Science word of the day: Autotroph

Pronunciation: AW'-tuh-trohf

What it means: Autotrophs are organisms that can feed themselves with inorganic substances such as light (for plants) or methane (certain microbes). Autotrophs were the first single-celled life-forms to colonize the planet, thriving on chemicals bubbling up from the subsurface at deep-sea vents or figuring out how to harness the sun for energy. Heterotrophs (like you, me and all fungi), arrived on the scene later to feast on these DIY-ers.

How to use it in a sentence: Stromatolites, microbial mats built by cyanobacteria, are autotrophs that thrived in ancient shallow seas.

Can you crack our science word of the day puzzle, Chain Word?

This year's El Niño will almost certainly become the strongest ever recorded, an analysis by a prominent climate researcher has warned. Though other scientists have cautioned that it's still too early to say what it will unleash.

Dynamical models now assign a 90% chance of the 2026-2027 El Niño being an all-time record event, sending temperatures in the Pacific Ocean up to around 3.6 degrees Celsius (6.5 degrees Fahrenheit) above average, according to an analysis by Zeke Hausfather, a research scientist at Berkeley Earth and an author of the Intergovernmental Panel on Climate Change's Seventh Assessment Report.

As the warm phase of a multiyear natural climate pattern, the El Niño could bring unprecedented temperature extremes to an already-warming world. The natural climate pattern is infamous for boosting global temperatures and fueling disruptive weather events such as floods and droughts.

A strong El Niño doesn't guarantee more severe weather impacts. The current El Niño models are also imperfect predictions of what's to come, and we won't know the true nature of this El Niño event until it peaks, likely later this year. However, forecasters have been warning of potentially supercharged El Niño conditions for months, and as more data emerges, there are more reasons to prepare.

According to projections by the World Meteorological Organization, the current El Niño — officially declared on June 11 — is on track to rapidly develop into a "strong" event between July and September. The National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center now predicts a more than 80% likelihood of very strong El Niño conditions taking hold by the end of the year, ranking this El Niño event among the largest in the historical record.

"These are striking forecasts," Emily Black, a professor of terrestrial processes and climate at the University of Reading and a senior scientist at the National Centre for Atmospheric Science in the U.K., told Live Science in an email. "El Niño forecasts always come with uncertainty, but the level of agreement between models at this time of year, combined with the observed warming already underway in the tropical Pacific, means this should be taken very seriously."

"The important point is that a very strong El Niño would substantially shift the odds of damaging weather in many parts of the world, particularly in the Global South — with severe impact on livelihoods," Black added.

The International Rescue Committee, a humanitarian organization, has warned that the intense El Niño conditions threaten to unleash severe flooding and drought across East Africa and Asia, hitting some of the most vulnerable communities, Al Jazeera reported Tuesday (July 14).

During El Niño, warmer waters gather east of the equatorial Pacific, forcing the jet stream south. In the U.S., this typically brings warmer, drier conditions to the Northeast, while the Gulf Coast and Southeast experience an increased risk of flooding. Globally, the net result of the warmer waters is more heat in the atmosphere, on top of the temperature rise from human-driven global warming.

"El Niño is a natural climate phenomenon, but it is now happening against the backdrop of a much warmer planet," Black said. "That matters because a strong El Niño releases heat and energy into an already warmed world."

"This does not mean every impact can be attributed simply to El Niño or simply to climate change," Black added. "The two interact. El Niño can load the dice towards drought in some regions, flooding in others, marine heatwaves, disrupted monsoons and unusually high global temperatures. Climate change makes many heat extremes more severe and can intensify heavy rainfall because a warmer atmosphere can hold more moisture."

The last El Niño event occurred between 2023 and 2024. Both years broke temperature records, with 2024 becoming the hottest on record and the first to breach the 1.5-degree- Celsius (2.7 degrees Fahrenheit) warming limit set by the 2016 Paris Agreement. The current El Niño is forecast to be more intense than the one in 2023 and 2024, with the projected "very strong" status putting it in a different class of severity.

The strongest El Niño in history?

