Amazing Science

By treating molecules as geometric tessellations, scientists devised a new way to forecast how 2D materials might self-assemble.

While conducting a study of Petermann Glacier in northwest Greenland, researchers at the University of California, Irvine and NASA's Jet Propulsion Laboratory uncovered a previously unseen way in which the ice and ocean interact. The glaciologists said their findings could mean that the climate community has been vastly underestimating the magnitude of future sea level rise caused by polar ice deterioration.

Using satellite radar data from three European missions, the UCI/NASA team learned that Petermann Glacier's grounding line -- where ice detaches from the land bed and begins floating in the ocean -- shifts substantially during tidal cycles, allowing warm seawater to intrude and melt ice at an accelerated rate. The group's results are the subject of a paper published in Proceedings of the National Academy of Sciences.

"Petermann's grounding line could be more accurately described as a grounding zone, because it migrates between 2 and 6 kilometers as tides come in and out," said lead author Enrico Ciraci, UCI assistant specialist in Earth system science and NASA postdoctoral fellow. "This is an order of magnitude larger than expected for grounding lines on a rigid bed."

He said the traditional view of grounding lines beneath ocean-reaching glaciers was that they did not migrate during tidal cycles, nor did they experience ice melt. But the new study replaces that thinking with knowledge that warm ocean water intrudes beneath the ice through preexisting subglacial channels, with the highest melt rates occurring at the grounding zone.

The researchers found that as Petermann Glacier's grounding line retreated nearly 4 kilometers -- 2½ miles -- between 2016 and 2022, warm water carved a 670-foot-tall cavity in the underside of the glacier, and that abscess remained there for all of 2022. "These ice-ocean interactions make the glaciers more sensitive to ocean warming," said senior co-author Eric Rignot, UCI professor of Earth system science and NASA JPL research scientist.

"These dynamics are not included in models, and if we were to include them, it would increase projections of sea level rise by up to 200 percent -- not just for Petermann but for all glaciers ending in the ocean, which is most of northern Greenland and all of Antarctica."

The Greenland ice sheet has lost billions of tons of ice to the ocean in the past few decades, the PNAS paper stresses, with most of the loss caused by warming of subsurface ocean waters, a product of Earth's changing climate. Exposure to ocean water melts the ice vigorously at the glacier front and erodes resistance to the movement of glaciers over the ground, causing the ice to slide more quickly to the sea, according to Rignot.

For the first time, scientists now have a continuous model of the the Earth's past 100 million years. This will provide a new tool to understand ocean chemistry and how geomorphology affects biological evolution.

Climate, tectonics and time combine to create powerful forces that craft the face of our planet. Add the gradual sculpting of the Earth's surface by rivers and what to us seems solid as rock is constantly changing. However, our understanding of this dynamic process has at best been patchy. Scientists have now published new research revealing a detailed and dynamic model of the Earth's surface over the past 100 million years. Working with scientists in France, University of Sydney geoscientists have published this new model in the journal Science.

For the first time, it provides a high-resolution understanding of how today's geophysical landscapes were created and how millions of tonnes of sediment have flowed to the oceans.

The annual Antarctic ozone hole reached an average area of 8.9 million square miles (23.2 million square kilometers) between Sept. 7 and Oct. 13, 2022. This depleted area of the ozone layer over the South Pole was slightly smaller than last year and generally continued the overall shrinking trend of recent years.

“Over time, steady progress is being made, and the hole is getting smaller,” said Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We see some wavering as weather changes and other factors make the numbers wiggle slightly from day to day and week to week. But overall, we see it decreasing through the past two decades. The elimination of ozone-depleting substances through the Montreal Protocol is shrinking the hole.”

The ozone layer – the portion of the stratosphere that protects our planet from the Sun’s ultraviolet rays – thins to form an “ozone hole” above the South Pole every September. Chemically active forms of chlorine and bromine in the atmosphere, derived from human-produced compounds, attach to high-altitude polar clouds each southern winter. The reactive chlorine and bromine then initiate ozone-destroying reactions as the Sun rises at the end of Antarctica’s winter.

Researchers at NASA and NOAA detect and measure the growth and breakup of the ozone hole with instruments aboard the Aura, Suomi NPP, and NOAA-20 satellites. On Oct. 5, 2022, those satellites observed a single-day maximum ozone hole of 10.2 million square miles (26.4 million square kilometers), slightly larger than last year.

As fossil fuel use continues to climb and a hotter planet edges closer to passing any safety limits, some scientists are exploring a controversial technological stopgap: spraying chemicals into the atmosphere to reflect away some of the sun's sunlight. Deploying the technology, using special planes, would be relatively cheap and simple, costing a few billion dollars a year, its backers say. And it could - if maintained - hold down global average temperatures, potentially staving off increasingly deadly climate-change impacts such as heatwaves, they argue.

"I do see it as a likely option" if plans to cut emissions fall short and dangers grow, said Emmi Yonekura, a researcher on the risks of climate "geoengineering" at RAND Corporation, a military-focused policy think-tank, during an online event.  But the technology, which mimics the sky-darkening effect of volcanic eruptions, also carries serious and unpredictable risks, critics say - with some scientists so worried that they believe research should stop and outdoor tests be banned. Threats range from potential shifts in rainfall patterns that could spur worsening hunger to rapid, uncontrollable temperature rise if the technology's use is suddenly stopped. The availability of such a planet-cooling option could also give climate polluters an unwarranted green-light to carry on - even though "stratospheric aerosol injection" (SAI) would only mask the problem, not solve it.

