AAAS Science – How effective are plastic bag bans?

Introduction

Inside the Rubin Observatory’s Decade-Long Sky Survey

Sarah Crespi: This is the Science Podcast for June 19th, 2025. I’m Sarah Crespi.

First up, the Vera C. Rubin Observatory is powering up in Chile, and it’s about to change astronomy forever. Once operational, this behemoth will capture the entire southern sky in a snapshot every three nights. Staff writer Daniel Clery traveled to the remote mountaintop to see the largest camera ever built for astronomy, and he shared his experience with producer Meagan Cantwell.

Meagan Cantwell: This year, the Vera Rubin Observatory begins a monumental, ten-year survey of the universe. I spoke with our staff writer, Daniel Clery, about how this telescope is set to transform our field.

Daniel Clery: Traditional telescopes focus on small, detailed targets. Rubin is the opposite—it’s built for immense surveys. The idea is to use a huge telescope to gather a flood of light from distant, faint objects. It will take a 30-second exposure, move, and take another, all night long. We’re talking about discovering ten times more solar system objects than we currently know—asteroids, moons, distant planets—plus billions of new galaxies. It’s industrial-scale astronomy, generating a torrent of data that requires massive infrastructure.

I traveled from England to central Chile to see this operation firsthand. The drive up to the summit reveals glimpses of other telescopes, but nothing prepares you for Rubin itself—an enormous building perched on a mountain peak, chosen for its exceptionally clear and stable skies.

Alysha Shugart (Deputy Manager, Observing Specialists): This was a premium site because it was accessible, with existing roadways.

Meagan Cantwell: Alysha Shugart has been on-site since 2020, watching the observatory evolve from a construction project into a scientific hub.

Daniel Clery: This is such a different way of observing. You must be inventing the process as you go.

Alysha Shugart: Absolutely. We are very much building the ship as we’re sailing it.

The control room feels like a NASA mission, with a wall of displays monitoring temperatures and heat flows to protect the sensitive equipment. Right now, much is done manually, but the goal is to train AI systems to take over. We see the observing specialists like airline pilots; 90% of the night is smooth, but you need us there for that critical 10%.

Entering the dome is awe-inspiring. The telescope is short, squat, and utterly massive.

Daniel Clery: It’s so big and fat!

Alysha Shugart: And I love it!

[Laughter]

Daniel Clery: Watching it move was disorienting; it was so smooth and silent. This 350-ton machine floats on a thin film of oil. Eventually, it will slew across the sky four to five times faster. The goal is to move as quickly as possible and then take the highest quality image possible.

Its three-mirror, three-lens design is unique, correcting for distortions at the edge of the field of view. The primary mirror, 8.4 meters across, is actively supported by motors on its back to counteract gravity’s pull and maintain a perfect shape.

Then there’s the camera—the largest ever made for astronomy, the size of a small car. Its sensor array is a grid of 189 large CCDs, capturing a field of view equivalent to 40 full moons. Every image is a deep, wide snapshot of the southern sky.

Meagan Cantwell: Once an image is taken, the data races from Chile to California for processing. Artifacts are removed, and each new image is compared to one from three days prior to detect any change—a distant quasar, a nearby asteroid. This generates millions of alerts nightly.

Alert brokers, which are software systems, sift through these alerts to classify them. For urgent events, like the collision of two neutron stars, the system can automatically request follow-up from other telescopes. In 2017, it took 11 hours to locate such an event. With Rubin, we could find it almost instantly.

The sheer volume of discoveries will be a challenge. Many scientists worry there aren’t enough other telescopes to follow up on everything Rubin will find.

As the survey progresses, the images will sharpen, enabling new science. Our understanding of galaxy evolution is currently based on the biggest, brightest ones. Rubin will reveal vast populations of dwarf galaxies, which are irregular and lumpy, not just smaller versions of the large ones.

A primary mission is to investigate dark energy, the mysterious force accelerating the universe’s expansion. By measuring how light from galaxies is distorted by intervening matter, scientists can map dark matter and measure the universe’s accelerating expansion with unprecedented precision.

But a modern threat looms: low Earth orbit satellites. Their bright trails already mar 1% of Rubin’s images. By the end of the survey, this could render much of the data unusable. Scientists are working with satellite companies to mitigate this, but the clock is ticking.

Solar system discoveries will come quickly, within the first year. The subtle signals of dark energy, however, may require the entire decade-long survey. Rubin will touch almost every area of astronomy, and teams are preparing for the cinematic production of data that begins later this year.

Sarah Crespi: Next, we look at the real-world impact of plastic bag regulations. While 2-5% of all plastic waste ends up in the ocean, even that small percentage represents a massive, costly problem for ecosystems and tourism. A major focus has been regulating thin plastic grocery bags. This week in Science, environmental economist Anna Papp and colleagues used citizen science data to measure how these rules affect marine litter.

Sarah Crespi: Hi, Anna. Welcome.

Anna Papp: Thank you for having me.

Sarah Crespi: I’ve always connected bag bans to general waste, not specifically oceans. How do bags from a store in the middle of the U.S. end up in the ocean?

Anna Papp: Their light weight makes them easy to transport by wind and water. They can escape from trash or recycling trucks, enter small streams, and eventually flow into rivers, lakes, and oceans.

Sarah Crespi: Before your study, what did we know about the effectiveness of these regulations?

