Antarctic Ocean Discovery Warns of Faster Global Warming

By Mikayla Mace, Arizona Daily Star

A group of scientists, including one from the University of Arizona, has new findings suggesting Antarctica's Southern Ocean — long known to play an integral role in climate change — may not be absorbing as much pollution as previously thought.

© (2018) Arizona Daily Star. This is the second of two stories produced and published in partnership with the newspaper for World Oceans Week. Read the first story, “Rising Seas Could Swell Arizona’s Population,” by Climate Central features journalist John Upton.
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The old belief was the ocean pulled about 13 percent of the world’s carbon dioxide — a greenhouse gas that contributes to climate change — out of the atmosphere, helping put the brakes on rising global temperatures.

To reach their contradictory conclusion, the team used state-of-the-art sensors to collect more data on the Southern Ocean than ever before, including during the perilous winter months that previously made the research difficult if not impossible.

Some oceanographers suspect that less CO2 is being absorbed because the westerlies — the winds that ring the southernmost continent — are tightening like a noose. As these powerful winds get more concentrated, they dig at the water, pushing it out and away.

The crew of the N.B. Palmer used satellite imagery to avoid large fields of sea ice during a mission to deploy and recover floats, which remotely monitor ocean conditions, but sometimes encounters were unavoidable. The research vessel can break through ice three feet thick while traveling at three knots.
Credit: Greta Shum/Climate Central

Water from below rises to take its place, dragging up decaying muck made of carbon from deep in the ocean that can then either be released into the atmosphere in the form of CO2 or slow the rate that CO2 is absorbed by the water. Either way, it's not good.

The Southern Ocean is far away, but “for Arizona, this is what matters,” said Joellen Russell, the University of Arizona oceanographer and co-author on the paper revealing these findings. “We don’t see the Southern Ocean, and yet it has reached out the icy hand.”

Joellen Russell, associate professor of geoscience at the University of Arizona, with a climate model of sea surface temperatures.
Credit: Kelly Presnell/Arizona Daily Star

Oceans, rivers, lakes and vegetation can moderate extreme changes in temperature. Southern Arizona has no such buffers, leaving us vulnerable as average global temperatures march upward.

“Everybody asks, ‘Why are you at the UA?’” Russell said about studying the Southern Ocean from the desert at the University of Arizona. She said the research is important to Arizona and the university supports her work.

Making measurements

The Southern Ocean is a formidable place, especially in winter. Winds can howl at nearly 100 mph, churning waves that can surge 80 feet high. The temperature dips below freezing for prolonged periods.

“Very few people who have a sane view of the world go down there in winter,” said Rik Wanninkhof, an oceanographer from the National Oceanic and Atmospheric Administration, and one of the paper’s co-authors.

For this reason, scientists know less about the Southern Ocean than the rest of the world’s oceans. What they do know is mostly limited to surface CO2 levels in the summer, when it’s safer to take measurements by ships with researchers aboard. Shipboard sensors that directly measure CO2 are the accepted scientific standard in these types of studies.

Understanding CO2 levels within the air, land and sea and how it is exchanged between the three is necessary for making more accurate future climate predictions.

To fill the gap in knowledge, Russell and her team have deployed an array of cylindrical tanks, called floats, that collect data on carbon and more in the Southern Ocean year-round. Russell leads the modeling component of this project called Southern Ocean Carbon and Climate Observations and Modeling, or SOCCOM.

Aboard the N.B. Palmer research vessel, marine technician MacKenzie Haberman assisted with the launch of a profiling float in the Southern Ocean, which remotely monitors ocean conditions.
Credit: Greta Shum/Climate Central

The floats drift 1,000 meters below the surface. Every 10 days, they plunge a thousand meters deeper, then bob up to the surface before returning to their original depth.

For three years, 35 floats equipped with state-of-the-art sensors the size of a coffee cup have been collecting data along the way and beaming it back to the researchers, like Russell in Tucson. Within hours, the data is freely available online.

They measure ocean acidity, or pH, and other metrics to understand the biogeochemistry of the elusive ocean, but not without controversy.