Early efforts to create rules to govern its use show signs of stalling, critics warn, making it more likely that one powerful state or even individual could go it alone, potentially to the detriment of others, sparking conflict. "The more we see extreme events like hurricanes, wildfires, also just heatwaves that have acute impacts - those may motivate key actors to try to protect themselves," said Jonathan Wiener, co-director of the Duke Center on Risk. Unilateral use of the technology "might be very difficult to deal with geopolitically", said Wiener, a law and environmental policy professor at Duke University in the United States. Where scientists and policy experts agree is that, as the world speeds towards the lower 1.5 degree-Celsius warming limit set in the Paris Agreement, serious thinking about what happens if the Earth's climate breaks down must happen - fast.

"We are now entering a situation where the likelihood of overshooting 1.5˚C degrees is higher than not overshooting it," said Janos Pasztor, executive director of the Carnegie Climate Governance Initiative (C2G), a think-tank focused on how to manage "climate-altering technologies".  With the world still "very far" from taking the aggressive steps needed to limit climate change, the impacts of a warming planet will worsen - and in some cases be "catastrophic", he warned. That means more extreme ways to cool the climate are now on the table. Pasztor told an online event it was important to weigh up the risks of taking such measures against not taking them. "Simply not doing either anything or enough ... in itself has huge risks," he said.

Tipping Points

To effectively limit warming, climate-heating emissions - largely from burning fossil fuels - need to fall 45% globally by 2030, scientists say. Instead, they are still rising, as oil and gas use continues to grow and investment in renewable energy alternatives lags. Scientists with the Intergovernmental Panel on Climate Change (IPCC) have warned that if global average temperatures exceed 1.5C above pre-industrial times, the world could see changes that will be hard to adapt to.  Those could include surging hunger as crops fail, as well as growing water shortages, migration and conflict. Deaths and financial losses from worsening heatwaves, wildfires, droughts, floods, hurricanes and sea level rise could also increase, affecting rich countries as well as poor.

More heat could melt Arctic and ocean permafrost that holds climate-heating methane, turbo-charging temperature rise and launching the planet into a vicious heating cycle that would be hard to reverse, scientists say. Some impacts of passing 1.5˚C - such as likely losses of many of the world's coral reefs - "will be irreversible, even if global warming is reduced", warned Thelma Krug, a climate scientist and vice chair of the IPCC.  With the World Meteorological Organization projecting that the 1.5C threshold could be passed, at least temporarily, within five years, a Climate Overshoot Commission of 16 world leaders was launched in May. 

It will look at controversial sun-dimming technologies, alongside efforts to remove carbon dioxide from the atmosphere and to adapt to new conditions.

SAI research has won some powerful financial backers, including Bill Gates and a range of venture capitalists and philanthropists, including at least one former oil executive.

The asteroid that killed off all non-avian dinosaurs made quite the splash when it hit the Yucatan Peninsula some 66 million years ago, generating a tsunami of epic proportions. Seafloor scars from this gigantic wave have been spotted in seismic data taken in Louisiana, offering new insights into this catastrophic event. Reaching over 50 feet tall, they're now the largest known ripples on Earth.

The megatsunami produced by the Chicxulub impact left a lasting mark on the seafloor, according to new research published in Earth and Planetary Science Letters and led by geophysicist Gary Kinsland from the University of Louisiana at Lafayette. The analysis suggests the wave caused the formation of “megaripples” along the bottom. These megaripples are now buried deep underground, but their existence is further confirmation of the power unleashed by the asteroid on that fateful Late Cretaceous day.

That the 6-mile-wide (10-kilometer) asteroid was able to carve the seafloor to such a degree is hardly a surprise. The kinetic energy generated by the impact was roughly 100 million megatons, which is akin to 10 billion Hiroshima-scale bombs going off at the same time. The collision triggered an impact winter that wiped out all non-avian dinosaurs and over 75% of all species on Earth. A simulation from 2018 found that the tsunami reached a maximum height of nearly 5,000 feet (1,500 meters).

The Chicxulub impact occurred in the shallow waters of the Yucatan Peninsula in what is now Mexico, resulting in a global-scale megatsunami (North and South America weren’t connected yet, so this big splash was literally felt around the world). Empirical evidence of the megatsunami is sorely lacking, but research presented in 2019 suggests debris—and even fish—from the impact site were blown thousands of miles away onto what is now southwestern North Dakota. Accordingly, the new paper describing the megaripples deepens our understanding of this cataclysmic event and further proves that a gigantic tsunami was generated by the asteroid impact.

And indeed it was. The new paper documents a series of large-scale megaripples located nearly 5,000 feet (1,500 meters) beneath the surface. The studied layer dates back to the time of the impact, marking the “first time such buried, geologically old, tsunami megaripples have been imaged,” according to the study.

