Eric Palkovacs, University of California, Santa Cruz

When the Lincoln Memorial Reflecting Pool turned green with algae just days after a US$15 million renovation, the U.S. government scrambled for chemicals and expensive technical solutions to fix the iconic landmark.

Trying to kill algae with chemicals is a common response when community ponds or other water features go green. But as a scientist who studies freshwater ecology, I can tell you there are better solutions that cost far less, last longer and carry less risk of harm to pets and wildlife.

Rather than battling against nature, these alternatives work with nature for long-term solutions. https://www.youtube.com/embed/nkqBQ1r0Kto?wmode=transparent&start=0 If you need to treat a slimy, green, algae-filled body of water, you shouldn’t drain and refill the water, which resets the entire ecosystem. Instead, one solution is quite simple and relies on nature, not chemicals.

What went wrong on the National Mall

The algal bloom that turned the Reflecting Pool a vibrant green shouldn’t have been a surprise.

The pool is big, more than a third of a mile long and around 165 feet wide. But it’s shallow, meaning it warms up quickly in the sun. When it was repainted “American flag blue” during the renovations in spring 2026, the new color darkened the pool, and darker colors absorb more heat.

On top of those conditions, the pool was refilled with water from the nutrient-rich tidal basin of the Potomac River. The combination of warm water and nutrients created prime conditions for algae to bloom, turning the water pea soup green.

As the national conversation over the Reflecting Pool shifts to political finger-pointing, an important environmental question deserves careful scrutiny: What is the best approach to maintain water quality in a case like this, whether for a national monument or a community water feature or pond?

Trying to chemically or mechanically remove algae can damage the structure of a water feature and may harm species in the water that could actually help solve the problem.

Importantly, chemical and mechanical solutions are only temporary fixes. When the Reflecting Pool is drained and filled again, there’s a good chance that algae will bloom again.

Natural algae control

Limnologists – scientists like me who study inland water bodies – have spent many decades learning why lakes and ponds turn green and how to clear them up.

Often, nutrient-rich waters fueled by fertilizer runoff from farm fields or sewage from cities are the sources that stimulate algal growth.

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However, natural ponds also host grazing zooplankton, which eat algae. For example, a type of zooplankton called Daphnia, known as water fleas because of the way these tiny crustaceans swim, can control algae by consuming it before it becomes a pea soup nuisance. Thus, a thriving Daphnia population can help maintain good water quality in a lake, pond or community water feature, even when nutrient levels spike.

In addition to being highly effective grazers, Daphnia have another superpower – they can evolve rapidly. Urban waterbodies are often harsh environments with a variety of challenges, including high temperatures, low levels of dissolved oxygen, and pollutants. Daphnia can adapt to tough conditions, making these creatures an ideal source of algae control in many urban ponds.

Rooted aquatic plants are also useful for algae control in ponds because they absorb nutrients. Thus, shallow ponds with thick beds of aquatic plants can often resist algal blooms when nutrient levels rise.

Why draining might not be the best solution

One downside to draining and refilling a pond or urban water feature to try to clean it is that doing so resets the aquatic ecosystem, erasing the signature of any past evolution that has taken place.

Imagine Daphnia in a shallow pond that experiences periodic heat waves throughout the summer. Through repeated exposure to high temperatures, natural selection favors heat-resistant genotypes that can thrive in an urban pond.

Daphnia and other grazing zooplankton can also evolve resistance to some types of cyanobacteria, also known as blue-green algae, which produce compounds that are toxic to people and pets. Daphnia that evolve resistance to those toxins can help control harmful cyanobacterial blooms.

If a Daphnia population that evolved to tolerate warm temperatures, low oxygen levels or cyanotoxins is removed, the new population likely won’t be ready to handle those local challenges. This evolutionarily naive population will perform poorly in its new environment, reducing its effectiveness at controlling algal blooms.

As a result, traditional mechanical and chemical approaches may actually work against the goal of minimizing algae in ponds and other water features.

Nature-based solutions

The use of Daphnia to control algal blooms is just one example of solving environmental challenges with nature-based solutions.

Growing urban forests to provide cooling and improve air quality to help reduce the need for more energy-intensive air conditioning is another example. Maintaining urban wetlands can help reduce flooding, protect property and recharge groundwater more effectively and for less money than building and maintaining levees. Coastal marshes similarly reduce erosion, buffer storm surges and support fisheries.

All these urban ecosystems protect biodiversity and support human health and well-being.

