Did comets help life begin on Earth? New simulations challenge the idea


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A phenomenon rarer than a solar eclipse and more powerful than any single storm system is unfolding this fall, and NASA is tracking it closely.
El Niño is a natural climate pattern that emerges roughly every two to seven years marked by warmer-than-normal water temperatures in parts of the equatorial Pacific. NASA scientists are keeping watch as it flips trade winds, redistributes ocean heat, scrambles rain patterns, and raises sea surface height across parts of the Pacific.
As of October, the National Oceanic and Atmospheric Administration (NOAA) has said that there’s an 83% chance that the strongest El Niño since 1950 is currently unfolding. People around the world, including farmers, firefighters, and coastal communities, are already experiencing the effects in different ways.
Follow along with these maps as NASA tracks El Niño from its epicenter in the equatorial Pacific Ocean.
One of the first clues appeared in satellite imagery in January 2026, when a swell of warm water called a Kelvin wave was spotted near Micronesia in the western Pacific. Kelvin waves are slow-moving pulses of water thousands of miles long. Like underwater freeways, they transfer heat from west to east across the Pacific. The warm water heats the air directly above it, making it rise. The change in air pressures weakens or even reverses the trade winds that typically blow in the opposing direction, from the Americas toward Asia, causing sea levels in the eastern Pacific to rise further, and waters to warm even more. This chain reaction signifies the start of an El Niño.
The map above shows that by early April, those Kelvin waves had reached the eastern Pacific, and sea surface temperatures had begun to warm. Warm water expands in volume, elevating local sea levels in some areas by as much as 1 to 1.3 feet (30 to 40 centimeters). The higher-than-normal water can be seen sloshing toward South America then moving up the coast to California. Sea levels that are six to eight inches (15 to 20 centimeters) lower than normal are visible around Indonesia and northern Australia.
“Kelvin waves are like the heartbeat of El Niño,” said Josh Willis, project scientist for sea level missions at NASA’s Jet Propulsion Laboratory in Southern California. “And our sea level satellites let us peer into the ocean and watch every beat.”
Scientists have used satellite altimetry to track the height of the ocean with ultraprecision since 1993. That unbroken data record continues today with the Sentinel-6 satellites. State-of-the-art radar altimeters aboard these satellites survey millions of square miles of ocean in a single day, complementing NOAA’s fleet of ocean sensors and buoys drifting and diving through the water below.
Warmer-than-normal seawater is one of the best-known indicators of El Niño. Already, sea surface temperatures in the eastern Pacific are about 3 degrees Fahrenheit (1.7 degrees Celsius) warmer than the long-term average and could jump another fraction of a degree in the coming months, Willis said.
Satellites carrying microwave and infrared radiometers can see through and around clouds to measure heat energy at the sea surface. Satellites in 2026 mapped the band of warmer-than-normal water as it expanded throughout the spring. The band, seen in dark red, stretches for millions of square miles from the heart of the Pacific to the coast of South America. Ocean temperatures can influence weather patterns around the world. Air above the water’s surface carries heat and moisture into the atmosphere, seeding rainstorms and rearranging weather patterns across the globe.
El Niño’s warm waters also change the color of the ocean. A NASA satellite is tracking these subtle shifts in hues, as equatorial Pacific waters have become measurably more blue over the last several months.
“Some people think of water as being just blue, but it’s amazing the multitude of colors the ocean can be,” said Matthew Kehrli, a lead research scientist for the PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) satellite team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
This spectrum is in part thanks to microscopic plants called phytoplankton, which form the basis of the marine food web. There are thousands of different species of phytoplankton, which come in shades like teal, brown, or green. This year, in areas of the Pacific Ocean along the equator that are typically lush with phytoplankton and greener as a result, these hues are waning.
This is an expected effect of El Niño. Phytoplankton thrive in cool, nutrient-rich waters, but during an El Niño, the weakening trade winds reduce the upwelling of nutrient-rich deep water to the ocean surface. With limited food supply, phytoplankton abundance drops. This decline can trigger cascading effects across the marine food web, forcing other marine life to relocate to new feeding grounds.
This year’s El Niño is the first since PACE launched in 2024, providing new views of the phenomenon. The Ocean Color Instrument aboard PACE observes the ocean in hyperspectral color — across several hundred different wavelengths of visible, near-infrared, and ultraviolet light — monitoring phytoplankton and other ocean-color changes in near-real time. With PACE data, researchers calculate the average color of the ocean, simplifying spectra of light into a single number, known as apparent visible wavelength.
The 2026 map above shows the green area along the equator in the western Pacific Ocean shrink as a bluer shade fills in, indicating fewer phytoplankton. In contrast, the map from 2025 shows how the green-hued section stays steady over time.
“You have expectations of what you would think would happen,” Kehrli said. “But to visually see the results with the data products that you’re working with in real time is gratifying.”
NASA scientists will continue to monitor the signs and impacts of this El Niño with its fleet of Earth-observing satellites.
“El Niño touches almost all of us in some way every time it occurs,” Willis said. “While many have seen what it can do, we look to the ocean to understand why.”
View and download these data visualizations here.

The Wildhorse grass fire in eastern Idaho erupted with a massive pulse of smoke. No one had expected it, but the wildfire had launched what’s known as a pyrocumulonimbus cloud, or pyroCb. It was an elusive weather phenomenon that scientists on NASA’s INSPYRE (INjected Smoke and PYRocumulonimbus Experiment) campaign spent weeks this summer hunting across western North America.
