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From the left: Hassan Ali NAEEM, Muhammad HUSSAIN and Shah Jahan ISHAQ

Actuarial Science Students Excel in CASH Algo Trading Challenge 2023 with Effective Trading Strategy

Congratulations to the HKU Team, MASS, for winning the Grand Champion, Silver in Best Return and Silver in Best Sharpe in the CASH Algo Trading Challenge 2023. The team consists of Muhammad HUSSAIN and Hassan Ali NAEEM, both second-year students majoring in Actuarial Science in the Department of Statistics and Actuarial Science, Faculty of Science, along with Shah Jahan ISHAQ, a second-year student majoring in Computer Science in the Department of Computer Science, Faculty of Engineering.  The CASH Algo Trading Challenge 2023 is a global competition for algorithmic trading that welcomes participants of all ages and backgrounds. The HKU MASS Team surpassed more than 500 participants from over 15 countries, including individuals with over 10 years of trading experience and students from prestigious universities such as Harvard, Stanford, and Imperial College London. Throughout the summer of 2023, which spanned nearly 4 months, they dedicated themselves to conducting thousands of backtests and closely monitoring their progress in order to develop an effective trading strategy. Their hard work and commitment paid off, resulting in their well-deserved victory.

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. Bismuth and cefiderocol showed synergistic effect both in vitro and in vivo (lung infectious model) against PAO1, a strain of Pseudomonas aeruginosa, as a metallo-sideromycin complex transported actively into bacterial cells.