Making a splash

Alison Gray, an oceanographer at the University of Washington, is the lead author on the study. She said there are two reasons the study may contradict what has previously been thought of about the Southern Ocean: The lack of winter-time observations at the ocean by other researchers and the fact that ocean carbon levels might vary throughout the year.

So while SOCCOM is making it possible to get more data than ever before, others question her nontraditional methods. They suggest that Gray’s alarming results are derived from error.

“Whether the Southern Ocean is absorbing a large quantity of CO2 from the atmosphere is a hot topic for environmental science and global policy making,” said Taro Takahashi, a geochemist from Columbia University, in an email. He is not involved with SOCCOM.

Takahashi is not entirely convinced the measurements reported by the authors are scientifically reliable enough to support their conclusions.

The issue with the findings is that researchers are not directly measuring CO2 but rather calculating it from the measurements taken with the new sensors, he said. The standard shipboard sensors don’t work at the depth the floats operate, and the traditional sensors are too large to fit on a float.

Pushback

Publishing the paper has been laborious as well, Russell said.

SOCCOM is like the disruptive startup in the carbon counting industry.

“(Reviewers) kept saying, ‘It’s a new sensor, so if you want us to trust it, we want more time and more of them,’ which is legitimate and annoying,” she said.

Additionally, while the floats are convenient year-round tools, some worry the floats will render measurements made by shipboard crews with the older, larger sensors obsolete. But Russell wants to reassure them: "We don’t think we should ever replace the ships because that together actually gets us this transformational science.”

The N.B. Palmer research vessel carried scientists across the Southern Ocean as they collected samples and launched floats, which remotely monitor ocean conditions. 
Credit: Ted Blanco/Climate Central

What’s next

Gray remains confident in her findings, "but we need to keep making measurements to verify our results," she said.

“Even assuming large uncertainty, our results are still significantly different than previous estimates," Gray said. "So even if we are off, the take-home message is the same."

The team only wants to improve the models with more data so that future climate predictions can bet more accurate, Gray said.

“If the Southern Ocean is not taking up as much carbon as we believed, it could be that things are changing more rapidly,” Wanninkhof said.

And that matters, even in a desert thousands of miles from the Antarctica since climate change will make extreme weather events more extreme in Arizona, he said.

© This story may not be republished by outlets other than Climate Central without permission from the Arizona Daily Star.

Rising Seas Could Swell Arizona’s Population

Arizona’s low taxes and living costs, friendly culture, arts scenes and easy access to outdoor activities make it an appealing state in which to settle.

And in decades ahead the state’s draw as a new home could be boosted as seas rise and oceans warm, forcing coastal residents to deal with fallout like strengthening storms, floods, mudslides and other disasters.

This was the first of two stories produced and published in partnership with the Arizona Daily Star for World Oceans Week. Read the second story, “Antarctic Ocean Discovery Warns of Faster Global Warming”, by Star science and higher ed reporter Mikayla Mace.
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“We see natural disasters all over the world; but to be very close to one, and experience the utter helplessness, as well as the repeated evacuations, is very, very stressful,” says Jenni Aguilar, who moved her family to a four-bedroom house near Tucson from California on Memorial Day.

Aguilar says the high cost of living in California already had her considering a move from the beach town of Carpinteria when heavy winter storms followed wildfires, causing mudslides that killed 21 people and convinced her to head east.

“We started looking here, and it just worked out,” said Aguilar, who moved to Milagro, a cohousing community just outside city limits, with her husband and two sons. Her daughter, future son-in-law and grandchild are moving in this weekend.

“We’re a pretty resilient family,” said Aguilar.

There are some adjustments to be made in a new desert climate. Jenni Aguilar collects ice in the kitchen of her family's new home just outside Tucson, AZ.
Credit: Ron Medvescek / Arizona Daily Star

Research published last year included Pima County among the top 9 percent of counties into which Americans are likely to move after being forced from their homes by another coastal climate threat — sea-level rise.

The study projected sea rise could bring 10,000 more residents this century to a county where about a million currently live.

Among the states, Arizona ranked sixth as a likely destination.

