Australia's warming climate transforms soil into a carbon emitter

Soil, often taken for granted, plays a critical role in the global carbon cycle and climate regulation. It acts as a natural carbon sink, sequestering carbon dioxide (CO2) from the atmosphere.

However, new research from Curtin University underscores how rising temperatures threaten to turn Australia’s soil into a net carbon emitter, exacerbating the climate crisis.

Soil’s role in climate regulation

Healthy soil teems with life and organic matter, storing vast quantities of carbon drawn from the atmosphere through plant activity.

This stored carbon helps mitigate climate change. However, the relationship between soil and climate is delicate.

As temperatures increase, the ability of the soil to hold carbon diminishes. Additionally, under certain conditions, it can even begin to release stored carbon back into the atmosphere.

Australia’s soil dilemma and climate change

“Unless farming methods are further improved so farmland soils can continue to store carbon, any gains and benefit will likely decrease by 2045 and worsen in time, if the Earth continues to warm at its current rate,” warns Professor Raphael Viscarra Rossel of Curtin University.

His team predicts a concerning shift: instead of sequestering carbon, Australian soil could become a significant emissions source.

This is particularly critical in sensitive coastal areas and the nation’s extensive rangelands, which hold an estimated 70% of the country’s soil carbon reserves.

The growing threat

Under a ‘middle-of-the-road’ emissions scenario, soil emissions could contribute over 14% of Australia’s total emissions by 2045. This proportion is likely to increase significantly by 2100, further complicating global efforts to limit warming.

Professor Viscarra Rossel stresses, “If emissions continue at the current rate, the Earth’s temperature is expected to reach 2 degrees above pre-industrial temperatures sometime this century, which is predicted to have dire consequences and potentially catastrophic impacts for the planet.”

Solutions for soil impacted by climate change

Australia faces a critical choice. Allowing soils to become carbon sources will severely undermine climate goals. Yet, the study emphasizes the potential for solutions:

Sustainable land management

Sustainable land management involves practices designed to protect natural resources, enhance agricultural productivity, and reduce CO2 emissions. Specifically, revitalizing grazing practices on rangelands can significantly improve soil health.

By managing the intensity and timing of grazing, we can encourage the growth of vegetation that captures more CO2 from the atmosphere.

This not only increases the soil’s carbon storage capacity but also enhances the resilience and biodiversity of ecosystems. These practices can lead to healthier soils that are more fertile and better able to retain water.

Indigenous Knowledge:

Indigenous communities have managed their lands for thousands of years using practices that are inherently sustainable and adapted to local environments.

One such practice is cultural burning, which involves controlled burns to manage the landscape.

Large, uncontrolled fires are definitely harmful. They release a lot of CO2 and harm ecosystems. Cultural burns are different.

They reduce the amount of fire fuel and make the soil healthier. It even helps the land hold more carbon. This approach honors indigenous wisdom and uses new innovations for the good of the planet.

Regenerative Agriculture:

Regenerative agriculture represents a paradigm shift in farming, moving beyond merely “doing no harm” to actively improving and restoring ecosystems.

This approach includes a variety of practices, such as cover cropping, reduced tillage, composting, and diversified crop rotations, all aimed at increasing soil organic matter. This not only sequesters more carbon but also enhances soil fertility and farm resilience.

Farmers adopting these techniques play a critical role in climate mitigation, transforming agriculture from a net emitter of CO2 to a potential net sink.

By focusing on soil health and ecosystem services, regenerative agriculture can produce more nutritious food, reduce dependency on chemical inputs, and build resilience to climate variability.

Insights from the study

“Ensuring Australia’s rangeland soils can maintain their carbon stocks is imperative: capturing and storing additional carbon will require interdisciplinary science, innovation, cultural awareness, and effective policies,” urges Professor Viscarra Rossel.

Addressing soil carbon loss requires a collaborative effort across sectors. Policymakers, scientists, land managers, and the broader community must prioritize soil health as integral to Australia’s climate resilience and a key element of global emissions strategies.

The study is published in Npj Climate and Atmospheric Science.

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