HKU Scientists Pioneer Dual Trojan Horse Approach to Combat Superbugs

In the relentless battle against antibiotic-resistant superbugs, science continues to unveil ingenious strategies to address their vulnerability. Like other bacteria, superbugs have a unique weakness – their dependence on iron for growth and survival. Iron serves as an essential nutrient that bacteria utilise for various cellular processes, including DNA replication, energy production, and other vital functions. In essence, iron is like a ‘food’ for bacteria. Building upon this understanding, a research team led by Professor Hongzhe SUN from the Department of Chemistry, The University of Hong Kong (HKU), introduced a ‘Dual Trojan Horse’ strategy, where a metal-based-drug and sideromycins, a class of antibiotic structurally resembling iron, work together in combating antibiotic-resistant bacteria. This approach allows these antibiotics to be delivered into bacterial cells through a pathway that mimics iron uptake. When bacteria encounter sideromycins, they are deceived into believing they are acquiring iron, prompting them to usher these compounds into their cells. This strategy not only enhances the effectiveness of sideromycins but also prolongs their lifespan, marking a significant advancement in our battle against antibiotic resistance. These promising results were successfully replicated in a live mice model, introducing an innovative strategy to combat antimicrobial resistance, offering hope in the fight against superbugs in clinic. These findings have recently been published a in Nature Communications entitled ‘Metallo-sideromycin as a dual functional complex for combating antimicrobial resistance (AMR)’. ‘We are short of new antibiotics, and infection caused by resistant bacteria (i.e. superbugs) may lead to another pandemic. We have uncovered a dual Trojan Horse strategy to restore antibiotics activity, such as cefiderocol, and hope to provide a novel arsenal for combating antimicrobial resistance,’ commented Professor Sun. Research Background Antimicrobial resistance (AMR) in bacterial infections has emerged as a significant global health concern. The overuse and misuse of existing antibiotics have accelerated the acquired drug resistance in bacteria, resulting in resistance to almost all antibiotics used in clinical settings across various bacteria strains. Gram-negative bacterial infections, such as those caused by Pseudomonas aeruginosa, pose significant challenges in treatment due to their complicated structure. For example, the high resistance of P. aeruginosa against conventional antibiotics can be attributed in part to the limited permeability of the outer membrane (OM) and the expression of ‘efflux pump’, specialised proteins within bacteria that actively remove antibiotics, thus reducing their effectiveness. These factors collectively impede the accumulation of antibiotics at the bacterial target site. Gram-negative bacteria, including Pseudomonas aeruginosa, can cause a range of infections in humans. These infections often affect the respiratory system, leading to pneumonia or lung infections, as well as urinary tract infections. They can also lead to skin and soft tissue infections, bloodstream infections (sepsis), and infections in wounds or surgical sites. In severe cases, these infections can be particularly challenging to treat due to the bacteria's resistance to antibiotics, making them a significant health concern. For these reasons, there is now an urgent need for both new antibiotic discovery and other modifications or strategies to enhance or prolong the antibacterial activity of existing clinical antibiotics. Sideromycin is a novel type of antibiotic where the parent antibiotics or prodrug incorporates a siderophore molecule that utlises iron transport system for delivery. This incorporation enables the active transport of the antibiotic into bacterial cell through nutrient pathways. Cefiderocol (FetrojaÒ) is a recently FDA-approved sideromycin antibiotic in 2019. The antibacterial activity of cefiderocol is improved under the iron-deficient condition because of the enhanced uptake of cefiderocol, with a component of catechol, which coordinate with iron and facilitate the transportation of cefiderocol-iron complex in P. aeruginosa. Although the frequency of resistance of P. aeruginosa to cefiderocol is much lower than its parent antibiotic ceftazidime, the resistance to cefiderocol was developed inevitably in several Gram-negative bacteria strains recently, for example, in Carbapenem-Resistant Escherichia coli strains and Acinetobacter baumannii in the burned infections. Resistance to cefiderocol was related to the production of β-lactamases, siderophore receptor mutations, expression of efflux pump and the combination of these mechanisms. Metal compounds have been used as promising antimicrobial agents for years and show low resistance frequency since they are multi-targeted modes of action. Bismuth (Bi3+) compounds have exhibited potent antibacterial properties against bacterial that have become resistant to a variety of antibiotics. These bismuth compounds act as versatile inhibitors of a group of enzymes called metallo-β-lactamase inhibitors, which are involved in antibiotic resistance. Gallium(Ga3+) also offers antibacterial activities by disrupting Iron (Fe3+)uptake system and iron homeostasis. Interestingly, catecholate siderophores exhibit exceptionally high affinity not only to iron (Fe3+), but also to metals like bismuth (Bi3+) and gallium (Ga3+). These metals behave similarly to iron when they link up with catecholate molecules. These special catechol-metal combinations have been observed to do two things: they can compete with iron to get inside bacterial cells, and they can imitate iron in biological systems, disrupting important iron functions. Thus, the team propose a dual ‘Trojan Horse’ strategy to ‘sneak in’ the antibiotic sideromycins and metal ions simultaneously through siderophore receptor, the same pathways that bacteria use to grab nutrients, leading to synergistic effect against bacterial infections. Key findings In this study, the team demonstrated a bismuth drug (CBS) could enhance the potency of cefiderocol against P. aeruginosa in both laboratory experiment (in vitro) and live animal test (in vivo). This enhancement included improved efficacy against biofilm formation by cefiderocol, suppression of the development of high-level bacterial resistance to cefiderocol, and restoration of the efficacy of cefiderocol against resistant P. aeruginosa strains, including those isolated from clinical cases involving real patients. Such phenomena are likely due to the competition of Bi3+ with Fe3+ to cefiderocol, which leads to decreased uptake of Fe3+ and increased uptake of antimicrobial Bi3+/Ga3+. This competition disrupts the integrity of bacterial membrane, making antibiotic more permeable. The in vitro interaction of Bi3+ with cefiderocol was confirmed by both UV-vis spectroscopy and MS spectrometry, analytical techniques which confirmed the interaction between Bi3+ and cefiderocol, resulting in the formation of a 1:1 complex of Bi3+-cefiderocol. The metallo-sideromycin might not only improve the efficiency of sideromycin, but also prolong the effective life span of this type of antibiotics. Their animal studies have further validated the efficacy of the approach. It is worth of further investigation of other sideromycins and metals, to thoroughly explore the potentials of metallo-sideromycins in treating infections caused by drug-resistant bacterial pathogens. The research team has filed a patient for the discovery. About the research team This study was done jointly by the Department of Chemistry, Department of Microbiology and Carol Yu Centre for Infection, The University of Hong Kong. Ms Chenyuan WANG and Dr Yushan XIA are the co-first authors of this paper. Other members of participating in the research include Dr Hongyan LI, Dr Patrick H TOY, Dr Runming WANG, postgraduate student Ms Jingru LI, and Mr Chun-Lung CHAN of Department of Chemistry, Professor Richard Yi-Tsun KAO of Department of Microbiology, Professor Pak-Leung HO of Carol Yu Centre for Infection. This research was supported by the Research Grants Council of Hong Kong SAR (R7070-18, 17308921, 2122-7S04), the Health and Medical Research Fund of the Health Bureau of Hong Kong SAR (CID HKU1-13) and The University of Hong Kong (URC (202107185074) and Norman & Cecilia Yip Foundation). About Professor Hongzhe Sun Professor Hongzhe Sun is the Norman & Cecilia Yip Professor in Bioinorganic Chemistry and Chair Professor of Chemistry at The University of Hong Kong. His research focuses on metalloproteomics and metallomics, the discovery of antimicrobial and antiviral agents, and inorganic chemical biology. Dr Hongyan Li is a Research Assistant Professor in the Department of Chemistry at The University of Hong Kong. Click here to learn more about the Research team.  Click here to view the research paper ‘Metallo-sideromycin as a dual functional complex for combating antimicrobial resistance’.  Bismuth and cefiderocol showed synergistic effect both in vitro and in vivo (lung infectious model) against PAO1, a strain of Pseudomonas aeruginosa, as a metallo-sideromycin complex transported actively into bacterial cells. Images adapted from Nature Communication, 2023, DOI: 10.1038/s41467-023-40828-3