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From national landmarks to city parks and backyard ponds, projects of all sizes can take advantage of nature-based solutions. While each specific project is unique, some general principles apply.

Ecosystems are most resilient when they are diverse and connected. So, it is beneficial to use a variety of species and genotypes and provide corridors that support the movement of organisms and their beneficial genes.

Urban climates are changing rapidly, so it helps to use species and genotypes that will thrive under future conditions, including rising temperatures.

Not every solution has to be engineered

The hubbub over the Reflecting Pool holds a mirror up to assumptions about how to solve pressing environmental challenges. The idea of just engineering one’s way out of any environmental crisis has limits.

Understanding ecology and nature’s mechanisms of ecosystem resilience can achieve sustainable solutions that benefit both nature and people.

Eric Palkovacs, Professor of Ecology and Evolutionary Biology, University of California, Santa Cruz

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

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Heat waves can leave homes dangerously hot – even for young, healthy adults

Zoltan Nagy, Eindhoven University of Technology

Most people know that heat waves can be dangerous, but what they may not realize is that the heat indoors can be much worse than outdoors.

When the power goes out and air conditioning stops, or in homes without cooling, a house starts to function like a greenhouse during a heat wave. Heat enters through windows and walls and has nowhere to go. Air stagnates.

Within hours, indoor temperatures can climb well above what the thermometer shows outside, especially on upper floors and in rooms with south-facing windows. Over longer periods, especially if temperatures don’t cool off overnight, conditions can become lethal.

Most heat-related deaths occur indoors. When a heat dome sent temperatures soaring in the Pacific Northwest in 2021, 98% of the more than 600 deaths in British Columbia happened inside homes. Washington and Oregon also saw high numbers of deaths in homes that lacked air conditioning.

In Europe, where only 1 in 10 households have air conditioning, heat waves killed an estimated 60,000 people in 2022 and 47,000 in 2023, largely inside buildings never designed for these temperatures.

People of all ages are at risk in heat waves like these. I spent eight years at the University of Texas at Austin studying how buildings respond to extreme heat. In a recent study, my team assessed the heat risk in every single-family home in Austin.

We found that even younger, healthy adults face far more risk than they realize.

How hot is too hot for a human body?

Your body maintains a core temperature of about 98.6 degrees Fahrenheit (37 degrees Celsius). To cool down, it pushes blood to the skin and sweats. But when air temperature is high, that convective cooling weakens. When humidity is also high, sweat cannot evaporate.

If the body has no way to release heat, core temperature rises. If the core temperature increases past about 104 F (40 C), the body’s thermoregulation starts to fail. Past 109 F (42.8 C), death becomes likely.

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What makes indoor heat especially dangerous is that it does not let up at night in homes that lack air conditioning. Outdoor temperatures typically drop after sunset, and someone outside can get a few hours of recovery. But a poorly insulated home that has been absorbing heat all day releases that heat slowly, keeping indoor temperatures elevated through the night. A person inside the home never gets a break.

After two or three nights of this, even healthy people start to be at serious risk for heat-related illnesses.

Why homes heat up more than people expect

People tend to underestimate indoor heat for a few reasons.

One is that the thermostat typically sits on one wall in one room. It does not tell what the temperature is in an upstairs bedroom or near a sun-facing window. In older, underinsulated homes, the actual felt temperature can exceed 90 F (32.2 C) even when a thermostat reads 75 F (23.9 C). The hot walls, ceilings and windows can radiate heat directly onto your body.

Another reason is that people assume all homes respond to heat the same way. However, a newer home with double-pane windows and good insulation acts like a thermos, keeping heat out for a longer time. An older home with single-pane windows and cracks in the walls heats up fast.

Two houses on the same street, exposed to the same outdoor conditions, can have completely different temperatures inside. And in a blackout, where neither home has cooling, those differences can become a matter of life and death.

What we found in Austin

Our study combined two datasets. From Austin’s tax appraisal records, we pulled basic property information, such as the year the home was built, the size and the number of stories for each of the city’s 213,000 single-family homes. We then matched each home to the most similar energy simulation models in a U.S. Department of Energy database that contains thousands of detailed, physics-based building energy models representing the U.S. residential building stock.

Using those models, we simulated each building’s indoor temperatures over time during a three-day heat wave and power outage with outdoor temperatures above 110 F (43 C).

We found that 85% of homes got hot enough to pose a significant risk of death for an elderly occupant. But what surprised us was the risk to younger people.

