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Science says plastic bag bans really do work

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When you outlaw or discourage the sale of plastic bags, fewer of them end up as litter on beaches.

That’s the intuitive finding of a paper published Thursday in the journal Science, which involved an analysis of policies to restrict plastic bag use across the United States. The study authors found that, in places with plastic bag bans or taxes, volunteers at shoreline cleanups collected 25 to 47 percent fewer plastic bags as a total fraction of items collected, compared to places with no plastic bag policies.

The study adds weight to less formal analyses of plastic bag bans conducted by advocacy organizations and could inform negotiations later this summer over the United Nations’ global plastics treaty. “These are large-scale, robust findings that show that these policies are effective in at least limiting plastic bags in the environment,” said Anna Papp, one of the study’s co-authors and an incoming environmental economics postdoc at MIT.

As litter, plastic bags entangle wildlife and kill more sea turtles, whales, dolphins, and porpoises than any other type of plastic. They also break down into microplastics that have been linked to metabolic disorder, neurotoxicity, and reproductive damage in humans; a study published on Wednesday found that communities living near high concentrations of marine microplastics had an increased risk of Type 2 diabetes, coronary artery disease, and stroke.

In response to these harms, cities and states across the country have passed laws that ban plastic bags from certain retail locations, or impose a small fee on them — usually 5 to 10 cents. At least a dozen states have banned plastic bags, including Delaware, New Jersey, and Vermont. Jurisdictions with plastic bag fees include Alexandria, Virginia; Duluth, Minnesota; and Howard County, Maryland.

Papp and her co-author — Kimberly Oremus, a marine sciences professor at Delaware University — said they got the idea for their study after learning about beach, riverbank, and lakeshore cleanups organized by the nonprofit Ocean Conservancy. These volunteer cleanups go all the way back to 1986, and reports from each year document the number and type of plastic items collected across jurisdictions. In more recent years, participants have logged their item counts and types in a mobile phone app.

That standardized data could help fill an important research gap, Oremus said, on the connection between plastic bag restrictions and shoreline pollution. Prior scientific analyses had tended to focus on consumer behavior — for example, by counting the number of shoppers who emerge from a supermarket with plastic versus reusable bags. Some studies had focused on plastic bags clogging storm drains, since this can create a flooding hazard. “What we were missing was a direct measurement of the litter in the environment,” Oremus said.

A small number of analyses looking at this had come from nonprofits, including the Ocean Conservancy, and had not undergone peer review, she added.

Papp and Oremus combined eight years of Ocean Conservancy’s data — constituting more than 45,000 cleanups across the U.S. from between 2016 and 2023 — with information on roughly 180 plastic bag bans and fees implemented between 2017 and 2023. They analyzed plastic bag collection in ZIP codes with and without plastic bag restrictions, and took into account differences in the bag policies, including whether they banned all bags or only certain kinds.

According to the analysis, plastic bags’ share of collected items increased over the study period: They represented a larger and larger fraction of all the pieces of plastic that volunteers picked up. But this increase was much slower in places covered by a plastic bag restriction, where volunteers collected 25 to 47 percent fewer plastic bags as a fraction of their total haul. The study showed the highest impact from state-level policies compared to local ones, and found that decreases in the share of plastic bags grew over time after bag policies went into effect.

The study looked at bags as a fraction of plastic items collected rather than the total number of plastic bags because this helped make the measurements more comparable between jurisdictions. “This measure is not sensitive to the size and frequency of cleanups, fluctuations in overall litter, and other factors,” Papp said.

The study also suggested that taxes — like a 10-cent charge per plastic bag — cause a greater reduction in shoreline litter than outright bans, though the researchers said this finding was inconclusive. Not a lot of jurisdictions have fees, Oremus said, so the sample size is small. And there could be explanations that extend beyond the fee itself: Washington, D.C., for example, uses revenue from its plastic bag fee to fund river and shoreline cleanups that might reduce the number of bags found by Ocean Conservancy volunteers. Oremus said it’s also possible that fees have greater coverage than bans — the latter sometimes apply to grocery stores but not to restaurants, for example — or that supermarkets and restaurants are less likely to flout a fee than a ban.

What is clearer, according to Papp, is that “partial bans” aren’t as effective. These policies outlaw plastic bags below a certain thickness, on the basis that thicker bags can count as “reusable” or “recyclable” and are less likely to become litter. Papp and Oremus’ study showed that jurisdictions covered by partial bag bans had the “smallest and least precise” effect on reducing plastic bag litter, potentially because consumers treated the thicker bags just like they had the thin ones.

