The program is now available for the top sustainability science and innovation event of the year. A collaboration between the Sustainability Research and Innovation Congress and Finland’s Sustainability Science Days, SRI/SSD2024 will bring together 2000 leading experts from across the world working toward a sustainability transformation.

The rich and engaging program features training workshops, interactive roundtables, networking events, cultural excursions, book launches, and more. You’ll have the opportunity to join discussions covering topics such as sustainability education and awareness, the science-policy interface, arctic and regional sustainability, and innovative approaches to renewable energy transitions.

Speakers include former Finnish President Tarja Halonen, Economist Kate Raworth, and former Bolivian Foreign Minister Fernando Huanacuni.

Special events will include evening receptions hosted by the City of Helsinki and the City of Espoo, an evening at Puistokatu 4 – a Space for Science and Hope, a plenary session by Indigenous youth leaders, and more.

SRI/SSD2024 will also include an “Open Day” in which the Congress opens its doors to the local audience while offering participants the opportunity to engage with the surrounding community. Coinciding with the annual “Helsinki Day,” the Open Day activities, designed with local partners, will transcend the walls of Aalto University and the University of Helsinki and expand to our host cities. The Open Day activities and additional special events will be announced soon.

“The SRI/SSD2024 program promises to foster collaborations, ignite action, and help drive the implementation of evidence-based solutions to sustainability challenges,” said Future Earth US Global Hub Director Erica Key, Belmont Forum Executive Director Nicole Arbour, and SRI Director Veera Mitzner. “The Congress represents a pivotal moment for professionals from all over the world to meet in Finland and chart a course to a more sustainable future.”

SRI/SSD2024 will be held 10-14 June at both the University of Helsinki and Aalto University in Helsinki and Espoo, Finland. You can still register for the Congress if you have not done so yet.

The program for the SRI2024 Africa Satellite Event is also available. It will be held 21-24 May in Durban, South Africa.

2024 is the fourth year of implementation of the UN Decade of Ocean Science for Sustainable Development. The goal of the framework is to deliver the science we need for the ocean we want by 2030.

To work toward that, the 2024 Ocean Decade Conference is being held in Barcelona, Spain from 10-12 April 2024. Members from three of our Global Research Networks focused on ocean sustainability, SOLAS, IMBeR and the Ocean Knowledge Action Network, are at the conference working to galvanize transformative actions for the ocean.

If you’re not in Barcelona, you can follow along online.

Find below where members of our community are participating in both satellite and conference events:

9 APRIL
10:00-11:30 at Mediatic Auditorium, Carrer de Roc Boronat, 117-127, Sant Martí, Barcelona, Spain & virtual
Unifying strategies to develop integrated global air-sea community networks

• Speakers include SOLAS Executive Direcot Li Li and SOLAS/SSC Member Joan Llort as moderator.

9 APRIL
17:00 – 19:00 at Parc de Recerca Biomèdica de Barcelona, Sea Hub
Knowledge-based climate-smart maritime spatial planning for ocean sustainable development

• IMBeR member Marta Ballesteros is a partner of one of the projects, ReMAP, and in charge of developing the Governance module for maritime spatial planning plans.

10 APRIL
13:15 – 14:45 at Southern Ocean Room (133+134), Barcelona International Convention Centre
Satellite event: Long-term engagement in the Polar oceans: A decade of international action

• Flash talk entitled Integrating Climate and Ecosystem Dynamics in the Southern Ocean will be given by Nadine Johnston, Programme Manager of Integrating Climate and Ecosystem Dynamics, an IMBeR Regional Program

10 APRIL
16:00 – 18:00 at Caribbean Sea Room (124+125)
Parallel session 1.6 – Challenge 5

• Led and facilitated by Richard Bellerby, co-chair of joint IMBeR-Future Earth Coasts Continental Margins Working Group

11 APRIL
11:30 – 13:00 at One Ocean Room (Plenary)
A will-o’-the wisp? Systematic integration of knowledge co-produced with the fishing industry into marine science and advice

• IMBeR member Marta Ballesteros is the presenter.

