By Austin Keating,Video by Tiffany Chen and Austin Keating, Nov. 22, 2017 –
Scientists take to the field to study rapid warming and cooling events in Earth’s past. They find clues in ice and rock, lakes and sediment across the globe. Rebuilding climate change patterns from the past enhances predictions for the future as human use of fossil fuels accelerates global warming.
Leading geologists and climate researchers shared their latest discoveries and new developments at the Comer Abrupt Climate Change Conference in southwestern Wisconsin this fall.
The Comer Family Foundation has supported climate science researchers for 15 years now. This year, scientists presented a wide array of new discoveries, such as looking at how heavy rainfall in California over the past year and years of drought prior to that are depleting snowpack that streams water into the region.
Researchers also presented new data on glacial melt in Greenland, as well as melt in the Bhutan region of the Himalayas, where the lower-elevation faces of glaciers are thinning as much as 10 feet per year, according to research presented at the conference by Joerg Schaefer of Columbia University’s Lamont-Doherty Earth Observatory. Sea level rise as Greeenland glaciers melt and strained freshwater resources for several countries due to thinning Himilayan glaciers pose major concerns.
PHOTO AT TOP: A visualization of aerosols in the atmosphere above China recorded by satellites in 2006. Human-sourced aerosols and other greenhouse gases coming from China are rising, and scientists at the Comer Conference advocated for policy action to curb the trend (Courtesy of NASA).
NOTE: Tiffany Chen and Austin Keating are Comer Scholars, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in Science and Environmental Journalism.
Methane, a greenhouse gas frozen by the megatons in Earth’s melting ice, holds the potential to dramatically turn up the thermostat for the planet. But new research shows that a bacterial hero from Earth’s soils and seas will keep the thawing gas at bay.
Methane-eating soil microbes will prevent large plumes of methane from reaching the atmosphere as frozen deposits of it begin to thaw due to climate change, according to a paper in Nature recently published by Vasilii Petrenko and Jeffrey Severinghaus of the Scripps Institution of Oceanography at the University of California, San Diego. While Severinghaus doesn’t study microbes directly, he’s able to show their effect on past climates by going to Antarctica and sampling ancient air, he told colleagues during a presentation at the Comer Abrupt Climate Change Conference in southwestern Wisconsin this fall.
Scientists previously thought thawing methane deposits may have caused an abrupt 50 percent rise in atmospheric methane concentration during a rapid warming period at the end of the Younger Dryas, a cold period that ended 11,600 years ago. The prospect raised alarms for a potentially devastating climate feedback from methane, which molecule for molecule, traps at least 25-times more heat in the atmosphere than carbon dioxide.
Through 10 years of sampling ancient air, Severinghaus, his graduate students and the rest of his team were able to show, however, that during the warming period, no detectable methane in the atmosphere came from thawed deposits.
They demonstrated this by looking at the radiocarbon content of 11,600-year-old Antarctic ice, exhuming a ton for each measurement at a precise and narrow vein of ancient ice originally deposited by snowfall on Younger Dryas glaciers. They gathered a corresponding control of modern-day air cleared of carbon-14 for each measurement as well.
Methane released from thawed deposits has no carbon-14, because it’s old and the radiocarbon content decayed long ago. But methane released from natural sources such as wetlands is fresh, and has detectable carbon-14. Carbon-14 builds up in the air and in all living organic things as cosmic rays bombard atoms in the atmosphere.
“If that 50 percent increase in methane concentration was actually caused by the tundra getting warm and burping out all of this methane, then the concentration of carbon-14 relative to the more abundant carbon-12 should have gone down by 30 percent,” Severinghaus said. “We should really see a huge signal if this idea is correct …and we don’t.”
He added that methane-consuming soil microbes at the time must have stopped most of the thawing methane from reaching the atmosphere—just as their oceanic cousins did when they ate 99.9 percent of the methane released during the Deepwater Horizon oil spill in 2010.
Wetlands, which belch methane when it rains, and other natural sources were the main culprits for the rise in methane during the Younger Dryas warming period, Severinghaus said.
“If it didn’t happen back then, it won’t happen now and it won’t happen in the future,” Severinghaus said. “We can focus our attention back on CO2 [carbon dioxide], which really is the problem, and not worry so much about methane. So check one thing off the list.”
Pennsylvania State Geology Professor Richard Alley concluded Severinghaus’s presentation by applauding the amount of work that went into the research.
“Jeff could stand up here and give five or six more talks that have come out of these samples, it’s just really spectacular,” Alley added.