Other analyses have shown that California’s partial bag ban led to an increase in the weight of plastic bags used per person between 2014 and 2021. The state closed this loophole last year by banning plastic bags outright, and Oregon followed suit with its own bag ban earlier this month. Lawmakers in other states, however, oppose bag bans altogether — at least 17 states have passed “preemption” laws preventing their cities and counties from restricting the sale of plastic bags.

Susanne Brander, an ecotoxicologist and associate professor at Oregon State University, applauded the research, though she said it’s unfortunate that plastic bag bans have become so politicized that a scientific study is needed to back their effectiveness. “We knew they were working, but this gives hard data to support that,” she said.

Brander is also a member of the Scientists’ Coalition for an Effective Plastics Treaty, which is advocating for the international agreement — which will enter its sixth round of negotiations in August — to include legally binding limits on plastic production and the use of some types of plastic. One of the articles in the current draft of the treaty proposes restrictions on individual items like balloon sticks, plastic drink stirrers, and “plastic-stemmed cotton bud sticks.” Brander said the new study makes “a strong argument” in favor of broader bans.

“Rather than asking scientists to go and say you need to study Styrofoam containers separately, and study plastic takeaway containers separately, I think we should be able to apply these findings broadly to other bans of harmful products,” she said.

Martin Wagner, a biology professor at the Norwegian University of Science and Technology who is also a member of the Scientists’ Coalition for an Effective Plastics Treaty, agreed with Brander. He also said the study could be used by U.N. member states to craft their own plastic reduction policies: “These political measures are often discussed in the absence of data — they just say, ‘Let’s ban some items,’” he said. Having concrete evidence that policies can reduce pollution will be “really helpful.”

Celeste Meiffren-Swango, state director of the nonprofit Environment Oregon, said the study in Science reinforces the recommendations of a report she co-authored last year. That report, “Plastic Bag Bans Work,” estimated that five U.S. policies in New Jersey; Vermont; Philadelphia; Portland, Oregon; and Santa Barbara, California, had prevented the use of 6 billion bags per year. Presumably, many of those avoided bags would have become litter.

“There are proven environmental benefits to passing plastic bag laws,” she said. “It’s not just that we want people to change their shopping habits.”

This article originally appeared in Grist at https://grist.org/science/plastic-bag-ban-beach-cleanups-ocean-conservancy-study/.

Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org

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A jury in North Dakota ordered Greenpeace to pay more than $660 million in damages to Energy Transfer, the company behind the Dakota Access Pipeline. Energy Transfer sued Greenpeace in 2019, alleging that it had orchestrated a vast conspiracy against the company by organizing historic protests on the Standing Rock Sioux reservation in 2016 and 2017.

In its lawsuit, Energy Transfer Partners accused three Greenpeace entities — two in the U.S. and one based in Amsterdam — of violating North Dakota trespassing and defamation laws, and of coordinating protests aimed to stop the 1,172-mile pipeline from transporting oil from North Dakota’s Bakken oil fields to a terminal in Illinois. Greenpeace maintained it played only a minor supporting role in the Indigenous-led movement.

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“This was obviously a test case meant to scare others from exercising their First Amendment rights to free speech and peaceful protest,” said Deepa Padmanabha, a senior legal adviser for Greenpeace USA. “They’re trying to buy silence; that silence is not for sale.”

Legal and Indigenous experts said the lawsuit was a“textbook” example of a “strategic lawsuit against public participation,” known colloquially as a SLAPP suit, a tactic used by corporations and wealthy individuals to drown their critics in legal fees. They also criticized Energy Transfer for using the lawsuit to undermine tribes’ treaty rights by exaggerating the role of out-of-state agitators.

The three Greenpeace entities named in the lawsuit — Greenpeace Inc., a U.S.-based advocacy arm; Greenpeace Funds, which raises money and is also based in the U.S.; and Greenpeace International, based in the Netherlands — are now planning their next moves, including an appeal to the North Dakota Supreme Court and a separate countersuit in the European Union.

As part of a previous appeal to move the trial more impartial court, Greenpeace submitted a 33-page document to the state Supreme Court explaining that the jurors in Morton County, North Dakota — where the trial occurred — would likely be biased against the defendants, since they were drawn from the same area where the anti-pipeline protests had taken place and disrupted daily life.

The request included results from a 2022 survey of 150 potential jurors in Morton County conducted by the National Jury Project, a litigation consulting company, which found 97 percent of residents said they could not be a fair or impartial juror in the lawsuit. Greenpeace also pointed out that nine of the 20 final jurors had either “direct personal experience” with the protests, or a friend or family member with direct personal experience.