11 APRIL
11:30 – 13:00 at One Ocean Room (Plenary)
From the science we need to the science we use: Addressing trade-offs in international fisheries governance fora

• IMBeR member Marta Ballesteros is co-author of the presentation.

When: 25-29 November 2024
Where: Aussois, Savoie, France
Who can apply?  Doctoral researchers and researchers who finished their PhD within the last 10 years (excluding periods of parental leave) who are living and working in Europe

The Pathways Autumn School aims to foster exchange of knowledge and learning through critical dialogue between early career researchers and senior researchers from the natural sciences, social sciences, and the humanities. It supports the urgent task of a more practical, inter- and transdisciplinary and inclusive approach to research capable of responding to interlinked environmental and social habitability challenges. By participating in the 5-day programme of workshops, keynote sessions and discussions, participants will be able to learn and reflect on how research can better contribute to creating conditions for a ‘good life’ for all on a habitable planet.

This year’s edition, titled “Transformative Research for a Just World and a Habitable Planet”, will allow the participants to reflect on the ways sustainability science can contribute to transforming societies towards new models which strive to achieve social equity and meet basic needs for all, while safeguarding the planet’s ecosystems and climate. Doctoral researchers and researchers who finished their PhD within the last 10 years (excluding periods of parental leave) who are living and working in Europe are invited to apply. 

The program, including the names of the confirmed speakers, will be updated on this website as it becomes available.

The call for applications is open until 22nd May 2024.

From as-yet-undiscovered biodiversity to resilient forests and the impact of food consumption on nature: 64 experts, including several from Future Earth, have now published their knowledge and recommendations in the form of “10 Must Knows from Biodiversity Science” for 2024.

The Leibniz Research Network Biodiversity’s new report provides policymakers and society with concrete ways to effectively conserve and sustainably use biodiversity at the local, national, and European levels and thereby also mitigate climate change. With this publication, the researchers contribute current scientific facts to the debate on the German National Biodiversity Strategy, which is to be adopted before the next United Nations Biodiversity Conference in autumn 2024.

“We are already exceeding planetary boundaries, both in terms of global warming and biodiversity loss. Joint responses are needed to counter these crises. We know that preserving biodiversity can significantly contribute to mitigating climate change, for example through biodiverse forests and rewetted peatlands that can act as carbon sinks. Only by focusing on measures to protect biodiversity can we succeed in tackling both crises at the same time,” says Kirsten Thonicke, lead author and Deputy Head of Research Department “Earth System Analysis” at the Potsdam Institute for Climate Impact Research (PIK), which coordinates the research network.

Following the great response to the “10 Must Knows from Biodiversity Science” first published in 2022, scientists from a total of 52 German and international research institutions have now contributed their expertise from the environmental, life, spatial, social, humanities and economic sciences to the new version.

“Our recommendations summarize the research available today for decision-makers. The “Must Knows” are intended to provide guidance on how to implement the globally agreed biodiversity targets in the German context,” says author Sibylle Schroer from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB). Dr. Schroer is also an International Project Officer at Future Earth Global Research Network EvolvES. “This also includes the awareness that so far we only understand a relatively small part of biodiversity. Recognising this fact is a crucial step towards more sustainable environmental policies. These policies should focus on ecosystem-based habitat management – and thus the functions and interactions between species and habitats, rather than just individual species and habitats.”

Concentrated biodiversity knowledge from 64 experts across all disciplines

To implement the 23 global biodiversity targets agreed by United Nations member states at the UN Biodiversity Conference in December 2022 (COP 15), the German National Biodiversity Strategy 2030 is currently being developed. The strategy aims to preserve and protect biodiversity in Germany. In order to provide up-to-date facts from the scientific community, the first version of the “10 Must Knows” from 2022 was expanded to include numerous aspects and brought up to date with the help of current literature. The new report addresses, among other things, how the impact of food consumption on biodiversity can be reduced in concrete terms: “Understanding and using biodiversity as a crucial production factor can help to stabilize yields, enhance agricultural resilience and turn us all into biodiversity managers, whether we are producers or consumers,” says author Jens Freitag from the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK). The authors offer practical suggestions for policymakers and provide citizens with specific options for taking action in society.

