Don’t Look to Mature Forests to Soak Up Carbon Dioxide Emissions: Results of Australian Study May Have Impact on New York State Carbon Neutrality Goals

April 23, 2020

Print This Article Share it With Friends

(Suny College of Environmental Science and Forestry) Research published today in Nature suggests mature forests are limited in their ability to absorb "extra" carbon as atmospheric carbon dioxide concentrations increase. These findings may have implications for New York state's carbon neutrality goals.

Dr. John Drake, assistant professor in ESF's Department of Sustainable Resources Management, is a co-author of the paper in collaboration with researchers at Western Sydney University.

The experiment, conducted at Western Sydney University's EucFACE (Eucalyptus Free Air CO2 Enrichment) found new evidence of limitations in the capacity of mature forests to translate rising atmospheric carbon dioxide concentrations into additional plant growth and carbon storage.

Carbon dioxide (CO2) is sometimes described as "food for plants" as it is the key ingredient in plant photosynthesis.

...

The researchers combined their measurements into a carbon budget that accounts for all the pathways of carbon into and out of the EucFACE forest ecosystem, through the trees, grasses, insects, soils and leaf litter. This carbon-tracking analysis showed that the extra carbon absorbed by the trees was quickly cycled through the soil and returned to the atmosphere, with around half the carbon being returned by the trees themselves, and half by fungi and bacteria in the soil.

"The trees convert the absorbed carbon into sugars, but they can't use those sugars to grow more, because they don't have access to additional nutrients from the soil. Instead, they send the sugars below-ground where they 'feed' soil microbes," said Dr. Belinda Medlyn, distinguished professor at the Hawkesbury Institute for the Environment.

These findings have global implications: models used to project future climate change, and impacts of climate change on plants and ecosystems, currently assume that mature forests will continue to absorb carbon over and above their current levels, acting as carbon sinks. The findings from EucFACE suggest that those sinks may be weaker or absent for mature forests. READ MORE

The fate of carbon in a mature forest under carbon dioxide enrichment (Nature)

USIPA, REA criticize Ember report on carbon neutrality of biomass (Biomass Magazine)

EU climate plan blows hot and cold on forestry, biomass (Energy Market Price)

Natural Debate: Do Forests Grow Better With Our Help or Without? (Yale Environment 360)

We can’t just plant our way out of the climate crisis (Carbon 180)

The risky climate bet of using forests to remove CO2 -- Forests absorb about 10 percent of the EU’s CO2 emissions. (Politico)

Excerpt from Biomass Magazine: “As the International Energy Agency has recently stated, ‘the most important climate change mitigation measure is to transform energy and transport systems so that we can leave fossil carbon in the ground. Biomass is a critical technology to achieve this, as it provides the necessary grid stability to support the widespread use of intermittent renewables like offshore wind,’” USIPA said.

According to the USIPA, the IEA has defined forest biomass as renewable if it is harvested from forest that are managed in a way such that there is no loss of productive capacity. This means that growth and harvest cycles can continue indefinitely and capacity to sequester carbon is not diminished.

That is the case in the U.S. Southeast, which is a major supplier of wood pellets to U.K. biomass power plants. The USIPA cites USDA analysis that shows forest stocks in the Southeast have increased by 20 percent over the past two decades and are double what they were in the 1950s.

“The leading science on this is well-established; biomass, when sustainably-produced, significantly lowers carbon emissions for power generation compared to coal,” said Seth Ginther, executive director of the USIPA. “That’s why the use of sustainable biomass is championed by the U.N. Intergovernmental Panel on Climate Change (IPCC) and other leading scientific bodies including the International Renewable Energy Agency, the European Forest Institute, and the U.S. National Association of University Forest Resource Programs.”

“While our industry welcomes robust scrutiny and debate on the issues, it’s important for us to recognize and acknowledge that we have reached a tipping point where the overwhelming data, evidence and peer reviewed research points to the fact that sustainable biomass is part of the climate change solution,” Ginther added.

The REA has also spoken out against the report. “This paper by Ember amounts to a misreading of the science, going against the UN’s IPCC and the U.K.’s CCC, with recommendations that would raise bills for consumers whilst undermining the path to Net Zero,” said Nina Skorupska, chief executive of the REA.

