For years, Kim Cobb was the Indiana Jones of climate science. The Georgia Tech professor flew to the caves of Borneo to study ancient and current climate conditions. She jetted to a remote South Pacific island to see the effects of warming on coral.
Add to that flights to Paris, Rome, Vancouver and elsewhere. All told, in the last three years, she's flown 29 times to study, meet or talk about global warming.
Then Cobb thought about how much her personal actions were contributing to the climate crisis, so she created a spreadsheet. She found that those flights added more than 73,000 pounds of heat-trapping carbon to the air.
Now she is about to ground herself, and she is not alone. Some climate scientists and activists are limiting their flying, their consumption of meat and their overall carbon footprints to avoid adding to the global warming they study. Cobb will fly just once next year, to attend a massive international science meeting in Chile.
"People want to be part of the solution," she said. "Especially when they spent their whole lives with their noses stuck up against" data showing the problem.
The issue divides climate scientists and activists and plays out on social media. Texas Tech's Katharine Hayhoe, an atmospheric scientist who flies once a month, often to talk to climate doubters in the evangelical Christian movement, was blasted on Twitter because she keeps flying.
Hayhoe and other still-flying scientists note that aviation is only 3% of global carbon emissions.
Jonathan Foley, executive director of the climate solutions think-tank Project Drawdown, limits his airline trips but will not stop flying because, he says, he must meet with donors to keep his organization alive. He calls flight shaming "the climate movement eating its own."
Over the next couple of weeks, climate scientists and environmental advocates will fly across the globe. Some will be jetting to Madrid for United Nations climate negotiations. Others, including Cobb, will fly to San Francisco for a major earth sciences conference, her last for a while.
"I feel real torn about that," said Indiana University's Shahzeen Attari, who studies human behavior and climate change. She calls Cobb an important climate communicator. "I don't want to clip her wings."
But Cobb and Hayhoe are judged by their audiences on how much energy they use themselves, Attari said.
Attari's research shows that audiences are turned off by scientists who use lots of energy at home. Listeners are more likely to respond to experts who use less electricity.
"It's like having an overweight doctor giving you dieting advice," Attari said. She found that scientists who fly to give talks bother people less.
In science, flying is "deeply embedded in how we do academic work," said Steven Allen, a management researcher at the University of Sheffield, who recently organized a symposium aimed at reducing flying in academia. He said the conference went well, with 60 people participating remotely from 12 countries.
Pennsylvania State University's Michael Mann, who flies but less than he used to, said moderation is key.
"I don't tell people they need to become childless, off-the-grid hermits. And I'm not one myself," Mann said in an email. "I do tell people that individual action is PART of the solution, and that there are many things we can do in our everyday lives that save us money, make us healthier, make us feel better about ourselves AND decrease our environmental footprint. Why wouldn't we do those things?"
Mann said he gets his electricity from renewables, drives a hybrid vehicle, doesn't eat meat and has one child.
When Hayhoe flies, she makes sure to bundle in several lectures and visits into one flight, including 30 talks in Alaska in one five-day trip. She said more people come out to see a lecture than if it were given remotely, and she also learns from talking to the people at lectures.
"They need a catalyst to get to the next step and me coming could be that catalyst," Hayhoe said.
Marshall Shepherd of the University of Georgia will receive a climate communications award at the American Geophysical Union conference Wednesday in San Francisco. But he won't pick it up in person, saving 1.2 tons of carbon by not flying. He said he doesn't judge those who fly but wrote about his decision to stay grounded in hopes that people "think about choices and all of the nuances involved in these decisions."
Former Vice President Al Gore, who has long been criticized by those who reject climate science for his personal energy use, said he has installed 1,000 solar panels at his farm, eats a vegan diet and drives an electric vehicle.
"As important as it to change lightbulbs," he said in an email, "it is far more important to change the policies and laws in the nation and places where we live."
Teen activist Greta Thunberg drew attention when she took a zero-carbon sailboat across the Atlantic instead of flying.
