Why is Mount Everest growing? | Technology Weekly

Compiled by Zhou Shuyi and Wang Xiang

If global warming exceeds 1.5°C, there may be no going back

The goal of the Paris Agreement is to limit the increase in global average temperature to within 2°C above pre-industrial levels, and to strive to control it to 1.5°C, but according to current trends, the prospect of achieving this goal is becoming increasingly slim. Therefore, some people have suggested that it may be possible to relax the current emission reduction targets of various countries, so that the average temperature rise temporarily exceeds 1.5°C, that is, "climate overshoot", and then later in this century, through large-scale carbon capture and storage and other means to reduce the level of carbon dioxide in the atmosphere, so that the temperature rise will fall back below 1.5°C. The logic of the overshoot path is that with the development of economy and technology, the cost of emission reduction will continue to decrease. Therefore, "overdrawing" future carbon emissions now can reduce the overall emission reduction cost and improve social and economic benefits.

A study published in Nature on October 9 expressed concerns about the risks of the above scenario. The new study pointed out that there is considerable uncertainty about whether and how the Earth can reverse climate overshoot. Climate overshoot will bring a series of irreversible and dangerous consequences such as sea level rise and species extinction. In fact, the most sensible solution may be to strictly reduce emissions as soon as possible.

The researchers simulated the overshoot path and long-term climate stability. They pointed out that the scenario of climate overshoot has a series of flaws. First, there is considerable uncertainty in the temperature increase predicted by current climate models. For example, a warming of 1.6°C is predicted, but the actual temperature rise may be as high as 3.1°C. We may be misled by the predicted numbers and fail to prepare adequately for low-probability but severe high-temperature scenarios. And even if net anthropogenic emissions of greenhouse gases are reduced to near zero (that is, net zero emissions are achieved), global warming may not stop - overshoot may trigger stronger positive feedback processes than expected, such as the melting of permafrost, releasing large amounts of greenhouse gases such as methane and carbon dioxide, further exacerbating warming.

Secondly, the overshoot path expects large-scale carbon removal measures to be deployed rapidly around the world, an assumption that the study believes is too optimistic. It is estimated that by 2100, about 40 billion tons of carbon will need to be removed from the atmosphere to limit temperature rise to 1.5°C. However, due to a series of practical conditions such as infrastructure, funding, environment, and public willingness, the actual feasible carbon capture and storage capacity will be lower than theoretical expectations. Even if enough carbon dioxide is removed, it will take decades for the temperature to fall.

Finally, climate overshoot will bring a series of irreversible consequences, including crop yield reduction, sea level rise, loss of species diversity, and many aspects of the Earth system may not be able to return to pre-overshoot levels. "Even if the temperature eventually falls back, a world that exceeded 1.5°C will look different from a world that did not exceed 1.5°C," said study author Joeri Rogelj.

Eat less and live longer, Nature study gives a novel explanation

Restricting calorie intake and intermittent fasting can prolong life, and previous studies attributed this to weight loss and improved metabolism. However, a study published in Nature on October 9th challenges this view: researchers conducted the largest animal dietary restriction study to date and found that dieting can indeed extend lifespan, but this effect is not entirely due to weight loss and related metabolic changes - factors such as immune health, genetics and "physiological resilience" play a more critical role in it.

Fat cells (artificially stained). Dieting can help you lose weight and extend your life, but the two effects are not necessarily related. | Steve Gschmeissner/SPL

The researchers selected 960 female mice with different genetic backgrounds to better simulate the genetic diversity of the human population and make the research results more clinically relevant. The mice were randomly divided into five groups: unrestricted diet, fasting one day a week, fasting for two consecutive days a week, "eight points full" (calorie intake restricted to 80% of baseline), "six points full" (calorie restriction to 60%). The dietary pattern of each group of mice began at six months old and lasted for life.