Under today’s climate conditions in Austin, about 15% of homes already have the potential to get hot enough without air conditioning to pose serious heat risks to healthy adults. Under future warming scenarios, that number jumps to as high as 65% if average summer highs reach 104 F (40 C). Further, climate projections for Austin show that heat waves will double in frequency by the end of the century.

We found three types of buildings and accompanying risks:

• Resilient homes, which are newer and well insulated, tended to have temperature and humidity conditions that would be survivable for an elderly occupant throughout the simulated heat wave with blackout.
• Critical-risk buildings, which are mostly older homes, became dangerous almost immediately.
• And then there was the middle group – homes where temperatures rose slowly during the simulated blackout, day by day, possibly giving occupants a false sense of security until it was too late.

Texas has already seen conditions like our case study’s – a heat wave paired with a power outage. In 2024, a derecho knocked out power for nearly 900,000 Houston households while the heat index climbed to 100 F (37.8 C). Seven weeks later, Hurricane Beryl cut power to 2.6 million homes, leaving them without power for over three days, with temperatures over 90 F (32.2 C).

What you can do to stay safe

If you can’t get cooling at home, there are steps you can take that can help.

Move to the lowest floor of your home, where it will be coolest. Close the blinds and curtains on sun-facing windows. Drink water constantly to stay hydrated, which is essential for regulating body temperature.

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If you’re facing a blackout, be sure to also check on elderly neighbors, especially those living alone. You can also try to find a public cooling center; many cities now open them during heat emergencies.

Longer term, upgrades such as reflective window film, attic insulation and lighter-colored roofing can reduce how much a home heats up. After the 2021 heat dome, British Columbia’s coroner recommended updating building codes to address heat.

Our own findings point in the same direction: We propose that new homes should be required by building codes to maintain conditions in which at least light physical activity remains possible for all occupants for at least 72 hours during a power outage.

As summers get hotter with climate change and blackouts become more frequent, the risks of people suffering heat illnesses will only continue to rise.

Zoltan Nagy, Professor of Building Services, Eindhoven University of Technology

Heat waves can leave homes dangerously hot – even for young, healthy adults

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

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How to Protect Yourself from a Smartphone Scam

(Feature Impact) The first sign is unexpectedly losing access to your cell phone. Soon after, when you connect to Wi-Fi, the gravity of the situation sinks in: a criminal has gained access to your cell phone number and is trying to siphon money from your credit cards and bank accounts.

The scam is called SIM swapping, or SIM hijacking, and it’s a concern for law enforcement in the United States and abroad as more than 5,000 people have reported SIM swapping scams to the FBI since 2022. Older adults, caregivers and families can benefit from understanding the warning signs of SIM swapping and taking simple security steps to prevent it from happening.

How SIM swapping works

A SIM card, or its digital version known as an eSIM, helps connect a phone number to a carrier network. In a SIM swapping scam, a criminal collects basic information about their victim, such as their name, birthdate and address, to try to move the victim’s phone number to a SIM card or eSIM profile the criminal controls.

Once complete, the scammer gains access to accounts you may be logged into on your phone, such as bank accounts or credit card apps, without touching your phone or being near you.

How to protect yourself from SIM swapping scams

Preparation is the best protection against SIM swapping. Cell phone users should use strong, unique passwords for each online account – password managers are a helpful tool in creating complex and randomized passwords. Use two-factor authentication where it’s offered; this adds an extra layer of security when accessing sensitive accounts.

Next, consumers should protect personal information they share online, whether on social media or in texts or emails asking for identifying data, such as PIN numbers, birthdates or one-time security codes. Be wary of anyone pushing you to share personal information, particularly if they’re pushy with their request or make it sound urgent.

Check your mobile carrier to see if it offers SIM protection. For example, Verizon customers can toggle on a protection feature on the carrier’s website or app to lock lines on their account to help prevent SIM changes.

If you get an unprompted notification that your SIM has been changed, or otherwise suspect you’ve been targeted in a SIM swapping scam, contact your banks immediately and have them freeze your accounts, including ones the criminals may not have targeted yet. Next, work with your cell phone provider to help regain access to your mobile device. If you’re able, share as much information as possible with law enforcement so they can investigate, or at least document trends, in how often this scam occurs.

To find more advice to protect against smartphone scams, visit Verizon.com.

Photo courtesy of Shutterstock

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SOURCE:

Verizon

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