The ripples are separated by distances averaging nearly 2,000 feet (600 meters) and have an average height of 52.5 feet (16 meters), “making them the largest ripples documented on Earth,” as the scientists write in their study. Kinsland and his colleagues say the orientation of the megaripples are consistent with having originated at the site of the asteroid impact. These features formed at depths reaching around 200 feet (60 meters), as the gigantic waves from the tsunami surged northward.

The global economy's business-as-usual approach to climate change has seen Earth's "vital signs" deteriorate to record levels, an influential group of scientists said Wednesday, warning that several climate tipping points were now imminent. The researchers, part of a group of more than 14,000 scientists who have signed on to an initiative declaring a worldwide climate emergency, said that governments had consistently failed to address the root cause of climate change: "the overexploitation of the Earth".

Since a similar assessment in 2019, they noted an "unprecedented surge" in climate-related disasters, including flooding in South America and Southeast Asia, record-shattering heatwaves and wildfires in Australia and the US, and devastating cyclones in Africa and South Asia. Of 31 "vital signs"—key metrics of planetary health that include greenhouse gas emissions, glacier thickness, sea-ice extent and deforestation—they found that 18 hit record highs or lows. For example, despite a dip in pollution linked to the pandemic, levels of atmospheric CO2 and methane hit all-time highs in 2021.

Greenland and Antarctica both recently showed all-time low levels of ice mass, and glaciers are melting 31 percent faster than they did just 15 years ago, the authors said. Both ocean heat and global sea levels set new records since 2019, and the annual loss rate of the Brazilian Amazon reached a 12-year high in 2020.


Highlights of a landmark Intergovernmental Panel on Climate Change (IPCC) draft report on the effects of a warming planet on nature. Echoing previous research, they said that forest degradation linked to fire, drought and logging was causing parts of the Brazilian Amazon to now act as a source of carbon, rather than absorb the gas from the atmosphere. Livestock such as cows and sheep are now at record levels, numbering more than four billion and with a mass exceeding that of all humans and wild land mammals combined, they said.

Tim Lenton, director of the University of Exeter's Global Systems Institute and study co-author, said the recent record-breaking heatwave in the Western United States and Canada showed that the climate had already begun to "behave in shocking, unexpected ways. We need to respond to the evidence that we are hitting climate tipping points with equally urgent action to decarbonize the global economy and start restoring instead of destroying nature," he said.

Three years ago, the place you are reading about now did not exist. Then, suddenly, an underwater volcano erupted in the middle of the South Pacific, and by the time the smoke and ash cleared, a new land mass stood revealed – an island that no-one had ever seen before. That's how the volcanic island of Hunga Tonga-Hunga Ha'apai (Hunga Tonga) came into the world in January 2015, nestling in between two existing, uninhabited Polynesian islands that make up part of the Kingdom of Tonga.

In the last 150 years, only three volcanic islands have emerged like this and survived for more than a few months, with the most famous of them being Surtsey – which appeared off the southern coast of Iceland during a four-year eruption that began in 1963. Scientists have studied Surtsey for decades, but Hunga Tonga – informally named after the submarine volcano above which it sits – is set apart by being the only kind of island like this to emerge in the era of the modern satellite, which gives us a whole new way of studying how these rocky land masses evolve. For example, just for fun, if you do a search for 'Hunga Tonga' in Google Maps' regular Maps view, you'll see an outdated illustration of two islands separated by an expanse of blue water. But if you flick the switch to Satellite view, the newly born island is revealed in all its glory.

That kind of perspective is what intrigues scientists, who are using satellite data to learn what they can about such volcanic upstarts, before erosion inevitably sees Hunga Tonga vanish away again under the waves. "There's a huge amount of material that came out from this eruption, possibly larger than at Surtsey," says geologist Vicki Ferrini from Columbia University, who is studying the island with researchers from NASA. "The other interesting thing is that the two islands that surround this new land mass have some pretty tough substrate, so there's something happening to help make this solidify and stay in place, chemically."

Initially, scientists estimated Hunga Tonga might only last for a few months before disappearing, but researchers now think the island – which covers some 200 hectares (nearly 500 acres) and extends as high as 120 meters (400 feet) above the ocean – could survive for as long as 30 years. Using satellite data updated in real time, the team is developing 3D maps of the island's topography, studying its shifting coastlines and the amount of its land that sits above sea level.

A new study finds that the Atlantic Ocean just had its hottest decade in at least 2,900 years. The new findings are published in the Proceedings of the National Academy of Sciences on Monday, and are another sign the climate is entering an unprecedented state.

More than 20 years after intoning, “The water’s getting warm, so you might as well swim,” Smash Mouth’s “All Star” continues to be prophetic. Case in point: A new study finds that the Atlantic Ocean just had its hottest decade in at least 2,900 years. Someone award Smash Mouth a PhD and calculate the h-index of their discography immediately.

The new findings, published in the Proceedings of the National Academy of Sciences on Monday, rely on a mix of ice and sediment cores as well as thermometer data to track the state of the Atlantic. The ocean has gone through a well-known up-and-down swing in sea surface temperature, known as the Atlantic multidecadal oscillation. Plotted over hundreds of years, the AMO looks like a pretty steady wave pattern. In its warm phase, it can lead to a greater number of intense hurricanes, while the opposite is true in its cool phase. In addition to hurricanes, the phase of the AMO also influences temperature and precipitation over landmasses both immediately adjacent to the ocean and as far away as India.