The results showed that the average lifespan of mice in the unrestricted diet group was 25 months, the average lifespan of mice in the two intermittent fasting groups was 28 months, the average lifespan of mice that were "eight-tenths full" was 30 months, and the average lifespan of mice that were "six-tenths full" was 34 months. This shows that both dieting methods can prolong lifespan, and the lifespan extension effect is positively correlated with the degree of dieting within a certain range. The analysis shows that the effects of dietary restriction on health and longevity are not completely "synchronous" - on the one hand, dietary restriction can improve the metabolism of mice, such as body fat and fasting blood sugar levels. These metabolic improvements may be beneficial to health, but are not directly related to life extension; on the other hand, extreme dietary restriction may damage health while prolonging lifespan: mice that were "six-tenths full" showed adverse signs such as muscle loss, low body temperature, hunger behavior and changes in the immune system, and were more susceptible to infection.

More importantly, the lifespan of mice in each group varied greatly, ranging from a few months to several years. The study showed that in addition to simple weight loss and metabolic regulation, there are other processes that regulate the life-extending effects of dietary restriction. The study found that compared with dietary restrictions, genetic factors play a more important role in influencing lifespan. The relationship between immune system health and red blood cell-related characteristics and lifespan is particularly evident.

It is worth noting that mice that adopted a strict diet strategy but did not lose much weight generally lived longer, while mice that "lost weight like crazy" tended to die earlier. This seems to contradict the traditional view that "weight loss leads to longevity." The study believes that dietary restrictions can be regarded as a "stressor", and maintaining weight means that individuals have stronger physiological "resilience", can maintain good immune function, and are more likely to live longer.

Experts warn against using animal experiments to extrapolate the effects of dieting on humans. However, this study shows that dietary restrictions that can extend lifespan may actually be harmful to certain aspects of physical health. "The new study further deepens our understanding that healthspan and lifespan are not the same thing."

For the first time, stem cell regenerative therapy has functionally cured type 1 diabetes

According to Xinhua News Agency, Chinese scientists have made a breakthrough in the study of induced pluripotent stem cells for the treatment of major diseases, and for the first time used stem cell regeneration therapy to functionally cure type 1 diabetes. The study used chemical reprogramming technology to induce pluripotent stem cells to prepare pancreatic islet cells, which were then transplanted into a type 1 diabetes patient, achieving a clinical functional cure. The relevant paper was published in Cell on September 25.

Diabetes is a major disease that threatens human health, and type 1 diabetes is one of the more serious types. Current commonly used treatments are difficult to achieve precise regulation of blood sugar, leading to a variety of complications that seriously affect the quality of life of patients. At present, the clinical efficacy of islet transplantation has made certain progress, but the shortage of pancreatic donors has greatly limited its widespread application. Islet cells prepared from human induced pluripotent stem cells are expected to break through this bottleneck.

It is reported that the patient had a history of type 1 diabetes for 11 years and was completely dependent on insulin treatment, but his blood sugar control was poor and he suffered from severe hypoglycemia many times. After the transplant, the patient restored endogenous autonomous and physiological blood sugar regulation. 75 days after the transplant, he was completely free from insulin injection treatment and continued for more than 1 year. At present, all diabetes-related indicators have reached the level of normal people, achieving clinical functional cure of type 1 diabetes. This clinical study is based on a large number of preclinical studies and national stem cell clinical research filings, and is of great value to the innovation of diabetes treatment strategies.

"Pancreatic islet cells prepared from pluripotent stem cells provide a new source for transplantation therapy of diabetes." Professor Deng Hongkui, director of the Stem Cell Research Center of Peking University, said that pluripotent stem cells have the characteristics of unlimited proliferation and the ability to differentiate into all functional cell types of an organism, and are the key "seed cells" in the field of regenerative medicine. The team has achieved the induction of human cells into pluripotent stem cells through the regulation of small chemical molecules, opening up a new way to prepare human pluripotent stem cells.

