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Every time I read a story with dire predictions about climate change impacts I imagine a gong the size of a barn door sending a warning echo off the mountains in the distance.

A team of scientists recently released a report stating that changes in the Arctic climate, everything from melting polar ice caps to warming waters and changing ocean salinity is happening faster than previously predicted. Currently, the atmospheric temperatures there are about 20 degrees Celsius warmer than normal and water temperatures are 4 degrees warmer than normal. The likelihood of no summer sea ice forming this century is very high.

Arctic tipping points

The Arctic Resilience Report states that all of this could push conditions in the Arctic toward 19 regime shifts or tipping points – climate situations that if reached, may prove to be irreversible. For example, the Greenland ice sheet is widely considered the Northern Hemisphere’s air conditioner. It is massive, nearly 1.1 million square miles, and it serves a critical role in keeping temperatures above the equator from getting too hot. This massive sheet of ice acts like a mirror, reflecting the sun’s powerful rays back into space and minimizing solar radiation warming.

The melting Greenland ice sheet. Photo by Marcus Carson

But as global temperatures have risen, the ice sheet has become thinner and smaller, and as waters around the sheet have become warmer, they have accelerated melting. This creates a cycle in which the sheet’s shrinking could accelerate localized climate change, which could further accelerate the ice sheet’s shrinking. If the ice sheet disappears (which could take centuries), scientists predict it could cause global sea levels to rise by more than 20 feet.

This is just one of the 19 tipping points. Others include: Arctic sea ice loss, which would have some of the same effects as the melting of the Greenland ice sheet; changes in ocean salinity and current, which could spread warmer water faster than normal, with global implications; changes in land-based ecosystems that could release more greenhouse gases and reduce ice/snow reflectivity; and changes in Arctic snow patterns, which could also increase global ocean temperatures that effect climate patterns such as the monsoon season in Asia.

Fisheries impact

And then there is the impact on fisheries. The report cites manmade climate change (greenhouse gases, warming oceans, pollution, etc.) as well as other external factors like fishing pressure, as drivers for what could result in fisheries collapses in the Arctic. This could play out in a couple of different ways. First, a combination of warming water, shifting current, salinity and acidification could alter the vital nutrient upwellings that produce the plankton forage fish feed on. If the forage fish don’t thrive, neither do commercially important species like salmon, cod, pollock and shrimp. Couple that with continued fishing pressure, and you’ve got a recipe for collapse.

Climate change could cause fisheries collapse in the Arctic and elsewhere. Photo by Marcus Carson

The question is, how could fisheries collapse in the Arctic affect fisheries elsewhere?

This is no small question.

Complex challenges

So I asked Marcus Carson, one of the lead authors of the 218-page report. He talked about what we know and don’t know about how rapidly things are changing. “Often, when we see these things, it’s really hard to set in motion the processes we need to take them back,” he said from his home in Sweden.

“The challenge is the relational understanding. We understand the silos [warming oceans, ice melt, carbon storage in peat bogs, etc.] pretty well. What we’re lacking is how these connections in these really complex systems really work.”

Marcus Carson. Photo by Mark Tozer

For example, he mentioned that ocean acidification, the process by which the overall acidity of the ocean increases due to increased environmental carbon release, was not included as one of the tipping points in the report because scientists couldn’t pinpoint how it will behave in concert with other factors like salinity, temperature, current, etc. What scientists do know is that the rate of acidification in the Arctic has increased twice as high as almost anywhere on earth, and that acidification is generally higher in colder water.

“What we don’t understand is the exact relation between climate change and ocean acidification where fisheries are involved,” he said. Many species follow temperature, which is the case with some species here in the Gulf of Maine. For example, as waters have warmed off Long Island Sound, lobsters have pushed north and east, and there is no sustainable lobster fishery there anymore.

We also know as we dump more carbon into the atmosphere and put more chemicals into our estuaries, the acidity goes up. But as Carson said, we don’t yet know how changes in acidification from these types of drivers will work in concert with temperature, salinity, current to affect marine food webs. Species that are more tolerant of some or all of these drivers will likely thrive more in a changing Arctic climate than others.

We need to better understand how all climate change factors could affect entire food webs. Photo by Mark Tozer

“There may be some biological variability that might get species competing with each other moving into the same space,” he said.

When it comes to impact on climate change in the Arctic affecting fisheries there and elsewhere, we still have to take a broad view. There will undoubtedly be an impact, especially when considering how currents will channel warmer, denser water globally.

A global climate

“There’s a saying around the working groups of the Arctic Council. ‘What happens in the Arctic doesn’t stay there.’ A lot of changes beyond seasonal fluctuations aren’t generated there. They start outside the Arctic, and get in there,” he said. And the changes in the Arctic may have global impacts.

“The implication with these 19 potential shifts … is that when these things start interacting with one another, the concern is that we could be setting forces in motion that are wildly out of our control,” he said.

The cycle continues. Melting ice sheet allows more solar rays to warm oceans and atmosphere, accelerating ice melt. Photo by Marcus Carson

Not surprisingly, almost every response option cited in the report for the 19 tipping points calls for some form of reducing global greenhouse gases and shifting toward renewable energy.

This is the same message a majority of scientists have been saying in ever growing numbers and volume. However, the incoming administration has virtually declared war on climate change science.

Asked about threats to defund NASA’s climate science regimen, Carson used the analogy of “tearing the instrument panel out of your plane while in flight. It’s like you want to poke our eyes out while we’re heading into these big changes.”

Indeed.

That gong is getting louder. Do you hear it?