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Four young scientists awarded China's Excellent Young Scientists Fund 2023

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From the left: Hassan Ali NAEEM, Muhammad HUSSAIN and Shah Jahan ISHAQ

Actuarial Science Students Excel in CASH Algo Trading Challenge 2023 with Effective Trading Strategy

Congratulations to the HKU Team, MASS, for winning the Grand Champion, Silver in Best Return and Silver in Best Sharpe in the CASH Algo Trading Challenge 2023. The team consists of Muhammad HUSSAIN and Hassan Ali NAEEM, both second-year students majoring in Actuarial Science in the Department of Statistics and Actuarial Science, Faculty of Science, along with Shah Jahan ISHAQ, a second-year student majoring in Computer Science in the Department of Computer Science, Faculty of Engineering.  The CASH Algo Trading Challenge 2023 is a global competition for algorithmic trading that welcomes participants of all ages and backgrounds. The HKU MASS Team surpassed more than 500 participants from over 15 countries, including individuals with over 10 years of trading experience and students from prestigious universities such as Harvard, Stanford, and Imperial College London. Throughout the summer of 2023, which spanned nearly 4 months, they dedicated themselves to conducting thousands of backtests and closely monitoring their progress in order to develop an effective trading strategy. Their hard work and commitment paid off, resulting in their well-deserved victory.

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. Bismuth and cefiderocol showed synergistic effect both in vitro and in vivo (lung infectious model) against PAO1, a strain of Pseudomonas aeruginosa, as a metallo-sideromycin complex transported actively into bacterial cells.