The BMBF Research Initiative for the Conservation of Biodiversity (FEdA) and the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig collaborated on the project. The “10 Must Knows” were commented on by experts from politics, administration, science and associations before publication.

The “10 Must Knows from Biodiversity Science 2024” are:

1. Achieving climate and biodiversity protection together
2. Enabling a healthy life on a healthy planet
3. Considering undiscovered biodiversity
4. Linking linguistic, cultural and biological diversity
5. Harmonising the diverse use of forest ecosystems and biodiversity conservation
6. Transforming agricultural and food systems
7. Protecting land and resources
8. Releasing transformative change through international collaboration and Education for Sustainable Development
9. Ensuring free access and open use of biodiversity-related data
10. Reducing biodiversity impacts from food consumption

Experts from Future Earth who contributed to the report include:

1. Sibylle Schroer, EvolvES
2. Cornelia Krug, bioDISCOVERY
3. Giles Sioen, Health Knowledge-Action Network and Future Earth Secretariat
4. Chadia Wannous, Health Knowledge-Action Network and oneHEALTH

Air quality is being notably degraded by a slew of pollutants, black carbon (BC), carbon monoxide (CO), sulfur dioxide (SO2), volatile organic compounds (VOCs), organic carbon (OC), carbon dioxide (CO2), nitrogen oxides (NOx), and methane (CH4). This has deleterious effects on human health and agricultural productivity, among other adverse impacts. Previous emission estimates have identified road transport as an important source of several of these pollutants in Africa. Regional emission inventories highlight the potential for substantially larger increases in the future, however, there is limited analyses at the national level to evaluate the current state of road transport emissions and projected changes into the future in individual African countries.

Mutheu Mbandi et al. set out to derive the first ‘bottom-up’ Kenyan transport emission inventory for emissions of both air pollutants and greenhouse gases (GHGs). The authors take it a step further by evaluating mitigation scenarios assessing the emission reductions associated with i) improved vehicle emission and fuel economy standards ii) improved public transport system, and iii) fuel share shift to more renewable energy sources. The study has shown:

• Emissions in the ‘Business as usual’ (BAU) model, were projected to increase 9-fold for NOX, 11-fold for CO2, 31-fold for Non-Methane Volatile Organic Compounds (NMVOC), 19-fold for Particulate Matter (PM), 11-fold for BC, and 28-fold for OC in 2050. 
• Projected increase in bodaboda (motorcycle) ownership will result in a large increase in estimated emissions, and therefore motorcycles should be considered as part of any mitigation strategy for Kenya.
• Combining better fuel economy with improved emissions standards was the most effective reduction scenario for almost all pollutants.

These results suggest that the comprehensive implementation of improvements in fuel economy and vehicle standards, and are also specific to bodaboda use in Kenya and policies that enforce these changes will be beneficial for improving air quality and reducing Kenya’s contribution to short and long-term climate warming.

Dr. Mutheu Mbandi is a part of the International Global Atmospheric Chemistry (IGAC) Global Research Network of Future Earth. She has done research in hazardous chemicals, climate change, mobility and air pollution and is focused on supporting evidence-based air quality management policies. Dr. Mutheu Mbandi is a Lecturer at the South Eastern Kenya University, Kenya and the co-founder of AfriSTEM Connection, a company working to increase STEM and sustainability awareness using emerging technologies in underserved communities in Africa. 

Mutheu Mbandi A., Malley CS., Schwela D., Vallack H., Emberson L., and Ashmore MR. (2023). Assessment of the impact of road transport policies on air pollution and greenhouse gas emissions in Kenya. Enerygy Strategy Reviews 49: 101120. 

