Category: Biodiversity

How Cutting Down Tropical Forests is Costing Lives Through Deadly Heat

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Animated map showing heat-related mortality rates linked to deforestation across Tropical Central and South America, with darker colors representing higher deaths per 100,000 people.
The maps show regions of Tropical Central and South America (a), Tropical Africa (b), and Southeast Asia (c). Colours show number of deaths per year per 100,000 people located in areas of forest loss (central estimate), aggregated by second-level administration divisions. Boundaries for second-level administration divisions are from GADM (https://gadm.org/index.html).

When we hear about deforestation, many of us think first about disappearing wildlife, endangered species, or the loss of carbon storage that slows climate change. All of that is true, but there’s another hidden danger. Cutting down tropical forests hurts our planet’s biodiversity and directly affects human health. New research shows that losing forests makes people hotter, sicker, and in many cases, more likely to die from extreme heat.

What the Study Found

A recent study published in Nature Climate Change looked at forest loss across the tropics between 2001 and 2020. The researchers found that when forests are cleared, the land surface warms up quickly. On average, deforested areas became almost 0.5 °C hotter than places that kept their trees.

That may not sound like much, but for people living in already hot, humid places, even small increases can push temperatures past safe limits. The study estimated that about 345 million people have been exposed to this extra warming caused by deforestation. That’s nearly the size of the entire U.S. population.

The Human Toll

The warming from deforestation is deadly. According to the study, deforestation is linked to about 28,000 extra heat-related deaths each year (Reddington et al., 2025). These deaths happen because the body can only handle so much heat before heart, lung, or kidney problems set in.

Some of the hardest-hit regions include:

  • Indonesia, Vietnam, and Malaysia, where heat deaths per 100,000 people are among the highest in the world.

  • Nigeria and the Democratic Republic of Congo, which also face significant impacts.

  • Southeast Asia overall, which accounts for more than half of all the deaths linked to deforestation-related heat.

In these countries, outdoor workers, such as farmers and construction workers, are especially vulnerable.

Why the Tropics Are Vulnerable

The tropics, regions close to the equator, are home to over 3.5 billion people. Many of these communities depend on outdoor work for their livelihoods. When forests are cut, not only does the land heat up, but shade disappears too. That makes outdoor work far more dangerous.

Health care access also plays a big role. In many tropical nations, hospitals and clinics are already under pressure, and people may not have reliable access to air conditioning, cooling centers, or emergency care. This limited ability to adapt means heat has a bigger impact on vulnerable groups, such as children, older adults, and outdoor workers.

Other Hidden Dangers

Heat isn’t the only risk linked to cutting forests. Deforestation also leads to:

  • Air pollution from fires: When forests are burned, smoke can spread across entire regions. In past years, haze from Indonesian forest fires exposed tens of millions of people to unsafe air, leading to thousands of premature deaths.

  • Spread of diseases: Clearing forests can increase the spread of diseases like malaria. In some places, standing water left after logging creates ideal breeding grounds for mosquitoes.

Together, these risks make deforestation not only an environmental problem but also a serious public health issue.

What Can Be Done

The good news is that protecting forests can prevent many of these heat-related deaths. Keeping trees standing provides shade, keeps local areas cooler, and reduces harmful smoke. On a larger scale, forests act as a buffer against climate change by storing carbon and releasing moisture into the air.

Steps that can help include:

  • Stronger protections for tropical forests through laws and enforcement.

  • Community-led conservation that involves local and Indigenous groups who know the land best.

  • Investment in health systems and cooling strategies to protect people who already live in areas affected by deforestation.

  • Global cooperation to reduce demand for products linked to deforestation, such as unsustainable palm oil, soy, and beef.

These actions can save thousands of lives each year.

Summing Up

The study’s message is clear: tropical forests aren’t just “carbon sinks” or wildlife havens. They are lifelines for millions of people. Losing them raises local temperatures, increases the risk of deadly heat, and harms human health in ways many of us never considered.

By protecting tropical forests, we preserve ecosystems while protecting people. Safeguarding these forests is a direct investment in healthier, safer communities around the world.