HKU Scientists Pioneer Dual Trojan Horse Approach to Combat Superbugs

In the relentless battle against antibiotic-resistant superbugs, science continues to unveil ingenious strategies to address their vulnerability. Like other bacteria, superbugs have a unique weakness – their dependence on iron for growth and survival. Iron serves as an essential nutrient that bacteria utilise for various cellular processes, including DNA replication, energy production, and other vital functions. In essence, iron is like a ‘food’ for bacteria. Building upon this understanding, a research team led by Professor Hongzhe SUN from the Department of Chemistry, The University of Hong Kong (HKU), introduced a ‘Dual Trojan Horse’ strategy, where a metal-based-drug and sideromycins, a class of antibiotic structurally resembling iron, work together in combating antibiotic-resistant bacteria. This approach allows these antibiotics to be delivered into bacterial cells through a pathway that mimics iron uptake. When bacteria encounter sideromycins, they are deceived into believing they are acquiring iron, prompting them to usher these compounds into their cells. This strategy not only enhances the effectiveness of sideromycins but also prolongs their lifespan, marking a significant advancement in our battle against antibiotic resistance. These promising results were successfully replicated in a live mice model, introducing an innovative strategy to combat antimicrobial resistance, offering hope in the fight against superbugs in clinic. These findings have recently been published a in Nature Communications entitled ‘Metallo-sideromycin as a dual functional complex for combating antimicrobial resistance (AMR)’. ‘We are short of new antibiotics, and infection caused by resistant bacteria (i.e. superbugs) may lead to another pandemic. We have uncovered a dual Trojan Horse strategy to restore antibiotics activity, such as cefiderocol, and hope to provide a novel arsenal for combating antimicrobial resistance,’ commented Professor Sun. Research Background Antimicrobial resistance (AMR) in bacterial infections has emerged as a significant global health concern. The overuse and misuse of existing antibiotics have accelerated the acquired drug resistance in bacteria, resulting in resistance to almost all antibiotics used in clinical settings across various bacteria strains. Gram-negative bacterial infections, such as those caused by Pseudomonas aeruginosa, pose significant challenges in treatment due to their complicated structure. For example, the high resistance of P. aeruginosa against conventional antibiotics can be attributed in part to the limited permeability of the outer membrane (OM) and the expression of ‘efflux pump’, specialised proteins within bacteria that actively remove antibiotics, thus reducing their effectiveness. These factors collectively impede the accumulation of antibiotics at the bacterial target site. Gram-negative bacteria, including Pseudomonas aeruginosa, can cause a range of infections in humans. These infections often affect the respiratory system, leading to pneumonia or lung infections, as well as urinary tract infections. They can also lead to skin and soft tissue infections, bloodstream infections (sepsis), and infections in wounds or surgical sites. In severe cases, these infections can be particularly challenging to treat due to the bacteria's resistance to antibiotics, making them a significant health concern. For these reasons, there is now an urgent need for both new antibiotic discovery and other modifications or strategies to enhance or prolong the antibacterial activity of existing clinical antibiotics. Sideromycin is a novel type of antibiotic where the parent antibiotics or prodrug incorporates a siderophore molecule that utlises iron transport system for delivery. This incorporation enables the active transport of the antibiotic into bacterial cell through nutrient pathways. Cefiderocol (FetrojaÒ) is a recently FDA-approved sideromycin antibiotic in 2019. The antibacterial activity of cefiderocol is improved under the iron-deficient condition because of the enhanced uptake of cefiderocol, with a component of catechol, which coordinate with iron and facilitate the transportation of cefiderocol-iron complex in P. aeruginosa. Although the frequency of resistance of P. aeruginosa to cefiderocol is much lower than its parent antibiotic ceftazidime, the resistance to cefiderocol was developed inevitably in several Gram-negative bacteria strains recently, for example, in Carbapenem-Resistant Escherichia coli strains and Acinetobacter baumannii in the burned infections. Resistance to cefiderocol was related to the production of