Understanding Nature’s Seasonal “Breathing” and the Carbon Cycle in Northern High Latitudes

Tree in four different seasons
Tree in four different seasons: winter, spring, summer, fall.

How Seasonal Shifts in the Northern High Latitudes Impact Global Carbon Levels and Climate Stability

Climate change affects not only temperatures but also how ecosystems manage and cycle carbon dioxide (CO₂). Below we explore how rising temperatures and increasing CO₂ levels in Arctic and boreal regions—collectively called northern high latitudes (NHL)—are creating seasonal shifts in CO₂ levels. These changes impact our planet’s “carbon thermostat” and could intensify global warming if left unchecked. Let’s dive into the drivers behind these changes and how we can use this knowledge to shape a healthier future for our planet.

Defining Seasonal Cycle Amplitude (SCA)

Imagine Earth “breathing” with each season: in the spring and summer, trees and plants in the northern high latitudes absorb CO₂ during photosynthesis, much like an inhale. They use this CO₂ to grow, pulling it from the atmosphere and helping cool the planet. When autumn and winter arrive, these plants release CO₂ back into the air as they decompose—much like an exhale. This seasonal fluctuation in CO₂ is known as the Seasonal Cycle Amplitude (SCA).

Over the last several decades, the “inhale” in summer and “exhale” in winter has become more extreme. Plants are taking in even more CO₂ in warmer months and releasing more in cooler ones. This intensifying cycle is linked to higher CO₂ levels in the air and warming temperatures in the NHL, turning nature’s “breath” into a stronger force in the global carbon cycle.

Primary Drivers of SCA Increase

The increase in the seasonal CO₂ cycle, especially in the NHL, is due to several interacting forces. Here’s a look at the primary drivers behind this intensified “breathing”:

  • Warming Temperatures: Arctic areas are warming faster than the rest of the world, which means that plants have a longer growing season to capture CO₂. This extended period of photosynthesis results in more CO₂ being absorbed during warmer months.

  • CO₂ Fertilization: Plants use CO₂ as fuel to grow. With more CO₂ in the atmosphere, plants have more “food” available, which can increase their growth and further boost CO₂ absorption.

  • Increased Respiration: Warmer temperatures cause more CO₂ to be released back into the atmosphere as organic matter decomposes. This process, called respiration, also happens in winter due to permafrost thaw, releasing even more CO₂.

These factors combined are driving an intensified cycle, making the NHL a more powerful influence on our planet’s CO₂ levels.

Regional Influences

Different regions within the NHL—primarily the Arctic areas of North America and Eurasia—play unique roles in this changing cycle. Here’s how each contributes:

  • Eurasian Boreal Forests: These forests, especially in Siberia, are major players in absorbing CO₂. Warmer temperatures have enabled these forests to grow longer and stronger, contributing significantly to CO₂ uptake.

  • North American Boreal Forests: Although North America’s boreal forests are also absorbing CO₂, they are more sensitive to drought. This means they may absorb less CO₂ during dry years compared to Eurasia’s forests, which are often moister due to atmospheric changes.

Differences in forest types, moisture levels, and permafrost also mean that these regions respond to climate change in varied ways, affecting their role in the carbon cycle.

Projections for the Future

Looking ahead, the seasonal cycle of CO₂ is expected to continue intensifying in the NHL throughout the 21st century. Under high-emission scenarios, scientists project that by the end of the century, the NHL’s seasonal CO₂ cycle could be 75% stronger than it was in the 1980s.

What does this mean for global climate? This intensified “breathing” cycle means the NHL will continue to influence Earth’s “carbon thermostat” more dramatically. With higher CO₂ intake in the growing season and increased release during the colder months, this cycle could speed up the warming effects of greenhouse gases on our climate.

Recommendations for the Future

To better understand and manage these changes, scientists recommend several strategies to improve our knowledge of the carbon cycle in the NHL and inform climate policy:

  • Expand Monitoring Networks: Building more observation stations in under-monitored areas like tundras and Siberian forests will provide a clearer picture of CO₂ dynamics and seasonal trends.

  • Refine Climate Models: Current models should better account for factors like permafrost thaw and snow cover to accurately predict seasonal CO₂ fluctuations.

  • Support More Research: Understanding the impacts of landscape changes—such as forest growth, wildfires, and vegetation shifts—will help pinpoint how each factor influences CO₂ release and capture.