Hausfather's analysis reports that there's around a 90% chance that the current El Niño will be the strongest ever recorded, with data from multimodel forecasts suggesting that it may obliterate the previous record.

"With the July runs now in from 667 ensemble members across 14 different seasonal forecast models, it looks like this year's El Niño is not only very likely to be the strongest event since reliable records began ‪—‬ it may end up the strongest by a truly mind-blowing margin," Hausfather wrote in The Climate Brink Substack post published Monday (July 13).

NOAA recognizes El Niño conditions when the eastern tropical Pacific Ocean is at least 0.5 C (0.9 F) warmer than the historical average, while wind, surface pressure and rainfall in the region are also consistent with El Niño conditions. The El Niño is then categorized as weak, moderate, strong or very strong. A very strong El Niño (above 2 C, or 3.6 F, warmer than the historical average) is often nicknamed a "super" El Niño, though it's not a scientific term.

The July models suggest that temperatures will likely sail past 2 C above average in the coming months and could potentially even exceed 3.5 C (6.3 F) above average by the end of the year. This is based on newly introduced sea surface temperature forecasts that account for rising background temperatures that can inflate El Niño warming figures. In the traditional and most widely used indices, the temperature-anomaly forecasts cluster closer to 4 C (7.2 F), with some even exceeding 4 C.

In The Climate Brink Substack, Hausfather noted that the multimodel median for the event's peak is currently forecast at 3.6 C (6.5 F), or around 0.8 C (1.4 F) hotter than the prior record holder (2.75 C, set in the 2015-2016 El Niño event). Hausfather wrote that around 91% of ensemble members (individual computer models) have this El Niño exceeding the 2015-2016 record at their peak — around 77% likelihood in the newly introduced indices.

However, Black stressed that the models are still estimates, and not guarantees.

"It is certainly plausible that this could become a record-breaking El Niño, and the latest forecasts make that a real possibility rather than a remote one," Black said. "However, I would still be cautious about treating any probability estimate as a certainty."

"There are two reasons for caution," she added. "First, this event has not peaked yet, and El Niño events usually reach their maximum strength later in the year. Second, 'strongest ever recorded' depends on the index, dataset and baseline used."

"Impacts are what matter"

The most severe El Niño events have left a trail of devastation in their wake. For example, the 2015-2016 El Niño saw a record-breaking hurricane season in the central North Pacific, severe drought in the Caribbean and Ethiopia, and, of course, abnormally hot global temperatures, according to NOAA's Climate.gov. If the forecasts pan out, the current El Niño will match or exceed the 2015-2016 event, as well as an even more infamous super El Niño that occurred between 1877 and 1878, long before modern recordkeeping of El Niño began in 1950.

The 1877-1878 event likely fueled an extreme drought that fed into the 1876-1878 global famine, which ultimately killed more than 50 million people — making it among the worst humanitarian crises in history. However, the disaster was far from just an environmental one, with extractive colonial agricultural policies helping to create conditions for a massive humanitarian crisis. Nonetheless, the famine highlights what can happen when environmental and socioeconomic factors converge.

Even though the world has changed a lot since the 19th century, experts have said a super El Niño could still cause severe shocks to our food systems. This is especially true at a time when researchers say food insecurity is not just confined to low-income countries and that climate change is already pushing agricultural systems to the brink.

The El Niño-Southern Oscillation cycle triggers a warm El Niño and then a cold La Niña roughly every two to seven years, with each phase typically lasting around nine to 12 months. Carbon Brief has predicted that 2026 is likely to be the second-warmest year on record, with the intensifying El Niño increasing the likelihood that 2027 will be the warmest year ever recorded.

The strength of an El Niño event does not necessarily correspond to the size of its influence or impact, according to the Climate Prediction Center. More severe events typically, but not always, increase the certainty of expected impacts. Black believes the impact of an El Niño event is more important than where it ranks in the observational record.

"Records are compelling, but impacts are what matter," Black said. "Even if it falls just short of a record, a very strong El Niño can still have serious consequences. Finally, these forecasts are concerning, but they are also useful: they give societies time to anticipate possible impacts and act before the worst effects are felt."

