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Lauren Sommer

They're purple, spiky and voracious, and just off the West Coast, there are more of them than you can count.

Purple sea urchins have exploded in recent years off California, covering the ocean floor in what divers describe as a "purple carpet." And they devour kelp: the once-lush forests of seaweed that hugged the coastline are disappearing. Since 2014, 95 percent of the kelp have vanished across a large part of Northern California, most of it bull kelp.

A few years ago, marine biologist Kyle Van Houtan spotted an online video that he couldn't quite believe. It showed a young great white shark, about five-feet long, swimming just off a pier in Central California.

"Our initial reaction was that it can't be true," Van Houtan says. "We know that they're in Southern California and Mexico, not in Monterey."

When they're young, white sharks typically live in the warm waters of Southern California, hundreds of miles from the cold, rough surf up north off Monterey.

As the blackouts in Texas dragged on, millions of residents quickly realized they had more to worry about than trying to light and heat their homes. The water coming out their faucets was no longer safe to drink.

Like falling dominos, infrastructure around Texas, dependent on electricity, began failing in the extreme cold. In Austin, the Ullrich Water Treatment Plant shut down due to an electrical failure. That, combined with low water pressure from broken pipes, meant residents had to boil their water.

Off the coast of England, there's a tiny, wind-swept island with the remains of a lifeboat rescue station from the mid-1800s. The workers who once ran the station on Hilbre Island did something that, unbeknownst to them, has become crucial for understanding the future of a hotter climate: They recorded the tides.

President Biden is moving quickly on climate change on his first day in office, saying he plans to sign a sweeping executive order to undo many of the Trump administration's environmental rollbacks.

With just a few weeks left, 2020 is in a dead-heat tie for the hottest year on record. But whether it claims the top spot misses the point, climate scientists say. There is no shortage of disquieting statistics about what is happening to the Earth.

After record-breaking wildfires this year, thousands of people across the West are still clearing piles of charred debris where their homes once stood in the hope of rebuilding their lives.

With climate change fueling bigger, more destructive wildfires, rebuilding offers an opportunity to create more fire-resistant communities by using building materials that can help homes survive the next blaze.

Jennifer Montano watches her two kids' faces as they quietly clamber out of the car in their driveway in Vacaville, Calif. It's been a week since the children were last home, but where their house once stood, there's ash and rubble now.

In August, the Montanos' house was destroyed by the LNU Lightning Complex Fire, one of more than 10,000 structures lost in record-breaking blazes across the West this year.

Each family had their reasons for ending up in harm's way.

For the Harts, it was the chance to have a large backyard in a quiet part of Ashland, Ore. The porch of the Baltimore house was perfect for Scott Harris' barbecue equipment. Kevin Boudreaux had grown up on the bayou and wanted to settle near his childhood home in Cameron, La.

California will phase out the sale of all gasoline-powered vehicles by 2035 in a bid to lead the U.S. in reducing greenhouse gas emissions by encouraging the state's drivers to switch to electric cars.

Gov. Gavin Newsom signed an executive order Wednesday that amounts to the most aggressive clean-car policy in the United States. Although it bans the sale of new gas cars and trucks after the 15-year deadline, it will still allow such vehicles to be owned and sold on the used-car market.

The upshot of climate change is that everyone alive is destined to experience unprecedented disasters. The most powerful hurricanes, the most intense wildfires, the most prolonged heat waves and the most frequent outbreaks of new diseases are all in our future. Records will be broken, again and again.

But the predicted destruction is still shocking when it unfolds at the same time.

At 3 a.m. on Friday morning, biologist Kelly Sorenson was awake, nervously watching the live webcam feed of a California condor nest on the Big Sur coast. He could see a 5-month-old chick, still unable to fly, as the flames of the Dolan Fire came into view.

"It was just terrifying," Sorenson said. "Having the live-streaming webcams was both a blessing and a nightmare because we had to watch the fire as it burned through the canyon."

Scorching heat across the Western United States has left California scrambling to avoid rolling blackouts, as air conditioners send electricity use soaring.

