Artist’s impression of K2-18 b.
NASA, ESA, CSA, Joseph Olmsted (STScI)Manoj Joshi, University of East Anglia; Andrew Rushby, Birkbeck, University of London, and Maria Di Paolo, University of East Anglia
A team of researchers has recently claimed they have discovered a gas called dimethyl sulphide (DMS) in the atmosphere of K2-18b, a planet orbiting a distant star.
The University of Cambridge team’s claims are potentially very exciting because, on Earth at least, the compound is produced by marine bacteria. The presence of this gas may be a sign of life on K2-18b too – but we can’t rush to conclusions just yet.
K2-18b has a radius 2.6 times that of Earth, a mass nearly nine times greater and orbits a star that is 124 light years away. We can’t directly tell what kinds of large scale characteristics it has, although one possibility is a world with a global liquid water ocean under a hydrogen-rich atmosphere.
Such a world might well be hospitable to life, but different ideas exist about the properties of this planet – and what that might mean for a DMS signature.
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Claims for the detection of life on other planets go back decades.
In the 1970s, one of the scientists working on the Viking mission to Mars claimed that his experiment had indicated there could be microorganisms in the Martian soil. However, these conclusions were widely refuted by other researchers.
In 1996, a team said that microscopic features resembling bacteria had been found in the Martian meteorite ALH84001. However, subsequent studies cast significant doubt on the discovery.
Since the early 2000s there have also been repeated claims for the detection of methane gas in the atmosphere of Mars, both by remote sensing by satellites and by in-situ observations by rovers.
Methane can be produced by several mechanisms. One of these potential sources involves production by microorganisms. Such sources are described by scientists as being “biotic”. Other sources of methane, such as volcanoes and hydrothermal vents, don’t require life and are said to be “abiotic”.
The claimed detection of phosphine gas in Venus’ atmosphere has been proposed as a biosignature.Nasa
Not all of the previous claims for evidence of extraterrestrial life involve the red planet. In 2020, Earth-based observations of Venus’s atmosphere implied the presence of low levels of phosphine gas.
Because phosphine gas can be produced by microbes, there was speculation that life might exist in Venus’s clouds. However, the detection of phosphine was later disputed by other scientists.
Proposed signs of life on other worlds are known as “biosignatures”. This is defined as “an object, substance, and/or pattern whose origin specifically requires a biological agent”. In other words, any detection requires all possible abiotic production pathways to be considered.
In addition to this, scientists face many challenges in the collection, interpretation, and planetary environmental context of possible biosignature gases. Understanding the composition of a planetary atmosphere from limited data, collected from light years away, is very difficult.
We also have to understand that these are often exotic environments, with conditions we do not experience on Earth. As such, exotic chemical processes may occur here too.
In order to characterise the atmospheres of exoplanets, we obtain what are called spectra. These are the fingerprints of molecules in the atmosphere that absorb light at specific wavelengths.
Once the data has been collected, it needs to be interpreted. Astronomers assess which chemicals, or combinations thereof, best fit the observations. It is an involved process and one that requires lots of computer based work. The process is especially challenging when dealing with exoplanets, where available data is at a premium.
Once these stages have been carried out, astronomers can then assign a confidence to the likelihood of a particular chemical signature being “real”. In the case of the recent discovery from K2-18b, the authors claim the detection of a feature that can only be explained by DMS with a likelihood of greater than 99.9%. In other words, there’s about a 1 in 1,500 chance that this feature is not actually there.
While the team behind the recent result favours a model of K2-18b as an ocean world, another team suggests it could actually have a magma (molten rock) ocean instead. It could also be a Neptune-like “gas dwarf” planet, with a small core shrouded in a thick layer of gas and ices. Both of these options would be much less favourable to the development of life – raising questions as to whether there are abiotic ways that DMS can form.
A higher bar?
