Next month, a Silicon Valley engineer plans to head out on a snowmobile from Barrow, on the northern tip of Alaska, to sprinkle reflective sand on a frozen lake to try to stop it from melting.

It’s part of a journey that began in 2006, after Leslie Field watched the climate change documentary “An Inconvenient Truth” and felt like she’d been “hit by a big fat truck.” Now, she hopes to gather global support over the next few years to ultimately cover more than 19,000 square miles of sea ice — an area about the size of Costa Rica — with a thin coating of tiny floating silica spheres, which she says will help reduce the world’s rising temperatures.

The cost estimate? $1 billion a year.

“I keep thinking, ‘If not me, who?’ ” Field, a former researcher at Chevron Corp. and HP Labs, said as she led a reporter through a wholesale flower shop that shares access with her office.

In the emerging field of geoengineering, which envisions large-scale efforts to fight climate change by directly manipulating the natural environment, Field’s privately funded Ice911 project is a small player. Under the Trump administration, these eclectic, messianic and mostly untested projects have been gaining unprecedented momentum.

For decades, scientists have warned that unchecked climate change will lead to catastrophes and have urged policymakers to curb greenhouse gases at their source. But politicians have dragged their heels, and under President Trump, progress has slowed. The Trump administration has challenged the scientific consensus on climate, moved to repeal curbs on power plant emissions, proposed sweeping cutbacks to renewable energy research and pledged to withdraw from global climate agreements.

Amid these developments, some close allies of Trump have taken a seemingly paradoxical stance: While denying climate change is a human-caused problem and rejecting proposals to cut greenhouse gases, they’re promoting what some experts worry is the risky solution of geoengineering.

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Former House Speaker Newt Gingrich, who has portrayed climate change as left-wing intellectuals’ “newest excuse to take contrl of lives,” has praised geoengineering for its “promise of addressing global warming concerns for just a few billion dollars a year.”

In December, Rep. Jerry McNerney, D-Stockton, introduced a bill seeking funds for geoengineering research and development. And in February, Trump signed a budget that includes tax breaks for new technologies to capture carbon dioxide from the atmosphere.

“The future is bright for geoengineering,” Republican Rep. Randy Weber of Texas, chairman of the energy subcommittee of the House Committee on Science, Space and Technology, said at a hearing in November.

In the past, Weber has grilled scientists on “global cooling” and rejected a carbon pollution tax as “blasphemy.” At the November hearing, he claimed that yet-untested proposals such as “placement of mirrors in space” and “brightening the clouds overhead … could have a cooling effect on our lower atmosphere.”

Harvard physicist David Keith said, “There’s much more broad support for this than there was just two years ago.” Keith, who wrote a 2013 book titled “A Case for Geoengineering,” leads one of the world’s most closely watched geoengineering research projects. Later this year, his team plans to conduct its first outdoor trial, launching a balloon over Tucson to disperse substances such as calcium carbonate dust or sulfur dioxide to reflect the sun’s rays back into space.

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The increasing interest in geoengineering, including from climate skeptics, owes partly to growing pessimism about humanity’s capacity — and will — to ward off the worst effects of climate change without some major technological breakthrough.

Over the past several years, scientists and entrepreneurs throughout the world have proposed more than a dozen kinds of geoengineering projects. One would send 16 trillion tiny robots into space to deflect the sun’s rays from the Earth. Another would build millions of wind-powered pumps in Arctic waters to push freezing water over the ice to thicken it. The “cloud-brightening” scheme praised by Weber last fall envisions shooting salt water into marine clouds to improve their reflective power.

These aren’t even the most radical ideas. Back in 1993, an Indian physicist considered whether the Earth could be cooled by somehow increasing the radius of the planet’s orbit around the sun. And in a widely condemned operation in 2012, a rogue California businessman conducted the world’s largest geoengineering project to date by dumping 100 tons of iron dust into the Pacific Ocean. His goal was to fertilize plankton to absorb carbon dioxide and then sell “credits” to fossil-fuel firms.

Solar radiation management proposals, such as the Harvard aerosol-spraying plan, have attracted the most interest, even while alarming some leading climate scientists.

“The idea of ‘fixing’ the climate by hacking the Earth’s reflection of sunlight is wildly, utterly, howlingly barking mad,” writes Oxford University physicist Raymond Pierrehumbert. He was a lead author of the Nobel Prizewinning Third Assessment Report from the U.N. Intergovernmental Panel on Climate Change.

He and other scientists say large-scale spraying of sulfur dioxide into the atmosphere could deplete the ozone layer, harm some plants and animals, and benefit some countries, while causing droughts in others.

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Field contends her Ice911 project, which she terms “Arctic restoration,” offers a safer alternative than solar radiation management, since it aims to restore rather than significantly change the environment.

Field began her research with buckets of cold water placed on the front deck of her home in Portola Valley, where she tested a variety of materials, including hay and daisies, to see how well they could prevent the sun’s rays from raising water temperatures. After settling on silica, she scaled up her experiments with trials on ice in California’s Sierra Nevada and on Canada’s Miquelon Lake.

Along the way, she raised funds from private donors, the largest contribution being a three-year, $1.3 million grant from a family foundation that she heard about through a wealthy friend with whom she volunteered at her sons’ school. Last May, Field and a small group of volunteers used an agricultural spreader, dragged by a snowmobile, to cover an area of ice the size of three football fields on an inland lake in Alaska.

Next week, Field plans to dispatch a buoy into the Arctic Ocean to monitor sea ice, and then return next month to try dispersing more sand on lake ice. She has not yet secured permits to perform tests on sea ice.

“Ice911 is the boots on the ground solution acting now to ease climate change by restoring Arctic ice,” reads Field’s fundraising pamphlet, in what she conceded in an interview was an overstatement. Ice911 has yet to have any impact on climate change. Before that can happen, she said, she needs to build credibility for her approach, which has yet to win respect from the so-called geo-clique — a small group of North American scientists who advise politicians and large funders.

Some scientists dismiss it as unrealistic and ineffective.

“This isn’t anything anyone is going to do,” said Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science’s Department of Global Ecology at Stanford University. “It’s not that effective, and you’d have to do it over millions of acres.”

Many scientists say that a major danger shared by all these planet-hacking options is their “moral hazard,” an insurance industry term describing how people behave more recklessly when they know they have a fallback.

Harvard’s Keith, whom Time magazine honored in 2009 as a “hero of the environment,” gives voice, often simultaneously, to both fears and hopes for geoengineering. In the span of a single conversation with comedian and TV host Stephen Colbert in 2013, he called geoengineering “ugly” and “horrifying” but also said, “It might actually save people and be useful.”

“If we don’t cut emissions, we’re sunk, and it would be criminal if people use this as an excuse to avoid that,” Keith said in an interview.

He worries about the new momentum in Washington.

“In some ways,” Keith said at a conference last fall, “the thing we fear the most is a tweet from Trump, saying, ‘Solar geoengineering solves everything! It’s great! We don’t need to bother to cut emissions.’ ”

Katherine Ellison is a freelance journalist. This story was produced by Reveal from the Center for Investigative Reporting, a nonprofit news organization. Learn more at revealnews.org. The Reveal podcast, produced with PRX, is at revealnews.org/podcast.