So the state of the AMO is big deal, especially knowing where it’s heading in a warming climate. To get a handle on where the AMO has been, the researchers turned to a surprising source: the sediment in a lake on Ellesmere Island in the Canadian Arctic. The region is one of the areas heavily influenced by shifts in Atlantic Ocean temperatures. When the Atlantic runs hot, it creates higher pressure over the region, resulting in thinner snowpack; less snowpack means less sediment runoff.

Researchers were able to analyze titanium in layer upon layer of lake sediment to create a time series of the past 2,900 years of Atlantic Ocean temperatures. The finding show the wave pattern of warm and cool periods extends into the past, including a big dip in the heart of the Little Ice Age that ran from 1300 until about 1860. Since then, it’s been rising steadily up, with a sharp peak in the past few decades.

The scientists also compared parts of the new Canadian Arctic to shorter, higher-resolution sediment cores from other locations, including one from off the southern coast of Iceland that covers the past 230 or so years. That record relies on Turborotalita quinqueloba, a tiny, cold-water-loving shelled creature, as a proxy for temperature. The core shows a drop in their numbers over the past century, with the rate of disappearance speeding up.

Taken together, the results show that “recent Atlantic warming is unparalleled” in at least 2,900 years. There are natural factors that could be influencing the shift, but it’s impossible to not consider the impact of climate change. The hallmark of climate change is heat, especially in the oceans. Marine heat waves have become more common and intense. Findings published just last month show rising heat is causing the oceans to stratify. Arctic sea ice plunged to its second lowest levels on record in September as well, again due to hotter oceans.

The extinction of prehistoric megafauna like the woolly mammoth, cave lion, and woolly rhinoceros at the end of the last ice age has often been attributed to the spread of early humans across the globe. Although overhunting led to the demise of some species, a study appearing August 13, 2020 in the journal Current Biology found that the extinction of the woolly rhinoceros may have had a different cause: climate change. By sequencing ancient DNA from 14 of these megaherbivores, researchers found that the woolly rhinoceros population remained stable and diverse until only a few thousand years before it disappeared from Siberia, when temperatures likely rose too high for the cold-adapted species.

"It was initially thought that humans appeared in northeastern Siberia fourteen or fifteen thousand years ago, around when the woolly rhinoceros went extinct. But recently, there have been several discoveries of much older human occupation sites, the most famous of which is around thirty thousand years old," says senior author Love Dalén, a professor of evolutionary genetics at the Centre for Palaeogenetics, a joint venture between Stockholm University and the Swedish Museum of Natural History. "So, the decline towards extinction of the woolly rhinoceros doesn't coincide so much with the first appearance of humans in the region. If anything, we actually see something looking a bit like an increase in population size during this period."

To learn about the size and stability of the woolly rhinoceros population in Siberia, the researchers studied the DNA from tissue, bone, and hair samples of 14 individuals. "We sequenced a complete nuclear genome to look back in time and estimate population sizes, and we also sequenced fourteen mitochondrial genomes to estimate the female effective population sizes," says co-first author Edana Lord, a PhD student at the Centre for Palaeogenetics.

By looking at the heterozygosity, or genetic diversity, of these genomes, the researchers were able to estimate the woolly rhino populations for tens of thousands of years before their extinction. "We examined changes in population size and estimated inbreeding," says co-first author Nicolas Dussex, a postdoctoral researcher at the Centre for Palaeogenetics. "We found that after an increase in population size at the start of a cold period some 29,000 years ago, the woolly rhino population size remained constant and that at this time, inbreeding was low."

This stability lasted until well after humans began living in Siberia, contrasting the declines that would be expected if the woolly rhinos went extinct due to hunting. "That's the interesting thing," says Lord. "We actually don't see a decrease in population size after 29,000 years ago. The data we looked at only goes up to 18,500 years ago, which is approximately 4,500 years before their extinction, so it implies that they declined sometime in that gap."

The DNA data also revealed genetic mutations that helped the woolly rhinoceros adapt to colder weather. One of these mutations, a type of receptor in the skin for sensing warm and cold temperatures, has also been found in woolly mammoths. Adaptations like this suggest the woolly rhinoceros, which was particularly suited to the frigid northeast Siberian climate, may have declined due to the heat of a brief warming period, known as the Bølling-Allerød interstadial, that coincided with their extinction towards the end of the last ice age.

Life as we know it could not exist without Earth's magnetic field and its ability to deflect dangerous ionizing particles from the solar wind and more far-flung cosmic rays. It is continuously generated by the motion of liquid iron in Earth's outer core, a phenomenon called the geodynamo.

Despite its fundamental importance, many questions remain unanswered about the geodynamo's origin and the energy sources that have sustained it over the millennia.

New work from an international team of researchers, including current and former Carnegie scientists Alexander Goncharov, Nicholas Holtgrewe, Sergey Lobanov, and Irina Chuvashova examines how the presence of lighter elements in the predominately iron core could affect the geodynamo's genesis and sustainability. Their findings are published by Nature Communications.

