, residents could choose a FEMA-contracted debris removal program or hire a private contractor, which was more expensive and required certifications for disposing of hazardous material.

“People think they’re just going to be able to get a dump truck and a backhoe, build their house and move on,” said Steve Rahmn, a Coffey Park resident who completed his rebuild in 2020. “Government’s got its due process.”

The Santa Rosa FEMA program offered the easiest path but suffered from bureaucratic bungles, such as FEMA’s policy of paying contractors based on the weight of debris they carried off site. Crews eager for maximum weight left sunken lots, and the state ultimately had to create a new program to replace homeowners’ missing dirt.

California Governor Gavin Newsom’s Office of Emergency Services this month announced similar debris removal options for private properties in the wake of the Palisades and Eaton fires. First, Environmental Protection Agency crews must remove hazardous waste, including electric-vehicle batteries, which began earlier this month. Los Angeles County Public Works Director Mark Pestrella has said debris removal could take six months to a year.

U.S. Congressman Mike Thompson, whose district includes Santa Rosa, said he has developed what he calls a “disaster booklet” to impart lessons to representatives from areas affected by wildfires. “There’s no need to reinvent the wheel,” he said, citing pre-approval of building plans as a model for faster reconstruction.

After crews finished debris removal in Santa Rosa, the neighborhood was a blank canvas, meaning residents had to get property lines surveyed again. Potentially every homeowner had to hire a surveyor in order to start drawing up plans for new homes.

That’s where the collective action began. Though scattered around the area and the country, residents kept in touch on social media, social meetings like “Wine Wednesdays” and an area newsletter. Many started meeting in the first few weeks at a local junior college and a performing arts center, said Okrepkie, and the numbers built as the weeks went by.

City planning officials attended the meetings and started making policies directly resulting from those discussions, said Gabe Osburn, Santa Rosa’s director of planning and economic development.

After hearing surveying concerns, city officials helped connect residents with local surveyors to speed up the process, Osburn said.

Discussions from those meetings also led to the city creating a “resilient” zone for fire-damaged areas, with reduced planning and design requirements.

“Anything that would be an impediment from a time standpoint, or a cost standpoint, we analyzed,” Osburn said.

In the wake of the Los Angeles-area fires, Newsom suspended certain state environmental reviews in the fire-affected areas, and Los Angeles Mayor Karen Bass signed an order creating a new permitting center to be staffed seven days a week in the fire-affected areas.

In Santa Rosa, local builders also sped up the recovery process by drawing up a handful of home designs that were pre-approved by local officials. This allowed many residents to choose from a menu of options and quickly build a house. Some homeowners, like Carol McHale, were not so lucky. She and her partner lost more than $100,000 of their personal savings after a builder asked for money upfront but never completed their rebuild. He was among several contractors who were convicted of fraud in the years after the fire.

McHale started over with another contractor, having to revisit every excruciating decision: Vinyl or hardwood floors, quartz or granite for kitchen counters, what paint color inside?

“We were making $10,000 decisions every day,” McHale said. “Even years later, it makes my stomach hurt.” But out of that painful experience, she also found hope: She and her partner, Erin Murphy, re-committed to their relationship, and will soon celebrate their 25th anniversary.

“People say ‘I don’t know how you did it,'” she said. “You do one day; you do the next one.”

‘I can control this’

The rebuilding process was often an emotional roller coaster, residents said.

Clopton chose to be his own general contractor, making substantial changes to the original design. He still hasn’t fully finished.

“Yes, they’ve gone out of their way to get rid of regulations, at the same time that they pile on other regulations,” he said. “This is a slog.”

Okrepkie said that after debris removal was complete, heavy rains in early 2018 delayed all construction, just as he was hoping to break ground. Work progressed, though, and by late 2019 the drywall was complete on his new home.

“All of a sudden you’re like, ‘This is the exact dimension of the living room I’m going to watch the Super Bowl in,” he recalled. “You see all the bedrooms upstairs and you say ‘I wonder which one my son is going to want?'”

For him, there was a satisfaction that came with rebuilding in the wake of a fire, a sense that he once again had control.