Pat Parenteau, an emeritus professor at the Vermont Law and Graduate School, said the chances that the North Dakota Supreme Court will overturn the lower court’s verdict are “probably less than 50 percent.” What may be more likely, he said, is that the Supreme Court will reduce the “outrageous” amount of money charged by the Morton County jury, which includes various penalties that doubled the $300 million in damages that Energy Transfer had originally claimed.

“The court does have a lot of discretion in reducing the amount of damages,” he said. He called the Morton County verdict “beyond punitive. This is scorched Earth, what we’re seeing here.”

Depending on what happens at the North Dakota Supreme Court, Parenteau also said there’s a basis for appealing the case to the U.S. Supreme Court, based on the First Amendment free speech issues involved. But, he added, the move could be “a really dangerous proposition,” with the court’s conservative supermajority and the precedent such a case could set. A federal decision in favor of Energy Transfer could limit any organizations’ ability to protest nationwide — and not just against pipelines.

Amsterdam-based Greenpeace International, which coordinates 24 independent Greenpeace chapters around the world but is legally separate from them, is also fighting back. It countersued Energy Partners in the Netherlands in February, making use of a new anti-SLAPP directive in the EU that went into effect in May 2024.

Greenpeace International is only on the hook for a tiny fraction of the more than $600 million charged against the three Greenpeace bodies by the Morton County jury. Its countersuit in the EU wouldn’t change what has happened in U.S. courts. Instead, it seeks to recover costs incurred by the Amsterdam-based branch during its years-long fights against the Morton County lawsuit and an earlier, federal case in 2017 that was eventually dismissed.

Greenpeace International’s trial will begin in Dutch courts in July and is the first test of the EU’s anti-SLAPP directive. According to Kristen Casper, general counsel for Greenpeace International, the branch in the EU has a strong case because the only action it took in support of the anti-pipeline protests was to sign an open letter — what she described as a clear case of protected public participation. Eric Heinze, a free speech expert and professor of law and humanities at Queen Mary University of London, said the case appeared “black and white.”

“Normally I don’t like to predict,” he said, “but if I had to put money on this I would bet for Greenpeace to win.”

While Greenpeace’s various entities may have to pay damages as ordered by U.S. courts, the result of the case in the EU, Casper said a victory would send an international message against “corporate bullying and weaponization of the law.” Padmanabha said that regardless of the damages that the Greenpeace USA incurs, the organization isn’t going away any time soon. “You can’t bankrupt the movement,” she said. “What we work on, our campaigns and our commitments — that is not going to change.”

In response to request for comment, Energy Transfer said the Morton County jury’s decision was a victory for the people of Mandan and “for all law-abiding Americans who understand the difference between the right to free speech and breaking the law. That Greenpeace has been held responsible is a win for all of us.”

Nick Estes, an assistant professor of American Indian studies at the University of Minnesota and member of the Lower Brule Sioux Tribe who wrote a book about the Dakota Access Pipeline protests, said the case was about more than just punishing Greenpeace — it was a proxy attack on the water protectors at Standing Rock and the broader environmental justice movement. He said it showed what could happen “if you step outside the path of what they consider as an acceptable form of protest.”

“They had to sidestep the actual context of the entire movement, around treaty rights, land rights, water rights, and tribal sovereignty because they couldn’t win that fight,” he said. “They had to go a circuitous route, and find a sympathetic court to attack the environmental movement.”

Janet Alkire, the chair of the Standing Rock Sioux Tribe, said in a March 3 statement that the Morton County case was “frivolously alleging defamation and seeking money damages, designed to shut down all voices supporting Standing Rock.” She said the company also used propaganda to discredit the tribe during and after the protests.

“Part of the attack on our tribe is to attack our allies,” Alkire wrote. “The Standing Rock Sioux Tribe will not be silenced.”

This story has been updated.

This article originally appeared in Grist at https://grist.org/indigenous/a-court-ordered-greenpeace-to-pay-a-pipeline-company-660m-what-happens-next/.

Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org

The Trump administration’s freeze on funding from the Inflation Reduction Act, the landmark climate law from the Biden era, has left farmers and rural businesses across the country on the hook for costly energy efficiency upgrades and renewable energy installations.

The grants are part of the Rural Energy for America Program, or REAP, originally created in the 2008 farm bill and supercharged by funding from the IRA. It provides farmers and other businesses in rural areas with relatively small grants and loans to help lower their energy bills by investing, say, in more energy-efficient farming equipment or installing small solar arrays.

By November 2024, the IRA had awarded more than $1 billion for nearly 7,000 REAP projects, which help rural businesses in low-income communities reduce the up-front costs of clean energy and save thousands on utility costs each year.