Source: Reddington, C. L., Smith, C., Butt, E. W., Baker, J. C. A., Oliveira, B. F. A., Yamba, E. I., & Spracklen, D. V. (2025). Tropical deforestation is associated with considerable heat-related mortality. Nature Climate Change. Advance online publication. https://doi.org/10.1038/s41558-025-02411-0

Tropical Bird Populations Plummet

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A Warning Sign for Our Planet

Two colorful tropical parrots perched side by side, one red-and-green and the other blue-and-yellow, against a backdrop of green foliage.
Tropical parrots, key seed dispersers and pollinators, highlight the biodiversity at risk as climate change accelerates bird population declines.

Why Tropical Birds Matter

When we think of the tropics, we often picture the sounds of colorful birds echoing through lush forests. From toucans and parrots in South America to hornbills in Asia and turacos in Africa, tropical birds are more than just symbols of beauty, they’re vital to keeping these ecosystems alive.

But new research published this week in Nature Climate Change delivers sobering news: tropical bird populations are collapsing. In many regions, numbers have dropped by more than half in just 30 years. These declines are warning signals that the ecosystems we all depend on are under threat.

The Study at a Glance

  • Published: August 2025
  • Source: Nature Climate Change
  • Finding: Many tropical bird species have lost more than 50% of their populations over three decades.
  • Causes: Deforestation, climate shifts, habitat fragmentation, and food scarcity.

Researchers analyzed decades of data from South America, Africa, and Southeast Asia. The breadth of the study makes it one of the strongest indicators yet of how climate change and human activity are reshaping entire ecosystems.

Why This Matters Beyond Birds

It may be tempting to think of this as a bird problem, but in reality, it’s a human problem. Birds play critical roles in the health of tropical forests. Many tropical plants rely on birds for pollination, making them essential partners in sustaining rainforest ecosystems. Birds also serve as seed dispersers, carrying seeds across vast distances and helping forests regenerate after storms, fires, or human disturbance. In addition, they act as natural pest control by consuming insects, which reduces crop damage and lowers the risk of diseases spreading.

If these birds vanish, the balance tips. Forests struggle to regenerate, pests multiply, and ecosystems weaken, leading to ripple effects that reach people everywhere. Think of birds as the “canaries in the coal mine” of the tropics. Their decline signals deeper problems unfolding quietly but rapidly.

What’s Driving the Decline?

The study highlights several overlapping causes:

  • Deforestation: Vast areas of tropical forest are cleared each year for farming, logging, and development. Birds lose nesting sites and food sources.

  • Climate Change: Rising temperatures disrupt breeding cycles, while shifting rainfall patterns reduce insect and fruit availability.

  • Habitat Fragmentation: When forests are broken into small, isolated patches, bird populations struggle to survive.

  • Direct Human Pressure: Hunting and the pet trade further threaten vulnerable species.

Together, these pressures create a perfect storm, pushing many species toward decline faster than conservation measures can keep up.

Lessons for the Rest of the World

What happens in the tropics doesn’t stay in the tropics. Healthy forests regulate Earth’s climate by absorbing massive amounts of carbon dioxide. Without birds to keep these forests resilient, the planet’s ability to fight climate change weakens.

In other words: when tropical birds decline, so does one of our best natural defenses against global warming.

Hope in Action

While the data is troubling, the study also points toward hope. Around the world, conservation efforts have proven effective when communities, governments, and organizations work together.

  • Protected Areas Work: Expanding reserves and enforcing protections stabilize bird populations.

  • Reforestation Efforts: Planting diverse native trees provides food and shelter.

  • Community-Led Conservation: When local people are empowered to steward forests, biodiversity thrives.

  • Climate Action: Reducing greenhouse gas emissions protects fragile ecosystems long-term.

Small victories are already happening. In Costa Rica, large-scale reforestation has allowed once-declining bird populations to rebound. Similar projects in Indonesia and parts of Africa show that recovery is possible with the right support.

What You Can Do

The tropical bird crisis may feel far away, but every choice we make has global consequences. Here are practical ways to help:

  • Support conservation groups working in tropical regions.

  • Choose sustainably sourced products like certified coffee or wood.

  • Advocate for strong climate policies in your community and beyond.
  • Reduce personal carbon footprints through energy choices and transportation.

Even small actions add up. Just as a single bird can carry seeds that grow into a new forest, one person’s choices can contribute to a healthier planet.

Birds keep forests alive, and forests keep our planet stable. If they falter, so do we. By protecting habitats, addressing climate change, and supporting conservation, we can ensure that the forests remain full of life, and that their songs continue for generations to come.

