marine ecosystems

The human impact on oceans

October 21, 2025 By EarthWise Leave a Comment

Vast and powerful, the oceans have sustained human life around the world for millennia. They provide food, natural resources, and livelihoods, supporting countless communities and economies. But despite their size and resilience, the oceans are under increasing pressure from climate change and human activity, pushing them toward a dangerous threshold.

According to a new study led by researchers from UC Santa Barbara, the cumulative human impact on the oceans is forecasted to double by 2050, which is just 25 years from now. These impacts include ocean warming, fisheries losses, sea level rise, acidification, and pollution.

The research team, which includes collaborators from Nelson Mandela University in South Africa, found that the tropics and poles will experience the fastest rate of change. And coastal regions, where most human activity takes place, will bear the heaviest consequences of those changes.

The research team calls the findings sobering – not only because the impacts are increasing, but because they’re increasing so quickly.

The study, which was recently published in the journal Science, shows that ocean warming from climate change and reductions in marine biomass from overfishing are expected to be the two largest contributors to future ocean impacts. If ecosystems cannot cope with these pressures, human societies will also feel the consequences.

But the research team stresses that it’s not too late. Stronger climate policies, better fisheries management, and protections for vulnerable habitats like salt marshes and mangroves could help slow or even reduce human impacts.

The research serves as both a warning, and a chance to act before it’s too late.

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Human impact on the ocean will double by 2050, UCSB scientists warn

Photo, posted July 11, 2018, courtesy of Ed Dunens via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ocean acidification and sharks

September 26, 2025 By EarthWise Leave a Comment

Carbon dioxide emissions from human activities are altering the chemistry of oceans. As more CO2 is released into the atmosphere, a significant portion of it is absorbed by seawater. This reduces the ocean’s pH, driving greater acidity, and disrupts marine ecosystems – a process known as ocean acidification. The acidifying oceans pose problems for many organisms, including sharks.

Sharks are one of the top marine predators. Their teeth are their weapons. Razor-sharp and constantly replaced, their teeth are essential for their survival. But new research, recently published in the journal Frontiers in Marine Science, has found that sharks may lose their edge as the oceans become more acidic.

Scientists in Germany examined the teeth of Blacktip reef sharks under current and future ocean acidification scenarios. Today, the ocean’s average pH is about 8.1. By the year 2300, it could fall to 7.3, making seawater nearly ten times more acidic than it is now.

Shark teeth, though made of tough mineralized phosphate, are not immune to corrosion. The researchers incubated discarded shark teeth in tanks with different pH levels. After just eight weeks, the teeth exposed to more acidic water showed visible damage, including cracks, holes, weakened roots, and appeared structurally more fragile.

Since species like Blacktip reef sharks swim with mouths open to breathe, their teeth are constantly exposed to seawater and at continuous risk of damage.

Protecting ocean chemistry may be critical to protecting the top marine predators themselves.

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‘Built for cutting flesh, not resisting acidity’: sharks may be losing deadly teeth to ocean acidification

Photo, posted June 16, 2023, courtesy of Ryan Hagerty / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sand mining and the environment

March 18, 2025 By EarthWise Leave a Comment

Sand mining is the world’s largest mining endeavor. It is responsible for 85% of all mineral extraction. It is also the least regulated, possibly the most corrupt, and likely the most environmentally destructive. Sand is the second-most exploited natural resource in the world after water. Its global use has tripled in the past two decades. More than 50 billion tons of sand is extracted from the environment each year.

Sand plays a critical role in much of human development around the world. It is a key ingredient of concrete, asphalt, glass, and electronics. It is relatively cheap and relatively easy to extract. But we use enormous amounts of it.

Sand mining is a major threat to rivers and marine ecosystems. It is linked to coastal erosion, habitat destruction, the spread of invasive species, and damage to fisheries.

The harm from sand mining is only beginning to attract widespread attention. A recent study by an international group of scientists published in the journal One Earth identifies threats posed by sand mining. Sand extraction in marine environments remains largely overlooked, despite sand and sediment dredging being the second most widespread human activity in coastal areas after fishing.

Sand is generally seen as an inert, abundant material, but it is an essential resource that shapes coastal and marine ecosystems, protects shorelines, and sustains both ecosystems and coastal communities. Sand extraction near populated coastlines is particularly problematic as climate change makes coastlines increasingly fragile.