But is the bar higher for claims of extraterrestrial life than for other areas of science? In a study claiming the detection of a biosignature, the usual level of scientific rigour expected for all research should apply to the collection and processing of the data, along with the interpretation of the results.
However, even when these standards have been met, claims that indicate the presence of life have in the past still been meet with high levels of scepticism. The reasons for this are probably best summed up by the phrase “extraordinary claims require extraordinary evidence”. This is attributed to the American planetary scientist, author and science communicator Carl Sagan.
While on Earth there are no known means of producing DMS without life, the chemical has been detected on a comet called 67/P, which was studied up close by the European Space Agency’s Rosetta spacecraft. DMS has even been detected in the interstellar medium, the space between stars, suggesting that it can be produced by non-biological, or abiotic, mechanisms.
Given the uncertainties about the nature of K2-18b, we cannot be sure if the presence of this gas might simply be a sign of non-biological processes we don’t yet understand.
The claimed discovery of DMS on K2-18b is interesting, exciting, and reflects huge advances in astronomy, planetary science and astrobiology. However, its possible implications mean that we have to consider the results very cautiously. We must also entertain alternative explanations before supporting such a profound conclusion as the presence of extraterrestrial life.Manoj Joshi, Professor of Climate Dynamics, University of East Anglia; Andrew Rushby, Lecturer, School of Natural Sciences, Birkbeck, University of London, and Maria Di Paolo, PhD Candidate, School of Engineering, Mathematics and Physics, University of East Anglia
This article is republished from The Conversation under a Creative Commons license. Read the original article.
This screenshot of an AI-generated video depicts Christopher Pelkey, who was killed in 2021.
Screenshot: Stacey Wales/YouTubeNir Eisikovits, UMass Boston and Daniel J. Feldman, UMass Boston
Christopher Pelkey was shot and killed in a road range incident in 2021. On May 8, 2025, at the sentencing hearing for his killer, an AI video reconstruction of Pelkey delivered a victim impact statement. The trial judge reported being deeply moved by this performance and issued the maximum sentence for manslaughter.
As part of the ceremonies to mark Israel’s 77th year of independence on April 30, 2025, officials had planned to host a concert featuring four iconic Israeli singers. All four had died years earlier. The plan was to conjure them using AI-generated sound and video. The dead performers were supposed to sing alongside Yardena Arazi, a famous and still very much alive artist. In the end Arazi pulled out, citing the political atmosphere, and the event didn’t happen.
In April, the BBC created a deep-fake version of the famous mystery writer Agatha Christie to teach a “maestro course on writing.” Fake Agatha would instruct aspiring murder mystery authors and “inspire” their “writing journey.”
The use of artificial intelligence to “reanimate” the dead for a variety of purposes is quickly gaining traction. Over the past few years, we’ve been studying the moral implications of AI at the Center for Applied Ethics at the University of Massachusetts, Boston, and we find these AI reanimations to be morally problematic.
Before we address the moral challenges the technology raises, it’s important to distinguish AI reanimations, or deepfakes, from so-called griefbots. Griefbots are chatbots trained on large swaths of data the dead leave behind – social media posts, texts, emails, videos. These chatbots mimic how the departed used to communicate and are meant to make life easier for surviving relations. The deepfakes we are discussing here have other aims; they are meant to promote legal, political and educational causes.
Chris Pelkey was shot and killed in 2021. This AI ‘reanimation’ of him was presented in court as a victim impact statement.
Moral quandaries
The first moral quandary the technology raises has to do with consent: Would the deceased have agreed to do what their likeness is doing? Would the dead Israeli singers have wanted to sing at an Independence ceremony organized by the nation’s current government? Would Pelkey, the road-rage victim, be comfortable with the script his family wrote for his avatar to recite? What would Christie think about her AI double teaching that class?
The answers to these questions can only be deduced circumstantially – from examining the kinds of things the dead did and the views they expressed when alive. And one could ask if the answers even matter. If those in charge of the estates agree to the reanimations, isn’t the question settled? After all, such trustees are the legal representatives of the departed.