Source: Goldwert, D., Patel, Y., Nielsen, K. S., Goldberg, M. H., & Vlasceanu, M. (2025). Climate action literacy interventions increase commitments to more effective mitigation behaviors. PNAS Nexus, 4(6), pgaf191.

Why the Great Barrier Reef’s Alarming Coral Loss Matters to All of Us

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Cover of the CCDH report titled “Healthy coral reef with diverse marine life under clear tropical waters, sunlight streaming through the surface.
A vibrant coral reef teeming with marine life, a reminder of what’s at stake in the fight against climate change.

The Great Barrier Reef is a living system that protects coastlines, supports marine life, sustains fisheries, and drives tourism economies. It’s also part of the cultural heritage of Australia’s First Nations peoples, who have cared for these waters for tens of thousands of years.

And right now, it’s under serious pressure.

The latest report from the Australian Institute of Marine Science (AIMS) delivers the clearest picture yet of what’s happening beneath the surface and the numbers are sobering. After the most widespread and severe coral bleaching event ever recorded on the Reef, coral cover has dropped sharply across all three major regions.

What the Scientists Found

Between August 2024 and May 2025, AIMS scientists surveyed 124 reefs. They found:

  • Largest annual coral loss in nearly 40 years of monitoring.

  • Declines in coral cover of 14% to 30% regionally, with some reefs losing up to 70.8% of their coral.

  • Nearly half of reefs (48%) saw declines; only 10% improved.

Bleaching wasn’t the only culprit. Cyclones, flood plumes, and outbreaks of the coral-eating crown-of-thorns starfish (Acanthaster cf. solaris) compounded the damage. But bleaching caused by marine heatwaves was by far the biggest driver.

The 2024 Bleaching Event: A Breaking Point

The 2024 bleaching was the fifth mass bleaching event on the Reef since 2016 and part of a global wave of bleaching that began in 2023. It was unprecedented in scale:

  • High to extreme bleaching was recorded on 49% of surveyed reefs.

  • Some areas in the Southern GBR experienced degree heating weeks (DHW) above 15—nearly double the threshold at which corals begin dying en masse.

  • Fast-growing Acropora corals, which help reefs recover quickly after damage, were among the hardest hit.

In plain terms: The heat didn’t just stress the Reef—it killed large sections outright.

How the Regions Fared

  • Northern GBR: Coral cover fell from 39.8% to 30% — a 24.8% drop, the largest annual decline on record for the region. Losses were worst around Lizard Island.

  • Central GBR: Dropped from 33.2% to 28.6% (–13.9%), with bleaching and flood plumes north of Cairns doing the most damage.

  • Southern GBR: Fell from 38.9% to 26.9% (–30.6%), the steepest annual drop ever recorded there. Many reefs saw more than half their coral vanish in a single year.

Why This Matters to All of Us

Coral reefs are the foundation of marine biodiversity. Without them coastal communities lose protection from storms and erosion. Fisheries decline, threatening food supplies and livelihoods. Tourism industries falter, hitting economies hard. Cultural heritage suffers, particularly for Traditional Owners whose histories and traditions are tied to these waters. And globally, reefs act as early warning systems. What happens here is a signal of what’s coming elsewhere.

Recovery Is Possible, But the Window Is Shrinking

Historically, reefs could bounce back from damage over a decade or more. Now, mass bleaching events are hitting roughly every two years. That’s not enough time for full recovery.

Still, there’s hope. The GBR remains one of the healthier large reef systems on Earth, and local interventions are making a difference:

  • Crown-of-thorns starfish control programs are slowing outbreaks.

  • Water quality improvements are reducing local stress.

  • Coral restoration projects are helping reseed damaged areas.

But without global action to curb greenhouse gas emissions, these efforts can only buy time.

The Bottom Line

The 2024–2025 coral loss is a signal that climate impacts are accelerating and hitting ecosystems faster than they can adapt. Protecting the Reef is not optional. It’s about safeguarding biodiversity, food security, culture, and the natural defenses that protect millions of people.

We still have a choice. Every fraction of a degree of avoided warming, every reef protected from starfish outbreaks, every local stress reduced—it all matters. The Reef’s survival depends on what we do next.

Source: Australian Institute of Marine Science. (2025). Long-term monitoring program: Annual summary report of coral reef condition 2024–25. Australian Institute of Marine Science.