By Valerie Nikolas, Jan. 14, 2019 – Glaciers in the Northern and Southern Hemispheres are rapidly retreating in sync, a trend unique to the accelerating pace of warming in which the Earth is currently caught. Researchers such as University of Maine geologist Noel Potter, who studies glacial retreat in New Zealand, observe this trend with increasing frequency.

Unlikely partnerships in drones and cosmic rays are helping to uncover insights unique to New Zealand’s Southern Alps. Using drone technology, PhotoScan software and isotope dating, Potter and his team mapped changes in the Hooker Glacier, located on the flank of Mount Cook, New Zealand’s highest mountain. His results show unprecedented levels of recession in the Hooker Glacier now compared to the last 1,500 years.

“The Southern Alps are really falling apart,” Potter said during his presentation at the fourteenth annual Comer Climate Conference held in October in southwest Wisconsin. “Collapse is immense. And the ice likely has not been as far back as it is today since these moraines were deposited.”

Researchers often refer to glaciers as the Earth’s “thermometers.” Because they are more sensitive to changes in temperature than other landforms, they can give a more accurate indication of regional climate variations.

Noel Potter near the Hooker Glacier with the DJI Phantom 4 drone he used to take aerial images of the landscape.

Potter and his team flew a DJI Phantom 4 drone above the Hooker Glacier, where it took thousands of aerial videos and photographs. They then stitched the photos together in Agisoft Photoscan software to make an “orthomosaic,” a highly detailed, 3-dimensional model of the landscape. Potter says the team’s orthomosaics are so detailed they can pick out individual boulders in the landscape.

The team used the orthomosaics to determine particular boulders to study, extracted pieces of quartz from those boulders and then used isotope dating to determine when and where ice was present at each site. Beryllium-10 is an isotope that gives scientists a glimpse into the past. The isotope is created as cosmic rays hurling through the solar system strike rock.

If you’ve ever peered out at a mountainous landscape, you’ve probably noticed long, narrow ridges in the side of the mountains. These ridges that form from sediment deposits on the sides of glaciers are called moraines, and glacial geologists like Potter study their rough edges to determine where a glacier’s ice reached and retreated at certain points in time.

“We use cosmogenic dates from boulders collected on these moraines to tell us when the glacier occupied the position marked by those moraines,” Potter said.

When a glacier retreats from a moraine, the isotope beryllium-10 collects at predictable levels once it shakes free of ice. Determining when the glacier freed the rock is called “cosmogenic dating” and it tells scientists how old particular moraines are. The term relates to the clock created as cosmic rays strike the rock and react with quartz to generate beryllium-10.

Potter and his colleagues collected data from 11 moraines just east of the main divide of the Southern Alps.

Hooker Glacier moraine ages, as determined by Potter et al.’s research. (Noel Potter)

The outermost, oldest left moraine was deposited roughly 1,500 years ago—around 497 A.D. The next oldest moraine studied was deposited around 1,100 years ago in 1066 A.D.

“We had moraines forming here in New Zealand when glaciers in the Alps of Europe were retreating,” Potter said. These New Zealand moraines were deposited well within the range of what is referred to as the Medieval Climate Optimum, the warm period in Europe which took place between 750 and 1250 A.D. This shows that more snow was accumulating in the Southern Alps during this time, meaning the Northern and Southern Hemispheres were not experiencing the same temperature fluctuations–the Southern Alps retreated later.

The terminal moraines are the most recent and were deposited as the ice began to retreat from what was once its point of furthest advance. These moraines were deposited between approximately 700 and 250 years ago, sometime between the years 1321 and 1787 A.D. These moraines were deposited during the time of the Little Ice Age, a cold snap in Europe that lasted roughly from 1250 to 1850 A.D.

Potter’s colleague Peter Strand explained that glaciers are high energy systems. Despite fluctuations in temperature, glaciers try to maintain a constant equilibrium between the area above the snow line and the area below, called the ablation area. The ablation area and the accumulation area must maintain a constant ratio, thus causing advances in colder temperatures and retreats in warmer conditions.

The Hooker Glacier in particular features a long ablation area, which is the only area where moraines form. This makes it an ideal area for studying the fluctuations in temperature during certain time periods.

“There’s so much moisture being added in the top and so much being lost through ablation at the bottom that the turnover time for ice going through these systems is quick, which makes them more responsive to changes in climate,” Potter explained.

The differences in the landscape are so dramatic, they can even be observed by the naked eye through comparing photographs of today with those of the early twentieth century.

Glacier fluctuations during the last 4,000 years. Glaciers in New Zealand remained at a steady state during some of the Bronze Age Optimum, a warm period of time in Europe, the Iron and Roman Age Optimum, a warm time in Europe, the Dark Ages Cold Period, a cool time in Europe and during the Medieval Warm Period, a warm time in Europe. (Noel Potter, 2018, modified after Schaefer, et al., 2009)

Potter’s team also found that the Hooker Lake, located at the foot of the Hooker Glacier, did not begin to form until between 1965 and 1976.

“Retreat from the terminal position has really accelerated since the lake began to form,” said Potter. “When a glacier like the Hooker is rocketing back to that lake it is just catching up quickly to a climate signal that has been imposed upon it for a while before.”

The changes in glacial position and appearance of a lake highlight the delicate balance between warming and cooling in the Earth’s “thermometers.”

“To counteract one Fahrenheit degree of warming [in this area], precipitation would have to increase 50 to 80 percent,” said Aaron Putman, a colleague of Potter’s at University of Maine.

The Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report, released in 2007, was one of the first major publications to shed light on the temperature differences in the Northern and Southern Hemispheres during the Little Ice Age.

Potter’s finding that the climate of New Zealand was independent of temperature fluctuations seen throughout Europe during the same time adds to a growing body of evidence that supports the IPCC’s report and confirms the paradigm shift about this time in the planet’s history.

“My research shows pretty clearly that natural variations in climate have regional, not global, effects in geologically recent times,” Potter said. “Only since the Industrial Revolution have we seen climate doing the same thing all around the world. The [2018] IPCC is warning about the consequences of the same warming we see in the glaciers when it starts to affect other systems with more chance to do harm to people.”

Photo at top: An aerial photograph of Mount Cook and the Hooker Glacier. (Drone footage from glaciologist Noel Potter’s DJI Phantom 4)



By Valerie Nikolas, Nov. 13, 2018 –

“We have to put a price on carbon,” Columbia University scientist Wallace Broecker, the geoclimatologist who coined the phrase “global warming” in a 1975 study, said at the Comer Climate Conference held in southwestern Wisconsin in early October.

The latest United Nations’ climate change report and the Nobel Prize in economics, both announced days after the conference, confirmed his remarks.

The dire U.N. Intergovernmental Panel on Climate Change report warns that the world has just 12 years to massively curb carbon emissions or risk unprecedented consequences including extreme weather events, drought, food shortages and widespread displacement. To fight the IPCC’s grim findings hope may lie in economic measures to incentivize the use of cleaner energy.

“I think it has to be a tax,” Broecker said. “And that money should go to taking carbon dioxide out of the air.”

Each year the world currently emits about 41 billion tons of carbon dioxide, a greenhouse gas that holds heat in the atmosphere and causes global warming. At this rate of emissions, the United Nations IPCC estimates that “global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from by 2030, reaching ‘net zero’ around 2050” to avoid catastrophic effects on the earth’s climate. The difficult question of how to accomplish that is only exacerbated by international and political tensions.

The 2018 Nobel Prize awarded two economists who have evaluated the economic cost of carbon emissions. William D. Nordhaus’s theory of the “social cost of carbon,” or SCC, is a concept used to evaluate climate change investments that has influenced $1 trillion in renewable energy and other carbon-reducing initiatives. Rooted in this theory is the idea that a crucial way to combat climate change is through economic growth that de-incentivizes activities that emit fossil fuels.

The essence of a carbon tax is to, “reward everything that every human or institution does to use fewer carbon fuels,” said energy policy analyst Charles Komanoff.

A carbon tax would be directed upstream, at companies that emit carbon as a byproduct, like the coal, natural gas and petroleum industries. These companies would be taxed a predetermined amount, which economists estimate would start low—around $10 per ton to begin with, Komanoff estimates.

Many companies are already investing in alternative energy such as solar fuels. Both Bill Gates and Exxon announced separate $1 million donations to clean energy initiatives in October.

“A carbon dividends policy that returns proceeds to consumers will unleash innovation and investment in new and existing technologies, putting us on course to reduce emissions in the fastest and most economical way possible, while also protecting American jobs and the security of our energy supply,” said David Fein, senior vice president of state governmental and regulatory affairs at Exelon Corporation.

Nordhaus’s Nobel Prize-winning work has found that the social cost of carbon required to stop at the Paris Agreement’s cap of 1.5°C  degrees of global warming would be $184 per ton of CO2 . A more realistic rate of $50 per ton could be achieved with a tax of $1.07 per gallon of gasoline.

Komanoff said even $10-$15 per ton of CO2 would be a feasible starting point. Initially, the tax would start low and increase incrementally as time went on. Proponents believe this will incentivize other forms of energy.

“Innovators will feel the price signal,” according to Komanoff, which would spur more new ideas for cleaner energy.

Other areas of the world, like Sweden and the British Columbia, have imposed similar taxes. But in the United States, tax efforts, especially those regarding something as daunting and seemingly nebulous as climate change, are difficult to push forward and typically met with stark political opposition.

In September, lawmakers in Washington State proposed an initiative to tax carbon $15 per metric ton, becoming the first in the United States to do so. Voters struck down Initiative 1631 in the Nov. 6 elections by 13 percentage points (43.7 percent in favor and 56.3 percent opposed).

“All serious analyses of the energy climate nexus show that wise policies to address it will improve the economy compared to ignoring it,” said Richard Alley, another scientist who attended the 2018 Comer Climate Conference.

Alley has previously guided the UN on climate change issues and was a lead author on the Fourth Assessment Report of the IPCC.

“I truly believe that if we use our scientific knowledge and what we know with respect for where we came from and commitment to where we’re going, we will end up better off,” Alley said. “We can’t afford not to.”

Photo at top: Using observations from NASA’s Orbiting Carbon Observatory-2, scientists have developed a new model of carbon behavior in our atmosphere from Sept. 1, 2014, to Aug. 31, 2015. Such models can be used to better understand and predict where carbon dioxide concentrations could be especially high or low. Credit: NASA Goddard Space Flight Center/K. Mersmann, M. Radcliff, producers. Atmospheric carbon dioxide acts as Earth’s thermostat. Rising concentrations of the greenhouse gas, due primarily to the burning of fossil fuels for energy, have driven Earth’s current long-term warming trend. The visualization highlights the advances scientists are making in understanding the processes that control how much emitted carbon dioxide stays in the atmosphere and how long it stays there — questions that ultimately will determine Earth’s future climate.

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