But now, that funding is in limbo. Under the current freeze, some farmers have already spent tens of thousands of dollars on projects and are waiting for the promised reimbursement. Others have had to delay work they were counting on to support their businesses, unsure when their funding will come through — or if it will.

REAP is administered by the U.S. Department of Agriculture. Secretary Brooke Rollins said the agency is “coming to the tail end of the review process” of evaluating grants awarded under the Biden administration.

“If our farmers and ranchers especially have already spent money under a commitment that was made, the goal is to make sure they are made whole,” Rollins told reporters in Atlanta last week.

But it’s not clear when the funds might be released, or whether all the farmers and business owners awaiting their money will receive it.

For Joshua Snedden, a REAP grant was the key to making his 10-acre farm in Monee, Illinois, more affordable and environmentally sustainable. But months after installing a pricey solar array, he’s still waiting on a reimbursement from the federal government — and the delay is threatening his bottom line.

“I’m holding out hope,” said Snedden, a first-generation farmer in northeast Illinois. “I’m trying to do everything within my power to make sure the funding is released.”

In December, his five-year old operation, Fox at the Fork, began sourcing its power from a new 18.48 kilowatt solar array which cost Snedden $86,364. The system currently offsets all the farm’s electricity use and then some.

REAP offers grants for up to half of a project like this, and loan guarantees for up to 75 percent of the cost. For Snedden, a $19,784 REAP reimbursement grant made this solar array possible. But the reimbursement, critical to Snedden’s cash flow, was frozen by Trump as part of a broader review of the USDA’s Biden-era commitments.

Joshua Snedden is a first-generation farmer who said he will continue whether or not he gets the federal funding for solar. Courtesy of Joshua Snedden

Snedden grows the produce he takes to market — everything from tomatoes to garlic to potatoes — on about an acre of his farm. He also plans to transform the rest of his land into a perennial crop system, which would include fruit trees like pears, plums, and apples planted alongside native flowers and grasses to support wildlife.

A solar array was always part of his plans, “but seemed like a pie in the sky” kind of project, he said, adding he thought it might take him a decade to afford such an investment.

The REAP program has been a lifeline for Illinois communities struggling with aging infrastructure and growing energy costs, according to Amanda Pankau with the Prairie Rivers Network, an organization advocating for environmental protection and climate change mitigation across Illinois.

“By lowering their electricity costs, rural small businesses and agricultural producers can put that money back into their business,” said Pankau.

That’s exactly what Snedden envisioned from his investment in the solar power system. The new solar array wouldn’t just make his farm more resilient to climate change, but also more financially viable, “because we could shift expenses from paying for energy to paying for more impactful inputs for the farm,” he said.

He anticipates that by switching to solar, Fox at the Fork will save close to $3,200 dollars a year on electric bills.

Now, Snedden is waiting for the USDA to hold up their end of the deal.

“The financial strain hurts,” said Snedden. “But I’m still planning to move forward growing crops and fighting for these funds.”

Jon and Brittany Klimstra are both scientists who are originally from western North Carolina. They returned to the area to start a farm and an orchard and are waiting for solar funds they were promised. Courtesy of Jon Klimstra

At the start of the year, Jon and Brittany Klimstra were nearly ready to install a solar array on their Polk County, North Carolina farm after being awarded a REAP grant in 2024.

As two former scientists who had moved back to western North Carolina 10 years ago to grow apples and be close to their families, it felt like a chance to both save money and live their values.

“We’ve certainly been interested in wanting to do something like this, whether it be for our personal home or for our farm buildings for a while,” said Jon. “It just was cost prohibitive up to this point without some type of funding.”

That funding came when they were awarded $12,590 from REAP for the installation. But, after the Trump administration’s funding freeze, the money never came.

“We were several site visits in, several engineering conversations. We’ve had electricians, the solar company,” said Brittany . “It’s been a very involved process.”

Since the grant is reimbursement-based, the Klimstras have already paid out-of-pocket for some costs related to the project. Plus, the farm had been banking on saving $1,300 in utilities expenses per year. In a given month, their electricity bill is $300-$400.

Apples from the orchard run by Jon and Brittany Klimstra. They were ready to install a solar array when the federal funding was frozen. Courtesy of Jon Klimstra

Across Appalachia, historically high energy costs have made the difference between survival and failure for many local businesses, said Heather Ransom, who works with Solar Holler, a solar company that serves parts of Virginia, West Virginia, Kentucky, and Ohio.

“We have seen incredible rate increases across the region in electricity over the past 10, even 20 years,” she said.