Heaven Lake is a crater lake at the top of Mount Changbaishan (also called Changbai Mountain) — a colossal, dormant volcano on the border between China and North Korea that formed through successive eruptions over the past 2.6 million years.

Known in China as Tianchi, the lake is the highest and largest crater lake in Northeast Asia, according to UNESCO. It is also the deepest lake in China, according to a study published in March. The lake sits at an elevation of around 7,200 feet (2,200 meters), covers roughly 3.6 square miles (9.2 square kilometers), and has a maximum depth of 1,224 feet (373 m), according to the study.

Heaven Lake is surrounded by 16 peaks that belong to Mount Changbaishan. The lake fills a caldera created by past eruptions, the biggest of which was the "millennium eruption" that took place in A.D. 946 and remains one of the largest eruptions in modern history.

Water started to pool on Mount Changbaishan's summit after the prehistoric Tianwenfeng eruption, which scientists dated to between 70,000 and 40,000 years ago. Heaven Lake has periodically emptied and refilled since then due to precipitation, snowmelt, and an active geothermal system beneath the volcano that forces water up through fault lines.

Although hundreds of reports in the early 2000s claimed there was a creature with a head shaped like that of a horse living in the water, scientists have repeatedly said they are skeptical that any large creature could survive in Heaven Lake.

Mount Changbaishan is one of the best-preserved stratovolcanoes from the past several million years, according to UNESCO. Stratovolcanoes, also known as composite volcanoes, are volcanic mountains built from alternating layers of solidified lava, volcanic ash and rocky debris. Mount Changbaishan is an "open-air classroom for volcanism" because it recorded the different stages of multiple eruptions in astounding detail.

In North Korea, Mount Changbaishan is known as Mount Paektu or Paeku Mountain, meaning "white-topped mountain." The volcano's Chinese name means "forever white mountain."

China, North Korea and South Korea have clashed over the volcano in the past, as the mountain holds cultural and geopolitical significance for the three countries. Two border treaties between China and North Korea in 1962 and 1964 divided the volcano and Heaven Lake roughly down the middle, with North Korea securing 54.5% of the lake.

In the 2000s, China moved to develop the region around the volcano, opening the Mount Changbai Airport and the Mount Changbai Eastern Railroad to connect the region with the rest of the country.

A geological park surrounding the Chinese site of the volcano was officially designated a UNESCO Global Geopark in 2024.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth.

A large pit discovered by an amateur astronomer on Google Maps in 2024 is actually a 390 million-year-old meteor impact crater, scientists have confirmed.

Joël Lapointe was planning a camping trail through Quebec's Côte-Nord region when he stumbled upon a large indentation in the terrain, CBC reported at the time. The pit, centered around Lake Marsal, was about 25 kilometers (15.5 miles) in diameter and a near-perfect ring — it didn't seem like a normal ditch. Lapointe eventually got in touch with French geophysicist Pierre Rochette, who said that the surrounding topography was "very suggestive" of an impact crater.

Initial testing of samples retrieved from the site contained a mineral called zircon often formed during meteor impacts. However, zircon's presence alone was not enough to prove the crater's extraterrestrial origin story. So a team of scientists had visited the pit in person.

"One of the key things we look for is evidence for shock metamorphism, which can only occur due to the immense pressures created by asteroid or cometary impacts — or nuclear explosions," Gordon Osinski, a professor of planetary geology at Western University, told Live Science in an email. "Most of these features are microscopic, so you can only confirm in the lab with samples."

But there is one feature Osinski said can be seen with the naked eye: grooves or lines in the rock's surface called shatter cones, which are caused by shockwaves passing through the ground.

In October 2025, Osinski and a team of geologists visited the site to investigate whether any of these features were present. "This was one of the most arduous expeditions I’ve ever done — and I’ve done 25 expeditions to the Arctic and 6 continents," he said. "The terrain was incredibly rough and rugged, plus [there were] lots of bugs."