Like all other resources on our planet, even sand cannot be taken for granted. It must be responsibly managed.

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The rising tide of sand mining: a growing threat to marine life

Photo, posted February 7, 2013, courtesy of Pamela Spaugy / U.S. Army Corps of Engineers via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Global Flood Risk From Melting Ice | Earth Wise

December 13, 2021 By EarthWise Leave a Comment

Approximately 10% of the land area on Earth is covered by ice. This includes glaciers, ice caps, and the ice sheets of Antarctica and Greenland. Nearly 70% of all fresh water on earth is locked away in ice. If all this land ice were to melt, global sea levels would rise by more than 200 feet.

According to new research led by researchers at the University of Leeds in the U.K., global warming is causing extreme ice melting events in Greenland to become more frequent and more intense over the past 40 years, leading to an increased risk of flooding worldwide.

According to the findings, which were recently published in the journal Nature Communications, approximately 3.85 trillion tons of ice has melted from the surface of Greenland and into the ocean during the past decade alone. That’s enough melted ice to cover all of New York City with nearly 15,000 feet of water.

Rising sea levels threaten the lives and livelihoods of those living in coastal communities around the world. Beyond the obvious risk of flooding in low-lying areas, rising seas also disrupt marine ecosystems that many coastal communities rely on for food and work.

Rising sea levels can also alter patterns of ocean and atmospheric circulation, which in turn affect weather conditions around the planet.

Estimates from models suggest that melting ice from Greenland will contribute between 1 inch and 9 inches to global sea level rise by 2100.

These findings are just another reminder of how we need to act urgently to mitigate climate change if we want to prevent the worst-case scenarios from becoming reality.

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Increased frequency of extreme ice melting in Greenland raises global flood risk

Photo, posted April 21, 2017, courtesy of Markus Trienke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wind Farms Slowing Each Other Down | Earth Wise

July 13, 2021 By EarthWise Leave a Comment

Offshore wind is booming in Europe. The expansion of wind energy in the German Bight and Baltic Sea has been especially dramatic. At this point, there are about 8 gigawatts of wind turbines in German waters, the equivalent of about 8 nuclear power plants. But space in this region is limited so that wind farms are sometimes built very close to one another.

A team of researchers from the Helmholtz Center Hereon, a major German research institute, has found that wind speeds downstream from large windfarms are significantly slowed down. In a study published in the journal Nature Scientific Reports, they found that this braking effect can result in astonishingly large-scale lowering of wind speeds.

On average, the regions of lowered wind can extend 20-30 miles and, under certain weather conditions, can even extend up to 60 miles. As a result, the output of a neighboring wind farm located within this distance can be reduced by 20 to 25 percent.

These wake effects are weather dependent. During stable weather conditions, which are typically the case in the spring in German waters, the effects can be especially large. During stormy times, such as in November and December, the atmosphere is so mixed that the wind farm wake effects are relatively small.

Based on their modeling, it is clear that if wind farms are planned to be located close together, these wake effects need to be taken into account. The researchers next want to investigate the effects that reduced wind speeds have on life in the sea. Ocean winds affect salt and oxygen content, temperatures, and nutrients in the water. It is important to find out how reduced winds might affect marine ecosystems.

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Are wind farms slowing each other down?

Photo, posted November 23, 2011, courtesy of David J Laporte via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Seagrasses And Ocean Acidification | Earth Wise

May 13, 2021 By EarthWise Leave a Comment

Seagrasses are the basis of important marine ecosystems. Sea turtles, bat rays, leopard sharks, fish, and harbor seals are just some of the marine creatures that visit seagrass ecosystems for the food and habitat they provide. They are nursery grounds for many aquatic animals and many birds visit seagrass meadows to dine on what lives within them. They may seem like slimy grasses that we walk through along some shorelines, but they are important.

These marine forests are valuable for many different reasons including climate mitigation and erosion control. A third of the carbon dioxide emitted across the globe is absorbed by the ocean and seagrass meadows are an important carbon sink.

A new study, recently published in the journal Global Change Biology, investigated how seagrasses can buffer ocean acidification. The six-year-long study found that these ecosystems can alleviate low ocean pH – that is, more acidic – conditions for extended periods of time, even at night in the absence of photosynthesis.