“I couldn’t control losing my house, or moving away, but I can control this,” he said. “I can control what my countertops look like. I think there’s a healthy aspect to that.”

Environmental researchers extract genetic material from a Chilean frog’s leg (Calyptocephalella gayi) in a wetland in the middle of a neighbourhood in the city of Quilpue, Chile, December 8, 2024.
| Photo Credit: Reuters

A giant frog species that hopped alongside dinosaurs and is considered a “living fossil” is now losing ground in its native Chile as climate change and human intervention damage its habitat.

The Calyptocephallela gayi, or Helmeted Water Toad, is one of the largest frogs in the world, growing up to over 30 cm (1 foot) in length and weighing up to 1 kg (2.2 lbs).

The amphibian has seen little genetic variation for millions of years, but now its future is at risk, scientists say.

“It’s sad that a species that managed to coexist with dinosaurs, that managed to resist a mass extinction, is now threatened by human beings,” said Melissa Cancino, a vetinarian and founder of Proyecto Anfibia, a group dedicated to amphibian research and education in Chile.

The Helmeted Water Toad’s environment spans from the northern region of Coquimbo to the southern island of Chiloe, but its population is suspected to have declined by at least 30% since 1990 and it is listed as “vulnerable” on the International Union for Conservation of Nature’s (IUCN) Red List.

Factors such as climate change, habitat interruption, environmental decline and pollution have all caused the Helmeted Water Toad’s numbers to dwindle, Cancino said. Poor water and waste management have also threatened the frog’s environment.

Matias Faundez, another member of Proyecto Anfibia, has seen the habitat degradation first hand.

“This estuary runs through the whole city, and has plenty of illegal run-offs,” he said as he waded through a stream outside of Valparaiso. “Even so, the frog manages to survive.”

A new machine-learning weather prediction model called GenCast can outperform the best traditional forecasting systems in at least some situations, according to a new paper.
| Photo Credit: NASA/GSFC, MODIS Rapid Response Team, Jacques Descloitres

A new machine-learning weather prediction model called GenCast can outperform the best traditional forecasting systems in at least some situations, according to a paper by Google DeepMind researchers published today in Nature.

Using a diffusion model approach similar to artificial intelligence (AI) image generators, the system generates multiple forecasts to capture the complex behaviour of the atmosphere. It does so with a fraction of the time and computing resources required for traditional approaches.

How weather forecasts work

The weather predictions we use in practice are produced by running multiple numerical simulations of the atmosphere.

Each simulation starts from a slightly different estimate of the current weather. This is because we don’t know exactly what the weather is at this instant everywhere in the world. To know that, we would need sensor measurements everywhere.

These numerical simulations use a model of the world’s atmosphere divided into a grid of three-dimensional blocks. By solving equations describing the fundamental physical laws of nature, the simulations predict what will happen in the atmosphere.

Known as general circulation models, these simulations need a lot of computing power. They are usually run at high-performance supercomputing facilities.

Machine-learning the weather

The past few years have seen an explosion in efforts to produce weather prediction models using machine learning. Typically, these approaches don’t incorporate our knowledge of the laws of nature the way general circulation models do.

Most of these models use some form of neural network to learn patterns in historical data and produce a single future forecast. However, this approach produces predictions that lose detail as they progress into the future, gradually becoming “smoother”. This smoothness is not what we see in real weather systems.

Researchers at Google’s DeepMind AI research lab have just published a paper in Nature describing their latest machine-learning model, GenCast.

GenCast mitigates this smoothing effect by generating an ensemble of multiple forecasts. Each individual forecast is less smooth, and better resembles the complexity observed in nature.

The best estimate of the actual future then comes from averaging the different forecasts. The size of the differences between the individual forecasts indicates how much uncertainty there is.

According to the GenCast paper, this probabilistic approach creates more accurate forecasts than the best numerical weather prediction system in the world – the one at the European Centre for Medium-Range Weather Forecasts.

