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How UC Berkeley Physicist Ernest Lawrence Helped Launch the Era of 'Big Science'

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PBS NewsHour

How NASA measures the death of a glacier from space

The south end of Bowman lake in Glacier National Park. Photo by Catherine Woods

The south end of Bowman lake in Glacier National Park. Photo by Catherine Woods

Editor’s note: This story is part of a two-part feature on the basic research of sea level rise

My photos from last summer capture a beauty that is disappearing faster and faster each year. But the images don’t do the experience justice. Standing on frozen ground, tasting air heavy with huckleberries, I had to perch on a lofty boulder in order to focus the whole ice mass in my smartphone screen. Only 25 glaciers remain inside Glacier National Park — down from 150 in the mid-19th century — and scientists estimate that these peaceful giants that sculpt the homes of grizzly bears and wildflowers will be gone by 2050.

It’s long been known that much of the Earth’s ice is melting. But we don’t know how fast that melt is occurring, or how soon the corresponding sea level rise could mean coastal cities and crops will be under the water. We need data to establish an effective plan against climate change, said Dan Fagre, an ecologist at the Northern Rocky Mountain Science Center of the US Geological Survey.

science-wednesday

“We [Glacier National Park] will be a story about what happened when climate change started,” Fagre said.

Glaciers are made from snowfall that turns into ice that is large enough to last through the warm months. People call them “living” glaciers because the bottom layer isn’t solid. They move and ooze, dragging rocks and sediment with them, Fagre said. Glaciers move under the pressure of their own weight and gravity, carving any earth that’s in the way, and they must be roughly 25 acres large to do so. But when their rate of melting outpaces the rate of freezing, they shrink and lose the necessary weight to slide and sculpt the surrounding earth. As they lose mass and weight, they slow down, losing the ability to push forward, until they eventually stop and melt away — like a snowbank at the end of winter.

The size of a glacier is a direct indicator of climate change, Fagre said. Glaciers can’t adapt to warmer weather with behavior the way that animals or insects might. So any changes you see are a direct result of the weather.

Grinnell Lake in East Glacier National Park. Photo by Catherine Woods

Grinnell Lake in East Glacier National Park. Photo by Catherine Woods

In 1850, Glacier National Park had 150 living glaciers — that’s six times more than it has now. Since at least that time, glaciers there have been declining. But 50 years ago, the rate of decline jumped and the number of glaciers in the park took a nosedive. The situation has become increasingly bleak with time. The snow is melting faster, forcing bears and birds to adapt to new food patterns. Less snow through July and August means warmer waters, which hurts endangered species like the bull trout and the meltwater stonefly. The hotter climate means less water in the forest, which can lead to an increase in the number of fires and a depleted water supply.

“People’s grandchildren or great-grandchildren will probably never see a glacier at Glacier National Park.” – Ecologist Dan Fagre

Fagre’s team does most of its glacier monitoring on the ground, using photography, tree ring studies and snow measurements. Tracking all 1,583 square miles of the park would be easier from space; but the technology to zoom in on the national park’s glaciers — which are “crumbs” compared to large ice masses in the north and south pole — isn’t in space… yet.

Meet ICESat-2. NASA’s new Ice Cloud and Land Elevation satellite is designed to provide a more detailed picture of the state of global ice melt than we’ve ever had. It will measure ice both big and small, in sea and on land. How, you ask? With a really cool laser.

Almost everything at NASA Goddard Space Flight Center in southern Maryland is big – big ideas, big 40-foot-high chambers for prepping the space satellites and a big love of ice from guys like Tom Neumann, the deputy project scientist for NASA’s ICESat-2.

40-foot-tall vacuum chamber at NASA Goddard Space Flight Center. Photo by Mike Fritz

40-foot-tall vacuum chamber at NASA Goddard Space Flight Center. Photo by Mike Fritz

“I’m a land ice guy” said Neumann, who looks like the world-saving physicist you might see in an apocalyptic blockbuster movie. His hair flows like a young Einstein around black-rimmed glasses and a warm smile.

