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.