Professor Deng Hongkui said that the initial success of the functional cells prepared by chemical reprogramming technology in the clinical treatment of diseases shows that chemical reprogramming is expected to become a universal underlying technology for the efficient preparation of various functional cell types, opening up a new path for the widespread application of cell therapy in the treatment of major diseases. (Xinhua News Agency)

Nighttime light pollution may increase Alzheimer's risk

Artificial light brings brightness to cities, but also casts a shadow on the mind. A new study shows that exposure to light pollution at night may significantly increase the risk of Alzheimer's disease (AD), and this association is particularly significant in people under 65 years old. The relevant paper was published in Frontiers in Neuroscience on September 6.

Light pollution is a growing problem. From 1992 to 2017, the global lighting radiation power observed by satellites surged by 49%. Over the past 12 years, the brightness of the night sky has risen by nearly 10% each year. Currently, about 80% of the world's population is troubled by light pollution.

In the new study, researchers used satellites to obtain outdoor light pollution data at night, combined with medical insurance records from 2012 to 2018, to evaluate the association between the prevalence of AD and the average light pollution intensity in 48 states in the United States. The study showed that in all age groups, the average light pollution intensity at night in each state was significantly positively correlated with the prevalence of AD. For people over 65 years old, this correlation is stronger than known AD risk factors such as alcoholism, chronic kidney disease, depression, heart failure and obesity, and weaker than atrial fibrillation, diabetes, hypertension and stroke; while for people under 65 years old, the correlation between light pollution intensity and AD prevalence is closer than all factors included in the analysis. The researchers said this may indicate that young people are particularly sensitive to night light. In addition, young people tend to live in urban areas, and their lifestyles may lead to more light pollution exposure. The specific mechanism of light pollution and Alzheimer's disease is still unclear. Studies have shown that exposure to strong light at night can disrupt the body's circadian rhythm, leading to shorter sleep time and poorer quality, which in turn increases the risk of disease.

The authors acknowledged that the new study has certain limitations. For example, the medical insurance data only shows the current place of residence of the population and cannot reflect the long-term residence and lighting conditions; the study also did not consider the important impact of indoor lighting factors such as mobile phones and TV screens. David Knopman, a clinical neurologist at the Mayo Clinic, questioned that the new study did not take into account the differences in sunshine time in different regions, nor did it take into account the impact of socioeconomic aspects: rural areas have weak medical conditions and a low diagnosis rate for Alzheimer's disease, but the actual incidence rate is not necessarily low. In addition, places with severe light pollution tend to be more prosperous - which may mean that air pollution will also be more serious, and air pollution is an important risk factor for Alzheimer's disease.

Robin Voigt-Zuwala, the author of the paper, agreed that the new study has many limitations and said further research is needed to include more factors. The author hopes that this study will encourage people to make "small changes" in their lifestyles, such as using blackout curtains or wearing an eye mask to sleep.

Melting glaciers force Switzerland and Italy to redraw border

According to CNN, Switzerland and Italy will redefine the border between the two countries near the Alps due to melting glaciers caused by climate change. The areas that need to be redrawn include the foot of the Matterhorn, one of the highest peaks in the Alps. People usually think that national borders are fixed, but in most areas of the Swiss-Italian border, the border is defined by natural glaciers and snowfields. "As the glaciers melt, these natural elements continue to evolve and redefine the border," the Swiss government said in a statement released on September 27 local time.

Switzerland and Italy reached a draft agreement on the border change in 2023. The Swiss government officially approved the adjustment on September 27, saying that the adjustment was "determined based on the economic interests of both parties." The approval process on the Italian side is underway. The Swiss government said that the content of the agreement and the details of the new border will be announced immediately after the two sides sign the agreement.