But putting aside the question of consent, a more fundamental question remains.
What do these reanimations do to the legacy and reputation of the dead? Doesn’t their reputation depend, to some extent, on the scarcity of appearance, on the fact that the dead can’t show up anymore? Dying can have a salutary effect on the reputation of prominent people; it was good for John F. Kennedy, and it was good for Israeli Prime Minister Yitzhak Rabin.
The fifth-century B.C. Athenian leader Pericles understood this well. In his famous Funeral Oration, delivered at the end of the first year of the Peloponnesian War, he asserts that a noble death can elevate one’s reputation and wash away their petty misdeeds. That is because the dead are beyond reach and their mystique grows postmortem. “Even extreme virtue will scarcely win you a reputation equal to” that of the dead, he insists.
Do AI reanimations devalue the currency of the dead by forcing them to keep popping up? Do they cheapen and destabilize their reputation by having them comment on events that happened long after their demise?
In addition, these AI representations can be a powerful tool to influence audiences for political or legal purposes. Bringing back a popular dead singer to legitimize a political event and reanimating a dead victim to offer testimony are acts intended to sway an audience’s judgment.
It’s one thing to channel a Churchill or a Roosevelt during a political speech by quoting them or even trying to sound like them. It’s another thing to have “them” speak alongside you. The potential of harnessing nostalgia is supercharged by this technology. Imagine, for example, what the Soviets, who literally worshipped Lenin’s dead body, would have done with a deep fake of their old icon.
Good intentions
You could argue that because these reanimations are uniquely engaging, they can be used for virtuous purposes. Consider a reanimated Martin Luther King Jr., speaking to our currently polarized and divided nation, urging moderation and unity. Wouldn’t that be grand? Or what about a reanimated Mordechai Anielewicz, the commander of the Warsaw Ghetto uprising, speaking at the trial of a Holocaust denier like David Irving?
But do we know what MLK would have thought about our current political divisions? Do we know what Anielewicz would have thought about restrictions on pernicious speech? Does bravely campaigning for civil rights mean we should call upon the digital ghost of King to comment on the impact of populism? Does fearlessly fighting the Nazis mean we should dredge up the AI shadow of an old hero to comment on free speech in the digital age?
No one can know with certainty what Martin Luther King Jr. would say about today’s society.AP Photo/Chick Harrity
Even if the political projects these AI avatars served were consistent with the deceased’s views, the problem of manipulation – of using the psychological power of deepfakes to appeal to emotions – remains.
But what about enlisting AI Agatha Christie to teach a writing class? Deep fakes may indeed have salutary uses in educational settings. The likeness of Christie could make students more enthusiastic about writing. Fake Aristotle could improve the chances that students engage with his austere Nicomachean Ethics. AI Einstein could help those who want to study physics get their heads around general relativity.
But producing these fakes comes with a great deal of responsibility. After all, given how engaging they can be, it’s possible that the interactions with these representations will be all that students pay attention to, rather than serving as a gateway to exploring the subject further.
Living on in the living
In a poem written in memory of W.B. Yeats, W.H. Auden tells us that, after the poet’s death, Yeats “became his admirers.” His memory was now “scattered among a hundred cities,” and his work subject to endless interpretation: “the words of a dead man are modified in the guts of the living.”
The dead live on in the many ways we reinterpret their words and works. Auden did that to Yeats, and we’re doing it to Auden right here. That’s how people stay in touch with those who are gone. In the end, we believe that using technological prowess to concretely bring them back disrespects them and, perhaps more importantly, is an act of disrespect to ourselves – to our capacity to abstract, think and imagine.
Nir Eisikovits, Professor of Philosophy and Director, Applied Ethics Center, UMass Boston and Daniel J. Feldman, Senior Research Fellow, Applied Ethics Center, UMass Boston
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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The Great Barrier Reef stretches for 1,429 miles just off Australia’s northeastern coast.
