In the far north, climate change is not some distant warning anymore. It is already reshaping the landscape.
Across Alaska and Canada, Arctic and boreal regions are warming up to four times faster than the global average.
That puts a huge amount of pressure on ecosystems that have long helped slow climate change by pulling carbon dioxide out of the atmosphere and storing it in trees, shrubs, and soil.
When forests stop helping
The trouble is, those ecosystems do not always stay helpful under stress.
As wildfires grow more intense, drought becomes more common, and other disturbances spread, parts of the north may start giving carbon back to the atmosphere instead of locking it away.
Once that happens, the whole climate system becomes harder to stabilize.
That is why scientists care so much about biomass, the total amount of living plant material across these landscapes.
Estimating carbon storage in forests
Biomass is one of the clearest ways to estimate how much carbon northern ecosystems are storing or losing. But getting those measurements right is harder than it sounds.
Now two new studies led by University of Utah researchers Wanwan Liang and Jon Wang are trying to make that picture clearer.
One looks at the many satellite-based biomass datasets already in use and shows they do not always agree.
The other introduces a new map that tracks biomass across Arctic and boreal North America over nearly 40 years, in much finer detail than before.
Together, the studies are basically asking a simple question: if the north is changing so quickly, are we even measuring that change properly?
Too many maps, too many answers
The first paper tackles a problem that many people outside the field probably never think about.
There are now a lot of remote-sensing datasets available for Arctic and boreal forests, but more does not necessarily mean better.
“There are so many datasets out there now, but there’s very little guidance for users on how to choose among them,” Liang said.
“Two maps can give completely different estimates for the same region and if you’re not an expert, it’s really hard to know which one to trust,” Wang added.
So the scientists compared nine biomass datasets across Arctic and boreal North America. Instead of trying to declare one universal winner, they wanted to understand which datasets are more useful for which purposes.
Some may work better for tracking wildfire damage. Others may be more reliable for estimating large-scale carbon budgets.
“It’s more like a guide,” Wang said. “Different maps are better for different purposes.”
A much sharper picture
The second study goes a step further by building a new biomass dataset from the ground up.
Liang led the development of the map using Landsat satellite imagery, airborne LiDAR data, and forest inventory records from both the U.S. and Canadian Forest Services.
The result is a dataset that tracks aboveground biomass every year from 1984 to the present. Its resolution is 30 meters, about the size of a baseball field.
That level of detail means researchers can now pick up not only large disturbances like wildfires, but also smaller changes such as logging, land conversion, and more localized shifts in vegetation.
“Anything happening at 30 meters or larger, we can detect,” Liang said.
Northern ecosystems are not changing in one uniform way. A sharper map helps scientists see those changes as they unfold, instead of flattening them into one broad average.
A hopeful idea, with a catch
For years, there has been a fairly hopeful idea floating around climate science: that warmer temperatures in the north might help forests grow more and absorb more carbon, partly offsetting emissions from fossil fuels.
But Wang says the evidence is nowhere near that simple.
“There’s been this idea that northern forests will just keep taking up more carbon as it gets warmer,” he said. “But we don’t actually know if that’s true.”
Yes, warming can sometimes help plants grow faster. But it can also increase drought stress, fuel larger fires, and encourage insect outbreaks that kill trees.
Once those trees die, they stop taking in carbon. And as they decay or burn, they release carbon back into the air.
So the real question is not just whether northern vegetation is growing. It is whether the north, on balance, is becoming a stronger carbon sink or starting to weaken as one.
Why better numbers matter
Governments use carbon estimates to shape climate policy and report greenhouse gas inventories. In countries like Canada, those numbers affect how emissions targets are set and judged.
If the underlying biomass datasets disagree, then the uncertainty does not stay in the lab. It spills into policymaking.
“When different datasets give different answers, it creates a lot of uncertainty,” Wang said. “And that makes decision-making harder.”
There are also more immediate uses. High-resolution biomass maps can help estimate how much carbon may be lost in a wildfire, identify especially vulnerable areas, and support better land use planning.
Keeping the data public
At a time when some carbon-related data is becoming tied up in private sector systems, Liang and Wang say their goal is to make these tools transparent and accessible.
“This is taxpayer-funded science,” Wang said. “We want people to be able to use it.”
The Arctic and boreal north are changing quickly, and the stakes are high. If these landscapes are shifting from carbon sinks toward carbon sources, the world needs to know that as clearly and as quickly as possible.
But before scientists can answer the biggest climate questions, they need to be sure they are measuring the forests correctly.
That is what this research is really about: not just more data, but better data, at a moment when getting the story right matters more than ever.
The studies are published in the journal Environmental Research Letters and Remote Sensing of Environment.