Climate Change Threatens U.S. Bridges

/ activist360

Key Findings from a Recent Study

A recent study published in PLOS ONE, authored by Susan Palu and Dr. Hussam Mahmoud, highlights the growing vulnerability of deteriorating U.S. bridges due to climate change. This research, conducted at Colorado State University, focuses on how rising temperatures and clogged expansion joints could jeopardize the structural integrity of thousands of bridges across the country.

The Researchers Behind the Study

Susan Palu was a master’s student in civil engineering when the study was conducted, bringing fresh academic insight into the challenges of aging infrastructure. Dr. Hussam Mahmoud, a professor at Colorado State University and the George T. Abell Professor in Infrastructure, is a renowned expert in sustainable infrastructure and community resilience. With a Ph.D. from the University of Illinois at Urbana-Champaign and over 300 publications to his name, Mahmoud’s research focuses on making infrastructure systems more resilient to natural hazards, including climate change​.

The Aging U.S. Bridge Infrastructure

As U.S. infrastructure ages, many bridges are approaching or exceeding their intended design life. Approximately 40% of U.S. bridges are over 50 years old, with around 54,560 classified as structurally deficient. While bridges have been inspected and maintained regularly, this study sheds light on a specific issue: malfunctioning expansion joints, small but critical components responsible for allowing bridge expansion and contraction during temperature changes.

Impact of Climate Change on Bridges

he study examines the effects of climate change on steel-span bridges, which were mass-produced during the highway boom of 1950s to 1970s, when the interstate highway system was being developed. These bridges, when subjected to higher future temperatures, are at risk of developing dangerous levels of thermal stress, especially when their expansion joints are clogged.

When debris builds up in these joints, it prevents the bridge from expanding as temperatures rise. This blockage causes axial pressure on the girders, which, combined with the weight of vehicles, could lead to structural fatigue, cracks, and even failure.

Researchers also studied how temperature changes during bridge construction impact their strength.
They looked at four scenarios: building bridges in winter, spring, summer, or fall. They found that:

  • If built in winter, 100% of bridges might be too weak.
  • If built in spring, 97% might be too weak.
  • If built in summer, 83% might be too weak.
  • If built in fall, 95% might be too weak.

Most Vulnerable Regions

The study identifies bridges in the Northern Rockies, Upper Midwest, and Northwest as the most vulnerable, particularly in states like North Dakota and South Dakota. These regions are likely to experience more severe temperature variations, exacerbating the effects of clogged joints and adding stress to already aging structures.

A Call for Action

With over 89,000 simply supported steel girder bridges analyzed, the study advocates for immediate attention to maintaining and clearing bridge expansion joints. It emphasizes that neglecting to address these climate-related challenges could lead to substantial economic and social costs. Prioritizing repair and maintenance will be essential to ensure the safety and longevity of U.S. infrastructure in the face of climate change.

Summing Up

This groundbreaking study, conducted by Susan Palu and Dr. Hussam Mahmoud at Colorado State University, offers critical insights into how climate change is accelerating the deterioration of U.S. bridges. Without intervention, the impact on national infrastructure could be catastrophic. Policymakers, engineers, and transportation authorities are urged to take immediate steps to mitigate these risks and protect public safety.

By staying ahead of these challenges, the U.S. can safeguard its infrastructure from the growing threat of climate change.

Source: Palu, S., & Mahmoud, H. (2019). Impact of climate change on the integrity of the superstructure of deteriorated U.S. bridges. PLOS ONE, 14(10), e0223307. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223307.

Understanding the Global Plastic Pollution Crisis

/ activist360

Overview of Plastic Pollution and the Role of the Global Plastics Treaty

Plastic pollution is one of the biggest challenges our world faces today. It affects our oceans, rivers, land, and even the air we breathe. Every year, millions of tons of plastic waste end up in the environment, creating serious problems for both people and nature. Let’s dive into the key facts about plastic pollution and the steps being taken to address it through the Global Plastics Treaty.

What is Plastic Pollution?

Plastic pollution happens when plastic waste escapes from managed systems like landfills and enters the environment. When this waste is no longer controlled, it becomes a major threat to ecosystems. Plastic pollution can be broken down into two types:

  • Macroplastics: These are larger pieces of plastic (greater than 5mm) like bottles, bags, and other visible plastic items.

  • Microplastics: Tiny plastic particles (smaller than 5mm) that often come from the breakdown of larger plastics.

How Much Plastic Waste is There?

In 2020, around 52.1 million metric tons of macroplastic waste entered the unmanaged environment. This is about 21% of all the plastic waste produced by cities and towns, also known as municipal plastic waste. Municipal plastic waste comes from homes, businesses, schools, and public spaces, according to a global emissions inventory study published in Nature​ (s41586-024-07758-6).

What is the Unmanaged Environment?

The “unmanaged environment” is any place where plastic waste is no longer being controlled. This includes uncollected waste, litter, and open dumping sites. Once plastic enters this environment, it can move freely and cause harm to wildlife, ecosystems, and even human health.

Why Does Open Burning Happen?

In many parts of the world, especially in developing countries, formal waste collection services are either unavailable or not sufficient. As a result, people resort to open burning of plastic waste as a way to get rid of it. Open burning is harmful because it releases dangerous chemicals into the air and contributes significantly to pollution.

Global North vs. Global South: Who’s Responsible?