Our planet accreted from the disk of dust and gas that surrounded our Sun in its youth. Eventually, the densest material sank inward in the forming planet, creating the layers that exist today -- core, mantle, and crust. Although, the core is predominately iron, seismic data indicates that some lighter elements like oxygen, silicon, sulfur, carbon, and hydrogen, were dissolved into it during the differentiation process.

Over time, the inner core crystallized and has been continuously cooling since then. On its own, could heat flowing out of the core and into the mantle drive the geodynamo? Or does this thermal convection need an extra boost from the buoyancy of light elements, not just heat, moving out of a condensing inner core?

Understanding the specifics of the core's chemical composition can help answer this question.

Silicates are predominant in the mantle, and after oxygen and iron, silicon is the third-most-abundant element in the Earth, so it is a likely option for one of the main lighter elements that could be alloyed with iron in the core. Led by Wen-Pin Hsieh of Academia Sinica and National Taiwan University, the researchers used lab-based mimicry of deep Earth conditions to simulate how the presence of silicon would affect the transmission of heat from the planet's iron core out into the mantle.

"The less thermally conductive the core material is, the lower the threshold needed to generate the geodynamo," Goncharov explained. "With a low enough threshold, the heat flux out of the core could be driven entirely by the thermal convection, with no need for the additional movement of material to make it work."

Lab-made quakes suggested that we should see hints of activity before a big event, but this pattern has been elusive in nature—until now.

The finding contradicts previous assumptions about the role of mobile plate tectonics in the development of life on Earth.

Scientists have taken a journey back in time to unlock the mysteries of Earth's early history, using tiny mineral crystals called zircons to study plate tectonics billions of years ago. The research sheds light on the conditions that existed in early Earth, revealing a complex interplay between Earth's crust, core, and the emergence of life.

Plate tectonics allows heat from Earth's interior to escape to the surface, forming continents and other geological features necessary for life to emerge. Accordingly, "there has been the assumption that plate tectonics is necessary for life," says John Tarduno, who teaches in the Department of Earth and Environmental Sciences at the University of Rochester. But new research casts doubt on that assumption.

Tarduno, the William R. Kenan, Jr. Professor, is lead author of a paper published in Nature examining plate tectonics from a time 3.9 billion years ago, when scientists believe the first traces of life appeared on Earth. The researchers found that mobile plate tectonics was not occurring during this time. Instead, they discovered, Earth was releasing heat through what is known as a stagnant lid regime. The results indicate that although plate tectonics is a key factor for sustaining life on Earth, it is not a requirement for life to originate on a terrestrial-like planet.

"We found there wasn't plate tectonics when life is first thought to originate, and that there wasn't plate tectonics for hundreds of millions of years after," says Tarduno. "Our data suggests that when we're looking for exoplanets that harbor life, the planets do not necessarily need to have plate tectonics."

After analyzing the achondrite meteorite samples, researchers discovered that water comprised less than two millionths of their mass. For comparison, the wettest meteorites -- a group called carbonaceous chondrites -- contain up to about 20% of water by weight, or 100,000 times more than the meteorite samples studied by Newcombe and her co-authors.

This means that the heating and melting of planetesimals leads to near-total water loss, regardless of where these planetesimals originated in the solar system and how much water they started out with. Newcombe and her co-authors discovered that, contrary to popular belief, not all outer solar system objects are rich in water. This led them to conclude that water was likely delivered to Earth via unmelted, or chondritic, meteorites.

Newcombe said their findings have applications beyond geology. Scientists of many disciplines -- and especially exoplanet researchers -- are interested in the origin of Earth's water because of its deep connections with life.

"Water is considered to be an ingredient for life to be able to flourish, so as we're looking out into the universe and finding all of these exoplanets, we're starting to work out which of those planetary systems could be potential hosts for life," Newcombe said. "In order to be able to understand these other solar systems, we want to understand our own."

When the Sun and Moon act on the Earth, our planet bulges a little bit due to these tidal forces. And, when something gravitationally pulls on a spinning, bulging object, that external force acts the same way that lightly putting your finger up against a spinning top acts: as a frictional force, slowing the rotation down. Over time, this can really add up!

This “braking” effect takes angular momentum away from the spinning Earth, causing it to rotate slower and slower over time. But angular momentum is something that’s fundamentally conserved; it cannot be created or destroyed, only transferred from one object to another. If the Earth’s rotation is slowing down, that angular momentum must transfer elsewhere.

So where is that elsewhere? Into the Moon, which spirals away from the Earth as the Earth’s rotation slows down. With every year that passes, these tidal forces lengthen the amount of time it takes for Earth to complete a full 360° rotation by a tiny, but barely perceptible amount. Compared to precisely one year ago today, our planet takes an extra 14 microseconds to complete a full rotation. This extra 14 microseconds per day adds up over time, which is why — on average — we have to add a leap second to our clock to keep them where they ought to be every 18 months.

Of course, this effect accumulates over longer periods of time, but there are other effects working alongside it:

• radiation from the Sun, which pushes Earth slightly outward in its orbit around the Sun,
• the solar wind — particles from the Sun — which collide with Earth and slightly slow its motion down,
• and mass loss from the Sun, which emits particles and converts mass into energy (via Einstein’s E = mc2) through nuclear fusion in its core, causing Earth to slowly spiral outwards, away from the Sun.

