The exhaust produced by ocean-going ships can contribute to our warming climate. Most ships burn fossil fuels, so they spew out atmosphere-warming compounds. But some of their contribution to global warming may be a result of lower emissions—not of carbon, but of sulfur.

One of the compounds produced by burning fossil fuels is sulfur dioxide. Sunlight can cause it to interact with other compounds. That can yield droplets of acid rain, plus tiny grains of sulfur. Water can condense around those grains, forming clouds. The sulfur can stay in the air for days, so it can contribute to clouds for a long time.

The sulfur-based clouds are bright, so they reflect a lot of sunlight into space. That helps keep down the surface temperature.

In 2020, the International Maritime Organization passed some new regulations. It required shipping to cut sulfur emissions by 80 percent—reducing acid rain and cutting air pollution around ports.

A recent study looked at the possible impact that’s had on global warming. Researchers analyzed more than a million satellite images of ocean clouds. They compared those to maps of global temperature increases. And they used computer models to study what it all means.

The work found a big drop in ship-created clouds. And the drop correlated with areas of greater warming. The researchers concluded that the loss of clouds could have added about a tenth of a degree Fahrenheit to global temperatures—and could add more in the years ahead.

The many creatures that dig into the sediments at the bottom of the ocean are ecosystem engineers. Their burrowing, foraging, and even pooping change the ocean landscape—not just close by, but miles away.

Sediments have been described as the oceans’ compost heaps. They contain bits of rock and dirt washed out to sea by rivers. They also contain bits of organic material—everything from dead skin cells to the wastes of all the fish and other animals in the water above. And they’re loaded with bacteria and algae.

Many organisms spend much or all of their lives near the bottom—from shallow coastal waters to the deepest ocean trenches. That includes worms, fish, crustaceans, and others.

These critters dig burrows to protect them from predators or provide a safe haven for mating. They sculpt patterns in the soft sand or mud to attract mates. They poke through the sediments to scare up food. Some even scoop up the sediments, filter out tasty morsels, then poop out everything that’s not edible.

All of that activity changes things. It moves sediments from one spot to another. It scatters bacteria. It lifts eggs into the water. It brings nutrients to microscopic organisms.

The immediate effects are on a small scale—over a few inches or feet. But they add up. Most of the sea floor is covered with sediments, and as long as there is oxygen, there are animals burrowing and moving the sediments around. So the effects of all these ecosystem engineers add up.

About 12 million tons of plastics enter the oceans every year—the equivalent of a full garbage truck every minute. The total includes millions of grocery bags. But restrictions on the bags appear to be having a positive effect. Several studies have found big reductions in the number of bags found on beaches.

Plastic bags are a huge problem for ocean life. Animals can get tangled up in them. Birds and turtles mistake them for jellyfish and eat them. And fish eat bits of plastic if the bags fall apart. So reducing the number of bags in the oceans can save the lives of many creatures.

One study looked at the beaches in the United Kingdom. Governments there began cutting back on the bags more than a decade ago. Some of them banned the bags, while others required stores to charge for them. Since the restrictions went into effect, the number of bags picked up on the beaches has gone down by 80 percent.

There have also been big reductions in the United States. A dozen states have banned the bags, along with a couple of hundred cities and counties. Others require consumers to pay for the bags. A study by Ocean Conservancy found that volunteers picked up 29 percent fewer bags in 2022 and ’23 compared to the years before Covid-19. The numbers went way up during the pandemic as bag rules were suspended.

Millions of bags are still washing into the oceans. So birds, turtles, and other life still face a threat from this common form of trash.

Depending on which side of the country you live on, you probably either hate or love sea urchins. Off the coast of California, there are too many of the spiny creatures. They’re destroying kelp beds, harming the entire ecosystem.

But off the coast of Florida—and throughout the Caribbean Sea—there aren’t enough urchins. And without them, coral reefs are dying off.

Long-spined sea urchins used to be common in the Caribbean. They have black spines that can be up to a foot long. And their “teeth” are rocky plates that allow them to scrape algae from corals and other hard surfaces.

In 1983, a disease raced across the Caribbean. Within two weeks, it had killed 97 percent of the urchins. And in 2022, a parasite hit the still-recovering urchin population, wiping out most of the urchins on most reefs.

Without the urchins, the algae population has exploded. Algae can cover the corals, blocking the sunlight the living corals need to survive. The algae also coat the surfaces that young corals latch themselves to, preventing them from establishing new colonies.

Combined with climate change, ocean pollution, and other problems, that’s cut the amount of corals across the Caribbean by about 80 percent since the 1970s.

Today, scientists are raising urchins in the lab, then dropping them on reefs. It’s too early to tell how that’s working out. But researchers are hopeful that the efforts will begin to restore balance to Caribbean reefs.

