The Frontiers Report 2025,  released by the UN Environment Programme, highlights four critical areas where environmental degradation intersects with human vulnerability: legacy pollution, melting glacier microbes, undamming rivers and climate risks for an ageing population that is growing.

By Eileen Travers

In a world increasingly shaped by climate extremes, environmental experts are delivering a blunt warning: four rapidly emerging threats could reshape life for millions unless urgent action is taken.

From ancient microbes awakening in melting glaciers to toxic pollutants unleashed by floods, the dangers are no longer distant or theoretical. They are here, and they are growing.

The Frontiers Report 2025, released by the UN Environment Programme (UNEP) on Saturday, highlights four critical areas where environmental degradation intersects with human vulnerability: legacy pollution, melting glacier microbes, undamming rivers and climate risks for an ageing population that is growing.

The report paints a vivid picture of how climate change is not only altering ecosystems but also exposing communities – especially the most vulnerable – to new and intensifying dangers. Some issues may be local or relatively small-scale issues today, but have the potential to become issues of regional or global concern if not addressed early, the report warned.

UNEP Executive Director Inger Andersen said action must be taken “to protect people, nature and economies from threats that will only grow with each passing year”.

Here’s what’s at stake and why it matters to all of us:

Melting glacier microbes

Climate scientists are saying many glaciers will not survive this century unless action is taking to slow the melting rate caused by climate change. That means those living downstream will face a tide of floods alongside threats posed by reactivated microbes in a warming cryosphere or frozen parts of the Earth.

Frozen in ice sheets, glaciers and permafrost are bacteria, fungi and viruses. While most are dead, some are dormant and some are active. As global temperatures hit record highs, these microorganisms will become more active in many ecosystems. Even if the melting can be slowed down by mitigating greenhouse gas emissions, efforts must assess and prepare for possible threats from potential pathogens.

Also crucial is documenting and preserving cryospheric microorganisms, which can shed light on the history of climate and evolution, help in finding therapies for diseases and develop innovative biotechnologies.

For millennia, diverse microorganisms have remained dormant in the cryosphere – regions where water is frozen solid, the report says. “Climate warming could reactivate and remobilize them into new environments, potentially altering microbial communities, introducing pathogens, or causing biodiversity loss as some might fail to survive thawing.”

Dismantling dams

In the Colombian Amazon, river water levels have dropped by up to 80 per cent, restricting access to drinking water and food supplies, leading to shuttering 130 schools, increasing children’s risk of recruitment, use and exploitation by non-State armed groups and resulting in increased respiratory infections, diarrhoeal diseases, malaria and acute malnutrition among youngsters under age five.

Part of what is making the problem worse in Colombia and other hot spots around the world are the plethora of dams operating at a time when climate change is triggering droughts around the world. Drought is keeping more than 420,000 children out of school in Brazil, Colombia and Peru alone, according to a report by the UN Children’s Fund (UNICEF).

As such, there is a growing need to remove dams and other barriers to rehabilitate river ecosystems, a process increasingly initiated by local communities, Indigenous Peoples, women and youth. Rivers and streams can recover remarkably once barriers are gone, but other stressors, from pollution to climate change, need to be addressed in parallel. Understanding the restoration outcomes of barrier removal is necessary not only to guide future removals, but also to inform decisions about existing and future barriers.

The report says, “While dams have provided significant benefits, they have also disrupted indigenous and fishing communities while damaging river ecosystems. Removing dams and barriers is an increasingly accepted strategy to restore river health, and has gained momentum, particularly in Europe and North America, where large, older dams that have become unsafe, obsolete, or economically unviable are being removed.”

Climate risks for the elderly

Older people face increased risks during extreme weather and suffer more from ongoing environmental degradation. As the World Meteorological Organization (WMO) predicts ever more hot weather, the elderly are suffering disproportionately, as seen in rising numbers of deaths and illnesses amid recent heat waves around the world.

At the same time, the world’s ageing population is growing: the global share of people over 65 years old will rise from 10 per cent in 2024 to 16 per cent by 2050. Most of them will live in cities, where they will be exposed to extreme heat and air pollution and experience more frequent disasters.

Older people are already more at risk, so effective adaptation strategies will need to evolve to protect these older populations.

The world is undergoing significant demographic and environmental shifts, with the global population aged 65 and older projected to increase from 10 per cent in 2024 to 16 per cent by 2050 – primarily in low- and middle-income countries, the report says. “Concurrently, climate change is exacerbating environmental risks such as heatwaves, air pollution, and floods, which disproportionately threaten older adults,” it says, adding that since environmental conditions critically influence health in later life, proactive urban planning must prioritize age-friendly, resilient cities with reduced pollution, improved accessibility, and expanded green spaces to safeguard this vulnerable population.

Legacy pollutants

Flooding has crippled communities in all regions of the world as the number of extreme weather events climb. Among the hidden dangers are legacy pollutants that have been secreted into the ground over time and released as extreme rainfall and floods wash away sediments and debris.

The Pakistan floods of 2010, flooding in the Niger Delta in 2012 and Hurricane Harvey off the coast of Texas in 2017 are all examples when floodwaters stirred up sediments, releasing heavy metals and persistent organic pollutants.

Evaluating sediments to understand hazards, rethinking flood protection to lean on nature-based solutions and investments in natural remediation of contaminated sediments are all options to deal with this problem.

The report says that many regions have faced an increase in the frequency and magnitude of severe storm events with extreme rainfalls and floods. While the direct effects of these floods on life and infrastructure are widely recognized, indirect outcomes are often overlooked. An underestimated issue is the remobilization and redistribution of chemical contaminants in river sediments by frequent and severe flooding, posing environmental challenges and socioeconomic repercussions.

This piece has been sourced from UN News.