Generative AI – for weather

GenCast is trained on what is called reanalysis data from the years 1979 to 2018. This data is produced by the kind of general circulation models we talked about earlier, which are additionally corrected to resemble actual historical weather observations to produce a more consistent picture of the world’s weather.

The GenCast model makes predictions of several variables such as temperature, pressure, humidity and wind speed at the surface and at 13 different heights, on a grid that divides the world up into 0.25-degree regions of latitude and longitude.

GenCast is what is called a “diffusion model”, similar to AI image generators. However, instead of taking text and producing an image, it takes the current state of the atmosphere and produces an estimate of what it will be like in 12 hours.

This works by first setting the values of the atmospheric variables 12 hours into the future as random noise. GenCast then uses a neural network to find structures in the noise that are compatible with the current and previous weather variables. An ensemble of multiple forecasts can be generated by starting with different random noise.

Forecasts are run out to 15 days, taking 8 minutes on a single processor called a tensor processor unit (TPU). This is significantly faster than a general circulation model. The training of the model took five days using 32 TPUs.

Machine-learning forecasts could become more widespread in the coming years as they become more efficient and reliable.

However, classical numerical weather prediction and reanalysed data will still be required. Not only are they needed to provide the initial conditions for the machine learning weather forecasts, they also produce the input data to continually fine-tune the machine learning models.

What about the climate?

Current machine learning weather forecasting systems are not appropriate for climate projections, for three reasons.

Firstly, to make weather predictions weeks into the future, you can assume that the ocean, land and sea ice won’t change. This is not the case for climate predictions over multiple decades.

Secondly, weather prediction is highly dependent on the details of the current weather. However, climate projections are concerned with the statistics of the climate decades into the future, for which today’s weather is irrelevant. Future carbon emissions are the greater determinant of the future state of the climate.

Thirdly, weather prediction is a “big data” problem. There are vast amounts of relevant observational data, which is what you need to train a complex machine learning model.

Climate projection is a “small data” problem, with relatively little available data. This is because the relevant physical phenomena (such as sea levels or climate drivers such as the El Niño–Southern Oscillation) evolve much more slowly than the weather.

There are ways to address these problems. One approach is to use our knowledge of physics to simplify our models, meaning they require less data for machine learning.

Another approach is to use physics-informed neural networks to try to fit the data and also satisfy the laws of nature. A third is to use physics to set “ground rules” for a system, then use machine learning to determine the specific model parameters.

Machine learning has a role to play in the future of both weather forecasting and climate projections. However, fundamental physics – fluid mechanics and thermodynamics – will continue to play a crucial role.

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

Pacific Island nation leaders pose for a group photograph with U.S. President Joe Biden during a summit at the White House in Washington, U.S., September 25, 2023.
| Photo Credit: Reuters

Pacific island nations at the centre of a strategic rivalry between the U.S. and China that brought infrastructure and funding hope President-elect Donald Trump stays engaged in the region but are wary of competition spilling into confrontation, diplomats say.

A 2023 defence deal giving the U.S. military access to ports and airfields across Papua New Guinea came with a pledge of $3.5 billion in infrastructure, equipment and training, according to PNG Foreign Minister Justin Tkatchenko, publicly disclosing an investment figure for the U.S. defence deal for the first time.

Papua New Guinea will continue to trade with China, even as U.S. military ties increase, he also told a resources conference in Sydney this week, highlighting a key worry among Pacific leaders about Trump’s tougher approach towards Beijing.

“The main concern is the Pacific doesn’t want to be forced into a position where it has to choose,” Meg Taylor, the secretary-general of the Pacific Islands Forum regional bloc during the first Trump Administration, told Reuters.

Washington was in “acute strategic competition” with China in the Pacific Ocean, where Beijing hopes to establish a military base, U.S. Deputy Secretary of State Kurt Campbell said last month.

He urged the incoming Trump Administration to not withdraw from the region, where Biden has opened embassies and increased coast guard patrols and aid.

While the U.S. has long held close defence ties with northern Pacific islands near its military base on Guam, Biden had sought to catch up to China’s influence-building in the South Pacific.