Europe is the fastest warming continent in the world, and its glaciers are significantly affected by climate change. In Switzerland, glaciers are melting at an alarming rate. In 2023, the country lost 4% of its total glacier volume, second only to the record 6% in 2022. Matthias Huss, head of the Swiss Glacier Monitoring Project (GLAMOS) and a glaciologist at the Swiss Federal Institute of Technology in Zurich, said that despite a lot of snow last winter, the rate of glacier melting this year is expected to ease, but the overall trend of melting has not been curbed.

Even with the most drastic climate measures, up to half of the world's glaciers are expected to disappear by 2100, which will cause a chain reaction, triggering more landslides and glacier collapses. In 2022, a glacier collapsed in the Italian Alps, killing 11 people. In addition, glacier melting may exacerbate freshwater shortages during heat waves. Huss said that changes in national boundaries are "just a small byproduct of glacier melting."
Why is Mount Everest growing?
Mount Everest is the highest peak in the world, with an altitude of 8,848.86 meters (measured in 2020). Previous studies have confirmed that Mount Everest was mainly formed by the collision of the Indian Plate and the Eurasian Plate. However, plate collision alone cannot fully explain why the altitude of Mount Everest is significantly higher than other peaks. For example, Mount Everest is nearly 250 meters higher than Mount K2, the second highest peak in the world, while the height difference between Mount K2 and the third and fourth highest peaks is only a few dozen meters. In addition, GPS data shows that Mount Everest has been rising at a rate of about 2 mm per year in recent years, exceeding traditional expectations. This suggests that in addition to ongoing regional tectonic movements, the uplift of Mount Everest may have been affected by some unique mechanism.

A study published in Nature Geoscience on September 30 showed that a river capture event that occurred about 89,000 years ago may be a key factor in driving the continued uplift of Mount Everest. River capture is a common phenomenon in orogenic belts, which refers to one river "stealing" the water flow of another river through erosion. After field scientific investigations, the research team found that the Kosi River basin in the Everest region has a unique water system evolution. The upper reaches of the basin, the Pengqu, are located on the Qinghai-Tibet Plateau and run east-west, while the lower reaches, the Arun River, cuts through the Himalayas and runs north-south. Comparative studies of river characteristics show that the modern Kosi River system is in an unstable state, which is most likely the result of the ancient Arun River capturing the ancient Pengqu.

Mount Everest and Arun River.

The research team combined the hydraulic erosion model with the nonlinear inversion method to reconstruct the process of the ancient Arun River's capture of the ancient Pengqu. The best simulation results fit the current river profile well, indicating that the capture event occurred about 89,000 years ago. This led to a sharp expansion of the downstream basin area, and the erosion rate of the river accelerated, with the maximum erosion depth reaching 12 mm per year. As the riverbed cut down, the surrounding rocks experienced "equilibrium rebound" due to the reduction in weight, which promoted the further uplift of Mount Everest.

The study estimated that the equilibrium rebound caused by river capture can increase the altitude of Mount Everest by about 0.2 to 0.5 mm per year, with a cumulative increase of 15 to 50 meters. This discovery not only confirms that river capture is one of the factors that helped Mount Everest become the top of the world, but also reveals the profound impact of river evolution on the height of mountains.

Hundreds of viruses live on your toothbrush and showerhead, but there's no need to worry

Even if you lean over to the dust, you can see a vast ocean of biodiversity. On toothbrushes and shower heads that people commonly use, researchers have found more than 600 types of viruses, many of which are "new faces" that have not been discovered by humans - this may not sound good, but the good news is that these viruses are bacteriophages, which specialize in infecting microorganisms and pose no threat to humans. By studying bacteriophages, we may be able to find new ways to kill drug-resistant bacteria.

Bacteriophage is a general term for viruses that can infect microorganisms such as bacteria, fungi, actinomycetes or spirochetes. It is named because some of them can cause the lysis of host bacteria. Bacteriophages have strict host specificity and cannot infect mammalian cells. They only live in susceptible host bacteria. Their mechanism of action is completely different from that of antibiotics, and they have unique advantages in treating drug-resistant bacterial infections. It is estimated that there are about 1032 bacteriophages on the earth, which is about ten times the number of bacteria. It can be said that wherever there are bacteria, there are traces of bacteriophages.