Auscape/Universal Images Group via Getty ImageNoam Vogt-Vincent, University of Hawaii
Tropical reefs might look like inanimate rock, but these colorful seascapes are built by tiny jellyfish-like animals called corals. While adult corals build solid structures that are firmly attached to the sea floor, baby corals are not confined to their reefs. They can drift with ocean currents over great distances to new locations that might give them a better chance of survival.
The underwater cities that corals construct are home to about a quarter of all known marine species. They are incredibly important for humans, too, contributing at least a trillion dollars per year in ecosystem services, such as protecting coastlines from wave damage and supporting fisheries and tourism.
Unfortunately, coral reefs are among the most vulnerable environments on the planet to climate change.
Since 2023, exceptionally warm ocean water has been fueling the planet’s fourth mass coral bleaching event on record, causing widespread mortality in corals around the world. This kind of harm is projected to worsen considerably over the coming decades as ocean temperatures rise.
A healthy coral reef in American Samoa, left, experiencing coral bleaching due to a severe marine heatwave, center, and eventually dying, right.The Ocean Agency and Ocean Image Bank., CC BY-NC
I am a marine scientist in Hawaii. My colleagues and I are trying to understand how coral reefs might change in the future, and whether new coral reefs might form at higher latitudes as the tropics become too warm and temperate regions become more hospitable. The results lead us to both good and bad news.
Corals can grow in new areas, but will they thrive?
Baby corals can drift freely with ocean currents, potentially traveling hundreds of miles before settling in new locations. That allows the distribution of corals to shift over time.
Major ocean currents can carry baby corals to temperate seas. If new coral reefs form there as the waters warm, these areas might act as refuges for tropical corals, reducing the corals’ risk of extinction.
A close-up of double star corals (Diploastrea heliopora) off Indonesia.Bernard DuPont/Flickr, CC BY-SA
Scientists know from the fossil record that coral reef expansions have occurred before. However, a big question remains: Can corals migrate fast enough to keep pace with climate change caused by humans? We developed a cutting-edge simulation to find the answer.
Field and laboratory studies have measured how coral growth depends on temperature, acidity and light intensity. We combined this information with data on ocean currents to create a global simulation that represents how corals respond to a changing environment – including their ability to adapt through evolution and shift their ranges.
Then, we used future climate projections to predict how coral reefs may respond to climate change.
We found that it will take centuries for coral reefs to shift away from the tropics. This is far too slow for temperate seas to save tropical coral species – they are facing severe threats right now and in the coming decades.
How coral reefs form.
Underwater cities in motion?
Under countries’ current greenhouse gas emissions policies, our simulations suggest that coral reefs will decline globally by a further 70% this century as ocean temperatures continue to rise. As bad as that sounds, it’s actually slightly more optimistic than previous studies that predicted losses as high as 99%.
Our simulations suggest that coral populations could expand in a few locations this century, primarily southern Australia, but these expansions may only amount to around 6,000 acres (2,400 hectares). While that might sound a lot, we expect to lose around 10 million acres (4 million hectares) of coral over the same period.
In other words, we are unlikely to see significant new tropical-style coral reefs forming in temperate waters within our lifetimes, so most tropical corals will not find refuge in higher latitude seas.
Even though the suitable water temperatures for corals are forecast to expand poleward by about 25 miles (40 kilometers) per decade, corals would face other challenges in new environments.
Our research suggests that coral range expansion is mainly limited by slower coral growth at higher latitudes, not by dispersal. Away from the equator, light intensity falls and temperature becomes more variable, reducing growth, and therefore the rate of range expansion, for many coral species.
It is likely that new coral reefs will eventually form beyond their current range, as history shows, but our results suggest this may take centuries.