In some places, the pH buffering from the seagrasses brings the local environments back to preindustrial pH conditions, like what the ocean might have experienced around the year 1750.

Seagrasses naturally absorb carbon as they photosynthesize when the sun is out, which drives the buffering ability. The study found the surprising result that the effects of pH buffering even persisted during the night, when there is no photosynthesis.

The study has implications for aquaculture management as well as climate change mitigation, and conservation and restoration efforts. Globally, seagrass ecosystems are in decline. These results show how important it is to help them survive and prosper.

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Seagrasses Turn Back the Clock on Ocean Acidification

Photo, posted October 13, 2010, courtesy of Claire Fackler, CINMS, NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Can We Tow Icebergs To Use Their Water? | Earth Wise

February 23, 2021 By EarthWise Leave a Comment

At any given time, there are thousands of icebergs adrift in Antarctica that are hundreds or even thousands of feet across. For at least fifty years, there has been speculation about whether such icebergs could be towed from the Antarctic to places experiencing freshwater shortages. The feasibility of such a scheme is still the subject of studies that nowadays include sophisticated computer modeling.

Places like the Persian Gulf, Cape Town, South Africa, and Perth, Australia all experience water shortages and could benefit tremendously from having a large iceberg towed to their waters.

How big an iceberg would it take to quench the thirst of a city like Cape Town? Computer models show that an iceberg 2,000 feet long and 650 feet thick could produce enough water to supply the city for more than a year. However, with water temperatures in the 60s in the area, even such a large iceberg would melt away within weeks. So, to get enough water for a year, it would require a much larger iceberg – one at least a couple of miles long.

Daunting problems include figuring out how many and what sort of ships would be required. An alternative to such giant icebergs would be finding a way to insulate the icebergs so they don’t melt as quickly, thereby allowing much smaller and more towable icebergs to be harvested.

Beyond these issues, there are the ecological issues of the effects of huge amounts of very cold fresh water affecting local marine ecosystems.

Despite a wide range of challenges, there is continued interest in the idea of using icebergs as a source of very pure fresh water. In an increasingly thirsty world, it might someday actually happen.

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Can icebergs be towed to water-starved cities?

Photo, posted November 1, 2007, courtesy of M A Felton via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Ocean Currents And Climate Change | Earth Wise

September 22, 2020 By EarthWise Leave a Comment

Oceans cover more than 70% of the earth and absorb 94% of incoming solar radiation. As a result, oceans play a major role in the climate system. With their massive size and capacity to store heat, oceans help keep temperature fluctuations in check. But oceans also play a more active role. Ocean currents are responsible for moving vast amounts of heat around the planet.

According to a paper recently published in the journal Nature Communications, the world’s strongest ocean currents will experience more intense marine heatwaves than the global average in the coming decades. These strong ocean currents play key roles in fisheries and ocean ecosystems.

Sections of the Gulf Stream near the United States, the Kuroshio Current near Japan, the East Australian Current near Australia, and the Antarctic Circumpolar Current will all see more intense marine heatwaves over the next 30 years.

Scientists from the University of Tasmania and CSIRO in Australia relied on high-resolution ocean modeling to carry out their research. They confirmed the model’s accuracy by comparing outputs with observations from 1982-2018. They then used the same model to project how marine heatwaves would alter with climate change out to 2050.

The model projects, for example, that intense marine heatwaves are more likely to form well off the coast of Tasmania, while more intense marine heatwaves along the Gulf Stream start to appear more frequently close to the shore from Virginia to New Brunswick, Canada.

Marine heatwaves are on the rise globally, but knowing where they will occur and how much hotter they will be will help policymakers, ecologists, and fisheries experts in their regional decision-making.

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Where marine heatwaves will intensify fastest: New analysis

Photo, posted April 17, 2016, courtesy of Nicolas Henderson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Effects Of One Degree

October 9, 2017 By EarthWise Leave a Comment

In discussions of global warming, we often hear about the effects of a 2-degree rise in temperature or a 1-degree rise in temperature. For most of us, such changes seem pretty insignificant. Of course, in our daily lives, a one-degree temperature change is not particularly noticeable. But in the context of climate change, we are talking about a change in average temperature over time, not the temperature on a particular day or at a particular time.