Crisis of forests may double climate mitigation costs

This is the hypothesis of researchers at the Potsdam Institute. Current models overestimate the mitigation potential of forests. In this scenario, a delay in response could make the climate goals unattainable

by Matteo Cavallito

 

Without appropriate action, the degradation of forests – a still underestimated problem – will eventually jeopardize the achievement of climate goals. Delaying action, on the other hand, means facing a sharp increase in economic, political and environmental costs instead. This is argued in a new study published in Nature Communications.

“Achieving the Paris Agreement’s CO2 emission reduction goals heavily relies on enhancing carbon storage and sequestration in forests globally” explains the research conducted by the scientists of the Potsdam Institute for Climate Impact Research (PIK). “Yet, the increasing vulnerability of carbon stored in forests to both climate change and human intervention is often neglected in current mitigation strategies.”

Forests are becoming increasingly fragile

The Earth’s ecosystem as a whole is capable of sequestering 13 billion tons of CO2 each year. Thus removing from the atmosphere about one-third of all anthropogenic emissions on the Planet. It is no coincidence, then, that today “any conceived climate stabilization target relies on the continuity of this vast carbon removal service.” Forests alone “accumulate most of the carbon sequestered this way, constituting two-thirds or 7.8 billion tonnes of CO2 per year.”

Forest ecosystems, however, “are vulnerable to environmental changes and direct human activities such as deforestation and degradation, rendering the permanence of the carbon stored in them uncertain.”

The integrity of these environments, in short, is increasingly threatened by natural events-such as wildfires, disease, drought and pests-exacerbated by global warming. As well as anthropogenic pressures such as deforestation. Yet the models on which global climate strategies are based often ignore these factors or severely underestimate them. The research, consequently, aimed to investigate the impact of this underestimation by also assessing “the consequences of postponed action to understand the importance of more accurate forest carbon projections for climate policy.”

A new model

According to the authors, in particular, models currently used to formulate climate policies make three mistakes: they underestimate hostile natural events, they overestimate fertilizer-induced plant growth, and finally, they incorrectly assume that there is “perfect efficiency in replacing forest land with agriculture” while ignoring the fact that, in many cases, cleared land actually remains unused for years.

To properly account for all these factors, the scientists therefore combined two models to simulate the global energy system, economy, land use and forest growth. In addition, they assumed different levels of forest disturbance.

In this way, the authors analyzed 54 different scenarios to simulate decision makers’ responses to different situations of forest degradation by calculating the cost of not taking timely action. According to their estimates, even a delay of only 5 years in responding to carbon loss from forests would double the cost of mitigation policies.

A 5 year delay costs twice as much

The reason, the researchers note, is obvious: delayed responses result in more costly emissions cuts and investments in carbon removal technologies when compared with those associated with immediate action even in the presence of more impactful disturbances. In just five years, for example, inaction would increase the need for land for mitigation interventions (such as reforestation or bioenergy) by about 149 million hectares, an area larger than the entire European Union.

Huge, then, is the impact on the carbon market. “Taking immediate foresighted action on forest carbon loss (FCL) results in a 22% increase in carbon price in 2030 and 2050 and a peak GDP loss of −2.4%,” the scientists explain. A delay, on the other hand, will result in “a 48% increase in the carbon price, with a peak GDP loss of −2.7%.” A slow response, in other words, “consistently requires twice the effort, regardless of the disturbance rate.”

Four strategies

“Right now, our climate strategies bet on forests not only remaining intact, but even expanding,” Michael Windisch, researcher and co-author of the study, explained in a news release. “However, with escalating wildfires like in California, and continued deforestation in the Amazon, that’s a gamble. Climate change itself puts forests’ immense carbon stores at risk.”

To avoid policy failure, the authors recommend that decision makers pursue four strategies:

1. a constant monitoring of forests;
2. an update of climate models;
3. an immediate conservation actions and decarbonization interventions in other sectors;
4. a prudent use of reforestation, which, not well planned, risks increasing exposure to future disturbances.

“We must act immediately to safeguard the carbon stored in forests,” Windisch continues. “Otherwise, compensating for potential forest carbon losses through steeper emissions cuts in key emission sectors like energy, industry and transport will become increasingly expensive and possibly unattainable.”