While the effects of angular momentum loss cause Earth to spin at a slower rate, meaning that as time goes on, it takes fewer “days” to make up a year, these effects all do something else entirely. When you push Earth outwards, when you slow Earth’s motion down, or when you decrease the mass of the Sun, it causes the year to lengthen. The greatest effect, as it turns out, comes from mass loss, as the Sun a total of about 5.6 million tons of mass each second from nuclear fusion (4 million) and the solar wind (1.6 million) combined, or the equivalent of 177 trillion tons of mass per year.

With each year that goes by, this mass loss means that Earth spirals outwards at a rate of approximately 1.5 cm (about 0.6 inches) every year. Over the history of our Solar System, taking into account how our Sun has changed, we’re somewhere around 50,000 km farther from the Sun versus 4.5 billion years ago. And we’re orbiting around the Sun at a slightly slower speed — about 0.01 km/s slower — today than we were back when the Solar System first formed. Consider that at our fastest, Earth moves through space at 30.29 km/s (18.83 mi/s), while at our slowest, we move at 29.29 km/s (18.20 mi/s), this difference is very, very small, and the effect can be completely neglected without losing pretty much any accuracy. Similarly, effects like earthquakes, ice melting, core formation, and thermal expansion of the Earth all exist, but only dominate on very short timescales where changes are relatively rapid.

What does, then, on the long timescales we’re considering? The dominant effect in determining how the length of a Tropical Year changes relative to a calendar year is set by tidal braking of the Earth. And the longer we wait, the greater the discrepancy becomes. It won’t be, astronomically speaking, all that long before adding a second here or there becomes a wildly insufficient fix for our changing planet.

The way we’ll need to modify our calendar, as the Earth’s rotation slightly slows down, is by removing days, rather than adding them. As time goes on initially, we’ll want to begin reducing the frequency of leap years; we’ll be able to eliminate them entirely after another ~4 million years passes. At that point, Earth will rotate a little more slowly, and a calendar year will correspond to precisely 365.0000 days. Beyond that point, we’ll need to start having “reverse” leap years, where we remove a day every so often, before we eventually go down to ~364 day years some ~21 million years into the future. As these changes occur, the day will lengthen to greater than 24 hours. Eventually, we’ll even pass Mars, with a 24 hour, 37 minute day, to become the planet with the 3rd longest day in the Solar System, behind only Mercury and Venus.

Some 66 million years ago, a 10-kilometer asteroid hit Earth, triggering a firestorm engulfing most of the North American continent, a tsunami with mountain-sized waves, and an earthquake so massive that it shook the planet for weeks to months after the collision. The amount of energy released in this "mega-earthquake" is estimated at 10^23 joules, which is about 50,000 times more energy than was released in the magnitude 9.1 Sumatra earthquake in 2004 - one of the most powerful earthquakes ever experienced by humankind.

In 2014, while doing fieldwork on Colombia's Gorgonilla Island, Bermúdez found spherule deposits—layers of sediment filled with small glass beads and shards known as "tektites" and "microtektites" that were ejected into the atmosphere during an asteroid impact. These glass beads formed when the heat and pressure of the impact melted and scattered the crust of the Earth, ejecting small, melted blobs up into the atmosphere, which then fell back to the surface as glass under the influence of gravity.

The rocks exposed on the coast of Gorgonilla Island tell a story from the bottom of the ocean—roughly 2 kilometers down. There, about 3,000 kilometers southwest of the site of the impact, sand, mud, and small ocean creatures were accumulating on the ocean floor when the asteroid hit. Layers of mud and sandstone as far as 10–15 meters below the sea floor experienced soft-sediment deformation that is preserved in the outcrops today, which Bermúdez attributes to the shaking from the impact.

Faults and deformation due to shaking continue up through the spherule-rich layer that was deposited post-impact, indicating that the shaking must have continued for the weeks and months it took for these finer-grained deposits to reach the ocean floor. Just above those spherule deposits, preserved fern spores signal the first recovery of plant-life after the impact.

Bermúdez explains, "The section I discovered on Gorgonilla Island is a fantastic place to study the Cretaceous–Paleogene boundary, because it is one of the best-preserved and it was located deep in the ocean, so it was not affected by tsunamis." Evidence of deformation from the mega-earthquake is also preserved in Mexico and the United States. At the El Papalote exposure in Mexico, Bermúdez observed evidence of liquefaction—when strong shaking causes water-saturated sediments to flow like a liquid. In Mississippi, Alabama, and Texas, Bermúdez documented faults and cracks likely associated with the mega-quake. He also documented tsunami deposits at several outcrops, left by an enormous wave that was part of the cascading catastrophes resulting from the asteroid collision.

Bermúdez will deliver a talk about his team's research at the GSA Connects meeting on Sunday, October 9. He will also present a poster about his observations of tsunami deposits and earthquake-related deformation on Monday, October 10th, 2022.