Do you have a recent publication within the Global South that you would like spotlighted? Share your publication with Makyba Charles-Ayinde at Makyba.charles-ayinde@futureearth.org for a possible feature!

New cohort of experts embark on the Earth Commissions second scientific assessment. Focus areas include quantifying safe and just boundaries for Novel Entities and the Ocean, a novel tipping points modelling inter-comparison project and advancing analysis on transformation and governance pathways.

Appointed and hosted by the global research network, Future Earth, and serving as the scientific cornerstone of the Global Commons Alliance, the Earth Commission is proud to announce the initiation of its second assessment. 

In May 2023 the Earth Commission – a broad group of international researchers from the natural and social sciences – launched the Safe and Just Earth System Boundaries for climate, biodiversity, freshwater, nutrients and aerosols. These quantified boundaries were published in Nature and provide one of the most holistic measurements of Earth’s finite limits, marking a step change in understanding how to protect people and the planet. The Commission’s second major study has been accepted for publication, expected to be public in May 2024.

Building on this strong foundation, the Earth Commission’s second assessment will refine and expand on the safe and just boundaries by: 

• Quantifying boundaries for new Earth System domains such as Novel Entities (including toxic substances) and the Ocean

• Increasing its focus on the just transformations necessary across all of society 

• Highlighting the justice, governance and economic requirements for those transformations. 

The renewed scientific workstreams will take into account the complex interactions between natural and social systems, justice, and human well-being to enhance the holistic Earth system boundaries framework under the following clusters:

• Safe and Just Boundaries 
• Transformation Pathways
• Justice, Governance and Economics
• Translation, Actors and Agency

Read more about the workstreams.

New cohort of experts embark on the second phase of scientific analysis 

The new cohort of experts embarking on the second cycle of scientific assessment was appointed by Future Earth, drawing on nominations from across and beyond its global research networks (over 160 nominations were considered). The final group, combining re-appointed and new Commissioners, was approved by the Directors’ Council of Future Earth.

To co-lead this next phase of scientific enquiry, the Earth Commission is delighted to have recently welcomed Prof. Fatima Denton from United Nations University to join Prof. Johan Rockström as Co-chair of the Commission.  Joining them are  a renewed cohort of expert natural and social scientists who will bring significant scientific expertise as new and previous Commissioners collaborate through the series of key workstreams. 

Earth Commission phase two cohort: 

Co-Chairs:

–   Fatima Denton, Professor and Director of the Institute for Natural Resources in Africa at the United Nations University

–   Johan Rockström, Professor and Director of the Potsdam Institute for Climate Impact Research and Professor in Earth System Science at the University of Potsdam

Earth Commissioners:

–   Xuemei Bai, Distinguished Professor, Australian National University 

–   Govindasamy Bala, Professor, Indian Institute of Science 

–   Stuart Bunn, Professor, Australian Rivers Institute, Griffith University 

–   Fabrice DeClerk, Science Director, Sr Scientist EAT, Alliance of Bioversity 

–   Joyeeta Gupta, Full professor of environment and development in the Global South at the Amsterdam Institute for Social Science Research of the University of Amsterdam and IHE Institute for Water Education

–   Carl Folke, Director of the Beijer Institute, Founder and Chair of the Scientific Committee of the Anthropocene Laboratory, the Royal Swedish Academy of Sciences, and Founder and Chair of the Board of the Stockholm Resilience Centre

–   Tim Lenton, Founding Director of the Global Systems Institute at the University of Exeter and Chair in Climate Change and Earth System Science

–   David Obura, Director, CORDIO East Africa – Coral reef ecology and sustainability, Chair IPBES (2023-2026)

–   Steven Lade, ARC Future Fellow at the Fenner School of Environment & Society, Australian National University; Docent (Associate Professor) at the Stockholm Resilience Centre.