But they eventually found what they were looking for — shatter cones. They also discovered big cliffs of impact melt rock, created by the intense temperatures and pressures produced by a meteor impact. "You can melt literally tens of cubic kilometres of the Earth's crust when you get a big enough asteroid hitting," Osinski told CBC.

Taking samples from the rocks, the team dated the crater at 390 million years old.

Osinski, who runs a website called Impact Earth dedicated to verifying meteor impact sites, is used to getting emails about strange looking satellite images. "I get lots of messages from the public thinking they have found a crater and 99/100 turn out not to be the case," he told Live Science. "This is one of those rare examples that shows this is possible."

So far, we know of roughly 200 impact craters on Earth, 31 of which have been found in Canada. "Typically about 1 or 2 craters are discovered per year, but these are typically less than 5-10 km [3 to 6 miles] in size," Osinski said. "[A crater of this size] is pretty rare."

The last meteor crater confirmed in Canada was in 2010.

After the new investigation confirmed the pit was punched out by a meteor impact, Osinski, Rochette and their team named it Uhaachatik Crater following discussions with the Ekuanitshit Innu council, a council representing the indigenous people in the area. The researchers will present their work at the Annual Meeting of the Meteorological Society in Germany next month.

Speaking to Radio-Canada, Lapointe said that he was very happy to hear his discovery had been confirmed as a genuine meteor crater. "It's not every day that an ordinary citizen finds a 390-million-year-old crater," he said. “I encourage everyone to not ignore intuition or an observation, even if it isn’t part of your field of expertise.”

Osinski and the team will continue their work on the collected samples to learn more about the impact site. "Any crater discovered offers us insight into how craters form and the effects that they can have on Earth’s geology, biology, and climate," he told Live Science.

The wildfires tearing across Canada are so extreme that the smoke billowing upward can be seen from space.

What is it?

Over 850 wildfires are currently devastating Canada, as reported by the Canadian Interagency Forest Fire Center. The fires are spreading across Manitoba, Saskatchewan and Ontario; most remain completely uncontrolled.

In addition to the immense destruction caused by the fires themselves, the smoke from these fires is causing serious concerns about dangerously poor air quality all across Canada and even in the northeastern United States. As far as New York, the air quality on Thursday (July 16) was labeled "very unhealthy" after the state activated emergency air quality protocols.

The smoke is so expansive it's clearly visible in this image captured on July 14 from Earth orbit.

Why is it noteworthy?

Studying wildfires and wildfire smoke from orbit can give us a bigger picture view of these catastrophic event. This data is important for disaster relief in the short term — but also in the long-term. With climate change continuing to progress due to human activities like burning coal for cheap power, we can expect natural disasters to worsen. Among the many effects of climate change, this includes longer and more intense wildfire seasons, especially in regions that are already susceptible to fire such as these regions across Canada.

The new image was captured by the NOAA-21 satellite with the instrument VIIRS (Visible Infrared Imagine Radiometer Suite). You can see massive plumes of smoke over southeastern Canada treading into the northeastern U.S. Thick smoke covers swaths of Canada's landscape and wisps of smoke trail all the way down through New York and across the U.S.

Most of this smoke, at least the smoke we can see in this satellite image, is coming from wildfires in northwestern Ontario. As the wildfires continue to burn, satellites like NOAA-21 will be keeping watch.

Towering glaciers flow down the Himalayas' northern slopes like icy giants cascading onto China's Tibetan Plateau.

What is it?

Back in May, from aboard the International Space Station 259 miles (417 kilometers) above Earth, NASA astronaut Jessica Meir peered out the station's windows with her camera and captured a breathtaking sight.

In that fleeting moment from space, she captured the northern slopes of the Himalaya mountains stretching into China. And atop the mountains, slow-moving rivers of glacial ice carve their way downhill.

This view shows the enormity of this mountain range, which separates Nepal from China's Tibetan Plateau. The Himalayas have the highest mountains in the world, including Mount Everest, with over 110 mountain peaks surpassing 24,000 feet (7,300 meters) of elevation above sea level. Ranging across five countries (Nepal, India, China, Bhutan and Pakistan) the mountain range is about 1,500 miles (2,400 kilometers) wide.