Through Solar Holler, REAP grants also passed into the hands of rural library systems and schools; the company installed 10,000 solar panels throughout the Wayne County, West Virginia school system. About $6 million worth of projects supported by Solar Holler are currently on hold.

In other parts of the region, community development financial institutions like the Mountain Association in eastern Kentucky combatted food deserts through helping local grocery stores apply for REAP.

Solar Holler also works in coal-producing parts of the region, where climate change discussions have been fraught with the realities of declining jobs and revenue from the coal industry. The program helped make the case for communities to veer away from coal and gas-fired energy.

“What REAP has helped us do is show people that it’s not just a decision that’s driven by environmental motives or whatever, it actually makes good business sense to go solar,” Ransom said. In her experience, saving money appeals to people of all political persuasions. “At the end of the day, we’ve installed just as much solar on red roofs as we do blue roofs, as we do rainbow roofs or whatever.”

Jim Lively has a local food market just minutes from the Sleeping Bear Dunes National Lakeshore in northern Michigan. He’s waiting for the federal money he was promised so he can put solar on the roof and offset the costs of opening up a campsite for RVs in this field. Izzy Ross / Grist

The Sleeping Bear Dunes National Lakeshore in northern Michigan draws over 1.5 million visitors every year. Jim Lively hopes some of those people will camp RVs at a nearby site he’s planning to open next to his family’s local food market. He wants to use solar panels to help power the campsite and offset electric bills for the market, where local farmers bring produce directly to the store.

Lively helped promote REAP during his time at an environmental nonprofit, where he’d worked for over two decades. So the program was on his mind when it came time to replace the market’s big, south-facing roof.

“We put on a metal roof, and worked with a contractor who was also familiar with the REAP program, and we said, ‘Let’s make sure we’re setting this up for solar,’” he said. “So it was kind of a no-brainer for us.”

They were told they had been approved for a REAP grant of $39,696 last summer — half of the project’s total cost — but didn’t feel the need to rush the solar installation. Then, at the end of January, Lively was notified that the funding had been paused.

The interior of the Lively NeighborFood Market, where owner Jim Lively likes to feature local produce. He was hoping to install a solar roof this year, but the funding has been stalled. Izzy Ross / Grist

The property runs on electricity, rather than natural gas, and Lively wants to keep it that way. But those electric bills have been expensive — about $2,000 a month last summer, he said. When they get the RV site up and running, he expects those bills to approach $3,000.

Selling local food means operating within tight margins. Lively said saving on energy would help, but they won’t be able to move ahead with the rooftop solar unless the REAP funding is guaranteed.

Continuing to power the property with electricity rather than fossil fuels is a kind of personal commitment for Lively. “Boy, solar is also the right thing to do,” he said. “And it’s going to be difficult to do that without that funding.”

The grants aren’t only for solar arrays and other renewable energy systems. Many are for energy efficiency improvements to help farmers save on utility bills, and in some cases cut emissions. In Georgia, for instance, one farm was awarded just under $233,000 for a more efficient grain dryer, an upgrade projected to save the farm more than $16,000 per year. Several farms were awarded funding to convert diesel-powered irrigation pumps to electric.

The USDA did not directly answer Grist’s emailed questions about the specific timeline for REAP funds, the amount of money under review, or the future of the program. Instead, an emailed statement criticized the Biden administration’s “misuse of hundreds of billions” of IRA and bipartisan infrastructure law (BIL) funds “all at the expense of the American taxpayer.”

“USDA has a solemn responsibility to be good stewards of the American people’s hard-earned taxpayer dollars and to ensure that every dollar spent goes to serve the people, not the bureaucracy. As part of this effort, Secretary Rollins is carefully reviewing this funding and will provide updates as soon as they are made available,” the email said.

Two federal judges have already ordered the Trump administration to release the impounded IRA and BIL funds. Earthjustice, a national environmental law organization, filed a lawsuit last week challenging the freeze of USDA funds on behalf of farmers and nonprofits.

“The administration is causing harm that can’t be fixed, and fairness requires that the funds continue to flow,” said Jill Tauber, vice president of litigation for climate and energy at Earthjustice.

Rollins released the first tranche of funding February 20 and announced the release of additional program funds earlier this month. That did not include the REAP funding.

The USDA announced Wednesday it would expedite funding for farmers under a different program in honor of National Agriculture Day, but as of March 20 had not made an announcement about REAP.

Rahul Bali of WABE contributed reporting to this story.

