A new study suggests Earth's subtropical low-cloud zones are shrinking, allowing more sunlight to reach the ocean and accelerating global warming. By combining satellite observations with climate models, researchers found strong evidence that decreased cloud cover is a consequence of rising CO2 levels, and not just natural variation. This positive feedback loop, where warming reduces clouds which then leads to more warming, could amplify the effects of climate change beyond current projections. The study highlights the importance of low clouds in regulating Earth's temperature and underscores the potential for even more rapid warming than previously anticipated.
This blog post explores the geometric relationship between the observer, the sun, and the horizon during sunset. It explains how the perceived "flattening" of the sun near the horizon is an optical illusion, and that the sun maintains its circular shape throughout its descent. The post utilizes basic geometry and trigonometry to demonstrate that the sun's lower edge touches the horizon before its upper edge, creating the illusion of a faster setting speed for the bottom half. This effect is independent of atmospheric refraction and is solely due to the relative positions of the observer, sun, and the tangential horizon line.
HN users discuss the geometric explanation of why sunsets appear elliptical. Several commenters express appreciation for the clear and intuitive explanation provided by the article, with some sharing personal anecdotes about observing this phenomenon. A few question the assumption of a perfectly spherical sun, noting that atmospheric refraction and the sun's actual shape could influence the observed ellipticity. Others delve into the mathematical details, discussing projections, conic sections, and the role of perspective. The practicality of using this knowledge for estimating the sun's distance or diameter is also debated, with some suggesting alternative methods like timing sunset duration.
Unlike Earth's middle atmosphere, which is primarily influenced by planetary waves, Mars's middle atmosphere appears to be dominated by gravity waves. Data from NASA's MAVEN spacecraft revealed these gravity waves, generated by lower atmospheric phenomena like topography and dust storms, transport significant energy and momentum vertically, shaping the Martian middle atmosphere's temperature and wind patterns. This discovery improves our understanding of Mars's atmospheric circulation and highlights a key difference between the two planets.
HN commenters discuss various aspects of the Martian atmosphere study. Some highlight the surprising role of gravity waves in shaping Mars' middle atmosphere compared to Earth, where other factors dominate. Several delve into the technical details, questioning the resolution of the Martian data and comparing the methods used to Earth-based atmospheric studies. A few commenters point out the challenges of accurately modeling such complex systems and the potential implications for future Mars missions. The discussion also touches on the differences in atmospheric density and composition between the two planets and how those differences contribute to the observed phenomena. Finally, some express general interest in the findings and their broader implications for understanding planetary atmospheres.
Seismic wave analysis suggests Earth's inner core isn't uniformly spherical. Researchers found that waves traveling through the eastern hemisphere of the inner core differ from those passing through the western hemisphere, indicating variations in its structure. This asymmetry may be caused by "localized deformation" potentially driven by differences in heat flow between the core and mantle, suggesting dynamic processes are shaping the inner core over time rather than uniform crystallization.
HN commenters discuss the difficulty of studying Earth's deep interior and the limitations of current models. Some express skepticism about the certainty of the findings, highlighting the indirect nature of the measurements and the potential for alternative explanations. Others point out the vast timescale involved in geological processes and the challenges of extrapolating short-term observations to long-term trends. The idea of the inner core rotating at a different speed than the mantle is mentioned, along with its potential implications for Earth's magnetic field. A few commenters speculate on the composition and behavior of the inner core, mentioning iron crystals and the possibility of non-uniform growth. One user questions the significance of a slightly deformed inner core and suggests it's not as dramatic as the title implies.
Analysis of asteroid Ryugu samples challenges the prevailing theory that Earth's oceans and the building blocks of life were delivered primarily by carbon-rich C-type asteroids. Ryugu, an S-type asteroid, contains organic molecules including uracil, one of RNA's components, suggesting that these vital ingredients could also have been supplied by a greater diversity of asteroid types, including S-types previously thought to be too dry. This doesn't rule out C-type asteroid contributions, but expands the potential sources of prebiotic material that seeded early Earth.
Several Hacker News commenters express skepticism about the study's conclusions regarding asteroid fragments and early life. Some question the connection between the specific organic molecules found and the actual emergence of life, highlighting the significant leap from complex molecules to self-replicating systems. Others point out the ongoing debate about abiogenesis and the various competing theories, suggesting this study adds to the complexity but doesn't offer definitive proof. A few commenters also raise methodological concerns, including potential contamination and the difficulty of extrapolating findings from limited samples to broader conclusions about the early Earth environment. Several users also discuss panspermia more generally, with some finding the asteroid hypothesis more compelling than Earth-based abiogenesis theories.