"I'm not telling anyone else what to do or what not to do," Thunberg told The Associated Press before her return boat trip. "I want to put focus on the fact that you basically can't live sustainable today. It's practically impossible."
Cobb is trying. In 2017, she started biking to work instead of driving. She's installed solar panels, dries clothes on a line, composts and gave up meat. All these made her feel better, physically and mentally, and gave her more hope that people can do enough to curb the worst of climate change.
But when she did the math, she found "all of this stuff is very small compared to flying."
Cobb began turning down flights and offering to talk remotely. This year she passed on 11 flights, including Paris, Beijing and Sydney.
"There hasn't been a single step I have taken that has not brought me a deeper appreciation for what we're up against and what's possible," Cobb said. "This gave me a profound appreciation for how individual action connects to collective action."
But there's a cost.
Cobb was invited to be the plenary speaker wrapping up a major ocean sciences conference next year in San Diego. It's a plum role. Cobb asked organizers if she could do it remotely. They said no. She promised to do many roles for the conference from Atlanta. Conference organizers withdrew the offer.
Brooks Hanson, executive vice president of the American Geophysical Union, which runs the conference, said in an email that the group supports remote presentations whenever possible. But the wrap-up speaker position "requires in-person interactions with attendees to get the vibe of the meeting and discussions," Hanson said.
Foley said that shows the problem: "Climate scientists and activists should walk the walk. But we can only walk so far. Then you bump into other things."
SpaceX made an early holiday delivery to the International Space Station on Sunday, dropping off super muscular "mighty mice," pest-killing worms and a smart, empathetic robot.
The station commander, Italy's Luca Parmitano, used a large robot arm to grab onto the Dragon three days after its launch from Cape Canaveral. The two spacecraft soared 260 miles (420 kilometers) above the South Pacific at the time of capture.
"Whenever we welcome a new vehicle on board, we take on board also a little bit of the soul of everybody that contributed to the project, so welcome on board," Parmitano told Mission Control.
The capsule holds 3 tons (2,720 kilograms) of supplies, including 40 mice for a muscle and bone experiment. Eight of them are genetically engineered with twice the normal muscle mass — and so are considered "mighty mice."' There also are 120,000 roundworms, or nematodes of a beneficial variety that are part of an agricultural study aimed at controlling pests.
The capsule also has a large, round robot head with artificial intelligence and the ability to sense astronauts' emotions. Named Cimon, it's an improved version of what flew up last year to be tested as an astronaut's helper.
NASA has tucked some Christmas presents in the shipment for the station's six-person crew, as well.
It's SpaceX's 19th delivery to the orbiting outpost for NASA over the past seven years.
The astronauts have another delivery coming Monday — this one launched by Russia from Kazakhstan on Friday.
Chinese consumers are much more likely than people in other major countries to purchase an electric vehicle or hybrid, showed a latest survey.
There is gathering pace behind electric vehicle appetite with over 50 percent of respondents willing to consider an electric or hybrid vehicle next time they replace vehicles, according to the survey released this week by global consulting firm OC&C Strategy Consultants.
"China is the clear leader in the electric and hybrid vehicle field," said the report, which surveyed more than 10,000 respondents across five countries, including the United States, China, France, Germany and the United Kingdom.
About 94 percent of Chinese respondents said they would consider buying that type of vehicle, followed by French consumers, with 77 percent of the people surveyed expressing such an intention.
The report showed Americans lag far behind the consumers in other surveyed countries in embracing electric or hybrid vehicles.
Fifty-three percent of U.S. consumers said they would mull purchasing one, largely due to concerns over access to charging stations away from home. Only 19 percent are likely to buy one.
Government incentives are a key driver in getting consumers to purchase electric vehicles, noted the survey.
China's support policies over the past few years have made it one of the fastest-growing new energy vehicle (NEV) markets. Last year, the country's NEV sales soared 61.74 percent to 1.26 million units, according to the China Association of Automobile Manufacturers.