Anna Papp: Previous studies, often using store checkout data, showed mixed results—some reductions, but also substitutions to thicker plastic bags. These studies didn’t measure the direct impact on environmental litter, which is the primary goal of these policies. Even if checkout numbers don’t change, behavior might—people might reuse thicker bags more, or they might be less likely to blow away.

Sarah Crespi: Quantifying this chain of events is hard. How did you get data on bags actually littering shorelines?

Anna Papp: The key was data from the Ocean Conservancy’s Clean Swell app. It’s crowdsourced; during cleanups, volunteers record the items they collect in over 60 categories, including plastic bags. This made our study possible.

Sarah Crespi: This is brilliant data, but cleanups aren’t standardized. If there’s less litter, do volunteers collect less? How did you account for that?

Anna Papp: We did extensive checks to compare similar cleanups over time. We normalized for the number of attendees, checked the total items collected, and even looked at factors like whether children were present, as that might affect the cleanup’s nature.

Sarah Crespi: You also had to consider the type of regulation—outright bans versus fees. What did you find?

Anna Papp: We differentiated between complete bans, partial bans, and taxes. In the U.S., bans were more common earlier, so our results for them are more precise. Taxes also appear effective, perhaps even more so in magnitude, but with fewer examples, this is still suggestive.

Sarah Crespi: What was the scale of your analysis?

Anna Papp: We looked at over 600 policies, 182 of which overlapped with our cleanup data. We analyzed over 45,000 cleanups across the U.S. from 2017 to 2023.

Sarah Crespi: And the result?

Anna Papp: We found a significant reduction. There was a 25% to 47% decrease in the share of collected items that were plastic bags after these policies took effect. It’s a sizable effect, showing these policies limit—but don’t eliminate—plastic bag litter.

Sarah Crespi: Can these findings be applied globally?

Anna Papp: There are limitations. In other countries, plastic bags may make up a larger portion of litter, and consumer behavior differs. Also, this focuses on one part of the plastic life cycle. Truly addressing plastic pollution will require efforts from production to waste management.

Sarah Crespi: Anna, thank you for joining me.

Anna Papp: Thank you so much.

The Next Frontier in Cardiovascular Medicine

Sarah Crespi: Finally, a sponsored segment from the Science/AAAS Custom Publishing Office, brought to you by the Icahn School of Medicine at Mount Sinai. Custom Publishing Director Erika Berg speaks with Professors Deepak Bhatt and Filip Swirski about the future of heart health.

Erika Berg: Heart disease is the leading cause of death in the U.S., a deeply personal reality for millions. But research is paving the way for a brighter future. I’m joined by Dr. Deepak Bhatt, Director of the Mount Sinai Fuster Heart Hospital, and Dr. Filip Swirski, Director of the Cardiovascular Research Institute.

What are the biggest barriers to reducing cardiovascular disease, and what gives you hope?

Deepak Bhatt: First, it’s about implementing what we already know—managing risk factors like cholesterol and blood pressure. The second layer is discovery: finding new pathways and treatments. This two-pronged approach is key to longer, healthier lives.

Filip Swirski: I’d echo that. We’re also recognizing the immense complexity of the disease. It’s multifactorial, requiring diverse teams and technological innovation to untangle.

Erika Berg: Deepak, how is clinical trial design evolving?

Deepak Bhatt: We’re innovating in both the therapies we test and the trial designs themselves. Adaptive trials are a great example—allowing us to modify the trial based on interim results, enriching for subgroups that benefit. This makes trials faster, more efficient, and can be enhanced with machine learning.

Erika Berg: Philip, how has the immune system’s role changed our view of heart disease?

Filip Swirski: We’ve long known in the lab that inflammation and immunity are key players. The broader realization is that the body’s systems are deeply interconnected. Understanding cardiovascular health means investigating how it communicates with the immune system, the nervous system, and others.

Erika Berg: How is AI transforming cardiology?

Deepak Bhatt: I’m leading a trial called “Transform,” using AI on coronary CT scans to predict risk in asymptomatic patients. We hope to go beyond where imaging has gone before and truly transform preventive care.

Erika Berg: Looking a decade ahead, what breakthrough will we be discussing?

Filip Swirski: I believe it will be in understanding the brain-body connection—specifically the brain-heart-immune axis. We’re on the precipice of discoveries showing that health is about the balance between all our physiological systems.

Deepak Bhatt: I think we’ll see a major shift from treating disease to preventing it through hyper-personalized care. Everyone will have genotyping and biomarker panels in their record. AI will integrate this with imaging and demographic data to create powerful, individual risk profiles. We’ll be able to tailor diet and therapy precisely—for you, a low-salt diet might be critical; for someone else, it’s less so, and medication is key. It will be a much more refined and effective way to prevent heart disease.

Erika Berg: Thank you both for a fascinating look into the future. And thank you to the Icahn School of Medicine at Mount Sinai for sponsoring this interview.

Conclusion

From the mountaintops of Chile to the shorelines of the United States, this episode has explored the power of systematic observation to reshape our understanding of the world, both vast and intimate. The Vera C. Rubin Observatory promises a revolutionary, data-driven decade of discovery, from our own solar system to the mysterious force of dark energy. Meanwhile, back on Earth, methodical citizen science has provided clear evidence that policy can directly improve our environment, showing a significant drop in plastic bag litter. As we look to the stars and protect our planet, the future of science lies in this potent combination of grand technological ambition and grounded, human-powered research.