The impact of climate change on dolphins

Sadly, though, dolphins and other marine mammals are some of the animals suffering most from the impacts of climate change. A 2023 study published by NOAA found that 70% of US marine mammals were vulnerable to the threat of warming waters, which can impact their food sources and habitats. As of 2025, many dolphin species are classed as endangered by the IUCN. That’s why, here at IFAW, we’re working hard to protect dolphins and their habitats.

We’re rescuing stranded dolphins in Cape Cod and sharing our expertise with teams around the world. We’re campaigning to reduce ocean noise and alter shipping routes to protect marine life from vessel strikes. We’re also implementing nature-based solutions to climate change, working with communities to protect biodiversity and support wildlife-friendly livelihoods. 

Here, we take a look at how climate change impacts not just marine ecosystems, but dolphins in particular. Read on to learn how climate change is impacting our oceans and rivers—from rising sea levels to ocean acidification to warming waters—and how this is making it harder for dolphin species to survive and thrive. 

Melting ice caps 

Rising ocean and freshwater temperatures 

Increasing water temperatures and ongoing droughts have impacted dolphins around the world.

In 2024, after the longest drought in the recorded history of the Amazon rainforest, the bodies of 200 river dolphins were found floating on Lake Tefé in Brazil. The drought and high temperatures led to lower water levels, stranding and killing so many of these animals. 

Scenes like this are now a regular occurrence. One year prior, IFAW responded to the stranding of hundreds of Amazon and Tucuxi river dolphins in the same lake after a period of high water temperatures and a lack of rainfall. Many of these dolphins became stuck, and more than 150 died. 

Since dolphins live in the water, they can’t sweat or pant like other mammals when they’re too hot. Instead, they have to send warmer blood to the periphery of their bodies—like their bellies, which is why they sometimes appear pink—and allow it to be cooled by the ocean. However, when ocean temperatures start to warm to the level of dolphins’ body temperatures, dolphins can no longer cool themselves down. 

In addition to these immediate effects of increased temperatures, researchers have also found that marine heat waves impact dolphin reproduction and calf survival in the long term. The survival rate for some dolphin species fell by 12% post-heatwave compared to pre-heatwave. It’s theorised that this could be due to lower prey availability. 

Reduction in the ocean’s oxygen content 

Rising temperatures also affect the level of dissolved oxygen in the ocean. There is an inverse relationship between temperature and dissolved oxygen—as temperatures increase in the ocean, dissolved oxygen levels decrease. 

Since the 1960s, global oceanic oxygen content has declined by more than 2%. But in some tropical waters, the loss is as high as 40%. 

Dolphins themselves do not take in dissolved oxygen—they breathe oxygen from the air when they swim to the ocean’s surface. However, dolphin prey is negatively impacted by these changes, as fish take in dissolved oxygen through their gills. 

As a reduction in dissolved oxygen puts stress on other marine species—impacting the abundance, quality, and distribution of prey—food chains are disrupted, and it becomes harder for dolphins to find the food they need. 

Changes in ocean noise 

Changes in the ocean’s chemistry—such as acidification that results from increased CO2 in the ocean—can impact how sound travels through the water. Dolphins rely on sounds for communication and echolocation, which they use to hunt. As the ocean’s pH decreases, it grows noisier, impacting dolphins’ ability to travel, hunt, and locate each other. 

Ocean noise pollution is already a major issue impacting dolphins, as boats send vibrations through the water that impede the communication channels of marine mammals. If this issue is not mitigated by changing vessel speed regulations, ocean noise will only be further exacerbated by changes in the ocean’s chemistry. 

Habitat loss and degradation

As climate change causes the bleaching of coral reefs and shifts in temperature patterns around the globe, dolphins are forced to change their breeding and feeding areas. It’s difficult for them to tolerate high water temperatures—especially for coastal and inland dolphins, who can’t dive into deeper ocean waters where the temperatures are cooler. 

Other climate change impacts, such as increasingly unpredictable severe weather, also affect dolphin habitat. Rainwater picks up agricultural runoff and sewage, which makes its way into rivers and oceans where dolphins live. Pollution and chemicals in the water impact the hormones and immune systems of dolphins and other marine mammals. They can reduce reproduction rates while increasing rates of disease.    

In 2025, Florida’s ‘red tides’—caused by algal blooms—are sparking concern. These algal blooms produce fatal toxins that present a serious threat to marine life. In 2023 alone, they killed around 100 dolphins. 

While these algal blooms are caused by pollution from runoff, they are exacerbated by climate change. As air and water temperatures increase, the ocean becomes a more suitable environment for such algae to thrive. If harmful algal blooms like these continue to grow, dolphins could lose much of their coastal habitat. 

Disease 

An increase in the unpredictability and frequency of severe storms not only impacts dolphins’ habitat but could also be tied to disease. A 2020 study of dolphins by researchers from California and Australia identified a new skin disease experienced by dolphins that is linked to climate change. 

Storms brought decreased salinity to the ocean, which caused patchy, raised lesions to spread over about 70% of some dolphins’ skin. This disease has been observed in dolphins living in coastal areas around the world. 

How can you help? 

Dolphins are severely impacted by issues like pollution and ocean noise, which are only exacerbated by climate change. IFAW is committed to reducing ocean noise pollution through the work of our Blue Speeds campaign, as we advocate for reduced vessel speed limits. 

In addition, IFAW works to promote innovative, nature-based climate solutions and recognises the pivotal role marine mammals play in the fight to mitigate climate change. Learn more about the marine conservation work we do around the world. 

IFAW also has a dedicated Marine Mammal Rescue team that responds to dolphin strandings on the ground. In October 2023, we deployed to Lake Tefé, Brazil, to help train local teams in the rescue and rehabilitation of river dolphins. In 2024 alone, we responded to 342 live dolphin strandings in Cape Cod, Massachusetts. 

Our Dolphin Rescue Center, opened in 2023, is a first-of-its-kind facility where we can rehabilitate stranded dolphins. IFAW has pioneered a world-class dolphin stranding response programme. We’ve changed survival odds for stranded dolphins and we continue to work around the world, doing all we can to protect dolphin species in the face of climate change and other threats.