β-lactamases, siderophore receptor mutations, expression of efflux pump and the combination of these mechanisms. Metal compounds have been used as promising antimicrobial agents for years and show low resistance frequency since they are multi-targeted modes of action. Bismuth (Bi3+) compounds have exhibited potent antibacterial properties against bacterial that have become resistant to a variety of antibiotics. These bismuth compounds act as versatile inhibitors of a group of enzymes called metallo-β-lactamase inhibitors, which are involved in antibiotic resistance. Gallium(Ga3+) also offers antibacterial activities by disrupting Iron (Fe3+)uptake system and iron homeostasis. Interestingly, catecholate siderophores exhibit exceptionally high affinity not only to iron (Fe3+), but also to metals like bismuth (Bi3+) and gallium (Ga3+). These metals behave similarly to iron when they link up with catecholate molecules. These special catechol-metal combinations have been observed to do two things: they can compete with iron to get inside bacterial cells, and they can imitate iron in biological systems, disrupting important iron functions. Thus, the team propose a dual ‘Trojan Horse’ strategy to ‘sneak in’ the antibiotic sideromycins and metal ions simultaneously through siderophore receptor, the same pathways that bacteria use to grab nutrients, leading to synergistic effect against bacterial infections. Key findings In this study, the team demonstrated a bismuth drug (CBS) could enhance the potency of cefiderocol against P. aeruginosa in both laboratory experiment (in vitro) and live animal test (in vivo). This enhancement included improved efficacy against biofilm formation by cefiderocol, suppression of the development of high-level bacterial resistance to cefiderocol, and restoration of the efficacy of cefiderocol against resistant P. aeruginosa strains, including those isolated from clinical cases involving real patients. Such phenomena are likely due to the competition of Bi3+ with Fe3+ to cefiderocol, which leads to decreased uptake of Fe3+ and increased uptake of antimicrobial Bi3+/Ga3+. This competition disrupts the integrity of bacterial membrane, making antibiotic more permeable. The in vitro interaction of Bi3+ with cefiderocol was confirmed by both UV-vis spectroscopy and MS spectrometry, analytical techniques which confirmed the interaction between Bi3+ and cefiderocol, resulting in the formation of a 1:1 complex of Bi3+-cefiderocol. The metallo-sideromycin might not only improve the efficiency of sideromycin, but also prolong the effective life span of this type of antibiotics. Their animal studies have further validated the efficacy of the approach. It is worth of further investigation of other sideromycins and metals, to thoroughly explore the potentials of metallo-sideromycins in treating infections caused by drug-resistant bacterial pathogens. The research team has filed a patient for the discovery. About the research team This study was done jointly by the Department of Chemistry, Department of Microbiology and Carol Yu Centre for Infection, The University of Hong Kong. Ms Chenyuan WANG and Dr Yushan XIA are the co-first authors of this paper. Other members of participating in the research include Dr Hongyan LI, Dr Patrick H TOY, Dr Runming WANG, postgraduate student Ms Jingru LI, and Mr Chun-Lung CHAN of Department of Chemistry, Professor Richard Yi-Tsun KAO of Department of Microbiology, Professor Pak-Leung HO of Carol Yu Centre for Infection. This research was supported by the Research Grants Council of Hong Kong SAR (R7070-18, 17308921, 2122-7S04), the Health and Medical Research Fund of the Health Bureau of Hong Kong SAR (CID HKU1-13) and The University of Hong Kong (URC (202107185074) and Norman & Cecilia Yip Foundation). About Professor Hongzhe Sun Professor Hongzhe Sun is the Norman & Cecilia Yip Professor in Bioinorganic Chemistry and Chair Professor of Chemistry at The University of Hong Kong. His research focuses on metalloproteomics and metallomics, the discovery of antimicrobial and antiviral agents, and inorganic chemical biology. Dr Hongyan Li is a Research Assistant Professor in the Department of Chemistry at The University of Hong Kong. Click here to learn more about the Research team.  Click here to view the research paper ‘Metallo-sideromycin as a dual functional complex for combating antimicrobial resistance’.  Bismuth and cefiderocol showed synergistic effect both in vitro and in vivo (lung infectious model) against PAO1, a strain of Pseudomonas aeruginosa, as a metallo-sideromycin complex transported actively into bacterial cells. Images adapted from Nature Communication, 2023, DOI: 10.1038/s41467-023-40828-3

