It's that time of the year when most Americans finish Thanksgiving leftovers and venture out in search for the best holiday sales. More importantly, they plan their household centerpiece of the season: the Christmas tree.

While some revel in the scent of a real tree and the joy of picking one out at a local farm, others prefer the simplicity of artificial trees they can reuse for Christmases to come.

But consumers are becoming more climate-conscious, and considering which tree has the lowest impact on our rapidly warming planet has become a vital part of the holiday decision. Plus, choosing a planet-friendly tree will likely get you on Santa's good list.

So, which kind of tree has the lowest carbon footprint — a natural tree or a store-bought plastic tree? It's complicated, experts say.

"It's definitely a lot more nuanced and complex than you think," Andy Finton, the landscape conservation director and forest ecologist for the Nature Conservancy in Massachusetts, told CNN.

We've made a list — and checked it twice — of the things to know before you choose between real and artificial.

The case for artificial trees

It's easy to imagine that reusing an artificial tree year after year is the more sustainable option. But Finton says that if an artificial tree is used for six years — the average amount of time people tend to keep them — "the carbon cost is definitely greater" than for a natural tree.

"If the artificial trees are used for a longer lifespan, that balance changes," Finton told CNN. "And I've read that it would take 20 years for the carbon balance to be about equivalent."

That's because artificial trees are typically made of polyvinyl chloride plastic, or PVC. Plastic is petroleum-based and created at pollution-belching petrochemical facilities. Studies have also linked PVC plastic to cancer and other public health and environmental risks.

Then there's the transportation aspect. According to the U.S. Department of Commerce, most artificial Christmas trees are imported into the US from China, meaning the products are carried by fossil fuel-powered ships across the Pacific Ocean, then moved by heavy freight trucks before it ultimately lands on the distributor's shelves or the consumer's doorstep.

The American Christmas Tree Association, a nonprofit that represents artificial tree manufacturers, commissioned WAP Sustainability Consulting for a study in 2018 that found the environmental impact of an artificial tree is better than a real tree if you use the fake tree for at least five years.

"Artificial trees were looked at [in the study] for factors such as manufacturing and overseas transportation," Jami Warner, executive director of ACTA, told CNN. "Planting, fertilizing and watering were taken into account for real trees, which have an approximate field cultivation period of seven to eight years."

What are the benefits of real trees?

On average, it takes seven years to fully grow a Christmas tree, according to the National Christmas Tree Association. And as it grows, it absorbs carbon dioxide from the air. Protecting forests and planting trees can help stave off the worst impacts of the climate crisis by removing the planet-warming gas from the atmosphere.

If trees are cut down or burned, they can release the carbon they've been storing back into the atmosphere. But Doug Hundley, spokesperson for the National Christmas Tree Association, which advocates for real trees, says the act of cutting down Christmas trees from a farm is balanced out when farmers immediately plant more seedlings to replace them.

"When we harvest the trees or cut them, we plant back very quickly," Hundley said.

If the idea of trekking through a forest to find the perfect tree is intriguing, you can buy a permit from the U.S. Forest Service, which encourages people to cut their own tree rather than buy an artificial one. According to Recreation.gov, cutting down thin trees in dense areas can improve forest health.

But Finton doesn't recommend pulling a Clark Griswold and chopping down a massive tree to haul home — especially if it's in an area you're not permitted for. He recommends getting a tree from a local farm, instead.

"To me, the benefit of going to a Christmas tree farm, which is different than cutting a tree in the forest, is that it concentrates the impact of removing trees into one location," he said. "And it puts the responsibility on the farmers to regenerate those trees."

There's also an economic benefit to going natural, since most of the trees people end up getting are grown at nearby farms. About 15,000 farms grow Christmas trees in the US alone, employing over 100,000 people either full or part-time in the industry, according to the National Christmas Tree Association.

"What we're doing by purchasing a natural Christmas tree is supporting local economies, local communities, local farmers and to me, that's a key part of the conservation equation," Finton said. "When a tree grower can reap economic benefits from their land, they're less likely to sell it for development and less likely to convert it to other uses."

Disposal matters

Trees pile up on the curbs after the holidays are over, and the final destination in many locations is landfills, where they contribute to emissions of methane — a powerful greenhouse gas roughly 80 times more potent that carbon dioxide.

"Real Christmas trees ending up in landfills is very much discouraged," Hundley said, adding that there needs to be "separate areas for yard waste where Christmas trees can go."

But some towns and cities repurpose the trees to benefit the climate and the environment. In New York City, trees left on curbs during a certain timeframe are picked up to be recycled or composted. The city sanitation department also hosts an initiative called MulchFest, where residents can bring their trees to be chipped for mulch and used to nourish other trees throughout the city.

"When the tree is finished being used by the homeowner, it's very easy and and common in America to have the tree chipped up into mulch — and that's stored carbon is put back in the ground," Hundley added.

Finton also says former Christmas trees can be reused for habitat restoration; they can help control erosion if placed along stream and river banks, and can even help underwater habitats thrive if they are placed in rivers and lakes.

The end of life for an artificial tree is much different. They end up in landfills — where they could take hundreds of years to decompose — or incinerators, where they release hazardous chemicals.

The bottom line

Weighing the complicated climate pros and cons, real Christmas trees have the edge. But if you choose to deck your halls artificially, get a tree you're going to love and reuse for many years.

Either way, Finton said, people should feel good about their decision and find other ways to tackle the climate crisis.

"It's a debate, but once you've made a decision, you should feel good about your decision, because there's so many other things we can do in our lives that have an even greater climate impact — such as driving less or advocating for policies that expand renewable energy," Finton said. "Enjoy the holidays and focus on other aspects of your life to reduce the impacts of climate change."

Retail sales in the U.S. took an unexpected dive in December as COVID-19 cases surged because of the omicron variant.

Figures released Friday by the Commerce Department show that they dropped 1.9% from November, although economists had forecasted that they only decline by 0.1%.

After four straight months of sales increases, the decline was attributed to several factors, including supply chain disruptions and decades-high inflation.

Total sales from October to December jumped 17.1% from the same period as a year ago.

It was still a good year for retailers, with sales rising 19.3% from last year.

PARIS (AP) — Global energy-related carbon dioxide emissions rose slightly in December compared with the same month of 2019, indicating the sharp drop seen due to the pandemic was short-lived.

Figures released Tuesday by the International Energy Agency show emissions from the production and use of oil, gas and coal were 2% higher in December 2020 than a year earlier.

The Paris-based agency said a resurgence in economic activity coupled with a lack of clean energy policies mean many countries are now seeing higher emissions than before the coronavirus outbreak.

Scientists have previously calculated that CO2 emissions fell by 7% during 2020 as people stayed home because of the pandemic. Carbon dioxide is the main greenhouse gas responsible for global warming.

The agency says the rebound in emissions is a stark warning that not enough is being done to accelerate clean energy transitions worldwide.

“If governments don’t move quickly with the right energy policies, this could put at risk the world’s historic opportunity to make 2019 the definitive peak in global emissions,” said Dr Fatih Birol, the IEA Executive Director. “In March 2020, the IEA urged governments to put clean energy at the heart of their economic stimulus plans to ensure a sustainable recovery. But our numbers show we are returning to carbon-intensive business-as-usual.”

Birol says this year is pivotal for international climate action, but the latest numbers are a sharp reminder of the immense challenge we face in rapidly transforming the global energy system.