–   Pablo Marquet, Full Professor in the Department of Ecology at the Pontificia Universidad Católica de Chile, External Professor, Santa Fe Institute and Associate Scientist, Center for Mathematical Modeling

–   Aditi Mukherji, Director, Climate Change Adaptation and Mitigation Impact Action Platform of the CGIAR

–   Taikan Oki, Special Advisor to the President, Professor at Graduate School of Engineering, The University of Tokyo

–   Peter Verburg, Professor, Vrije Universiteit Amsterdam, Swiss Federal Institute WSL

–   Ricarda Winkelmann, Founding Director, Max Planck Institute of Geoanthropology. Professor, University of Potsdam and Potsdam Institute for Climate Impact Research

–   Miriam Diamond, Professor, University of Toronto 

–   Juan Camilo Cárdenas, Professor of Economics at the Universidad de los Andes in Colombia and the University of Massachusetts Amherst (USA), Director of the Sustainable Development Goals Center for Latin America and the Caribbean (CODS)

–   Laura Pereira, Associate Professor, Sustainability Transformations and Futures at the Global Change Institute at Wits University, Researcher, Stockholm Resilience Centre

–   Keywan Riahi, Director of the Energy, Climate, and Environment Program at the International Institute for Applied Systems Analysis (IIASA)

–   Rashid Sumaila, University Killam Professor and Canada Research Chair (Tier 1) in Interdisciplinary Ocean and Fisheries Economics at the Institute for the Oceans and Fisheries, and the School of Public Policy and Global Affairs, University of British Columbia

–   Detlef van Vuuren, Project leader of the IMAGE integrated assessment modeling team at the PBL Netherlands Environmental Assessment Agency and professor in Integrated Assessment of Global Environmental Change at the Faculty of Geosciences, Utrecht University

– Cunde Xiao, Director of State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University

Read more about the Earth Commissioners.

Based on his world–renowned research on the virtual water trade, digital river mapping, and inclusion of human activity in the water cycle – Taikan Oki wins the Stockholm Water Prize 2024.

Future Earth is proud to share that on 22 March, the Stockholm Water Prize Laureate was announced as Professor Taikan Oki. Professor Oki is a world-renowned researcher in hydrology. His work has contributed to more sustainable management of water on a global scale, through more realistic and practical climate adaptation measures, the inclusion of human activity in the water cycle, and a more accurate depiction of the world’s river flows.

He was instrumental in developing a global river routing model for climate applications and global water resource assessment (the Total Runoff Integrating Pathways – TRIP system) currently used worldwide. He was also the first to accurately measure the value of virtual water. His research led to a better understanding of food importation and its impact on the virtual water trade and water scarcity.

In its citation, the Stockholm Water Prize Nominating Committee states:

“Professor Taikan Oki’s work has greatly advanced our understanding of the nexus among hydrology, climate change and sustainability. Through numerical modeling of complex systems, he has demonstrated exceptional scholarship that provides important insights into how humans alter water, climate, and the biosphere. His major scientific contributions have shed light on ‘total water storage’ as a critical variable in water management and climate change. Professor Oki is selected for the award for his outstanding contributions to global water balance studies, global virtual water flows, and the spatial and temporal variability of annually renewable water.”

On becoming the 2024 Stockholm Water Prize Laureate, Professor Oki says:

“I feel really moved and lucky to have won this award. I never thought that I could have gotten the prize myself. After getting this prize, I am eager to foster the younger generation and continue to contribute to the international academic community on hydrology. I also feel I must further contribute to solving the world’s water issues through research, like previous laureates.”

Future Earth Global Hub Director Japan had this to share about Prof. Oki’s award:

“I would like to sincerely congratulate Prof. Taikan Oki on his award winning of the Stockholm Water Prize 2024. By measuring the value of virtual water, Prof. Oki has shed light on water movement across countries and societal sectors, amongst other scientific achievements. His findings are also valuable assets for Future Earth science and he demonstrates how science contributes to society through his work.”

