An unknown blob floating off the coast of Alaska and giant jellyfish in the Sea of Japan have some worried that these are signs of global warming.

Last week, the internet was swamped by the story of a dark, floating mass stretching for miles through the Arctic Ocean. The goo was fibrous, hairy. When it touched floating ice, it looked almost black. But what was it? An oil slick? Some sort of immense, shapeless organism adrift in some of the planet's most remote waters? Maybe a worrisome sign of global climate change?

Analysis of the stuff revealed that the blob wasn't oil but a plant — a massive bloom of algae. While that may seem less dangerous, people are still uneasy. It's something the mostly Inupiat Eskimo residents along Alaska's northern coast say they cannot remember seeing before.

Algal blooms are a common and often menacing event along many U.S. coastlines, including Alaska. Some strains are toxic and can close beaches and poison seafood, posing a hazard to consumers.

"We've observed large blooms in the past off Barrow, although none of them at all like this," Barry Sherr, an Oregon State University professor of oceanography, said in an e-mail. "The fact that the locals say they've never seen anything like it suggests that it might represent some exotic species which has drifted into the region, perhaps as a result of global change. For the moment, that's just a guess."

And in Japan, giant jellyfish have descended on the Sea of Japan, causing untold devastation to coastal villages and leaving a trail of destruction and human misery behind.

The massive sea creatures, called Nomura's jellyfish, can grow 6 feet in diameter and weigh more than 450 pounds. Scientists think they originate in the Yellow Sea and in Chinese waters, and for the third year since 2005, ocean currents are transporting them into the Sea of Japan.

The jellyfish stay together in packs and as they drift northward, they get caught in fishermen's nets where they get trapped and tear holes and ruin catches.
Fishermen often use expensive mazelike nets that stretch for hundreds of kilometers. When swarms of giant jellyfish tear them, the result can be devastating to fishing villages.

It's not clear why waves of Nomura's jellyfish have made it to the Sea of Japan in recent years. Some have speculated that overfishing, pollution or rising ocean temperatures may have depleted the kinds of fish that prey on Nomura's jellyfish in the polyp stage. However, no one is certain.

Some are saying that these phenomena are just a peek into what we can expect to happen as the oceans continue to warm and humans carry on polluting the seas.

Want to do something about pollution?

• Reduce lawn pesticides and fertilizers- they can pollute the water.
• Use non-toxic cleaning products - toxic products can hurt the environment and your health.