U.S. Secretary of Defence Lloyd Austin visited Fiji last month, opening negotiations for a military agreement. The defence deal with PNG, the most populous Pacific Island country, was signed last year in response to a Chinese security pact with Solomon Islands.

‘Wait and see’

It was “wait and see” on Trump, PNG’s Tkatchenko said on Monday, while noting that work on the defence agreement had already started with runways, wharfs and fuel storage facilities under construction.

“That agreement is over $3.5 billion in investment in infrastructure development, training, equipment for the benefit of security in our region,” he said.

A U.S. State Department spokesman said the agreement “aims to address shared defense and security challenges in Papua New Guinea”, and “does not have a dollar amount associated with it”.

Trump’s pick for Secretary of State, Marco Rubio, is a China hawk who previously pressed the need to block Beijing from building the subsea cables that connect Pacific Islands, and is likely to maintain a focus on the region, Pacific analysts and diplomats said.

“During his past presidency Trump demonstrated he understood the strategic importance of the Pacific, given its close proximity to the U.S., shared ocean borders, and critical military and telecommunication assets in the North Pacific,” said Meg Keen, senior fellow for the Lowy Institute’s Pacific Islands Program.

U.S. diplomacy with island states on the front line of sea level rise could be complicated by Trump’s threats to withdraw from the Paris Agreement climate pact, however.

“The climate issues are the most important issues for the region, that is the fundamental security issue for the Pacific and we know that President Trump doesn’t believe in climate change,” said Taylor, the former regional bloc leader.

Other diplomats said U.S. funding for climate adaptation projects vital to small Pacific states was likely to continue, even if rebadged.

Pacific leaders balancing ties with Beijing and Washington were also bracing for Rubio’s tough talk on China.

“More confrontation in the Pacific will not be welcome and could work against the U.S.,” said Keen.

“A Trump administration might take a harder line, but the art of the deal is not to alienate leaders important to regional security.”

Monarch butterflies gather on a shrub at Piedra Herrada sanctuary in the mountains near Valle de Bravo, Mexico, Wednesday, January 4, 2023.
| Photo Credit: AP

The U.S. Fish and Wildlife Service proposed listing the monarch butterfly as a threatened species on Tuesday (December 10, 2024), citing a significant decline in the iconic black and orange insects that has pushed them toward extinction.

Why it’s important

Monarch butterflies, known for migrating thousands of miles (km) across North America, have experienced a decades-long U.S. population decline due to habitat loss caused by human activities such as farming and urban development, widespread use of pesticides and climate change.

Environmental groups have been pushing for U.S. protection of the winged pollinators for a decade.

Key quote

“The iconic monarch butterfly is cherished across North America, captivating children and adults throughout its fascinating lifecycle,” U.S. FWS Director Martha Williams said in a statement.

“Despite its fragility, it is remarkably resilient, like many things in nature when we just give them a chance. Science shows that the monarch needs that chance, and this proposed listing invites and builds on unprecedented public participation in shaping monarch conservation efforts,” she added

Context

Despite being recognized as needing federal protection under the Endangered Species Act four years ago, the monarch butterfly waited behind dozens of other species facing more immediate threats.

The ESA, signed into law in 1973, is credited with helping to save the bald eagle, California condor and numerous other animals and plants from extinction. ESA protection makes it illegal to kill or harm species classified as threatened or endangered without a special permit.

By the numbers

The eastern migratory monarch population has declined by about 80% since the 1980s, while the western migratory population has dropped by more than 95%. The declines put the western populations at greater than 99% chance of extinction by 2080, according to the FWS.

The agency is proposing to designate 4,395 acres (1,780 hectares) in California as “critical habitat” for the butterflies. Federal agencies are prohibited from destroying or modifying areas with that designation.

What’s next

The public will have until March 12, 2025 to comment on the proposal to list the monarch butterfly. The service will then evaluate the comments and any additional information on the species to determine whether to list the monarch butterfly.

The first of three KLM passenger planes heading to New York takes off from Schiphol airport in Amsterdam, Netherlands, Monday April 19, 2010.
| Photo Credit: AP

Amsterdam Schiphol airport’s total flight capacity will be lowered by 4% next year in an effort to cut noise pollution, the Dutch government said on Friday (December 6, 2024).