Taking these steps will help scientists and policymakers better gauge the impact of NHL ecosystems on the global carbon cycle and adapt climate policies accordingly.

Summing Up

Understanding the “breathing” cycles of the NHL offers a valuable key to shaping our climate future. By integrating more data from these regions, scientists can strengthen climate models, allowing for improved predictions and more precise climate targets. These insights also enhance policy decisions, as a better grasp of Arctic and boreal ecosystem dynamics can guide effective climate policies tailored to address the growing impact of CO₂ levels from these areas.

This seasonal “breathing” of Earth’s northern high latitudes reminds us that even the planet’s most remote areas have a crucial role in our shared climate future. By monitoring and adapting to these changes, we can contribute to a healthier, more balanced Earth.


Source: Liu, Z., Rogers, B. M., Keppel-Aleks, G., et al. (2024). Seasonal CO₂ amplitude in northern high latitudes. Nature Reviews Earth & Environment, 5(11), 802–817. https://www.umt.edu/news/2024/11/110824ntsg.php

What is a wetland? An ecologist explains

Photo by Tyler Butler on Unsplash
Photo by Tyler Butler on Unsplash

By Jon Sweetman, The Conversation US CC BY-NC-ND 4.0)

Wetlands are areas of land that are covered by water, or have flooded or waterlogged soils. They can have water on them either permanently or for just part of the year.

Whether it’s year-round or seasonal, this period of water saturation produces hydric soils, which contain little or no oxygen. But this doesn’t mean that they are lifeless: Wetlands are full of unique water-loving plants and wildlife that have adapted to wet environments.

Wetlands can take many different forms, depending on the local climate, water conditions and land forms and features. For example, swamps are dominated by woody trees or shrubs. Marshes often have more grasslike plants, such as cattails and bulrushes. Bogs and fens are areas that accumulate peat – deposits of dead and partly decomposed plant materials that form organic-rich soil.

Trillions of dollars in ecological benefits

Wetlands are important environments for many reasons. They provide ecological services whose value has been estimated to be worth more than US$47 trillion per year.

For example, wetlands support very high levels of biodiversity. Scientists estimate that 40% of all species on Earth live or breed in wetlands.

Wetlands are critical homes or stopovers for many species of migratory birds. In the central U.S. and Canada, for example, wetlands in the so-called prairie pothole region on the Great Plains support up to three-quarters of North America’s breeding ducks.

The hunting and conservation group Ducks Unlimited works to conserve prairie pothole wetlands on North America’s Great Plains.

Along with providing important habitat for everything from microbes to frogs to waterfowl, wetlands also work to improve water quality. They can capture surface runoff from cities and farmlands and work as natural water filters, trapping excess nutrients that otherwise might create dead zones in lakes and bays. Wetlands can also help remove other pollutants and trap suspended sediments that cloud water bodies, which can kill aquatic plants and animals.

Because wetlands are often in low-lying areas of the landscape, they can store and slowly release surface water. Wetlands can be extremely important for reducing the impacts of flooding. In some places, water entering wetlands can also recharge groundwater aquifers that are important for irrigation and drinking water.

Wetlands also act as important carbon sinks. As wetland plants grow, they remove carbon dioxide from the atmosphere. They they die, sink to the bottom of the wetland and decompose very slowly.

Over time, the carbon they contain accumulates in wetland soils, where it can be stored for hundreds of years. Conserving and restoring wetlands is an important strategy for regulating greenhouse gases and mitigating the impacts of climate change.

Resources at risk

Despite the many valuable services they provide, wetlands are constantly being destroyed by draining them or filling them in, mainly for farming and development. Since 1970, the planet has lost 35% of its wetlands, a rate three times faster than the loss of forests.

Destruction and degradation of wetlands has led to the loss of many organisms that rely on wetland habitat, including birds, amphibians, fish, mammals and many insects. As one example, many dragonfly and damselfly species are declining worldwide as the freshwater wetlands where they breed are drained and filled in. A marsh or bog may not look like a productive place, but wetlands teem with life and are critically important parts of our environment.


Disclosure statement
Jon Sweetman receives funding from the US EPA for work on wetland restoration. He is affiliated with the Society for Freshwater Science, the Ecological Society of America, and the Society of Wetland Scientists