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Four young scientists awarded China's Excellent Young Scientists Fund 2023

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Professor Xiang David LI receives 2024 Tetrahedron Young Investigator Award (Bioorganic and Medicinal Chemistry)

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Professor Sir Fraser Stoddart

Nobel Laureate Professor Sir Fraser Stoddart joins HKU as Chair Professor of Chemistry

The University of Hong Kong (HKU) is proud to announce the appointment of Professor Sir Fraser Stoddart, a distinguished chemist and Nobel Laureate, as a Chair Professor in the Department of Chemistry, Faculty of Science. “I look upon my role as a professor to be more about mentoring and helping young people to come up with fresh ideas and fulfil their ambitions in their research endeavours. By my providing lots of support, they can explore their ideas, bring them to fruition, and produce results that end up being published in the high-profile scientific literature,” said Professor Stoddart. Professor Stoddart brings with him a wealth of experience and expertise in the fields of chemistry, materials science and molecular nanotechnology. He has served as a Board of Trustees Professor of Chemistry at Northwestern University in the United States for the past 16 years. As a result of his transformative research that led to the establishment of a new bond, i.e., the mechanical bond, in chemistry, Professor Stoddart has changed the way chemists think about chemical bonding. By employing the tenets of molecular recognition, he was able to develop highly efficient syntheses of mechanically interlocked molecular topologies and architectures, e.g., catenanes and rotaxanes. He went on to demonstrate that some of these molecular topologies and architectures can be endowed with bistability, leading to the construction of molecular switches that can be integrated into nanoelectronic devices and nanoelectromechanical systems (NEMS). Recently, his research has been targeted towards the fabrication of molecular pumps and electric molecular motors. By leveraging the concepts of kinetic asymmetry and trajectory thermodynamics, he has designed pumping cassettes which preside over the unidirectional movements of the components of mechanically interlocked molecules. The precision with which these pumping cassettes operate can be harnessed to synthesize molecularly homogeneous polyrotaxanes with prescribed numbers of rings. Some of these contemporary polymers exhibit unique stimuli-responsive properties. Professor Stoddart's ground-breaking research has earned him numerous accolades and awards, including the prestigious 2007 King Faisal International Prize in Science. In 2016, he was jointly awarded the Nobel Prize in Chemistry, along with Bernard L. Feringa and Jean-Pierre Sauvage, for his fundamental investigations on the design and synthesis of molecular machines. At HKU, he will continue to expand the repertoire of molecular machines with a keen interest in collaborating with willing partners in the broader scientific community in Hong Kong and beyond. “The HKU community will share my enthusiasm in extending a warm welcome to Professor Stoddart at the University, and we anticipate the valuable contributions he will bring to our research and academic pursuits,” said Professor Xiang Zhang, President and Vice-Chancellor of HKU. "Professor Stoddart's global reputation and recognition will enhance our internationally leading research strengths. His appointment demonstrates our commitment to attracting the best and brightest minds to HKU and testifies to HKU's academic excellence." Professor Zhang added. The appointment of Professor Stoddart reinforces HKU's position as a leading institution in research and teaching. The University looks forward to the fundamental advances that his work will bring to chemistry, materials science and molecular nanotechnology.

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 Freshwater swamps in the Mississippi Delta (Louisiana, USA) are being replaced by marsh or open water due to rising sea levels. Image Credit: Nicole Khan, University of Hong Kong

Critical Research Underscores the Urgency of Staying Below the 2°C Limit for Safeguarding Coastal Ecosystems