Traffic at Schiphol, one of Europe’s busiest hubs, will be limited to 478,000 flights per year from 2025, down from the current cap of 500,000 flights per year.

The government had said in September that it would likely lower the cap as it aimed to reduce disturbance for people living close to the airport by 20%.

Dutch airline KLM said the new cap was “incomprehensible” as it maintained that the use of quieter airplanes would be a better way to achieve noise reduction goals than cutting the number of flights.

“Reduction of flight movements is not an end in itself and is expected to be legally unsustainable. We await the advice of the European Commission,” the airline said.

The Dutch arm of airline group Air France KLM, the largest airline at Schiphol, on Thursday had urged the government to rethink its strategy, as it repeated its pledge to invest 7 billion euros in quieter planes in the coming years.

The government said the new flight cap was expected to reduce noise by 15%, while it would look for ways to reduce an additional 5% at a later stage.

An effort to limit flights to around 450,000 was taken off the table last year following pressure from the industry and after objections from the European Union, which said the government should first look at other options to cut noise.

A Dutch court in March ordered the government to do more to cut noise pollution at Schiphol, saying the interests of people disturbed by the airport had been ignored for years.

The Hague:

The United Nations’ top court next week begins hearings on the legal obligation of countries to fight climate change and the consequences for states of contributing to global warming, the outcome of which could influence litigation worldwide.

While the advisory opinions of the International Court of Justice’s (ICJ) are non-binding, they are legally and politically significant. Experts say the ICJ’s eventual opinion on climate change will likely be cited in climate change-driven lawsuits in courts from Europe to Latin America and beyond.

The hearings begin a week after developing nations denounced as woefully inadequate an agreement reached at the COP29 summit for countries to provide $300 billion in annual climate finance by 2035 to help poorer nations cope with climate change.

Ralph Regenvanu, Vanuatu’s special envoy for climate change and the environment, said it was imperative fossil fuels be phased out and more money provided to poorer nations bearing the brunt of climate change, such as his Pacific island nation.

“We’re not seeing that in the outcome of the COPs,” Regenvanu told Reuters.

“We are hoping (the ICJ) can provide a new avenue to break through the inertia we experience when trying to talk about climate justice,” he added.

Fiji’s Attorney General Graham Leung called the hearings an historic opportunity for small island developing states in their quest for climate change justice.

CLIMATE LITIGATION

Climate litigation is on the rise.

Earlier this year, Europe’s top human rights court ruled that the Swiss government had violated the rights of its citizens by failing to do enough to combat climate change. But it also rejected two other cases, pointing to the complexities of the growing wave of climate litigation.

Vanuatu, one of the small developing nations that pushed for an ICJ advisory opinion, says it disproportionately suffers the effects of climate change as a result of increasingly intense storms and rising sea levels.

Vanuatu will be the first of 98 countries and twelve international organisations to present arguments to the ICJ, also known as the World Court. It is the United Nations’ highest court for resolving international disputes between states and can be tasked by the U.N. General Assembly to give advisory opinions.

In 2023, the assembly asked it for a formal opinion on questions including the legal obligations of states to protect the climate system and whether large states that contribute to greenhouse gas emissions may be liable for damages, in particular to small island nations.

“As COP29 failed to provide a clear direction for climate justice and ambition, any developments from the ICJ will now only become more weighty,” said Lea Main-Klingst, a lawyer with ClientEarth.

Aside from small island states and numerous Western and developing countries, the court will also hear from the world’s top two emitters of greenhouse gases, the United States and China. Oil producer group OPEC will also give its views.

The hearings will start at 10 a.m. (0900 GMT) local time on Monday and run until Dec. 13. The court’s opinion will be delivered in 2025.
 

