How will changing tundra landscapes affect Earth's climate?

Tundra landscapes are not only among the coldest places on Earth but are also undergoing some of the most dramatic transformations due to climate change.

According to a recent study, these changes are reshaping the natural world in significant ways.

The far northern reaches of the Earth, including the tundra and boreal forests, are witnessing notable shifts in vegetation structure.

For generations, these lands have been the domain of hardy grasses, shrubs, and mosses – their resilience matched only by the tenacity of the local inhabitants.

However, with the ongoing trend of global warming, the once sparse and lonely tundra could become significantly taller and greener in the coming decades.

Tundra’s transformation over the next century

Research conducted by scientists from NASA suggests that we can expect the tundra greening trend to persist through the current century.

The evolving forest structure could potentially absorb more carbon dioxide (CO2), a notorious greenhouse gas. However, it could also lead to increased permafrost thawing, which might release stored, ancient carbon into the atmosphere.

The research was informed by millions of data points from the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) and Landsat missions.

A tale of two biomes

Geographically, boreal forests predominantly grow between 50 and 60 degrees north latitude, encompassing large parts of Alaska, Canada, Scandinavia, and Russia. These forests are home to evergreen species such as pine, spruce, and fir.

Moving farther north, we encounter the tundra biome with its permafrost and limited growing season, which makes it a challenging environment for large trees or dense forests. Instead, shrubs, mosses, and grasses have become the primary vegetation.

The transition between these two biomes has been particularly intriguing. Previous studies had noticed an increase in plant growth and northward movement, encroaching into areas previously dominated by tundra shrubs and grasses.

The recently published NASA study reveals an even more significant presence of trees and shrubs in these tundra regions and adjacent transitional forests, where boreal regions meet the tundra. These changes are predicted to continue until at least the end of the century.

Tundra transformation: Shifting vegetation patterns

“The results from this study advance a growing body of work that recognizes a shift in vegetation patterns within the boreal forest biome,” said lead researcher Paul Montesano.

“We’ve used satellite data to track the increased vegetation growth in this biome since 1984, and we found that it’s similar to what computer models predict for the decades to come. This paints a picture of continued change for the next 80 or so years that is particularly strong in transitional forests.”

The changes in vegetation height and concentration could produce a range of effects on our global climate. As study co-author Chris Neigh suggests, the vegetation increase might offset some of the impact of rising CO2 emissions by absorbing more CO2 through photosynthesis, leading to carbon storage in trees, shrubs, and soil.

Conversely, this change might also cause permafrost areas to thaw, as darker vegetation absorbs more sunlight. This could potentially release CO2 and methane that has been stored in the soil for thousands of years.

How NASA is predicting the future

Harnessing the strengths of satellite data, machine learning, climate variables, and climate models, NASA scientists have embarked on a mission to model and predict future forest structures.

They analyzed nearly 20 million data points from NASA’s ICESat-2 and then matched these data points with thousands of scenes of North American boreal forests from 1984 to 2020, sourced from Landsat, a joint mission of NASA and the U.S. Geological Survey.

It’s these advanced computing capabilities that allow researchers to create models from such large quantities of data, known as “big data” projects.

NASA is utilizing technology like ICESat-2’s lidar, an advanced laser instrument that measures the height of Earth’s surface features from space.

Melanie Frost, a remote sensing scientist at NASA, emphasized the importance of understanding these environmental changes, as they are intertwined with our climate models.

“Our climate is changing and, as it changes, it affects almost everything in nature. It’s important for scientists to understand how things are changing and use that knowledge to inform our climate models,” said Frost.

As the future unfolds, keeping a close eye on transformative trends in the tundra will be integral to our understanding – and perhaps even our mitigation – of global climate change.

The study is published in the journal Nature Communications Earth & Environment.

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