NASA Goddard is ICESat-2’s birthplace. The satellite lives in a three-story, dust-free “clean room” with slatted doors that resemble a garage from the outside. Black tape covered the panels to keep light from the satellite’s laser from seeping out during testing. The laser was off on the day of my visit, and I got to peek inside through a viewing window. A half dozen scientists in full body protective gear, or “bunny suits,” were darting around the satellite. The room is kept so pristine that the team must print all of their checklists on a special flake-free paper.

ICESat-2 engineering station at the NASA Goddard Space Flight Center. Photo by Nsikan Akpan

ICESat-2 engineering station at the NASA Goddard Space Flight Center. Photo by Nsikan Akpan

Scientist work on ICESat-2 in clean room at NASA Goddard Space Flight Center. Photo by Mike Fritz

Scientist work on ICESat-2 in clean room at NASA Goddard Space Flight Center. Photo by Mike Fritz

ICESat-2. Photo by Michael Fritz

ICESat-2. Photo by Michael Fritz

Using a laser to survey the globe isn’t new. The satellite’s predecessor — ICESat-1 — used Lidar (think radar, but with a laser) to measure ice from 2003 to 2009. But ICESat-2’s laser, referred to as Advanced Topographic Laser Altimeter System or ATLAS, is designed to capture much more detail.

“It’s so powerful that it can tell if you mowed your front lawn last weekend,” said project scientist Thorsten Markus.

Here’s how it works. Light particles, or photons from the laser will continuously beam down to Earth with 10,000 emitted per second. These photons will reflect off water, snow, grass and rock — and then bounce back into space. A receiver on ATLAS will detect returning photons. (Note: The photons from ICESat-2 are harmless — an infinitesimally small fraction when compared to the photons in daily sunlight.)

Scientists will determine distance by measuring how long it takes each photon to depart the satellite, bounce off the earth and return to the satellite. Clocks on ATLAS are extremely precise — they measure time within “a billionth of a second,” Neumann said.

So what does all this tell us about ice? Imagine a floating piece of ice in the Arctic Ocean. To measure this piece of ice, the photons bounce off the ice itself and the water that surrounds it. Now imagine one ATLAS photon bouncing off the frigid water and returning back to the satellite. As the satellite moves forward in space, another photon will strike adjacent to where the last photon landed, on top of the floating ice. The laser keeps moving until it covers the entire piece of ice and surrounding water. Then scientists can calculate the difference between the distance traveled by the photon that made contact with water and the photon that made contact with ice. That difference is how much the ice sticks out of the water, which can be used to calculate total ice thickness.

The ATLAS box structure, which houses ICESat-2's laser, is lowered onto the shaker table to test whether it will
         withstand the strong jolts and vibrations during launch.  Photo by NASA's Goddard Space Flight Center/Debbie McCallum

The ATLAS box structure, which houses ICESat-2’s laser, is lowered onto the shaker table to test whether it will withstand the strong jolts and vibrations during launch. Photo by NASA’s Goddard Space Flight Center/Debbie McCallum

But wait, it gets better. Onboard ICESat-2, the laser snakes through a seven-foot obstacle course before leaving the satellite. Bouncing off mirrors and passing through optics, it breaks into three pairs, for a total of six beams. This setup allows ICESat-2 to take a measurement on the ground around every two feet. Not bad for a satellite 300 miles from Earth.

Measuring the thickness of the ice is important, but scientists also need to know the rate of change. “ICESat-2 will take the same measurements over the same track every 90 days,” Neumann said. “So if you compare the data today with data 90 days from now, and then 90 days later, you can see how the ice is changing through time.”

Before it launches in 2017, ICESat-2 must pass a series of tests. Inside a huge vacuum chamber, ICESat-2 will have to face both frigid and hot temperatures, simulating what it will experience as it passes in and out of the sun’s rays. Because the satellite will hitch a ride into space on the NASA Delta II rocket, scientist will also put the satellite on a giant vibrating platform, as they do with all satellites, to see if it can withstand the vigorous shaking experienced during a launch.

