Potential last-ditch efforts to avert the worst impacts of global warming by geoengineering Earth's climate could themselves be harmful, a new study suggests.

Why it matters: With global concentrations of greenhouse gases continuing on an upward trajectory — and no sign of the end of fossil fuel use — some researchers are turning to technological fixes like geoengineering the climate. But the new study underscores the potential unintended and unknown consequences of the technology.

“In some ways this study is a note of caution that with a planetary scale technology like this there may be a lot of outcomes that surprise us. There is so much more that we don’t know than we do know.”

Background: Right now, the world is on course to experience a greater amount of global warming than the 2°C, or 3.6°F, target under the Paris Climate Agreement.

Scientists are studying whether the planet can be veiled in particles that would reflect incoming sunlight and offset warming of the planet.

• These solar radiation management (SRM) schemes are a type of geoengineering that would involve wrapping Earth in a "stratospheric veil."
• Groups at Harvard and other universities are focusing on taking geoengineering from the theoretical to the technically deployable stage during the next several years.

What's new: A study published in Nature this week finds reason to be cautious about assuming that SRM would benefit crops by protecting plants from heat-related impacts and making sunlight more diffuse.

The researchers used computer modeling that incorporates two large past volcanic eruptions — El Chichón in 1982 and Mount Pinatubo in 1991 — as an analog to SRM plans.

Powerful volcanic eruptions can loft the chemical precursors to sulfate aerosols into the stratosphere. Mount Pinatubo, for example, sent 20 million tons of sulfur dioxide into the upper atmosphere, where it then formed aerosols.

What they found: The damages seen during the mid-20th century from the way that sulfate aerosols scatter sunlight are about equal to the projected benefits to crops from cooling the planet. The net effect, then, would "attenuate little of the global agricultural damage from climate change," the study says.

Go deeper: Read the whole post.

The Democratic Republic of the Congo started using an experimental vaccine against the deadly Ebola virus yesterday after identifying it as the virulent Zaire strain, Eileen Drage O'Reilly writes. The latest outbreak has spread to a conflict region and is suspected of killing at least 36 people during its first week.

Why it matters: Testing and approving an Ebola vaccine is a priority for global health officials as further outbreaks are expected. The U.S. hopes to get the Food and Drug Administration to consider approval for a vaccine in 18 months or so.

"As I said before in May [during a prior DRC Ebola outbreak], 'It's not over yet, folks, because this is going to come back.'"

Background: Out of the four Ebola strains that humans can catch, the Zaire strain currently in DRC is the deadliest — but it's also one targeted by most of the vaccines and treatments, Fauci tells Axios. The DRC and surrounding countries often have outbreaks because they have a "reservoir" of infected bats and non-human primates that can transmit the disease to humans — "so this is not a fluke," Fauci says.

Driving the news: DRC officials now are vaccinating with 3,220 doses of the experimental rVSV-ZEBOV vaccine, wielding it as a ring vaccine where the circle of people in contact with the infected are vaccinated as well. They have requested more.

Go deeper: Read Eileen's story.

The Mendocino Complex fire is officially the largest wildfire on record in California, with more than 304,402 Acres acres burned as of Thursday. It's made up of two separate fires burning in close proximity, and it has already eclipsed last year's record-setting Thomas Fire, which torched about 281,000 acres.

The graphic above shows how the destruction compares to the size of Washington, D.C. and Manhattan. The fire is 51% contained, and will likely keep burning through at least September. Typically fire season doesn't peak in the state until the fall.

Go deeper:

• By the numbers: Unprecedented devastation of California's wildfires
• How the Carr Fire morphed into a towering, deadly "fire tornado"

California heat: The state had its hottest month on record in July, with average temperatures 5°F above the 20th century average. Death Valley, California, set a record for the hottest month of any location on Earth, NOAA found. The heat helped set the stage for the devastating wildfires across the state.

Human origins: A new paper calls for more open-mindedness in the long-running academic debate over how Native Americans first arrived in the Americas, writes Eileen Drage O'Reilly. Multiple migratory routes are viable, based on genetic and physical evidence, the researchers say.

California water: In response to the deadly wildfire outbreak, the Trump administration ordered NOAA to prioritize water for firefighting, rather than sustaining endangered species such as Chinook salmon and Delta smelt.

Coal change: As the developed world slows its coal consumption, the developing one is ramping its up, meaning consumption overall is likely to increase, according to Axios Expert Voices contributor Anna Mikulska, a senior fellow at the University of Pennsylvania's Kleinman Center for Energy Policy.

Space Force: Vice President Mike Pence announced the Defense Department is establishing a Space Force, and it could ultimately be a sixth branch of the military, Lauren Meier reports.

Walrus clues: Bones from Greenland are repainting a picture of Viking life and trade, and offer possible answers for the rapid, mysterious demise of their communities in 1400, the AP reports. It suggests walrus ivory drove Greenland's wealth, and perhaps a drop in demand — due in part to Europe's Black Death — lead to their disappearance.

Dog deceit: Researchers report in the Journal of Zoology that dogs adapt the angle of their leg lift during urination according to size. Smaller dogs reach to more extreme angles so that when others pass their scent they seem larger.

Bye, bye, beavers: Chile and Argentina introduced 20 Canadian beavers in the 1940s. Now there are 200,000, and they've decimated native beaches and taken over the landscape in remote areas of Patagonia. The governments are teaming up to kill 100,000 of the animals, writes Ben Goldfarb of the Washington Post.

"Hothouse earth": Anxiety built this week after a report came out suggesting that even limiting global warming to 2°C, or 3.6°F, may lead to a devastating domino effect of damage. Scientist Richard Betts breaking down what the report does and doesn't mean for The Conversation.

NASA is scheduled to launch the first space mission to enter the Sun's corona from Cape Canaveral Air Force Station in Florida on Saturday, Henrietta Reily writes.

The big picture: The Parker Solar Probe stands out for just how close to the Sun it plans to go: less that 3.82 million miles away. By comparison, we live a comfortable 93 million miles from our solar system's star. Assuming a successful launch, the probe will also become the fastest-moving man-made object ever, traveling at 340,000 miles per hour.

Why it matters: At a press conference on Thursday, project scientist Nicola Fox said that engineers and scientists have been waiting 60 years to be able to develop the right technology to build this type of probe. "We know a lot about the sun," she said, but there are key mysteries that will be unsolvable until a spacecraft can reach closer to its surface.

"The corona that we all saw during the total solar eclipse is 300 times hotter than the surface of the sun, and we want to figure out why that’s happening. Why is this atmosphere continually expanding and accelerating away from the star?"

Answering these questions will improve scientific understanding and could also help build resiliency on Earth against volatile space weather.

Go deeper:

• Read more about the mission here.
• What we still don't know about the Sun