SpaceX launched a 3-ton shipment to the International Space Station on Thursday, including "mighty mice" for a muscle study, a robot sensitive to astronauts' emotions and a miniature version of a brewery's malt house.
The Dragon capsule also is delivering holiday goodies for the six station residents. NASA's Kenny Todd isn't giving any hints, but said, "Santa's sleigh, I think, is certified for the vacuum of space."
The recycled capsule should arrive Sunday.
The Falcon rocket blasted off from Cape Canaveral a day late because of high winds. SpaceX recovered the new booster on a barge just off the coast in the Atlantic several minutes following liftoff so it could be reused. SpaceX employees in Southern California cheered when the booster landed, and again a few minutes later when the capsule reached orbit.
This is SpaceX's 19th supply run for NASA.
Forty mice are aboard, including eight "mighty mice" with twice the muscle mass of ordinary mice, according to the experiment's chief scientist, Dr. Se-Jin Lee of the Jackson Laboratory in Farmington, Connecticut.
Researchers plan to bulk up some of the non-mighty space mice during or after their month-long flight in an attempt to build up muscle and bone. This therapy could one day help astronauts stay fit on lengthy space trips, said Lee and Dr. Emily Germain-Lee of Connecticut Children's Medical Center.
Before and after liftoff, the couple sang part of the theme song to the mid-20th century superhero TV cartoon "Mighty Mouse"' and even had others joining in at the launch site.
Germain-Lee was too emotional to sing right at liftoff. "I was sobbing so hard that I couldn't even get my breath," she told The Associated Press.
In addition, there are barley grains aboard the Dragon for a beer-malting experiment by Anheuser-Busch. It's the third in a series of Budweiser experiments to look at how barley germination is affected by weightlessness.
The shipment also includes a large, plastic 3-D printed robot head with artificial intelligence, according to its German creators. It's named Cimon, pronounced Simon, the same as the prototype that flew up last year. This upgraded version is designed to show empathy to its human colleagues in orbit.
Cimon will spend up to three years at the space station, three times longer than its recently returned predecessor. The goal, said IBM's Matthias Biniok, is to provide astronauts with constantly updated robotic helpers, especially at the moon and Mars.
The space station currently is home to three Americans, two Russians and one Italian.
Russia plans to launch its own cargo ship to the outpost Friday.
China's lunar rover Yutu-2 has driven 345.059 meters on the far side of the moon to conduct scientific exploration of the virgin territory.
Both the lander and the rover of the Chang'e-4 probe have ended their work for the 12th lunar day, and switched to dormant mode for the lunar night, the Lunar Exploration and Space Program Center of the China National Space Administration (CNSA) said Wednesday.
Due to the complicated geological environment and the rugged and heavily cratered terrain on the far side of the moon, Chinese space engineers carefully planned the driving routes of the rover to ensure its safety.
Driving slowly but steadily, the Yutu-2 is expected to continue traveling on the moon and make more scientific discoveries, said CNSA.
China's Chang'e-4 probe, launched on Dec. 8, 2018, made the first-ever soft landing on the Von Karman Crater in the South Pole-Aitken Basin on the far side of the moon on Jan. 3, 2019.
A lunar day equals 14 days on Earth, a lunar night is the same length. The Chang'e-4 probe switches to dormant mode during the lunar night due to a lack of solar power.
During the 12th lunar day of the probe on the moon, the scientific instruments on the lander and rover worked well, and a new batch of scientific detection data was sent to the core research team for analysis.
As a result of the tidal locking effect, the moon's revolution cycle is the same as its rotation cycle, and the same side always faces Earth.
The far side of the moon has unique features, and scientists expect Chang'e-4 could bring breakthrough findings.
The scientific tasks of the Chang'e-4 mission include conducting low-frequency radio astronomical observation, surveying the terrain and landforms, detecting the mineral composition and shallow lunar surface structure and measuring neutron radiation and neutral atoms.
The Chang'e-4 mission embodies China's hope to combine wisdom in space exploration with four payloads developed by the Netherlands, Germany, Sweden and Saudi Arabia.