Taikan Oki is a professor at the University of Tokyo in the Department of Civil Engineering at the Graduate School of Engineering in Japan. He is a Future Earth Governing Council member and Chair of the Future Earth Promotion and Engagement Committee under the Science Council of Japan. A man of many talents, Oki has also held the titles of the Special Advisor to the President at the University of Tokyo, the Senior Vice Rector for the United Nations University, and the Assistant Secretary General at the United Nations, alongside his professorship at the University of Tokyo. In 1995, Oki and his wife (also a scientist) spent two years at the NASA Goddard Space Flight Center in Maryland, USA as visiting scientists. They have two children.

 Professor Oki says that he has been inspired in his work by many other Stockholm Water Prize Laureates, among them Professor Antony Allan, also credited for seminal work on the concept of virtual water. Additionally, he names Stockholm International Water Institute’s late senior advisor, Professor Malin Falkenmark, as a great inspiration to him.

The Stockholm Water Prize is awarded by the Stockholm Water Foundation in cooperation with the Royal Swedish Academy of Sciences. The Prize will be presented to the laureate Professor Oki by H.M. King Carl XVI Gustaf of Sweden, official patron of the Prize, on 28 August during World Water Week in Stockholm. Founding partners of Stockholm Water Prize are Ålandsbanken, Bacardi, PDJ Foundation, WEF, and Xylem.

 

For media inquiries, contact:
Jakob Schabus, jakob@schabus@siwi.org, +46 720 50 60 39

Watch the announcement:

化学者らは、少し化学的に調整するだけで、2日以内に使い捨てのバイオプラスチックを構成要素に分解する強力な酵素を作り出しました。

文：Anthropocene Team
2024年2月1日

キングス・カレッジ・ロンドンの研究者らが、プラスチックをリサイクルするための構成要素に分解する方法を発見しました。このプロセスは40時間もかからず、バイオベースの洗濯洗剤によく含まれる酵素を使用します。

Cell Reports Physical Science誌で報告されたこのプロセスは、ポリ乳酸（PLA）と呼ばれる使い捨てプラスチックをリサイクルする効率的な方法につながる可能性があります。化学が専門のAlex Brogan教授は、「ポリ乳酸を選んだのは、このプラスチックに適切なリサイクル方法がないからだ。私たちの開発によって、このプラスチックは90℃で40時間以内に構成要素に変換することができた」と言っています。

PLAはトウモロコシのデンプンやサトウキビといった再生可能な資源から作られますが、石油由来のプラスチックと同様に大きな環境問題となっています。PLAは最も一般的な商業用バイオプラスチックで、2021年には世界で45万7000トンが生産され、主に使い捨ての食品容器、カップ、食器に使用されています。

これらのプラスチックのほとんどは、生分解されない埋立地に送られてしまいます。PLAが生分解されるのは工業用堆肥の中でだけで、60℃で分解されるのに12週間かかります。このため、工業用堆肥は「プラスチックを肥料や敷きわら（Mulch）に変えるという、かなりエネルギー集約的で時間のかかるプロセスになる」とBrogan教授は指摘します。

プラスチックのリサイクルを含め、あらゆる工業処理に酵素を使用することは、他の化学薬品よりも効率的であるため魅力的です。しかし、特にプラスチックの分解に必要な比較的高い温度では、酵素は不安定になるという課題もあります。

そこで研究者らは、この仕事に適した酵素を探すことにしました。医療用インプラントに関する文献に目を向け、インプラントにも一般的に使用されているPLAを分解する「問題のある」酵素を見つけました。「この「問題 」を 「利点 」に変えたのだ」と教授は言います。

彼らが選んだ酵素はカンジダ・アンタークティカ由来リパーゼB（CaLB）で、洗濯洗剤によく含まれるどこにでもある酵素です。研究者らは、イオン液体と呼ばれる種類の溶媒に溶けて安定するように、この酵素を化学的に改良しました。イオン液体には、一般的なプラスチックを可溶性の断片に変換する能力があり、酵素はこれを分解できます。「私たちの戦略は単純な化学変化であり、理論的には、あらゆる種類のプラスチックに対応できるよう、あらゆる酵素をアップグレードするために使用することができる」とBrogan教授は言います。

