Melting Arctic Sea Ice Impacts Greenland Caribou: The Effects of Climate Change

As Arctic sea ice shrinks, all manner of animals are being impacted. Yet you wouldn't necessarily think that caribou in Greenland are being affected. Now, researchers have discovered that the melting ice may be indirectly causing fewer caribou to give birth to calves every spring.

Vegetation in Greenland "greens" at a certain point in the year. The start of this plant-growing season is extremely important to caribou, which rely on the plants for nourishment. At the beginning, the researchers just wanted to find out how closely the calving season corresponded to the start of the plant-growing season. Yet they found a bit more than they bargained for.

"I initially was interested simply in determining how closely timed the calving seasons was to the onset of vegetation green-up without a thought as to how this relationship might be affected by climate change," said Eric Post, one of the researchers, in a news release. "Until this study, identifying the environmental driver of this change has been the biggest challenge, one that we're getting a better understanding of now that we have more years of data."

As sea ice continues to decline, local temperatures on caribou calving grounds have increased. This has helped advance the growing season on the site. But exactly how does that affect the caribou?

The caribou have been using the area as a calving site for over 3,000 years, as shown by archaeological evidence. They typically arrive from their west-to-east migratory journey in late May or early June. Seeking young plants to eat around the time they give birth, these caribou show up expecting tons of plants to eat. Yet it seems as if the nutrition of these plants is declining.

"Since plants are emerging earlier in the year, they tend to be older and past their peak nutritional value by the time the hungry caribou arrive to eat them," said Jeffrey Kerby, one of the researchers, in a news release. "The animals show up expecting a food bonanza, but they find that the cafeteria already has closed."

So what does this mean? It turns out that while the plants can adapt to the shifting climate, the caribou can't. Their reproductive cycles are timed by seasonal changes in daylight length rather than by temperature, which could be bad news for the caribou.

The findings reveal that melting sea ice isn't just impacting species that live on the ice or in the water. Instead, it's also affecting species on land. As temperatures continue to rise, ecosystems are being impacted which, in turn, could drastically alter the way species thrive in their environment.

The findings are published in the journal Nature Communications.