President Trump is attacking Democrats on a new front: suburbia.

"They want to eliminate single-family zoning, bringing who knows into your suburbs," Trump said on a July campaign call.

When humpback whales migrated to Glacier Bay in Alaska this year to spend the long summer days feeding, they arrived to something unusual: quieter waters.

As the COVID-19 pandemic slows international shipping and keeps cruise ships docked, scientists are finding measurably less noise in the ocean. That could provide momentary relief for whales and other marine mammals that are highly sensitive to noise.

With the coronavirus pandemic eroding state budgets across the country, many communities risk having this disaster make them less prepared for looming climate-driven disasters.

Still recovering from devastating wildfires, California was poised to spend billions of dollars to prepare for future fires and other extreme weather disasters. The infrastructure projects, designed to make communities and homes more resistant to wildfire, have long been overlooked, fire experts say.

But with a $54 billion budget deficit, the programs are being put on hold.

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With traffic dramatically down in recent months, the United States is in the middle of an accidental experiment showing what happens to air pollution when millions of people stop driving.

As the climate has warmed, Antarctica and Greenland have lost enough ice in the last 16 years to fill Lake Michigan, according to results from a new NASA mission.

Put another way, more than 5,000 gigatons of ice has melted (a gigaton equals one billion metric tons or enough to fill 400,000 Olympic-sized swimming pools), which drove up sea levels around the world.

The findings show how the massive ice sheets at the far ends of the planet will affect millions of people on coastlines everywhere.

In early February, the Centers for Disease Control and Prevention was looking for ways to stop the novel coronavirus before it got out of control in the United States.

Deep in the Pacific Ocean, six-foot-long Humboldt squid are known for being aggressive, cannibalistic and, according to new research, good communicators.

Known as "red devils," the squid can rapidly change the color of their skin, making different patterns to communicate, something other squid species are known to do.

As coronavirus numbers have ticked steadily upwards in some U.S. states and cities, officials have watched one specific figure to see whether they're facing a flattening curve or runaway outbreak: the doubling rate.

Simply put, it's how many days it takes for the number of coronavirus cases, hospitalizations or deaths to double. The shorter the time frame, the steeper the curve and the faster the growth.

Widespread cancellations of commercial flights are creating problems for meteorologists around the world. That's because weather forecasting models rely on temperature and wind data gathered by thousands of planes flying overhead.

The National Weather Service uses more than 250 million measurements from aircraft every year, which are fed into complex weather computer models. As of the end of March, meteorological data provided by U.S. aircraft had dropped by half.

International climate change negotiations scheduled for later this year are being postponed due to the ongoing coronavirus pandemic. United Nations officials say a conference is no longer possible, delaying what many hoped would be an ambitious climate agreement among nations.

With tests scarce, epidemiologists are looking at hospitalizations as an indicator of how the novel coronavirus is spreading. But in some of the areas of the country worst-hit by COVID-19, states and counties aren't releasing that data.

The result is an incomplete picture of where the pandemic is surging, even in hotspots such as Washington and California.

Academic science labs around the U.S. are rapidly gearing up to run coronavirus tests for patients in need. They're drawing resources from across campus: technology, chemicals and a formidable workforce — graduate students.

"Normally, when people say they need someone in an emergency, it's not a science grad student," says Katie Cabral, a bioengineering Ph.D. student at the University of California, San Francisco. "But in this case, my particular qualifications are exactly what is needed."

As China seeks to control the spread of COVID-19, fewer cars are driving, fewer factories are running and — in some places — skies are clearer.

Air pollution levels have dropped by roughly a quarter over the last month as coal-fired power plants and industrial facilities have ramped down so employees in high-risk areas can stay home. Levels of nitrogen dioxide, a pollutant primarily from burning fossil fuels, were down as much as 30%, according to NASA.

Winters are warming faster than other seasons across much of the United States. While that may sound like a welcome change for those bundled in scarves and hats, it's causing a cascade of unpredictable impacts in communities across the country.

Temperatures continue to steadily rise around the globe, but that trend isn't spread evenly across the map or even the yearly calendar.