“The carbon accounting rules that govern the renewables sector were reaffirmed just last year by the IPCC, the UN’s climate change body,” Skorupska continued. They’re also endorsed by the U.K.’s independent Committee on Climate Change. They acknowledge the way in which land sector emissions are counted, including the growth and harvesting of biomass, balancing out the stack emissions from biomass power. Removing this approach leads to double accounting of carbon, which is both inaccurate and adds to electricity bills.

“The UK should continue to build on its success with biomass, promoting its world-leading regulations and developing key technologies like BECCS.”

A full copy of the report can be downloaded from the Ember website. READ MORE

Excerpt from Energy Market Price: Will the EU impose a cap on the number of trees that can be felled in Europe each year? Judging by the Commission’s 2030 climate plan, presented last week, this is now looking like a distinct possibility.

...

The EU executive argues that “we need a growing sink in order for the EU to achieve climate neutrality by 2050” and calls for improved forest management as well as “re- and afforestation” initiatives to restore degraded land and preserve biodiversity.

“We really have to take care of our forests,” said Frans Timmermans, the EU executive vice-president in charge of climate action. “We need to make sure our forests stay healthy and this is going to be a momentous task,” he told journalists.

Forest owners wouldn’t contradict the Commission on this point. Time and again, they have highlighted the role of “sustainable forest management practices” in environmental conservation and how those can support the EU’s biodiversity and climate objectives.

...

“This approach is rather unfortunate as it omits two other major climate benefits provided by forests: carbon storage in EU forests and wood products and carbon substitution with wood replacing fossil-based products and energy,” said Fanny-Pomme Langue, secretary-general of the Confederation of European Forest Owners (CEPF).

For forest owners, the key is to maintain forests as “productive” economic tools providing them with the revenues necessary to take care of their land. And that implies thinning, harvesting and replanting trees as part of “active” forest management practices.

“Forest owners are custodians of forests’ future and their focus is to maintain productive, healthy and vital ecosystems,” said Sven-Erik Hammar, board member of CEPF.

This was the view espoused by the European Parliament’s agriculture committee, which backed a report earlier this month charting “the way forward” for the EU’s upcoming forest strategy, expected to be published in the coming months.

...

Because trees absorb CO2 as they grow, harvesting them to make wood products is indeed considered as a “climate positive” economic activity which sequesters carbon in the form of furniture or building materials.

More controversial however is when wood is burned in biomass plants to produce electricity, or as a way of heating people’s homes.

Critics say burning wood immediately releases CO2 which took years or even decades to accumulate during the tree’s growth phase. This, they argue, creates a “carbon debt” for future generations until new trees can grow back and suck an equivalent amount of CO2.

...

“Any unsustainable intensification of forest harvesting for bioenergy purposes should be avoided,” the EU executive warned, saying “the use of whole trees and food and feed crops for energy production – produced in the EU or imported – should be minimised” in order to limit the impact on climate and biodiversity.

Bioenergy producers dispute this, saying “active forest management” practices “will optimise the carbon flow” and promote carbon sinks in addition to providing much-needed jobs and economic activity for rural areas.

“It is important to stress that bioenergy is not a driving force of forest harvesting,” said Bioenergy Europe, a trade association. In fact, forest cover in the EU increased by 5.8% in 1995-2015 while bioenergy consumption “more than doubled” during the same period, it points out.

“The increase in bioenergy has been possible thanks to a better use of residues from the forest-based industries and increased synergies with the wood-based industry,” said Jean-Marc Jossart, secretary-general of Bioenergy Europe.

...

Importantly, Jossart said a distinction should be made between “carbon sinks” – the capacity of forests to capture carbon – and the “carbon stock”, which is the total amount of carbon stored in the forest at a certain moment in time.

“A forest management based on maximising the carbon stock will not deliver efficiently against climate change because of maturation of trees and carbon losses” due to fires and insects, which are becoming more frequent because of climate change, he argued.

...

Although it keeps the door open to bioenergies in general, the Commission’s 2030 climate plan says “a shift towards growing woody biomass,” and “advanced biogas and biofuels” could alleviate the situation” and help restore healthy forests.

“Bioenergy production should come from better use of biomass wastes and residues and sustainable cultivation of energy crops, rather replacing the production of first-generation food-crop-based biofuels,” the EU executive says.

...

For the bioenergy sector, incentives are fine as long as they allow foresters to “actively manage their forests through planting, thinning, harvesting and replanting”.

“If conversely, these subsidies are there to leave the forests untouched, this will have the adverse effects of reducing their resilience,” it argues. READ MORE