NASA's ATLAS laser box structure sits on a shaking platform designed to test whether satellites can withstand the
         intense vibrations during launch. ATLAS is the laser system for the ICESat-2 satellite, which will measure global rates of
         melting ice.  Photo by NASA Goddard Space Flight Center/Kate Ramsayer

NASA’s ATLAS laser box structure sits on a shaking platform designed to test whether satellites can withstand the intense vibrations during launch. ATLAS is the laser system for the ICESat-2 satellite, which will measure global rates of melting ice.
Photo by NASA Goddard Space Flight Center/Kate Ramsayer

Speaker used to test satellites for vibration integrity at vacuum chamber at NASA Goddard Space Flight Center. Photo
         by Mike Fritz

Speaker used to test satellites for vibration integrity at vacuum chamber at NASA Goddard Space Flight Center. Photo by Mike Fritz

Many are rooting for ICESat-2 to pass these tests. Just like ICESat-1, ICESat-2 data will be made available to the public. “I hope everyone uses this data; it’s going to be fabulous data. It’s going to change everything,” Neumann said.

ICESat-2’s smaller footprint will be important for Sinead Farrell, a scientist at the University of Maryland that used ICESat data in the past. She studies sea ice or floating chunks of ocean ice that are much smaller than a glacier. Only one-eighth of sea ice is above water, and LIDAR can only measure ice above the water, which makes sea ice tough to quantify with accuracy.

Since ICESat-1 completed its mission, her team has turned to data from an interim NASA project called Operation IceBridge – a lidar-equipped plane designed to monitor the most problematic areas until ICESat-2 is launched. But IceBridge is only a temporary solution, as it would cost at least a billion dollars more to have a plane cover all the ground that ICESat-2 will cover.

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NASA video outlining the results from ICESat-1 and IceBridge

ICESat-2’s range will be bigger, and its use will extend beyond ice. In fact, Amy Neuenschwander, an engineer at University of Texas’ Center for Space Research, plans on using the data to measure tree height.

“What might take months and months to measure ten trees in a plot in Africa, you can do with one pass from a satellite,” Neuenschwander said.

Farrell said sea ice influences climate change by acting like a baseball cap, a blanket and a conveyor belt. The white surface of sea ice reflects light better than liquid ocean water. So the presence of sea ice keeps sun rays from warming the seas, much like a baseball cap keeps your face cool. Sea ice behaves like a blanket by preventing water molecules from easily escaping into the atmosphere via evaporation. Water vapor in the atmosphere leads to further heating, worsening ice melt, Farrell said. Finally, ocean particles — water molecules, silt, salts — from the surface to the sea floor are constantly in motion. They slowly move along a conveyer belt — pivoting from top to bottom as they reach the edge of the sea. This is called Thermohaline circulation, and it is driven by how salty and warm the ocean becomes in warmer season. Melting sea ice has the potential to slow or halt this natural churning of the ocean.

“We know that sea ice plays an important role in the thermohaline circulation, but it remains unclear exactly what influence a diminishing sea ice pack would have on the global ocean circulation. Through new measurements, such as those expected from ICESat-2, we hope to learn more about these processes,” Farrell said.

Between 2003 and 2012, the Arctic Ocean lost about 580 square miles of winter sea ice, Farrell said. That is a little over half the size of Rhode Island. With less sea ice, we can expect warmer waters, more evaporation and altered currents. All of this is happening at an accelerated rate, Farrell said.

Upturned sea ice blocks in the Beaufort Sea, Arctic Ocean. Photo by NOAA/Sinead Farrell

Upturned sea ice blocks in the Beaufort Sea, Arctic Ocean. Photo by NOAA/Sinead Farrell

Ilukissat, Greenland, 217 miles north of the Arctic Circle. Photo by Ken Burton/Vancouver Maritime Museum

Ilukissat, Greenland, 217 miles north of the Arctic Circle. Photo by Ken Burton/Vancouver Maritime Museum

Ice melt is the primary contributor to sea level rise, which is increasing three to four millimeters per year, said Ted Scambos, a glaciologist at University of Colorado’s National Snow and Ice Data Center. Scambos used ICESat data to monitor Antarctic ice shelves – floating sheets of ice attached to the earthy mainland. Ice shelves can act as gatekeepers to larger glaciers. But when an ice shelf collapses, humongous glaciers move rapidly into open warmer waters and start to shrink. This event can cause an abrupt rise in sea level. Scambos will use ICESat-2 data to help predict how long these weakening ice shelves will hold.