WITHOUT THE OCEAN, climate change on land would be even more catastrophic. The seas have absorbed over 90 percent of the excess heat from greenhouse gas emissions, essentially saving humanity from itself. But it’s taking a toll: The ocean, too, is rapidly warming. And just as we have heat waves on land, parts of the ocean can experience temperature spikes too.

New research exposes just how bad the problem has gotten. Researchers from the Monterey Bay Aquarium began their calculation by analyzing surface temperature data from 1870 to 1919, sampled from across the globe. (Yes, ships have been taking the ocean’s temperature for 150 years.) Once they knew the historical high temperatures for each month in different parts of the ocean, they had a baseline for marine temperature extremes before the escalation of climate change. In the 19th century, only 2 percent of the ocean surface experienced such extremes. 

Then they compared this data to readings in the same places taken from 1920 to 2019. Their results show that by the year 2014, half of the ocean surface was logging temperatures once considered extreme—exceeding those historical highs. By 2019, that figure was 57 percent. In 150 years, the occurrence of extreme heat had become the new normal. 

These spikes are different from the overall rise in water temperature, which is also caused by global warming. For one thing, a particular region can come back down off of a high when winter arrives. And the location of the spikes can vary over time, meaning some places were affected earlier than others. So while half the ocean surface was logging temperature extremes by 2014, the South Atlantic had actually crossed that threshold back in 1998. 

“And that is ludicrous,” says ecologist Kyle Van Houtan, president and CEO of the Loggerhead Marinelife Center, who coauthored today’s paper in the journal PLOS Climate describing the findings. (Van Houtan did the research in his previous role as the chief scientist at the aquarium, with marine biologist Kisei Tanaka, now at the National Oceanic and Atmospheric Administration.) “There's some major changes going on right now in the ocean, and we think that this calculation, this index, of marine heat that we built is helping to describe why,” he continues. “I think extreme marine heat is much more of a problem than we thought it was. It's actually common today, which is scary, because historically it was just extreme—it was rare.”

“The trends they're seeing are consistent with results from a lot of other papers that conclude that marine heat waves are becoming more frequent, they're warmer, and they're lasting longer,” says Bridget Seegers, an oceanographer at NASA, who wasn’t involved in the work. (She was, though, among the researchers who recently reported that 2021 was the sixth hottest year ever recorded.)

A shutdown would have devastating global impacts and must not be allowed to happen, researchers say

Climate scientists have detected warning signs of the collapse of the Gulf Stream, one of the planet’s main potential tipping points. The research found “an almost complete loss of stability over the last century” of the currents that researchers call the Atlantic meridional overturning circulation (AMOC). The currents are already at their slowest point in at least 1,600 years, but the new analysis shows they may be nearing a shutdown.

Such an event would have catastrophic consequences around the world, severely disrupting the rains that billions of people depend on for food in India, South America and West Africa; increasing storms and lowering temperatures in Europe; and pushing up the sea level in the eastern North America. It would also further endanger the Amazon rainforest and Antarctic ice sheets.

The complexity of the AMOC system and uncertainty over levels of future global heating make it impossible to forecast the date of any collapse for now. It could be within a decade or two, or several centuries away. But the colossal impact it would have means it must never be allowed to happen, the scientists said.

“The signs of destabilization being visible already is something that I wouldn’t have expected and that I find scary,” said Niklas Boers, from the Potsdam Institute for Climate Impact Research in Germany, who did the research. “It’s something you just can’t allow to happen.”

It is not known what level of CO2 would trigger an AMOC collapse, he said. “So the only thing to do is keep emissions as low as possible. The likelihood of this extremely high-impact event happening increases with every gram of CO2 that we put into the atmosphere”.

Earlier this year, the Earth saw a huge dip in carbon emissions as nations around the globe locked down to slow the spread of the coronavirus. It offered a glimpse into what the world might look like if we took drastic steps to reduce our carbon emissions to slow the spread of global warming: For a brief moment, smog-choked cities around the world had clear skies.

But according to a new modeling study published in Scientific Reports, even if we made such drastic reductions permanent, it would still not be enough. The study suggests that if we stopped all human-made greenhouse gas emissions immediately, the Earth’s temperatures would continue to rise because of self-sustaining melting ice and permafrost. These “feedback loops” — in which melting ice causes less sunlight to be reflected back into space, which in turn raises temperatures and causes more ice melt — have already been set into motion, the researchers argue.

Humanity “is beyond the point-of-no-return when it comes to halt the melting of the permafrost using greenhouse gas cuts as the single tool,” Jørgen Randers, PhD, professor emeritus of climate strategy at BI Norwegian Business School and lead author of the study, tells Future Human in an email. That’s not to say we should give up on reducing emissions: Rather, Randers says that the world "should accelerate its effort to cut greenhouse gas emissions (in order to postpone as much as possible the temperature rise) and start developing the technologies for large scale removal of greenhouse gases from the atmosphere.”

For decades, climate scientists have tried to predict the so-called tipping point at which it would be too late to stop global warming — too late to limit the amount the temperature rises, the amount of sea level rise, and the number of lives claimed by both and other climate-induced ecological disasters — through reducing carbon emissions alone. Climate scientists point to either 2030 or 2050 as deadlines for the world to get to zero emissions before runaway climate change kicks in. But according to the new study, no matter how much we reduce emissions now, warming will continue, and the self-sustained melting of Arctic ice and permafrost that has already begun could continue for 500 years.