Rats are in many ways better adapted to cities than the humans that built them. While urbanites struggle with crowds, sparse parking spaces, and their upstairs neighbors stomping around at 4 a.m., rats are living their best lives. Huddled safely underground, they pop up at night to chew through heaps of food waste in dumpsters and hot dogs left on stoops.

Now scientists have found yet another gnawing advantage for rats. A study published on Friday in the journal Science Advances found that as temperatures climb in cities, rat populations are growing, even as city dwellers suffer. “In cities that have experienced the fastest warming temperatures, they tended to have faster increases in their rat numbers as well,” said Jonathan Richardson, an urban ecologist at the University of Richmond and lead author of the paper. “Females will reach sexual maturity faster. They’re able to breed more, and typically their litters are larger at warmer temperatures in the lab.

The analysis used public complaints about rats and inspection records from 16 cities between 2007 and 2024, which collectively served as a proxy for rat populations. In 11 of those cities, rat numbers surged during that period. The winner of the Most Rats Gained award goes to Washington, D.C., with a 390 percent increase according to the city’s last decade of data, followed by San Francisco (300 percent), Toronto (186 percent), and New York City (162 percent). Meanwhile, a few cities actually saw their rat populations decrease, including New Orleans, Tokyo, and Louisville, Kentucky, due in part to more diligent pest control.

“It’s a first step at answering this question, that if you get a bunch of rat scientists into a room we’re bound to ask each other: How might climate change play into rat populations?” said Kaylee Byers, a health researcher at Simon Fraser University in Canada, who wasn’t involved in the study.

Beyond the physiological factors that influence breeding, rat behavior changes with temperature, too. If it’s too cold out, the rodents tend to huddle underground — in basements, sewers, and really anywhere else in the subterranean built environment. Once it warms up, rats emerge and gorge, but also bring food back to their nests to store in caches. Climate change is also altering the timing of seasons: If the weather stays warmer a week or two longer into the early winter, and if spring comes a week or two earlier, that’s more time to forage. “Rats are really well-adapted to take advantage of a food resource and convert that to new baby rats that you’ll see in your neighborhood,” Richardson said.

While temperatures are rising globally, they’re getting particularly extreme in cities thanks to the urban heat island effect. Buildings and concrete absorb the sun’s energy, raising temperatures up to 27 degrees Fahrenheit higher than in surrounding rural areas and releasing that heat at night. That’s especially dangerous in the summer for urbanites during prolonged heat waves. But in the winter, that bit of extra heat could be helping rats.

Rising temperatures were the dominant force helping rat populations grow, but they weren’t the only factor, the study found. Urban human populations are exploding around the world, and they’re wasting a lot of food for rats to find. As cities expand around their edges, they have to add new infrastructure, which rats colonize. And when cities build new sewer systems to handle more people, they often leave the old ones in place, providing a welcoming environment for rats. “The vestigial urban infrastructure that’s down there, it doesn’t really matter for us,” Richardson said. “But for a rat, that’s like a free highway.”

The researchers also found that cities with fewer green spaces had higher growth of rat populations. It’s not clear yet why that might be, they said. No two green spaces are the same: A small urban park might teem with rats because office workers flock there to eat lunch, then drop their leftovers in trash bins, whereas the interior of a larger space like Central Park might provide less food and fewer places for rodents to hide from predators like hawks and coyotes.

So how can a city control its rat population as temperatures rise? For one, by getting more data like the numbers found in this study. “You can’t manage what you can’t measure,” said Niamh M. Quinn, who studies human-wildlife interactions at the University of California Division of Agriculture and Natural Resources but wasn’t involved in the research. “We live in an infinite sea of rats, so you can’t just manage small pockets. You have to have municipal rat management.”

New Orleans has succeeded by being proactive, Richardson said, such as with education campaigns teaching building owners how to rat-proof their structures, and insisting that if they do see rats to call the city for eradication. Cities can’t just poison their way out of this problem without hurting other animals, he said, because that poison makes its way into the stomachs of rat-eating predators.

“Right now, our approach to rat management is very reactive,” Byers said. “We’re not thinking about the future at all. We need to do that if we’re actually concerned about rats, and if we want to manage the risks associated with them.”

One of the biggest myths about renewable energy is that it isn’t reliable. Sure, the sun sets every night and winds calm down, putting solar panels and turbines to sleep. But when those renewables are humming, they’re providing the grid with electricity and charging banks of batteries, which then supply power at night.

A new study in the journal Renewable Energy that looked at California’s deployment of renewable power highlights just how reliable the future of energy might be. It found that last year, from late winter to early summer, renewables fulfilled 100 percent of the state’s electricity demand for up to 10 hours on 98 of 116 days, a record for California. Not only were there no blackouts during that time, thanks in part to backup battery power, but at their peak the renewables provided up to 162 percent of the grid’s needs — adding extra electricity California could export to neighboring states or use to fill batteries.