To Scambos, ICESat-2 is the next step in combating climate change. “We need to transition from a science of discovery about climate change to a science of monitoring – how does this happen and how is it progressing?”

In the meantime, David Greene, an environmental policy expert at the University of Tennessee suggests that everyone take a hard look at their energy consumption. Walk and bike more, he said, reserve your air conditioner for freeway driving, and brake and accelerate less. A lighter car with “less drag” is a greener car.

But that will only take us so far. Even if we were to drastically change our behavior, Glacier National Park would be glacier-less within this century, Neumann said. If all of Greenland melted away, he said, it would raise sea-level by 21 feet. But if the rate of sea-level rise stays constant, that will take 20,000 years. So there is still time to save the large masses of land ice.

The post How NASA measures the death of a glacier from space appeared first on PBS NewsHour.

Can you guess how many trees are on Earth?

Beech forest,  Gorbea Natural Park, Spain. Photo by Westend61/Via Getty Images

Beech forest, Gorbea Natural Park, Spain. Photo by Westend61/Via Getty Images

How many trees are on the planet? Go ahead and guess. One for every person or around 7 billion? 100 billion?

The best guess is 3.04 trillion or 422 times the human population, according to a study published today in the journal Nature. The collaborative investigation, which engaged researchers from 15 countries, provides one of the most sweeping estimates of tree density ever.

Led by Yale University environmental scientist Thomas Crowther, the study combined satellite imagery with a boatload of on-the-ground observations — 429,775 — from studies conducted over the last decade. The study also collected information from forestry databases, such as the Smithsonian Tropical Research. The team defined a tree as any plant with woody stems larger than 3.9 inches diameter at breast height. The field measurements spanned the planet’s 14 recognized ecosystems, as defined by the Nature Conservancy — from boreal forest to deserts to tundra to the tropics.

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By using supercomputer algorithms, the researchers painted a map of global tree populations with a resolution of a square-kilometer. The new findings corrects the former estimate of tree population, 400 billion trees, which was made using satellite imagery and estimates of forest area but didn’t include on-the-ground recordings.

So assuming a worldwide human population of 7.2 billion, rather than there being 61 trees per person, there are 422 per person. Tropical forests harbor the most trees or about 43 percent of the global population, while temperate climates house 22 percent. Russia (641 billion), Canada (318 billion), Brazil (301 billion), the U.S. (228 billion) and China (139 billion) top the list of countries with the most trees.

The data aren’t just a snapshot of the present, but provide glimpses into the past and future too. The researchers estimate that Earth has lost nearly half of its trees — 46 percent — since the start of human civilization. And due to ongoing deforestation and human land-use, the planet is losing about 15 billion trees per year or two trees for every person. The highest rate of deforestation is occurring in the tropics.

“We’ve nearly halved the number of trees on the planet, and we’ve seen the impacts on climate and human health as a result,” Crowther said in a press statement. “This study highlights how much more effort is needed if we are to restore healthy forests worldwide.”

This is the global map of tree density at the square-kilometer pixel scale. Photo by Crowther et al., Nature, 2015.

This is the global map of tree density at the square-kilometer pixel scale. Photo by Crowther et al., Nature, 2015.

The post Can you guess how many trees are on Earth? appeared first on PBS NewsHour.

Scientists find a fat hormone toggles a runner’s high

Rita Jeptoo of Kenya crosses the finish line to win the 118th Boston Marathon on April 21, 2014 in Boston. Photo by Jim
         Rogash/Getty Images

Rita Jeptoo of Kenya crosses the finish line to win the 118th Boston Marathon on April 21, 2014 in Boston. Photo by Jim Rogash/Getty Images

A long run feels the worst until it feels the best. That’s primarily thanks to the runner’s high — those euphoric feelings that strike halfway through an endurance workout.

Now, researchers have charted what happens to the brain to produce a runner’s high. The sensation is tied to low levels of leptin — a brain hormone that tempers food consumption when you’ve had enough to eat, according to a study published today in the journal Cell Metabolism. The scientists sketch out a switch in a precise set of brain cells that drives the urge to run in mice. Leptin regulates this switch, causing the animals to seek opportunities to run as well as allowing them to run for twice as long as usual.

