How whales help us fight climate change - The Climate Question podcast, BBC World Service

Key Concepts

• Whale Poo & Carbon Sequestration: Whale fecal matter, particularly from krill-feeding baleen whales, is rich in carbon and contributes to carbon storage on the ocean floor.
• Whale Earwax as a Historical Record: Whale earwax layers contain a chronological record of stress hormones (cortisol) and can reveal past stressors like whaling and wartime noise pollution.
• Sea Ice & Whale Productivity: The presence of sea ice is crucial for the productivity of the Antarctic ecosystem, impacting krill populations and, consequently, whale health and reproduction.
• Baleen Whales: Whales that filter feed using baleen plates instead of teeth, primarily consuming krill.
• Flukes: The tail fins of whales and dolphins, used for identification and tracking.
• Carbon Sequestration: The process of capturing and storing atmospheric carbon dioxide.
• Convex Seascape Survey: A global mission to understand the relationship between the ocean and climate, focusing on Antarctic seabed sediment analysis.

Whale Contributions to Climate Regulation & Scientific Insights

This discussion centers on the surprising role whales play in climate regulation and the innovative ways scientists are studying them to understand climate change impacts. The program, "The Climate Question," explores how whales, through their biology and behavior, influence carbon cycling and provide a historical record of environmental stressors.

Whale Poo & Carbon Cycling

The program begins with a striking example: humpback whale feces. Humpback whales consume massive quantities of krill, which are orange in color. This results in orange, glittery poo that sinks to the ocean floor, effectively sequestering carbon. This process is significant because it removes carbon from the atmosphere and stores it for centuries. The amount of carbon stored by whales is estimated to be substantial – potentially more than some trees store in 500 years.

Evolutionary History & Whale Diversity

The conversation highlights several fascinating facts about whales. They are a diverse group, inhabiting various environments (hot, cold, salt, and fresh water). Surprisingly, whales share a common ancestor with hippos. Furthermore, the term "dolphin" and "porpoise" are often misapplied, and whale tails are correctly referred to as "flukes," which are unique to each individual and used for identification.

Whale Songs & Communication

A quiz segment reveals that humpback whale songs can last up to 30 minutes, with the longest recorded song reaching 22 hours. These songs vary regionally, demonstrating distinct "accents" similar to human languages. The songs evolve over time and are complex, consisting of repeated themes.

Bowhead Whales & Ice Navigation

Bowhead whales, Arctic whales, possess exceptionally thick heads (20-100cm) and are capable of breaking through ice to navigate melting ice flows. Their mouths are the largest of any animal on Earth.

Sperm Whale Sleep Patterns

Sperm whales sleep vertically, dangling their tails downwards, and only switch off half of their brain at a time to maintain breathing through their blowhole.

Antarctic Seabed Research & the Convex Seascape Survey

Scientists are currently conducting a large-scale research project in the Antarctic, the Convex Seascape Survey, to analyze sediment cores from the seabed. These cores contain layers of material accumulated over centuries, including whale remains, fecal matter, and other organic matter. By analyzing the DNA and carbon content of these layers, researchers aim to reconstruct the history of carbon storage in the region and understand the impact of past events, such as industrial whaling, on the ocean ecosystem. The samples are meticulously preserved at -80°C and shared with a global team of scientists.

The Impact of Whaling & Noise Pollution

Victoria Gill, science and climate correspondent for BBC News, explains that industrial whaling significantly reduced whale populations. However, whales are now making a comeback. The research aims to determine how past whaling activities affected carbon storage in the seabed. Furthermore, analysis of whale earwax reveals a historical record of stress levels. During World War II, despite a decrease in whaling, whale stress increased due to the noise pollution from naval activity (guns, bombs, etc.). This demonstrates the significant impact of anthropogenic noise on whale well-being.

Sea Ice, Krill, & Whale Reproduction

The program emphasizes the critical role of sea ice in the Antarctic ecosystem. Sea ice supports algae growth, which forms the base of the food chain, feeding krill. Krill are the primary food source for many whale species. A decline in sea ice leads to reduced krill populations and negatively impacts whale reproduction. Recent monitoring shows that fewer baby whales are born in years following periods of low sea ice.

Whale Earwax as a Biomarker of Stress

Professor Helen Czerski explains the fascinating adaptation of whale ears. While whales evolved from land mammals with external ears, their ears became internalized to reduce drag in the water. They now hear through their jawbones. Earwax accumulates in layers, creating a chronological record of the whale’s life. Scientists analyze this earwax for cortisol, a stress hormone, to track historical stress levels.

Current Whale Stressors & Future Research

While whales have rebounded from whaling, they now face new stressors, including warming waters, shifting food sources, ship strikes, and ongoing noise pollution. The combination of these stressors is likely contributing to increased stress levels in whale populations, as indicated by recent earwax analysis. Further research is needed to fully understand the complex interplay between these factors and their impact on whale health and the ocean ecosystem.

Quote: "Whale earwax raises a few questions because the first one is why do whales have earwax? And that is because whales evolved from land mammals that were like us." - Professor Helen Czerski

Quote: "There's an enormous peak in the early 1970s, just before whaling was banned." - Victoria Gill (referring to cortisol levels in whale earwax)

Data/Statistics:

• Whales may store an average of 33 tonnes of carbon.
• Bowhead whale heads can be 20-100 centimeters thick.
• Longest whale song recorded: 22 hours.
• Earwax analysis can provide a record of whale stress going back 150 years.

Conclusion

The program effectively demonstrates the crucial, and often overlooked, role whales play in climate regulation. Through carbon sequestration via their fecal matter and bodies, and as indicators of ocean health through their earwax, whales offer valuable insights into the changing climate. Ongoing research, like the Convex Seascape Survey, is essential to understanding the complex relationship between whales, the ocean, and the global climate system. The program highlights the need for continued conservation efforts to protect these magnificent creatures and the vital ecosystem services they provide.