When we talk about plastic pollution, the world is often divided into the Global North and the Global South:

  • The Global North includes wealthier, high-income countries like the United States, Western Europe, and Japan. These countries have better waste management systems and tend to have less uncollected waste.

  • The Global South includes developing countries in regions like Africa, Latin America, and Southeast Asia. These countries struggle with waste collection, and uncollected plastic waste is a major source of pollution.

Plastic Pollution Hotspots

Certain regions are considered plastic pollution hotspots due to their high levels of unmanaged plastic waste:

  • Southern Asia, Sub-Saharan Africa, and Southeast Asia have the highest levels of plastic pollution.

  • India is the largest global emitter, contributing nearly one-fifth of all plastic waste emissions, followed by countries like Nigeria and Indonesia.

  • In contrast, the Global North has lower levels of pollution because of better waste management practices, though littering is still a problem.

What is the Global Plastics Treaty?

The Global Plastics Treaty is a global agreement being negotiated under the United Nations Environment Programme (UNEP) to tackle plastic pollution. The treaty aims to reduce plastic waste, improve recycling, and promote better waste management worldwide. This treaty brings together representatives from governments, industries, scientists, and environmental groups to find solutions.

Negotiations began in 2023. The next Intergovernmental Negotiating Committee (INC) meeting for the Global Plastics Treaty is scheduled for November 25–December 1, 2024 in Busan, South Korea. This meeting is called INC-5 and is expected to finalize the text of the treaty.

Why Does This Matter?

Plastic pollution has lasting effects on the environment and human health. Once plastic waste enters the environment, it can break down into microplastics, which are even harder to clean up. Without immediate action, plastic waste will continue to harm ecosystems, wildlife, and people.

Call to Action

Plastic pollution is a global issue that needs urgent attention. While some countries have made progress in managing their plastic waste, others face major challenges. The Global Plastics Treaty offers hope for coordinated global action to reduce plastic pollution and protect our planet for future generations. Tackling uncollected waste and improving waste management systems, especially in developing countries, will be key steps toward solving this crisis.

By understanding the sources and impacts of plastic pollution, we can all play a part in making our world a cleaner, healthier place.

New Study Shows West Antarctic Ice Sheet Might Be Safer from Collapse This Century

/ activist360
Lemaire Canal in West Antarctic
Glacier breaking edge in the Lemaire Canal. The Lemaire Canal is a narrow ship passage. It separates the island of Booth from the Antarctic Peninsula. Credit: W. Bulach, CC BY-SA 4.0, via Wikimedia Commons, December 8, 2005.

Some Climate Threats May Be Less Urgent, But Action Is Still Needed to Protect Ice Sheets

A recent study led by researchers at Dartmouth College brings some good news about the West Antarctic Ice Sheet, particularly Thwaites Glacier. Scientists have found that this massive ice sheet might be less likely to collapse during the 21st century than we previously feared. This discovery could mean that the threat of rapidly rising sea levels is not as immediate as some had thought.

What Is MICI and Why Does It Matter?

MICI stands for Marine Ice Cliff Instability. It’s a big concern in the world of climate science. The idea is that if the floating ice shelves around Antarctica collapse, they could expose tall ice cliffs. These cliffs might break apart quickly, leading to more ice melting and causing sea levels to rise around the world. Previous studies suggested that MICI could cause the West Antarctic Ice Sheet to collapse, leading to significant sea level rise by the end of this century.

How This Study Was Done

Scientists from several universities used advanced computer models to simulate what might happen to Thwaites Glacier if its ice shelf collapses. They applied new methods to gain a clearer understanding of the ice sheet’s stability. These models are more detailed and realistic than the ones used in older studies.

The new methods took into account how the ice both bends and breaks. This made the models more realistic in showing how the ice sheet might behave if the ice shelves collapse and tall cliffs are exposed.

The study also used more advanced and detailed models. By using three different models (ISSM, STREAMICE, and Úa), the researchers made sure their results were not limited to just one type of model. This approach gave a clearer picture of how stable the West Antarctic Ice Sheet might be, especially concerning MICI.

Key Findings: Less Risk of Collapse

The study’s results are reassuring. Even in the worst-case scenarios, where the ice shelf collapses completely, the models show that the glacier would likely remain stable throughout the 21st century. The exposed ice cliffs wouldn’t be tall enough to cause the runaway collapse that was previously feared.

Two important factors help keep the glacier stable:

  1. Faster Ice Movement: If the ice shelf collapses, the ice behind it would begin moving faster, which surprisingly helps prevent the cliffs from breaking apart.

  2. Thinning Ice: The ice near the front would become thinner, making the cliffs less likely to reach dangerous heights.

Why This Matters for Sea Levels

This study suggests that the scenarios where sea levels rise quickly due to the collapse of the West Antarctic Ice Sheet might not happen as soon as we thought. However, the scientists warn that other processes could still cause the ice to melt over the long term. We shouldn’t assume everything is fine, but it’s a relief to know that we might have more time to address these challenges.

Call to Action

This study is a reminder that while some climate threats may be less urgent than we feared, we still need to take action. Ice sheets like the West Antarctic are still at risk in the long run.

Morlighem, M., Goldberg, D., Barnes, J. M., Bassis, J. N., Benn, D. I., Crawford, A. J., Gudmundsson, G. H., & Seroussi, H. (2024). The West Antarctic Ice Sheet may not be vulnerable to marine ice cliff instability during the 21st century. Science Advances, 10(eado7794).