“It simply will not stop from cutting manmade greenhouse gasses,” says Randers. “We need to do something more in order to stop it.” He and co-author Ulrich Goluke, an associate professor at Business School Lausanne in Switzerland, make the case that it’s time to pursue more aggressive climate strategies, like carbon sequestration.

LOCKDOWN EARTH - The lack of human activity during lockdown caused human-linked vibrations in the Earth to drop by an average of 50% between March and May 2020.

The lack of human activity during lockdown caused human-linked vibrations in the Earth to drop by an average of 50% between March and May 2020. This quiet period, likely caused by the total global effect of social distancing measures, closure of services and industry, and drops in tourism and travel, is the longest and most pronounced quiet period of seismic noise in recorded history.

The new research, led by the Royal Observatory of Belgium and five other institutions around the world including Imperial College London, showed that the dampening of ‘seismic noise’ caused by humans was more pronounced in more densely populated areas.

The relative quietness allowed researchers to listen in to previously concealed earthquake signals, and could help us differentiate between human and natural seismic noise more clearly than ever before.

Co-author Dr Stephen Hicks, from Imperial’s Department of Earth Science and Engineering, said: “This quiet period is the longest and largest dampening of human-caused seismic noise since we started monitoring the Earth in detail using vast monitoring networks of seismometers.

“Our study uniquely highlights just how much human activities impact the solid Earth, and could let us see more clearly than ever what differentiates human and natural noise.” The paper been published in the journal Science.

A new study reveals that changes in the direction of the Earth’s magnetic field may take place 10 times faster than previously thought.

A team of researchers led by Arizona State University School of Earth and Space Exploration Professor Lindy Elkins-Tanton has provided the first ever direct evidence that extensive coal burning in Siberia is a cause of the Permo-Triassic Extinction, the Earth’s most severe extinction event.

A team of researchers led by Arizona State University School of Earth and Space Exploration Professor Lindy Elkins-Tanton has provided the first ever direct evidence that extensive coal burning in Siberia is a cause of the Permo-Triassic Extinction, the Earth’s most severe extinction event. The results of their study have been recently published in the journal Geology.

For this study, the international team led by Elkins-Tanton focused on the volcaniclastic rocks of the Siberian Traps, a region of volcanic rock in Russia. The massive eruptive event that formed the traps is one of the largest known volcanic events in the last 500 million years. The eruptions continued for roughly 2 million years and spanned the Permian-Triassic boundary. Today, the area is covered by about 3 million square miles of basaltic rock.

This is ideal ground for researchers seeking an understanding of the Permo-Triassic extinction event, which affected all life on Earth approximately 252 million years ago. During this event, up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct.

Calculations of sea water temperature indicate that at the peak of the extinction, the Earth underwent lethally hot global warming, in which equatorial ocean temperatures exceeded 104 degrees Fahrenheit. It took millions of years for ecosystems to be re-established and for species to recover.

Among the possible causes of this extinction event, and one of the most long-hypothesized, is that massive burning coal led to catastrophic global warming, which in turn was devastating to life. To search for evidence to support this hypothesis, Elkins-Tanton and her team began looking at the Siberian Traps region, where it was known that the magmas and lavas from volcanic events burned a combination of vegetation and coal.

While samples of volcaniclastics in the region were initially difficult to find, the team eventually discovered a scientific paper describing outcrops near the Angara River. “We found towering river cliffs of nothing but volcaniclastics, lining the river for hundreds of miles. It was geologically astounding,” Elkins-Tanton said.

By measuring chemistry of fossilized seashells, researchers found that the Earth was already experiencing carbon cycle instability when the asteroid hit that wiped out the dinosaurs.

New evidence gleaned from Antarctic seashells confirms that Earth was already unstable before the asteroid impact that wiped out the dinosaurs. The study, led by researchers at Northwestern University, is the first to measure the calcium isotope composition of fossilized clam and snail shells, which date back to the Cretaceous-Paleogene mass extinction event. The researchers found that — in the run-up to the extinction event — the shells’ chemistry shifted in response to a surge of carbon in the oceans.

This carbon influx was likely due to long-term eruptions from the Deccan Traps, a 200,000-square-mile volcanic province located in modern India. During the years leading up to the asteroid impact, the Deccan Traps spewed massive amounts of carbon dioxide (CO2) into the atmosphere. The concentration of CO2 acidified the oceans, directly affecting the organisms living there.

“Our data suggest that the environment was changing before the asteroid impact,” said Benjamin Linzmeier, the study’s first author. “Those changes appear to correlate with the eruption of the Deccan Traps.”

The study will be published in the January 2020 issue of the journal Geology, which comes out later this month.

Jacobson is a professor of Earth and planetary sciences in Northwestern’s Weinberg College of Arts and Sciences. Linzmeier was a postdoctoral researcher with the Ubben Program for Climate and Carbon Science at the Institute for Sustainability and Energy at Northwestern when the research was conducted. He is now a postdoctoral fellow at the University of Wisconsin-Madison in the Department of Geoscience.