Marika Holland on tipping point for Arctic sea ice

Marika Holland: If you lose sea ice it leads to more warming, which leads to more sea ice loss, which leads to more warming. So there’s vicious cycle that sets up when you start losing sea ice cover.

Marika Holland, a scientist at the National Center for Atmospheric Research, is researching whether there might be a ‘tipping point’ for Arctic sea ice – a point at which sea ice will disappear and never recover, even if the climate cools. So far though she hasn’t found evidence for that tipping point.

Marika Holland: There’s been a lot of speculation from some scientists that we could have already passed a tipping point, or be close to a tipping point. I’m trying to investigate this using climate models.

Holland’s models look at the physical response of sea ice to different levels of greenhouse gas emissions.

Marika Holland: We’re still on this path of decreasing sea ice cover, but if things were stabilized in terms of greenhouse gas concentrations, we might be able to stabilize the sea ice cover as well.

In other words, Holland’s research suggests that summertime sea ice – which is predicted to disappear by mid-century – could possibly recover to its previous extent and thickness.

Marika Holland: I think it’s a strong suggestion that reducing emissions of greenhouse gases, fossil fuel burning can actually have an impact on Arctic sea ice cover, that not all hope is lost.

Scientists are most concerned about the loss of Arctic sea ice in the summer – when the ice, which reaches its fullest extent in the winter, retreats. Some believe that the Arctic will be ice free by mid-century, which would have a big impact on the polar ecosystem, global climate, wind patterns, and more.

Marika Holland: The biggest thing we know is that sea ice cover in the Arctic is being lost. There’s been significant trends in the summer sea ice cover in particular. So we’re seeing less and less sea ice over time, and we’re also seeing that the ice is becoming thinner and thinner.

Holland said ultimately, what happens in the Arctic depends whether or not humans reduce emissions of carbon dioxide and other greenhouse gases.

Marika Holland: In some respects, the best case scenario is if we can avoid a seasonally ice-free Arctic, meaning an Arctic which has no ice during the summer months. The worst case scenario is that we lose summertime sea ice and we start to see reductions during winter as well. There’s uncertainty and questions about what level of greenhouse gas concentrations those scenarios relate to. But the path that we’re on is losing summertime sea ice cover. In order to avoid that would require dramatic action.

She added that it’s important to realize that melting ice in the Arctic has an impact on our global climate system.

Marika Holland: The Arctic seems like a very remote place. While sea ice loss is happening there, it seems like a distant problem. But you really can’t compartmentalize things [in the climate system]. I mean, the Arctic is connected to the global system. Things that happen in the Arctic matter outside of the Arctic.