In this Tuesday, Jan. 20, 2015, file photo a plume of smoke billows from the coal-fired Merrimack Station in Bow, N.H. (Jim Cole/AP)

WHAT HAPPENS if humans fail to cut carbon dioxide emissions enough to prevent worsening climate change? A new report from the National Research Council of the National Academy of Sciences contemplates some very unattractive — but potentially necessary — backup plans.

Ending deforestation seems like an obvious answer. But, the report found, planting more trees won’t do enough to suck CO2 out of the air. Instead, humans might have to use decidedly less natural methods to counteract global warming. The report discusses two options. Scientists could try to reduce the amount of carbon dioxide in the atmosphere. Or they could reflect more sunlight back into space. This is called climate intervention or geoengineering, and it’s very controversial in scientific and environmental circles.

Geoengineering poses all kinds of problems. Directly removing carbon dioxide from the air is a very slow process, and the removed gas would need to be stored somewhere. Fertilizing the ocean with tiny bits of iron would encourage phytoplankton to grow and consume CO2, but it could alter the ocean environment in unknown ways. Spraying sulfur dioxide particles — which spew out of erupting volcanoes naturally — would reflect sunlight, but doing so would also thin the ozone layer, change rain patterns and potentially encourage international conflict. Other ideas, such as painting rooftops and streets white, might help. But no strategy to increase reflection would solve problems such as ocean acidification, which would continue so long as carbon dioxide levels are high.

The financial cost of researching, building and operating climate intervention projects would be formidable. Facilities to remove carbon dioxide from the air, the report notes, might well cost more than simply replacing polluting power plants with renewables. Cheaper techniques such as blasting sulfur dioxide into the sky would require perpetual effort absent serious cuts in carbon dioxide output. The longer the world hesitates to put global emissions on a downward slope, the harder the cleanup task will be.

Given the risks associated with climate intervention, it makes no sense to bet the climate on the ingenuity of future generations. But the planet should have a backup plan — or, at least, the beginnings of a backup plan. The National Academy report points out that policymakers and scientists have hardly embarked on the basic research, analysis and planning.

Further research could encourage people to put more faith in the potential of geoengineering, even though cutting carbon dioxide emissions remains the better option. That could help those who resist greenhouse emissions reductions. But there’s also a risk that those same people will win out anyway, leaving the world with little recourse absent a backup plan.

Congress has not been wise in its handling of the domestic discretionary budget over the past several years, shortsightedly declining to invest in important research and infrastructure. With the resources available, low-carbon energy technologies should remain the funding priority. But the National Academy report should at least put climate intervention on the table as worthy of some support.