To wrap up 2025, we look back at six stories that resonated most with our readers. From urban biodiversity and nature-based solutions to extreme heat, green finance and global sustainability agendas, these pieces capture a defining year for cities and regions.

Together, they underline ICLEI’s role in 2025: Connecting local solutions with national and global goals, and supporting cities and regions to translate ambition into practical, more equitable action – especially at a time when global uncertainty made local leadership more essential than ever.

1. Ten reasons to promote urban biodiversity

As cities continue to expand, biodiversity has often been pushed aside. Yet urban areas have also become critical spaces for restoring balance with nature, especially as momentum among local and subnational governments grew from Biodiversity COP15 to COP16, hosted in 2024 in Cali, Colombia.

Through platforms like CitiesWithNature, cities showed how protecting ecosystems delivers tangible benefits: Cleaner air and water, reduced climate risks, healthier food systems, and better quality of life. Urban biodiversity emerged not as a “nice to have,” but as a foundation for resilient, livable cities in a rapidly urbanizing world.

2. Belém, Brazil’s largest Amazonian city, to host COP30

When COP30 came to Brazil, global attention turned to Belém, the largest city in the Amazon. It was a powerful reminder that the Amazon is not only a forest, but also an urban region where millions of people live and where decisions on energy, land use and development directly shape the biome’s future.

Belém stepped forward as a leading voice for Amazonian cities, advancing low-carbon development, resilience, biodiversity and inclusion—supported by strong climate data and long-term planning. Alongside this local leadership, regional cooperation and access to green finance helped elevate Amazonian cities as decisive actors in safeguarding one of the planet’s most critical ecosystems.

3. Global sustainability agendas: 10 things we’re watching for in 2025

2025 unfolded as a fragile year for global sustainability. Elections and leadership changes across major economies tested long-standing commitments, while several multilateral processes struggled to deliver the ambition demanded by the planetary crisis.

In this uncertain context, cities and regions became anchors of continuity. From biodiversity and climate to finance and social development, subnational governments helped sustain momentum—pushing for multilevel cooperation, influencing national climate plans, and mobilizing communities when global processes weakened.

The road to COP30 became the central arena. Initiatives such as CHAMP, Town Hall COPs and Daring Cities reinforced the message that without cities and regions fully engaged, global ambition would falter.

4. How green bonds are shaping the future of sustainable investment

Green bonds and sustainability-linked financing are increasingly central to the transition to a net zero, climate-resilient economy—helping unlock capital for the infrastructure cities and countries need to deliver transformative solutions. In simple terms, green bonds allow investors to directly finance an issuer’s climate- or environmentally-linked projects, while the issuer repays the investment over time with interest.

Momentum has grown fast, driven by rising investor demand, stronger transparency measures and evolving regulatory frameworks designed to reduce greenwashing and boost confidence. At the same time, challenges remain—especially around harmonizing definitions and taxonomies, and closing the wider climate finance gap that public funding alone cannot meet.

This is where ICLEI’s support becomes practical. Through the Transformative Actions Program (TAP), ICLEI helps cities and regions develop investment-ready project pipelines and connect ambition with finance—so local sustainability projects can move from plans to funded action.

5. Four steps to finance nature-based solutions in cities

As cities faced rising heat, extreme weather and inequality, nature-based solutions offered powerful answers, but financing them remained a major barrier. Urban forests, wetlands and green corridors delivered multiple benefits, yet struggled to fit conventional infrastructure funding models.

The challenge lay in systems not designed for long-term, cross-sector value. Cities needed enabling environments, better integration of nature into planning and budgets, and investment-ready projects that could attract diverse funding sources, especially for smaller and capacity-constrained municipalities.

Examples from around the world showed that with the right frameworks and partnerships, nature-based solutions could move from plans to reality, functioning as critical urban infrastructure rather than optional add-ons.

6. Heat is rising. Here’s how cities are rising to respond.

Extreme heat became the most dangerous and unequal climate threat of 2025, amplified in cities by the urban heat island effect and disproportionately affecting the most vulnerable. What was once treated as an occasional emergency evolved into a chronic, structural risk.

Cities responded by rethinking heat governance: creating dedicated heat offices, expanding cooling infrastructure, redesigning streets and public spaces, and prioritizing long-term planning alongside immediate protection.

Through local action, science, and global partnerships, cities demonstrated that while heat is rising everywhere, so is urban leadership, turning this challenge into a catalyst for more resilient and equitable urban futures.

Bonus track: 

​​7. What does an ecological civilization look like? China’s Guiyang City is showing the way

8. Five reasons why oceans are important to cities and why cities are important for our oceans