Fish hide out in the safety of Kingman Reef, in the Pacific Ocean between the Hawaiian Islands and American Samoa. Coral reefs provide protection for many species, particularly young fish.USFWS, Pacific Islands
Some coral species are adapted to the more challenging environmental conditions at higher latitudes, and these corals are increasing in abundance, but they are much less diverse and structurally complex than their tropical counterparts.
Scientists have used human-assisted migration to try to restore damaged coral reefs by transplanting live corals. However, coral restoration is controversial, as it is expensive and cannot be scaled up globally. Since coral range expansion appears to be limited by challenging environmental conditions at higher latitudes rather than by dispersal, human-assisted migration is also unlikely to help them expand more quickly.
Importantly, these potential higher latitude refuges already have rich, distinct ecosystems. Establishing tropical corals within those ecosystems might disrupt existing species, so rapid expansions might not be a good thing in the first place.
A temperate reef near southern Australia, which could be threatened by expansions of tropical coral species.Stefan Andrews/Ocean Image Bank, CC BY-NC
No known alternative to cutting emissions
Despite enthusiasm for coral restoration, there is little evidence to suggest that methods like this can mitigate the global decline of coral reefs.
As our study shows, migration would take centuries, while the most severe climate change harm for corals will occur within decades, making it unlikely that subtropical and temperate seas can act as coral refuges.
What can help corals is reducing greenhouse gas emissions that are driving global warming. Our study suggests that reducing emissions at a faster pace, in accordance with the Paris climate agreement, could cut the coral loss by half compared with current policies. That could boost reef health for centuries to come.
This means that there is still hope for these irreplaceable coral ecosystems, but time is running out.Noam Vogt-Vincent, Postdoctoral Fellow in Marine Biology, University of Hawaii
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Arizona Monsoon 2025 Forecast: Above-Normal Rainfall Expected Across the State
The Climate Prediction Center’s 2025 outlook predicts above-normal rainfall for Arizona’s monsoon season, with higher temperatures expected statewide. Learn what this means for Phoenix and how to prepare.
Arizona residents can anticipate a wetter-than-average monsoon season in 2025, according to the latest outlook from the Climate Prediction Center. The forecast indicates a 33% to 50% chance of above-normal precipitation across most of the state, with the highest probabilities in east-central Arizona.
What’s Driving the Forecast?
Several factors contribute to the optimistic precipitation outlook:
Soil Moisture Conditions: Unusually dry soil across the Southwest can enhance monsoon activity. Dry soils heat up more quickly, potentially strengthening the thermal low that draws moisture into the region. ENSO-Neutral Conditions: The Climate Prediction Center notes a 74% chance of ENSO-neutral conditions persisting through the Northern Hemisphere summer. Such conditions often lead to more typical monsoon patterns, without the suppressing effects associated with El Niño.
What to Expect in Phoenix
For Phoenix, the outlook suggests a 39% chance of above-normal precipitation, a 33% chance of near-normal precipitation, and a 28% chance of below-normal precipitation during the July-September monsoon period. While the probabilities don’t guarantee a wetter season, the highest likelihood leans toward increased rainfall.
Preparing for Monsoon Season
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With the potential for increased rainfall, it’s essential to prepare for the associated hazards:
Flash Flooding: Heavy downpours can lead to sudden flash floods, especially in urban areas and dry washes. Dust Storms (Haboobs): Strong winds ahead of thunderstorms can create massive dust storms, reducing visibility and air quality. Lightning and Downburst Winds: Severe thunderstorms can produce dangerous lightning and sudden, strong wind gusts.
Safety Tips
Stay Informed: Monitor weather forecasts and alerts from trusted sources like the National Weather Service. Avoid Flooded Areas: Never drive through flooded roadways; turn around, don’t drown. Secure Outdoor Items: High winds can turn unsecured objects into projectiles. Prepare an Emergency Kit: Include essentials like water, non-perishable food, flashlight, batteries, and first aid supplies.
For a detailed overview of the 2025 Arizona Monsoon Outlook, you can watch the following video:
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