“People are already making those moves from coastal areas into Tucson,” said University of Georgia geographer Mathew Hauer, author of the study, published in Nature Climate Change. “There’s a lot of different reasons as to why any one person might make that move. Sea-level rise might be the straw that breaks the camel’s back, if you will. It might be that little push that people need.”

Rising temperatures are melting ice, while ocean water is expanding as it warms. Ice sheet modeling indicates Antarctica’s ice sheet could crumble at a quickening pace as warming water and air gnaw at its edges, hastening sea rise. A federal climate science assessment last year concluded seas are “very likely” to rise this century by one to more than four feet. A worst-case scenario would see some American shores inundated with more than 10 feet of sea-level rise during that period.

Most of the heat trapped by greenhouse gas pollution goes into the oceans. As well as influencing migration by raising the seas, that ocean heat fuels stronger storms and monsoon rain — both of which reach into Arizona. And by moving heat and heat-trapping carbon between the water and the atmosphere, ocean conditions affect inland temperatures.

Migration hard to predict

Complicating efforts to predict how Arizona will be impacted by migration from rising seas, experts say its ability to accommodate growth could wither under other impacts from climate change — rising temperatures and worsening water shortfalls.

The Tucson skyline.
Credit: Andrew/flickr

Research published last month in the Journal of the Association of Environmental and Resource Economists found that the population west of Texas, Colorado and Montana could swell more than a tenth during the next 50 years because of migration within the U.S. from climate change, largely from the South and Midwest.

Previous research by the same economists showed extreme heat, on the other hand, can drive away residents, which could affect populations and economies in cities like Tucson.

“If it’s too hot for you in Tucson, the college graduates are more likely to move out, rather than low-income or people who are less mobile,” said one of the researchers, Qin Fan, an economist at California State University, Fresno.

Perhaps more than anything else, water shortages could hobble growth in Tucson — even without climate change, which is projected to make them worse.

“The Southwest, ever since the Second World War, has experienced this absolutely explosive urban growth, and that growth has been based on cheap water and cheap electricity,” said Thomas Sheridan, an anthropology professor at the University of Arizona. “There’s no major new source of water on the horizon.”

Rising seas

Closer to America’s shores, some streets flood now even in fine weather, with high tides overtopping coastlines that were developed when local water levels were more than a foot lower.

Rising flood insurance rates are adding to coastal housing costs. Homes along some of the most flood-prone roads have lost much of their value, while damaged houses left vacant following storms blight neighborhoods along the Gulf Coast and up through the Mid-Atlantic.

“We’re going to get to a threshold,” said David Wrathall, a geographer at Oregon State University investigating future migration from sea-level rise. “There will be low levels of migration, and then suddenly there’s going to be these moments where lots of people are going to come into the system all at the same time. Not just from one location, but from lots of coastal locations simultaneously.”

Flooding in Fairmount Avenue near Arizona Avenue at high tide during a storm.
Credit: Ted Blanco/Climate Central

A major uncertainty in all climate research is future pollution rates. The more pollution that’s released from fossil fuels, farming and deforestation, the more severe the impacts from climate change will be.

Governments from Tucson to China are starting to take steps to slow warming and adapt to it, even as the Trump administration dismantles federal climate programs.

Hauer’s research considered how many people in coastal U.S. counties could be forced to find new homes if high levels of pollution this century cause seas to rise six feet.

Then he modeled where they might go.

Hauer’s research showed 13.1 million Americans would be at risk of losing their homes by 2100 — when today’s toddlers could be old and vulnerable. The figure included more than 2.5 million people leaving Florida and nearly 1.5 million arriving in Texas.

Other popular destinations may include counties in Georgia, North Carolina and Pennsylvania as well as Arizona.

The research didn’t account for effects of migration from low-lying and vulnerable places outside the 50 states, like Puerto Rico, the Marshall Islands, Bangladesh and the Yucatan Peninsula, where rising seas and strengthening storms will drive countless more to seek new homes.

Instead, it examined one of the ways that warming could affect the movement of families around the U.S. — which for many is already a familiar process.

“We’ve lived in a lot of places — we’re somewhat semi-nomadic,” said Aguilar, who moved to Tucson after the mudslides.

“I don’t know that a lot of Americans like to call themselves that. But a lot of Americans are that.”