Why is it incredible?

With the range being so incredibly expansive, this view from space offers a unique vantage point from which we can see a large swath of the mountains in motion. Even in a helicopter, you would get a fairly localized view of individual mountains in the Himalayas. This view provides a striking scene that you cannot see from the surface of our planet.

This view is also a reminder of how important space is in our evolving understanding of climate change. As our planet continues to change and sea levels rise with warming temperatures, we can see glacial movement from space. This is an important resource to researchers fighting to better understand climate change so we can better fight it. With access to information about glaciers and how they melt, move and flow across the world, we can be better prepared to protect our planet and its inhabitants.

Extreme coastal flooding events are occurring far more frequently in our warming world than ever before, threatening countless communities that will only become more vulnerable as climate change intensifies.

A recent study found that once-in-a-century flooding events now strike on our planet about once a decade. The study, published June 10 in the journal Nature Climate Change, also found that human-driven climate change has quadrupled the frequency of coastal sea level extremes since 1900.

The findings were released alongside another study by a separate team, published in the journal Science Advances, that found human-caused sea level rise was clearly measurable at 97% of sites sampled around the world, and was responsible for around 58% of the observed daily extreme water level exceedances between 2000 and 2018. In other words, human activities are the primary drivers behind sea level extremes — which include storm surges, high tides and rising sea level anomalies.

As the ocean's potential to devastate coastal communities surges, Live Science spoke with Sönke Dangendorf, lead author of the Nature Climate Change study, to learn more about what's to come. Here's what he had to say.

Patrick Pester: How do you separate human-driven sea level rise from natural forces?

Sönke Dangendorf: The absolute basis for doing these kinds of investigations is to work with observations, but observations are unfortunately sparse. We have a few more than 100 tide gauges [distributed worldwide] that offer long, century-scale records of sea level change since the early 20th century. We see that sea levels are changing at those locations, but we cannot tell a whole lot about what is happening elsewhere. So, what we can do is use the same climate models that we use to produce future projections of sea level change.

If you compare observations with the models, then the models need to be able to reproduce what the observations have shown. That was the first step we did, and indeed we proved in this study that the climate models are capable of reproducing observed climate. The nice thing with climate models then is that if you are able to reproduce what has been observed, you can start doing experiments. For instance, you can keep greenhouse gases constant in the modeling and then assess the influence of natural climate variability on the changes that we have observed. That's what we did in the study.

We found that we have seen already a 12-fold increase on average globally in what used to be a once-in-100-year event in 1900. And when we do these forcing experiments, we have also seen that anthropogenic forcing [human-driven change], in particular since the 1970s, has become the dominant force.

PP: What does this mean for coastal communities around the world?

SD: A couple of centimeters of sea level rise doesn't sound like a whole lot in theory, but if you live along the coast, it hits you much harder than you might think. Just an example: I used to live along the U.S. East Coast in Norfolk, Virginia. The community was built along the water, and they used to be fine in the 1950s and 1960s; they wouldn't see flooding at all, or maybe just once every five or six years. But due to sea level rise, what happens now is that high tide leads to flooding. You see flooded streets, and that affects your commute, so people increasingly cannot make it to work.

It affects your daily life suddenly. And then it makes it very hard for you and your coastal community because you have increasing insurance costs — the accumulated costs of these events can easily be as much as a major hurricane making landfall. So, this is a daily experience that many people already have, and it's a direct impact of sea level rise.

With respect to what we assessed in these more extreme events, people may absorb a once-in-a-100-year event once in their lifetime. They may experience something like a Storm Sandy, and they may be able to recover from that, but if you think about recovering from that basically every eight years — the frequency of these events nowadays compared to 1900 — that's of course way more difficult and not feasible for many people.

PP: What can we do?

SD: We can adapt. The silver lining here is that we have shown humans are the dominant forcing factor behind these changes. That's the silver lining because it means if we react, we can do something about it.