PHOTO AT TOP: Vasilii Petrenko works in the Severinghaus lab, and went to Antarctica to measure radiocarbon in ancient glacial ice. This chamber melts the ice so he can capture and measure the methane content, as the ice traps air bubbles of the atmosphere as it existed 11,600 years ago during a rapid warming event.(Courtesy of Jeffrey Severinghaus)
Note: Austin Keating is a Comer Scholar, a Medill scholarship program supported by the Comer Family Foundation to promote graduate studies in environmental journalism.
Carp caught at the event will provide data to develop water jets that can keep the invasive fish from moving upstream to the Great Lakes By Austin Keating, Aug 31, 2017 –
Photo at top: Some of the carp caught at Redneck Fishing provide research that can prevent the invasive species from entering the Great Lakes. (Austin Keating/Medill)
At the annual Redneck Fishing Tournament in early August, teams of Asian carp catchers unload their hauls into a semi-trailer full of the invasive, dead fish.
Most of the harvest went to cat food and fertilizer factories, but several dozen were taken by the U.S. Army Corps of Engineers for study in the battle to keep the jumping Asian carp out of the Great Lakes — where they could spread prolifically and ruin the area’s $7 billion fishing economy.
Jan Jeffrey Hoover, a research fishery biologist for the U.S. Army Engineer Research and Development Center in Vicksburg, Mississippi, went to the Redneck Fishing Tournament in the small western Illinois town of Bath to take measurements from the larger carp caught at the event. These measurements will help the corps replicate their serendipitous success at blocking large numbers of Asian carp from the Upper Mississippi River.
“Because the water there is restricted through a series of gates [north of St. Louis], it comes out at a higher velocity — for a relatively short distance — but enough that it’s impeded the entry of Asian carp into the Upper Mississippi River. We can exploit that technology, and we can exploit that weakness in the carp’s biology, by replicating hydraulic conditions that mimic that flow,” Hoover said.
At Redneck Fishing, the race to net the most Asian carp in four separate heats resulted in a catch of more than 2,700 of the fish. The carp that elude capture continue up the Illinois River and are prevented from reaching Lake Michigan by an electric barrier.
If funding is approved, the jet-enabled new layer of protection would have to be fine-tuned to keep out silver carp, a greater threat than the bighead carp, both of which are found in the Illinois and Des Plaines rivers, Hoover said. Silver carp, unlike bighead carp, jump when stirred by a wake and noise. They also occur in substantially larger numbers and have higher burst-swimming speeds than the bighead carp.
Both types of carp have gradually inched closer to Lake Michigan since flooding from fish farms in southern states introduced them into the Mississippi River in the late 1970s.
Finding the right water flow to impede Northern Illinois-adapted carp requires data on fish length and weight, which Hoover gathered at the event. He only picked the largest fish because they swim faster.
Having weight and length measurements for the fastest fish will allow the corps to develop maximum water velocities that prevent most carp from moving upstream.
Data are also gathered using water tunnels like this to evaluate swimming behavior and endurance at different water velocities.
Hoover also collected data that will be useful for lowering the count of Asian carp in Illinois rivers through other harvest events like Redneck Fishing.
“We’re collecting measurements on some of the fish they’re collecting here. And we’re dissecting them to look at their reproductive condition and the stage at which they’re reproducing,” Hoover said, adding that he also collected bones for age determinations and eggs to establish the number of offspring from individual females.
All of this can be incorporated into a harvest estimate through population modeling “to learn what rates of harvests would be useful in pushing … populations into a downward spiral,” Hoover said.
Bath — and its slice of the Illinois River — is a global hotspot for Asian carp. That’s why “harvesting events” like Redneck Fishing are so important. Not only does the yearly event help keep the population in this section of the river at bay, but it also gives scientists hundreds of fish to choose from for scientific study.
The weekend-long event in early August brings hundreds of tourists and locals to the small town with a population of about 300. Speed boats full of people holding nets follow pontoon boats that stir the carp with deep wakes, causing them to jump out of the water.
“Asian carp have a variety of impacts, not the least of which is public safety when they fly from the water and strike boaters. But more insidious are the environmental impacts that the species pose. Particularly in side-channels like this off of main-stem rivers like the Illinois and Mississippi rivers,” Hoover said. “Asian carp — once they get into a system like this — render it void of zooplankton. And that’s a food source for commercially desirable fish.”
Lifelong Bath resident Robin Daniels has volunteered at every Redneck Fishing tournament since the extravaganza began 11 years ago. While they were able to fill a semi-trailer full of the fish, prior years had much larger harvests. The turnout this year was lower, and the water level was high due to rain — making the fish less likely to jump, she said.
“I don’t think the carp are as bad because, in previous years, they’ve caught so many,” she said. “I grew up on this river, boated on this river. I would have never thought of seeing a flying fish back in those days. So we’ve all experienced a big change in this area.”