A research study led by Macquarie University, in collaboration with scientists from various institutions worldwide, including Dr Nicole KHAN from the Department of Earth Sciences at HKU, has been published in Nature. The study issues a warning about the potential devastation of coastal habitats due to rising sea levels, drawing on evidence from the last Ice Age. The research integrates diverse strands of evidence to establish the precise thresholds of coastal wetland resilience in the face of rapid sea-level rise. It also provides crucial estimates regarding the extent to which coastal wetlands will be susceptible to these accelerated rates, considering various warming scenarios that lie ahead.  Ancient Land Connections Expose Ice Age Sea-Level Rise During the Ice Age, approximately 17,000 years ago, it was possible to walk from Germany to England, Russia to America, and mainland Australia to Tasmania because the sea levels were about 120 meters lower than today. However, as the Ice Age ended, the oceans rose rapidly, averaging one meter per century. This rapid rise in sea levels resulted in the separation of land masses that were previously connected, leading to significant loss of coastal habitat. The recovery process following the last Ice Age spanned thousands of years. The research conducted by scientists from 17 institutions in Australia, Singapore, Germany, the USA, Hong Kong, and the UK serves as a warning. It highlights that rapid sea-level rise and the retreat of coastal habitats will occur once again if warming levels exceed the targets set by the Paris Agreement. The central aim of the agreement is to strengthen the global response to climate change by ensuring that the global temperature rise this century remains well below 2°C above pre-industrial levels, and to pursue efforts to limit the temperature increase even further to 1.5°C.   Embanked salt marsh in Ningbo, China has nowhere to migrate further inland as sea levels rise in the future. Image Credit: Nicole Khan, University of Hong Kong.   The study emphasizes the essential role played by mangroves, marshes, coral reefs, and coral islands in protecting coastlines, trapping carbon, nurturing juvenile fish, and sustaining millions of coastal residents. The report delves into how these coastal habitats retreated and adapted as the last Ice Age ended and how they are likely to cope with the predicted sea-level rises of this century. Lead author Professor Neil SAINTILAN, a specialist in coastal wetlands from Macquarie University said, ‘Our research shows that these coastal habitats can likely adapt to some degree of rising sea levels, but they will reach a tipping point beyond sea-level rises triggered by more than 1.5 to 2°C of global warming.’ However, without effective mitigation measures, the projected relative sea-level rises under current climate change scenarios will surpass the capacity of coastal habitats like mangroves and tidal marshes to adjust, leading to instability and significant changes in coastal ecosystems. Mangroves and tidal marshes act as buffers between the ocean and the land, absorbing wave action, preventing erosion, and playing a crucial role in biodiversity and carbon sequestration. These habitats accumulate sediment and slowly move inland, allowing them to adapt to rising sea levels. However, these habitats can struggle to survive when higher sea levels lead to waterlogging, posing a threat to natural mangrove forests and the associated benefits they provide. Similarly, coral reefs protect coral islands by forming coastal ecosystems that shield the land from the open sea. Beyond 1.5-2°C of global warming, these islands will start disappearing as waves overtop the coral reefs that protect them. Coastal ecosystems play a significant role in carbon dioxide absorption, climate change mitigation, and protection against ocean storms. However, efforts are required to support and preserve these ecosystems. Subsidence, the gradual sinking of land, further exacerbates the exposure of ecosystems to rising sea levels. Decoding Past Sea Levels for Future Projections  The study of past sea levels is one of the most important fields of climate science study and is the basis for sea-level projections. The scientists analyzed the conversion of coastal ecosystems to open water and reviewed how they adapted to sea-level rise following the last Ice Age. Dr Nicole Khan of HKU Department of Earth Sciences specialises in the development and synthesis of records to examine the evolution and driving mechanisms of sea-level fluctuations spanning approximately 20,000 years. Leveraging these records, she delves into unraveling the dynamic responses of coastal wetland ecosystems, including mangroves and tidal marshes, to these historical transformations. Dr Khan stated, ‘If we can limit warming to 2°C by 2100, only a small percentage of these ecosystems will be exposed to these high rates, but at 3°C and higher, more than 50% of tidal marshes and nearly all mangrove ecosystems will be vulnerable to rapid sea-level rise.’ Dr Khan regards these results as highly alarming. ‘They clearly show the importance of limiting warming to below 2°C to maintain conditions favorable to coastal ecosystem survival and sustain all the benefits these ecosystems provide to us. Our findings should be considered in coastal wetland conservation efforts and nature-based solutions for carbon sequestration (e.g., blue carbon storage) or protection from coastal flooding, both in Hong Kong and globally. The journal paper, entitled ‘Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C. Nature (2023).’, can be found at the following link: www.nature.com/articles/s41586-023-06448-z This article is a modified version based on the draft provided by Macquarie University. Wetland erosion at Towra Point Sydney. Towra Point is a wetland listed as internationally significant under the Ramsar convention. Sea level rise is one of a number of stressors in this system. Image Credit: Neil Saintilan  

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