研究者らは、改良した酵素をイオン液体に溶かし、PLAプラスチックカップの破片をその溶液に浸しました。プラスチック片は24時間以内に溶液に完全に溶解し、さらに90℃で、破片はプラスチックの構成要素である乳酸に16時間で完全に分解しました。この乳酸は、より多くのプラスチックや他の化学物質を作るのに使うことができます。

「より大規模な作業が可能になるシュレッダーなどのより精密な前処理を加えることで、この工程をどのように改善できるか、エンジニアと協力し検討している」とBrogan教授は言っています。チームはまた、溶液から乳酸を分離する最も効率的な方法を探しています。「私たちが示さなければならない主な改良点は、分解されたプラスチックで再びプラスチックを作り、この資源を循環する（ループを閉じる）ことができるということだ」と教授は指摘します。

出典: Susana M. Meza Huaman, Jake H. Nicholson, Alex P.S. Brogan. A general route to retooling hydrolytic enzymes toward plastic degradation. Cell Reports Physical Science, 2024.

Image: ©Anthropocene Magazine

新しい研究によってラッコが海岸の浸食を遅らせることが実証されました。これは頂点捕食者の再導入が広範囲に利点をもたらすことを示しています。 

文：Warren Cornwall
2024年2月7日

イエローストーンのオオカミの奇跡については多くの人が知っています。1990年代半ばにオオカミがイエローストーン国立公園に再導入されると、制御不能になったエルクの群れによって採食され無精ひげを生やされた渓流沿いの茂みが回復し始めました。その結果、河岸の浸食は減少し、小川沿いの緑を好む鳴禽類などの生物も戻ってきました。さらにその近くではアスペンが繁茂しました。

エルクの個体数を減らしたことにオオカミがこの変化にどの程度関係しているのか、またどの程度がエルクの行動が微妙に変化したによるのかということについては議論があるものの、全体的な変化は劇的なものでした。一種類のカリスマ的な捕食者の復活が生態系全体に波及するという考えに人々は魅了されたのです。その結果はナショナル・ジオグラフィック誌などで大々的に報じられました。

しかし、ラッコと塩性湿地については聞いたことがありますか？おそらくないと思います。

その豪華な毛皮のために絶滅寸前まで狩られたこの沿岸哺乳類、ラッコが、急速に失われつつある塩性湿地でオオカミのような役割を果たしていることが、新しい研究で判明しました。この発見は、頂点捕食者が持つ変幻自在の能力と、その復活によってもたらされる生態系への潜在的な恩恵を浮き彫りにしています。

「これは疑問を投げかけるものだ。かつて頂点捕食者であった種を再導入することで同様の利益をもたらす可能性がある生態系は、世界中にどれだけあるだろうか」と、この研究に携わったデューク大学の生態学者、Brian Silliman氏は言います。

この研究では、カリフォルニア州モントレー湾の端にある潮の満ち引きの激しい河口、エルクホーンスラウ（Elkhorn Slough）に焦点を当てました。1956年から2003年の間に、この地域は塩性湿地の50％を失っています。

このような塩性湿地は、海岸線が海に浸食されるのを防ぐために不可欠であり、世界中で減少の一途をたどっています。このような被害は、人間の手によって沿岸の水の流れが変化したこと、海が上昇したこと、そして湿地帯の植物の根を弱らせる栄養塩汚染が重なったことが原因とされることが多くあります。

しかしエルクホーンスラウではラッコが復活したことが、彼らが以前に姿を消したことも一因であった可能性を示唆しています。以前は30万頭ものラッコが、バハ・カリフォルニアからアリューシャン列島までの北米西部の沿岸海域を泳いでいました。しかし1700年代にヨーロッパ人によって始められた毛皮貿易によって絶滅寸前にまで追い込まれ、1900年代初頭にはその数はわずか数千頭にまで減少しました。カリフォルニア沿岸に生息していたミナミラッコは、1900年代初頭にわずかに発見されるまでは絶滅したと考えられていました。