The reaction to changes in climate is often delayed, so we have sea level rise that we are already committed to. For instance, if you look into projections, they all agree with respect to what happens until around 2060, independently of how much greenhouse gases are emitted. There's no way around that. We could stop emitting greenhouse gases today, and we would still experience it. So, we need to adapt to that sea level rise, but if we mitigate climate change, if we stop emitting greenhouse gases, then we can avoid dangerous sea level rise, and that's very important.

PP: What will the world look like in 2060 with the committed sea level rise?

SD: According to the last IPCC [Intergovernmental Panel on Climate Change] report, what used to be a once-in-a-100-year event in the present day will occur annually at 19% to 31% of tide gauge locations by 2050. So, at about a quarter of the locations, you will experience these once-in-a-100-year events annually, and that is something that is just mind-blowing.

The changes are happening much quicker in low-latitude locations. The reason is that in the tropics you typically have a less variable climate. You don't have these massive swings all the time. For instance, in the North Sea, we have a storm season, and we have huge tide ranges. We are already adapted to pretty massive changes of multiple meters, so a couple of centimeters of sea level rise do not play out that hard, but in the tropics, where it's more calm, it makes a huge difference.

As an analogy, think about two hurdle runners. You have one hurdle runner that's compared to the tropics; he jumps very consistently but always below the hurdle, so he never makes it over. Then you have another hurdle runner that's the North Sea type of guy. His jumps are very variable. Sometimes he's very high and makes it over that hurdle, but very often he also jumps very low. Now think about lowering that hurdle, which is comparable to increasing sea levels. Suddenly, that hurdle runner who is very consistent makes it over all of the time, while the guy from the North Sea may jump over the hurdle a couple more times, but he also still has the very extreme lows. So, the constant jumper is way more sensitive to these changes.

Editor's note: This interview has been edited and condensed for clarity.

This stunning astronaut photo shows the last time one of NASA's iconic space shuttles photobombed astronauts' view of Earth as the spacecraft docked with the ISS.

NASA's Space Shuttle Program included five plane-like spacecraft — Columbia, Challenger, Discovery, Atlantis and Endeavour — which collectively completed 135 missions between 1981 and 2011, racking up more than 32,000 hours in space. During that time, they helped to construct the ISS and, later, ferry astronauts to and from the station. The space shuttles also helped to deploy and maintain several other important spacecraft, including the Hubble Space Telescope.

The last space shuttle to fly was Atlantis, which successfully completed 33 missions (the second-highest total, behind Discovery).

This photo shows Atlantis approaching the ISS for the last time as it passed over the distinctive turquoise waters of the Bahamas. The space shuttle's bay doors are open, exposing its cargo area. This was standard procedure for all space shuttles once they reached low Earth orbit because it prevented the spacecraft's radiators from overheating.

The open doors also enabled the shuttle's docking mechanism, located within its cargo bay, to attach to the ISS, thus creating a pressurized seal so that astronauts could move between the two spacecraft.

Atlantis' final flight began on July 8, 2011, when it launched from the Kennedy Space Center in Florida vertically strapped to a massive fuel tank and a pair of rocket boosters. It returned to Earth on July 21, gliding down to land onto a runway at the launch site. (The spacecraft is now on display at the Kennedy Space Center Visitor Complex.)

In addition to helping construct the ISS, NASA's space shuttles visited Russia's Mir space station, serviced Hubble, and deployed both the Magellan probe to Venus and the Galileo probe to Jupiter. In total, the space shuttle orbited Earth 4,848 times, traveling nearly 126 million miles (203 million kilometers) — more than 525 times the distance between Earth and the moon.

Astronaut photos of the space shuttles were popular because they offered "punctuated snapshots of distinct places on Earth" that were "framed by a human eye," NASA representatives wrote in 2011. "These images speak to people."

While the Space Shuttle Program achieved a lot during its 30-year history, it famously suffered two tragedies: the 1986 Challenger and 2003 Columbia disasters, which killed all crewmembers on board.

NASA eventually canceled the program in 2011, citing the high cost of maintaining the aging spacecraft and a reduced need for the vehicles after the completion of the ISS the same year. To this day, the space shuttles remain the only winged spacecraft to carry humans into space.

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