Pyrocumulonimbus clouds rise above intense fires, producing lightning and rain along with powerful winds that can whip the flames below into a fury. The largest pyroCbs funnel smoke 30,000 to 50,000 feet (10 to 15 kilometers) above Earth’s surface, as high as the cruising altitudes of commercial jets and even into the stratosphere.
The significance of pyroCbs emerged around the turn of the 21st century, when satellite observations revealed smoke reaching altitudes previously associated with major volcanic eruptions. Once in the stratosphere, pyroCb smoke can spread across continents, circle the globe, and persist far longer than it would in the lower atmosphere.
Despite their massive size, pyroCb clouds remain mysterious. But it’s important to understand how they form and connect with the atmosphere, because their smoke can affect climate and weather far from the fires that produced them and long after they’ve extinguished. They also can produce dangerous fire-generated winds.
“We still do not understand if they’re driven by fire energetics, or fire intensity, or by atmospheric conditions above,” said Olga Kalashnikova, a researcher with NASA’s Jet Propulsion Laboratory in Southern California, who is one of the principal investigators leading INSPYRE, the first aircraft campaign designed specifically around studying pyroCbs.
For six weeks this summer, INSPYRE researchers climbed aboard a Gulfstream jet for a series of flights from the plane’s home base at the National Center for Atmospheric Research (NCAR) near Boulder, Colorado. Scientists collected smoke particles, sampled gases, photographed ice crystals, and monitored radiation passing through clouds and reflected back into space. The aircraft crisscrossed above, below, and through clouds to get a close-up view of fire-induced weather and smoke.
Meanwhile, NASA’s high-flying ER-2 aircraft, loaded with 14 instruments, tracked fire intensity, updraft speeds, smoke, and cloud properties from above, while crews drove trucks equipped with sensors to view the same events from the ground. Ultimately, the team will investigate how wildfire-generated clouds transport smoke upward, how clouds transform particles and gases in smoke, how much reaches the stratosphere, and what happens once it gets there.
Firefighters will benefit from a better understanding of when pyroCbs are likely to develop and how they affect fire conditions on the ground. “A unique thing about pyrocumulonimbus is they are fire-generated weather, meaning the fire makes its own weather,” said Neil Lareau, an atmospheric scientist at the University of Nevada, Reno, who led INSPYRE’s ground observations. “The fire is making its own thunderstorm, and in the process of doing that, it’s also making its own wind.”
Neil Lareau
University of Nevada
Lareau hopes the research will lead to warnings comparable to the alerts meteorologists issue for severe thunderstorms. For example, he said, a forecast would warn firefighters that a developing cloud could soon produce a dangerous downdraft and wind shift, giving fire managers time to pull personnel off the line.
Additionally, INSPYRE could also improve Earth system models. PyroCbs can carry enormous quantities of smoke into the stratosphere, where particles can persist for months or longer and affect how much solar energy the atmosphere absorbs and how much reaches Earth’s surface. Most numerical prediction models don’t explicitly include the effects of pyroCbs and their smoke injections, said Dave Peterson, a Naval Research Laboratory meteorologist and INSPYRE’s co-principal investigator. Measurements of the particles, gases, and radiation associated with these events will give scientists data to test and improve simulations of their effects on Earth’s weather and climate.
To study wildfire smoke and clouds, and perhaps catch a pyroCb in action, the INSPYRE team first had to find one. The challenge was getting an aircraft to the right place at the right time. Pyrocumulonimbus clouds can develop in minutes and subside just as quickly, while reaching fires hundreds of miles away takes hours of preparation, flight time, and coordination with air traffic controllers.
But on Aug. 26, the team got lucky. The Gulfstream was returning from a fire farther west when Sarah Woods, a National Center for Atmospheric Research scientist serving as spotter, got word that the Wildhorse fire was unexpectedly intense.
The fire hadn’t initially attracted much attention. “We knew there was a grass fire there, and everyone’s like, it’s just a grass fire; we’re not going to worry about it,” Peterson said. “And it ended up being the main event.”
DAVE PETERSON
Naval Research Laboratory
When the flight path neared the Wildhorse fire, Woods spotted the fresh remains of a pyroCb from her cramped jump seat behind the pilots. “It looks just like a big thunderstorm, and so as you approach it, you look for a visual indication of the fire on the ground,” said Woods.
Seeing the fire on the ground far below confirmed that the cloud was fire-generated. At Woods’ request, the pilots swung the plane around and spent the next three hours flying back and forth through the cloud plume and the trail of smoke drifting northwest toward Wyoming.
The chance encounter gave the INSPYRE team measurements of a pyroCb plume roughly an hour after the cloud first erupted. Other flights coordinated between the Gulfstream jet and ER-2 added crucial observations of active fire-driven atmospheric airflow that will help document how the resulting smoke plumes evolve over the days and weeks that follow.
Measurements from the Gulfstream and ER-2 will now be combined with satellite and ground observations and compared with models.
“When clouds form, they modify chemistry,” said Kalashnikova, the JPL-based principal investigator. That altered smoke can have different effects on radiation, she said, making it important to understand both how pyroCbs form and the smoke that emerges from them.
In the summer of 2026, the challenge was finding the clouds and collecting the measurements. Now comes the work of understanding what they found.