Scientists studying seismic waves traveling through the Earth's core have found evidence suggesting the inner core's growth isn't uniform. Analysis indicates the eastern hemisphere of the inner core under Indonesia's Banda Sea is growing faster than the western hemisphere under Brazil. This asymmetrical growth may be influencing the Earth's magnetic field, as the inner core's crystallization releases heat that drives the churning motion of the outer core, responsible for generating the field. While the exact mechanisms and implications remain uncertain, this research offers new insights into the complex dynamics deep within our planet.
HN commenters discuss the study's methodology and implications. Several express skepticism about the ability to accurately measure such deep Earth phenomena, questioning the certainty of the "paused" or reversed rotation claims. Some suggest alternative explanations for the observed data, like changes in the mantle's electromagnetic field influencing measurements. Others find the research fascinating, speculating about potential effects on Earth's magnetic field and the length of a day, albeit minor ones. A few highlight the limitations of current understanding of the Earth's interior and the need for further research. The overall tone is one of cautious interest mixed with scientific scrutiny.
A new study estimates a staggering 20 quadrillion ants roam the Earth, totaling roughly 2.5 million ants for every human. Researchers synthesized 489 studies spanning continents and habitats to reach this figure, representing a biomass of 12 megatons of dry carbon, exceeding that of wild birds and mammals combined. This global ant census highlights the insects' crucial ecological roles, including seed dispersal and nutrient cycling, and provides a baseline for monitoring future population changes due to threats like habitat destruction and climate change.
Hacker News users reacted to the ant population study with a mixture of awe and skepticism. Several commenters questioned the methodology, particularly the extrapolation from limited data points, citing potential biases in sampling locations and methods. Some pointed out the difficulty of accurately measuring ant populations in diverse environments like rainforests and deserts. Others focused on the staggering biomass represented by 20 quadrillion ants, comparing it to that of humans and other species, and pondering the ecological implications. A few commenters joked about the potential computing power of a networked ant colony, while others expressed concern about the impact of human activity on insect populations. The overall sentiment leaned towards fascination with the sheer number of ants, tempered by healthy scientific skepticism about the precision of the estimate.
Summary of Comments ( 51 )
https://news.ycombinator.com/item?id=43592756
Hacker News users discuss the study's implications and methodology. Several express concern about the potential for a positive feedback loop, where warming reduces cloud cover, leading to further warming. Some question the reliability of satellite data used in the research, citing potential biases and the short timescale of observation. Others highlight the complexity of cloud behavior and the difficulty of modeling it accurately, suggesting the need for more research. A few commenters point to the broader context of climate change and the urgency of addressing it, regardless of the specific findings of this study. One compelling comment argues that reducing emissions remains crucial, even if this particular feedback mechanism proves less significant than suggested. Another highlights the potential impact of reduced cloud cover on ecosystems, particularly deserts.
The Hacker News thread linked discusses the Science article "Earth's clouds are shrinking, boosting global warming." Several commenters express skepticism about the certainty of the findings, citing the complexity of cloud behavior and the difficulty of modeling it accurately.
One commenter points out that clouds are notoriously difficult to simulate in climate models, and that changes in cloud cover are a significant source of uncertainty in climate projections. They suggest that the observed shrinking cloud cover could be a temporary fluctuation rather than a long-term trend. This sentiment is echoed by others who emphasize the chaotic nature of weather systems and the need for longer-term data to confirm the study's conclusions.
Another commenter raises the issue of solar cycles and their potential influence on cloud formation, questioning whether the observed changes might be related to solar activity rather than solely to anthropogenic warming. This prompts a discussion about the relative contributions of various factors to climate change.
Several commenters discuss the limitations of observational data and the challenges of distinguishing between cause and effect in complex systems like the Earth's climate. They note the possibility of feedback loops, where changes in cloud cover could be both a cause and a consequence of warming.
Some commenters express concern about the potential implications of shrinking cloud cover, highlighting the role of clouds in reflecting sunlight and regulating the Earth's temperature. They worry that a decrease in cloud cover could exacerbate global warming and lead to more extreme weather events.
There is also discussion about the reliability of climate models and the importance of scientific skepticism. Some commenters caution against overinterpreting the study's findings, while others emphasize the need to take action to address climate change even in the face of uncertainty.
A few commenters provide links to related research and resources, offering additional context and perspectives on the issue of cloud cover and climate change. Some of these links lead to discussions about specific cloud types and their differing effects on the climate system.
Overall, the comments reflect a mix of skepticism, concern, and cautious optimism. While some question the certainty of the study's findings, many acknowledge the potential seriousness of shrinking cloud cover and the need for further research to understand its implications. The thread highlights the ongoing debate about the complexities of climate change and the challenges of predicting its future trajectory.