1900年代後半、保護団体と政府機関は絶滅危惧種保護法で保護されているミナミラッコを復活される取り組みに着手しました。モントレー湾では、モントレー湾水族館が引き取った親のいない若いラッコを放す場所として、エルクホーンスラウを選びました。

ラッコの数が増えるにつれ、塩性湿地内の環境も変化しました。2008年から2018年にかけて、エルニーニョの激しい気候サイクルに関連した個体数の暴落の後、ラッコの数がわずか11頭から120頭近くまで回復したため、河口域の潮汐クリークの浸食は約70％減少しました。

この結果は示唆的ではあるものの、ラッコと浸食の関連性を示す証拠とは言い切れません。この関係がどのように作用するかも説明できません。

より詳細な情報を得るため、研究者らはメインの湿地に流れ込む5つの小さな潮の流れ込む小川を訪れました。それぞれの場所で、ラッコが入らないように湿地の一部をフェンスで囲い、他の場所は開放しました。そして3年間にわたり、それぞれの湿地の運命の分かれ目を観察しました。

その結果、ラッコの存在が湿原の状態に劇的な変化をもたらすことがわかったのです。また、その理由も明らかになりました。それは、ラッコが湿原に生息する小さな穴掘ガニをよく食べるからだったのです。 

ラッコの成獣は、太平洋の冷たい海に耐えるため、毎日体重の25％（20～25パウンド）を食べる必要があります。そしてカニは彼らの大好物のひとつです。3年後、ラッコの手の届かないフェンスで囲まれた場所では、カニの密度は68％も高くなっていました。

カニの巣穴の数も多くなっていました。同時に、柵の内側の湿地帯の草の生育は悪化し、葉や茎の量が48％、根の量が15％減少していました。これは流される可能性のある土砂を捕えるのに重要な機能であると、科学者たちは1月下旬にネイチャー誌に報告しています。 

この結果は、カニが穴を掘って植物の根を食べることから、カニが湿地の衰退の原因であることを示しています。また、海面上昇や継続的な汚染に直面しても、ラッコが湿地の救世主となる可能性を示しています。ラッコの数が多い潮汐のある小川では、小川の浸食は年間わずか5センチで、ラッコの数が少ない小川に比べて69％も低く、以前は年間30センチも浸食されていたのに比べて違いは歴然としています。

ソノマ州立大学の生物学教授で、Silliman氏のデューク研究室の元ポスドク研究員であるBrent Hughes氏は、「ラッコが戻ってきたからといって、失われたものが元に戻るわけではないが、他のあらゆる圧力にさらされているにもかかわらず、これらのシステムが再び安定する可能性があるところまで、ラッコの減少を遅らせることができた」と指摘します。

この発見は、他の沿岸生態系が頂点捕食者の復活から恩恵を受ける可能性があるかどうかという問題を提起しています。科学者らは、これらの場所の多くが、かつてクマ、ワニ、サメ、オオカミ、ライオン、イルカなどの獰猛な生き物で満たされていたことを指摘しています。西海岸の大部分ではラッコはまだほとんど生息していません。

侵食を食い止め、衰退した海岸を復活させようと人々が奮闘するなか、肉食動物の復活は比較的安価で効果的な取り組みとなるでしょう。「これらの小川の堤防を再建し、湿地帯を回復させるには何百万ドルもかかる。ラッコはカニの食べ放題と引き換えに無料で湿地帯を安定させている」とSilliman氏はエルクホーンスラウについて言っています。

出典：Hughes et. al. “Top-predator recovery abates geomorphic decline of a coastal ecosystem.” Nature, Jan. 31, 2024

Photo by mana5280 on Unsplash

Each year, some of the world’s leading scientists are invited to review the most pressing findings in climate change-related research. Summarized into 10 concise insights, the result, 10 Insights in Climate Science, has always been a rich and valuable synthesis for policy and society at large. Future Earth, The Earth League, and the World Climate Research Programme launch the report each year at COP with the support of the UNFCCC Executive Secretary.

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