The ocean floor near Los Angeles is the largest graveyard for whales yet seen. Surveys have found evidence of more than 60 whale skeletons there. Scientists have used sonar and video cameras to map a couple of ocean basins that are centered about 15 miles offshore.

Researchers have been studying the region for years, in part because it was a dumping ground for DDT and related chemicals. Scientists are seeing how that affects life in the ocean, and how it might impact human health.

The most detailed mapping came in 2021 and 2023. It revealed many barrels of toxic chemicals, along with unexploded depth charges and other weapons from World War II.

It also revealed seven confirmed whale skeletons, of six different species, with hints of many others—more than the total seen in the rest of the world combined.

The remains of whales can feed fish and other critters for months. And, worms and microbes eventually consume even the bones. Researchers say there could be many reasons for the apparent bounty of whale skeletons. For one thing, few areas of the ocean floor have been scanned in as much detail as this one. For another, the region is packed with both whales and ships, so whales are more likely to be killed in collisions. And the deep water in the region contains little oxygen, which keeps the skeletons from decomposing.

Future expeditions will continue to map the region—perhaps finding even more remains in this graveyard for whales.

The image of more than a hundred thousand aircraft carriers floating through the air might sound like a scene from a Doctor Strange movie. But the weight of all those carriers equals the amount of carbon dioxide that humanity has pumped into the air every year over the past decade or so—11 billion tons per year. The carbon dioxide traps heat, warming the atmosphere.

The oceans help slow that process by absorbing about a quarter of the CO2 from the air, according to a recent report. More CO2 was being absorbed in parts of the North Atlantic and Southern Oceans.

Some of the carbon dioxide is dissolved into the water as winds blow across the surface. And some is taken in by microscopic organisms, which use sunlight to convert the CO2 into food.

The process is more efficient when the ocean surface is warmer. So more carbon is absorbed during El Niño years. But we’ve had several La Niña events in recent years, which bring cooler waters, reducing the carbon uptake.

Over time, a lot of the CO2 works its way into the deep ocean, allowing the surface to absorb even more. Some of it accumulates in the sediments on the ocean floor, where it can form rocks.

The extra carbon dioxide creates problems for the oceans as well. In the atmosphere it warms the water, and in the water it interferes with some creatures’ ability to make their shells, for example. So those floating “aircraft carriers” are a big problem—no matter where they dock.

When a hurricane or tropical storm rolls through, most birds fly around it, or find refuge in the calm “eye” at its center. But not the Desertas petrel. It can ride out the storm, then follow the system for days—all to catch an easy meal.

The petrel nests on a tiny, craggy island off the northwestern coast of Africa. There are only a few hundred of the birds, which are about the size of a pigeon. They’re strong fliers: every year they make a 7500-mile round-trip to the eastern North Atlantic Ocean.

Researchers attached GPS devices to 33 petrels. They tracked the birds for several weeks a year for four years. And they compared the birds’ movements to the paths of six hurricanes during those periods. And they got a surprise: About a third of the birds followed the storms—something that no other ocean-going birds have ever been seen to do. Some of the petrels stuck with the hurricanes for up to five days and 1500 miles.

The reason appears to be food. The hurricanes churned up the ocean, bringing water packed with nutrients to the surface. And that probably attracted some of the petrels’ favorite foods: squid and small fish and crustaceans.

The birds normally have to wait for night for these creatures to rise to the surface. But during the storms, there should have been an abundant supply near the surface around the clock. And the smorgasbord could’ve continued for days—providing a good reason for Desertas petrels to tag along.

The massive fire that engulfed Lahaina, on the Hawaiian island of Maui, killed more than a hundred people, and burned down more than 2200 buildings. And it had a much wider impact as well—on the offshore coral reef.

The fire roared to life on the morning of August 8th, 2023. Fueled by drought, low humidity, and strong winds, it destroyed much of Lahaina, displacing more than 10,000 people.

Ash from the fire drifted offshore and settled atop the reef. Firefighting chemicals and debris from the fire washed into the ocean as well. The contamination threatened the reef and the many creatures that live there. And any damage to the reef could heighten the human misery, because people depend on the reef for food and tourism dollars.

Within days, researchers from the University of Hawaii began studying the reef system. They sampled the water, and set out water-quality sensors at key locations. They also worked with locals to catch fish from the best fishing spots. All of the samples were then analyzed for traces of contamination.

Early analysis revealed high levels of copper—possibly from coatings on the hulls of boats that burned in the fire. It also showed high levels of lead. The levels of both elements have since gone down to safe levels. Zinc went up as well, and climbed even higher after heavy rains washed more contaminants into the water.

Scientists continue to monitor the reef—seeing how it recovers from a human and environmental tragedy.