Leptin is a “fat hormone” that tells your mind that you’re full of food. When you eat, leptin levels rise and you become lethargic. In contrast, when animals lose leptin in their brains, they become hyperactive gluttons, uncontrollably seeking and consuming food. They can’t be sated.

However, this low-leptin turbo boost is seen in another scenario: endurance runners. Marathon runners tend to eat less, which reduces the amount of leptin in their bodies. An earlier study found that marathon runners with the lowest leptin run faster and take the least time to complete their races, regardless of their body mass index. Rodents run faster and longer with less leptin, too. These trends suggest that leptin may govern the will to run, but how?

The new study shows that leptin toggles a runner’s desire by cutting access to a reward chemical — dopamine — in one of the brain’s motivation centers, the ventral tegmental area. Dopamine in the ventral tegmental area promotes the sensations of elation and satisfaction felt after eating a big meal or having sex.

But leptin doesn’t act alone. A protein called STAT3 is an intermediary in this leptin-based running switch. Leptin and STAT3 are molecular buddies. When leptin hormone soaks neurons in the brain, STAT3 is produced inside the cells, but when leptin levels fall, so too does STAT3.

Falling STAT3 levels are a runner’s version of a green light, according to this new study from the University of Montreal. When the team genetically deleted STAT3 from the ventral tegmental area in mice, the rodents “jogged” 6.8 miles per day on their cage’s running wheel — nearly twice as much as the average for a normal mice, or 3.7 miles per day. When put into a cage with two separate chambers — one with a regular running wheel and one with a broken wheel — the STAT3-deficient mice spent more time in the working “exercise room” than normal mice, even if they weren’t running.

The researchers found that losing STAT3 blunted dopamine levels in the mice’s ventral tegmental area. A dopamine drop in the ventral tegmental area can trigger reward-seeking in humans. So, the team argues that marathon runners are reward seekers driven by low levels of leptin and STAT3.

“Our study suggests that people with lower fat-adjusted leptin levels, such as high-performance marathon runners, could potentially be more susceptible to the rewarding effects of running and thus possibly more inclined to exercise,” said neuroscientist Stephanie Fulton of the University of Montreal in a press statement.

In other words, a hormone behind the urge to eat — leptin — also controls the desire to run, according to their findings. Humans and animals may have evolved this switch to maintain their energy levels for hunting at times when food was scarce.

“We think that a fall in leptin levels increases motivation for physical activity as a means to enhance exploration and the pursuit of food,” Fulton said, though she admits other metabolic signals outside of leptin might be involved in the runner’s high, too.

Her team plans to look for those signals while peering into whether leptin triggers other aspects of a runner’s high, such as better muscle stamina or the pain relief caused by the release of natural opioid chemicals.

The post Scientists find a fat hormone toggles a runner’s high appeared first on PBS NewsHour.

WATCH: 26 years ago, Oliver Sacks wanted to be remembered like this

Watch this Oliver Sacks interview from 1989.

In 1989, not long after Oliver Sacks wrote the bestseller, “The Man Who Mistook His Wife for a Hat,” and just before his 1973 memoir “Awakenings” made its movie debut starring Robin Williams, “The MacNeil/Lehrer NewsHour” interviewed the famed neurologist.

Sacks — who died on Sunday at age 82 after a long bout with cancer — talked about his research, breakthroughs and commitment to recording the stories of those who might otherwise be forgotten.

“I have a need to look at people, who perhaps through no fault of their own, through biological chance, have been thrust out of the mainstream, and in general, to see the tremendous adaptability of the human organism and the human spirit,” Sacks said.

When correspondent Joanna Simon asked Sacks how he’d like to be remembered in 100 years, he said:

“I would like to be thought that I had listened carefully to what patients and others had told me, that I had tried to imagine what it was like for them, and that I had tried to convey this. And to use a biblical term, the feeling, ‘he bore witness.’”

The post WATCH: 26 years ago, Oliver Sacks wanted to be remembered like this appeared first on PBS NewsHour.