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Clouds are pictured over the residential buildings in Beirut’s southern suburbs, amid the ongoing hostilities between Hezbollah and Israeli forces, as seen from Baabda, Lebanon, November 11, 2024.
| Photo Credit: Reuters

Clouds form when water vapor – an invisible gas in the atmosphere – sticks to tiny floating particles, such as dust, and turns into liquid water droplets or ice crystals. In a newly published study, we show that microplastic particles can have the same effects, producing ice crystals at temperatures 5 to 10 degrees Celsius (9 to 18 degrees Fahrenheit) warmer than droplets without microplastics.

This suggests that microplastics in the air may affect weather and climate by producing clouds in conditions where they would not form otherwise.

We are atmospheric chemists who study how different types of particles form ice when they come into contact with liquid water. This process, which occurs constantly in the atmosphere, is called nucleation.

Clouds in the atmosphere can be made up of liquid water droplets, ice particles or a mixture of the two. In clouds in the mid- to upper atmosphere where temperatures are between 32 and minus 36 F (0 to minus 38 C), ice crystals normally form around mineral dust particles from dry soils or biological particles, such as pollen or bacteria.

Microplastics are less than 5 millimeters wide – about the size of a pencil eraser. Some are microscopic. Scientists have found them in Antarctic deep seas, the summit of Mount Everest and fresh Antarctic snow. Because these fragments are so small, they can be easily transported in the air.

Why it matters

Ice in clouds has important effects on weather and climate because most precipitation typically starts as ice particles.

Many cloud tops in nontropical zones around the world extend high enough into the atmosphere that cold air causes some of their moisture to freeze. Then, once ice forms, it draws water vapor from the liquid droplets around it, and the crystals grow heavy enough to fall. If ice doesn’t develop, clouds tend to evaporate rather than causing rain or snowfall.

While children learn in grade school that water freezes at 32 F (0 C), that’s not always true. Without something to nucleate onto, such as dust particles, water can be supercooled to temperatures as low as minus 36 F (minus 38 C) before it freezes.

For freezing to occur at warmer temperatures, some kind of material that won’t dissolve in water needs to be present in the droplet. This particle provides a surface where the first ice crystal can form. If microplastics are present, they could cause ice crystals to form, potentially increasing rain or snowfall.

Clouds also affect weather and climate in several ways. They reflect incoming sunlight away from Earth’s surface, which has a cooling effect, and absorb some radiation that is emitted from Earth’s surface, which has a warming effect.

The amount of sunlight reflected depends on how much liquid water vs. ice a cloud contains. If microplastics increase the presence of ice particles in clouds compared with liquid water droplets, this shifting ratio could change clouds’ effect on Earth’s energy balance.

How we did our work

To see whether microplastic fragments could serve as nuclei for water droplets, we used four of the most prevalent types of plastics in the atmosphere: low density polyethylene, polypropylene, polyvinyl chloride and polyethylene terephthalate. Each was tested both in a pristine state and after exposure to ultraviolet light, ozone and acids. All of these are present in the atmosphere and could affect the composition of the microplastics.

We suspended the microplastics in small water droplets and slowly cooled the droplets to observe when they froze. We also analyzed the plastic fragments’ surfaces to determine their molecular structure, since ice nucleation could depend on the microplastics’ surface chemistry.

For most of the plastics we studied, 50% of the droplets were frozen by the time they cooled to minus 8 F (minus 22 C). These results parallel those from another recent study by Canadian scientists, who also found that some types of microplastics nucleate ice at warmer temperatures than droplets without microplastics.

Exposure to ultraviolet radiation, ozone and acids tended to decrease ice nucleation activity on the particles. This suggests that ice nucleation is sensitive to small chemical changes on the surface of microplastic particles. However, these plastics still nucleated ice, so they could still affect the amount of ice in clouds.

What still isn’t known

To understand how microplastics affect weather and climate, we need to know their concentrations at the altitudes where clouds form. We also need to understand the concentration of microplastics compared with other particles that could nucleate ice, such as mineral dust and biological particles, to see whether microplastics are present at comparable levels. These measurements would allow us to model the impact of microplastics on cloud formation.

Plastic fragments come in many sizes and compositions. In future research, we plan to work with plastics that contain additives, such as plasticizers and colorants, as well as with smaller plastic particles.

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