“This study really finds that we can keep the grid stable with more and more renewables,” said Mark Z. Jacobson, a civil and environmental engineer at Stanford University and lead author of the new paper. “Every major renewable — geothermal, hydro, wind, solar in particular, even offshore wind — is lower cost than fossil fuels” on average, globally.

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Yet Californians pay the second highest rates for electricity in the country. That’s not because of renewables, but in part because utilities’ electrical equipment has set off wildfires — like the Camp Fire started by Pacific Gas and Electric’s power lines, which devastated the town of Paradise and killed 85 people — and now they’re passing the costs that come from lawsuits and burying transmission lines to their customers. While investigators don’t know for sure what sparked all of the wildfires that have ravaged Los Angeles this month, they’ll be scrutinizing electrical equipment in the area. Power lines are especially prone to failing in high winds, like the 100-mile-per-hour gusts that turned these Southern California fires into monsters.

Even with the incessant challenge of wildfires, California utilities are rapidly shifting to clean energy, with about half of the state’s power generated by renewables like hydropower, wind, and solar. The study compared 116 days in 2024 to the same period in 2023 and discovered California’s output from solar was 31 percent higher and wind 8 percent. After increasing more than 30-fold between 2020 and 2023, the state’s battery capacity doubled between 2023 and 2024, and is now equivalent to the juice produced by more than four nuclear power plants. According to the study, all that new clean tech helped California’s power plants burn 40 percent less fossil fuel for electricty last year.

Those batteries help grid operators be more flexible in meeting demand for electricity, which tends to peak when people return home in the early evening and switch on appliances like air conditioners — just when the grid is losing solar power. “Now we’re seeing the batteries get charged up in the middle of the day, and then meet the portion of the demand in the evening, especially during those hot summer days,” said Mark Rothleder, chief operating officer of the California Independent System Operator, the nonprofit that runs the state’s grid.

Another pervasive myth about renewables is that they won’t be able to support a lot more electric vehicles, induction stoves, and heat pumps plugging into the grid. But here, too, California busts the myth: Between 2023 and 2024, demand on the state’s grid during the study period actually dropped by about 1 percent.

Why? In part because some customers installed their own solar panels, using that free solar energy instead of drawing power from the grid. In 2016, almost none of those customers had batteries to store that solar power to use at night. But battery adoption rose each of the following years, reaching 13 percent of buildings installing solar in 2023, then skyrocketing to 38 percent last year. (That is, of the 1,222 megawatts of solar capacity added last year, 464 megawatts included batteries.) That reduces demand on the grid because those customers can now use their solar power at night.

Batteries also help utilities get better returns on their investments in solar panels. A solar farm makes all its money selling electricity during the day. But if it has batteries attached to the farm, it can also provide energy in the evening, when electricity prices rise due to increased demand. “That evening battery contribution is very key to the economics working out well,” said Jan Kleissl, director of the Center for Energy Research at the University of California, San Diego, who wasn’t involved in the new paper.

So utilities are incentivized to invest in batteries, which also provide reliable backup power to avoid blackouts. But like any technology, batteries can fail. Last week, a battery storage plant caught fire on California’s central coast, the largest of its kind in the world, but it only knocked out 2 percent of the state’s energy storage capacity. A grid fully running on renewables will have a lot of redundancy built in, beyond multiple battery plants: Electric school buses and other EVs, for instance, are beginning to send power back to the grid when a utility needs it — a potentially vast network of backup energy.

But here’s where the economics get funky. The more renewables on the grid, the lower the electricity prices tend to be for customers, according to the new study. From October 1, 2023 to September 30, 2024, South Dakota, Montana, and Iowa provided 110 percent, 87 percent, and 79 percent, respectively, of their electricity demand with renewables, particularly wind and hydropower. Accordingly, the three have some of the lowest electricity prices in the country.

California, on the other hand, got 47 percent of its power from renewables over the same period, yet wildfires and other factors have translated into higher electricity prices. The California Public Utilities Commission, for instance, authorized its three largest utilities to collect $27 billion in wildfire prevention and insurance costs from ratepayers between 2019 and 2023.

Climate change is making California ever more prone to burn — a growing challenge for utilities. But the state’s banner year for solar and batteries just poked a whole lot of holes in the notion that renewables aren’t reliable.