In the new study, researchers collected samples from 92 shower heads and 36 toothbrushes in the bathrooms of American residents. By sequencing the sample DNA, it was found that these samples contained a total of more than 600 phages, and the types of phages in each sample were different. "We found that there was basically no overlap in the types of phages between shower heads and toothbrushes, or even between any two samples," said Erica Hartmann, an author of the paper and a researcher at Northwestern University in the United States. "Each shower head and each toothbrush is like an isolated island, which highlights the amazing diversity of phages."

The phage species in the samples varied.

The researchers noticed that mycobacteriophages were more abundant in the samples than other types of phages. Mycobacteriophages infect mycobacteria, a species of bacteria that causes diseases such as leprosy, tuberculosis and chronic lung infections. The researchers envision that phages could one day be used to treat these infections.

The authors of the paper also reminded the public not to worry too much about microorganisms in the home, and that they only need to clean the shower head and replace the toothbrush regularly. "Microorganisms are everywhere, and most of them will not make us sick." Hartman said that the misuse of disinfectants can easily make microorganisms resistant to drugs, making them more difficult to treat. The relevant paper was published on October 9 in Frontiers in Microbiomes.

The lasting damage to mental health caused by studying for a doctorate is greater than the accidental death of a parent

Studying for a doctorate is a journey of self-cultivation. Only the person who drinks the water knows whether it is hot or cold. A study of all doctoral students in Sweden showed that studying for a doctorate would cause great damage to mental health, and the negative impact even exceeded the accidental death of a parent. After starting their doctoral studies, the use of psychiatric drugs and hospitalization for mental health problems by doctoral students increased significantly, and continued to rise during their doctoral studies. By the fifth year of their doctoral studies (usually the last year), the use of psychiatric drugs by doctoral students increased by about 40% compared to before their doctoral studies, and then dropped significantly. The relevant paper was published on SSRN as a preprint and has not been peer-reviewed.

Compared with before PhD, the use of psychiatric drugs increased sharply after PhD. | Nature News

Previous studies have shown that mental health problems are common among doctoral students. A 2021 meta-analysis showed that among more than 23,000 doctoral student respondents, 24% reported symptoms of depression and 17% reported symptoms of anxiety.

In the new study, the authors retrieved Swedish healthcare records and included more than 20,000 doctoral students who studied for a doctorate in Sweden from 2006 to 2017, covering all subject areas, tracking their mental health care and comparing them with master's degree holders who did not pursue a doctorate (highly educated controls) and the general population.

Before doctoral studies, the use of antidepressants, sedatives and other psychiatric drugs by prospective doctoral students was similar to that of other highly educated people and lower than that of the general population. However, their use of psychiatric drugs increased significantly after doctoral studies compared with other people, reaching a peak in the fifth year of the doctoral program, close to that of the general population and significantly higher than that of other highly educated people. The analysis of hospitalization reflected a similar trend.

The researchers compared the effects of PhD study on psychiatric drug use with those of traumatic life events, such as the unexpected death of a parent, and found that the effects of PhD study were greater in magnitude and lasted longer.

The study also found that there are differences in drug use in different disciplines. In the field of natural sciences, the use of psychotropic drugs by doctoral students increased sharply compared with before their doctoral studies, rising by 100% in the fifth year; in the humanities and social sciences, it rose by nearly 50%. Medical students were an exception - their drug use rate did not increase. In addition, compared with individuals under 26 years old, individuals aged 31 and above when they began their doctoral studies were 1.51 to 1.65 times more likely to use psychotropic drugs; women were 1.67 times more likely than men. For those individuals who had used psychotropic drugs before their doctoral studies, they were 2.84 times more likely to use psychotropic drugs during their doctoral studies than those with no relevant history of use.

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