Solar panels and wind turbines give the world bountiful energy — but come with a conundrum. When it’s sunny and windy out, in many places these renewables produce more electricity than is actually needed at the time. Then when the sun isn’t shining and wind isn’t blowing, those renewables provide little to no electricity when it’s sorely needed.

So for the grid of tomorrow to go 100 percent renewable, it needs to store a lot more energy. You’ve probably heard about giant lithium-ion batteries stockpiling that energy for later use. But when providing backup power, even a big battery bank will usually drain in four hours. The need for an alternative has the United States government, researchers, and startups scrambling to develop more “long-duration energy storage” that can provide a minimum of 10 hours of backup power — often by using reservoirs, caverns, and other parts of the landscape as batteries.

A new study from several universities and national labs in the United States and Canada shows that large-scale deployment of long-duration energy storage isn’t just feasible but essential for renewables to reach their full potential, and would even cut utility bills. It looked specifically at the Western Interconnection, a chunk of the grid that includes the western U.S. and Canada, plus a bit of northern Mexico. The study found that building more long-duration energy storage there would reduce electricity prices by more than 70 percent in times of high demand.

“It’s like an orchestra,” said Patricia Hidalgo-Gonzalez, director of the Renewable Energy and Advanced Mathematics Laboratory at the University of California, San Diego and coauthor of the paper published last month in the journal Nature Communications. “We need to think about all these factors, how they work. But bringing in more storage can only help in making this more cost-effective.”

The technologies already exist to hold renewable energy for at least half a day, with more on the way. One technique is known as pumped storage hydropower: When the grid is humming with renewable power, a facility pumps water uphill into a reservoir. Then, when solar or wind power drops off, the facility lets the water loose to flow back down into another reservoir, turning turbines that produce electricity. It’s exploiting energy from the wind and the sun, along with the power of gravity.

“Battery storage on its own — or what people call short-duration energy storage — is very important,” said Martin Staadecker, an energy systems researcher at the Massachusetts Institute of Technology and lead author of the new study. “But you can’t just rely on lithium-ion batteries, because it would be very expensive to have enough to actually provide power for an entire week.”

As of 2022, the U.S. had 43 pumped storage hydropower facilities with a combined generation capacity of 22 gigawatts. (For perspective, the U.S. has around 150 gigawatts of wind power and 140 gigawatts of solar.) According to the Department of Energy, the U.S. has the potential to double its capacity for that kind of energy storage. In 2021, the Biden administration launched its Long Duration Storage Shot, part of the Energy Earthshots initiative, aiming to reduce the costs of the technology by 90 percent in a decade. And last year, it announced $325 million for 15 long-duration energy storage projects, including one that stores heat energy in concrete and others to make newfangled batteries made of iron, water, and air.

The researchers looked at long-duration energy storage without considering the particular technique involved, asking what would be the cheapest way to get the Western Interconnection to be 100 percent emissions-free. Their study found that long-duration energy storage would be particularly beneficial to a utility’s customers, reducing electricity costs in times of high demand on the grid, like in the late afternoon as people return home and switch on appliances at the same time that solar power on the grid is waning. More storage also means more backup power for ever-hotter heat waves, when whole regions flick on their AC units.

Companies are figuring out how to store energy underground, too. A company called Hydrostor, based in Toronto, Canada, uses excess renewable energy on the grid to pump compressed air into subterranean caverns filled with water. That forces the water aboveground into a reservoir. When the grid needs electricity, Hydrostor lets that water flow back into the chamber, pushing the air back to the surface to drive turbines. “We’re kind of creating a piston underground of water,” said Jon Norman, president of Hydrostor. “We’re actually building a cavity out using techniques that they use in the hydrocarbon storage industry to store propane and butane.”

If a region runs low on renewable power, like when the sun sets, it would have to import carbon-free electricity from elsewhere. But that requires transmission lines that cut through hundreds or thousands of miles of land, which are difficult to get approved and expensive to build. The new study found that it would cost between $83 billion and $130 billion to deploy the amount of long-duration energy storage in the modeling — depending on how the price of the technology declines as it matures.

With long-duration energy storage, utilities can deploy more solar panels and wind turbines locally and store up their energy, rather than having to ship it from somewhere else. Kevin Schneider, an electrical engineer who studies the grid at the Pacific Northwest National Laboratory but wasn’t involved in the new research, said that could reduce the significant costs of building long-distance transmission lines. “Getting that flexibility in the system, where you can have a reservoir of electricity that you can store up and then release, that’s what allows us to not have to build as much infrastructure, and also be a little bit more resilient.”

The grid of tomorrow, then, may hum with renewable energy stored both in giant battery banks, but also stored in the landscape itself. Solar and wind power would be wasted no more.