Mangrove canopy. CIFOR/Sigit Deni Sasmito

“Alternative pathways” to climate change mitigation stir controversy

No silver bullet

BONN, Germany (Landscape News) — To stabilize global warming below 2 degrees Celsius relative to pre-industrial levels, climate modeling scenarios put forward by the Intergovernmental Panel on Climate Change rely on planting trees and plants to produce bioenergy in combination with underground carbon storage. However, this approach is not without risks. A new study published in Nature Climate Change highlights the need for alternative pathways to climate change mitigation.

Under the terms of the 2015 U.N. Paris Agreement on climate change, countries committed to limiting global warming to 1.5 or 2 degrees C compared to pre-industrial levels. Achieving this goal requires not only the reduction of carbon emissions, but also the active removal of carbon from the atmosphere according to most scenarios.

In theory, carbon removal could be achieved through a process known as Bio Energy with Carbon Capture and Storage (BECCS). This means that when burning biomass to produce energy, the carbon released can be captured and stored into geologic formations hundreds of meters under the Earth’s surface. When carbon storage below ground is combined with planting new plants and trees above ground (which absorb carbon while they grow), the total amount of carbon in the atmosphere will decrease.


BECCS is controversial. Scientists have been pointing at the uncertainties that surround the approach. A study published in the journal Energy and Environmental Science in 2017 showed that the outcomes of BECCS are highly context-specific. In some cases, it could even lead to a net increase of carbon.

There are also concerns related to increased demand for land to grow bioenergy crops, competing with land for food production and nature conservation. Moreover, the technology to store carbon underground is not yet fully tested. It is not clear how it will pan out, and whether the carbon will actually stay underground.

Finally, there are issues related to the social acceptability of the approach. Test pilots with underground carbon storage have been met with resistance by people living in the pilot areas, known as the “not in my backyard” (NIMBY) phenomenon. Hence the need for alternatives to BECCS.


A group of researchers spearheaded by Detlef van Vuuren—professor at the Faculty of Geosciences of Utrecht University and senior researcher at the Netherlands Environmental Assessment Agency—decided to look into the possibilities to achieve climate goals without BECCS. They explored six alternative pathways:

  • All energy end-use sectors are rapidly electrified based on renewable energy;
  • The best available technologies for energy efficiency are quickly adopted;
  • Agricultural intensification leads to improved crop yields and efficient livestock systems;
  • Rapid reduction in emissions of non-CO2 greenhouse gas emissions such as methane;
  • Reduced population growth, in line with the U.N.’s lowest scenario; and
  • Widespread lifestyle changes, including lower levels of meat consumption and changes in transport habits.

Using an integrated assessment model, the researchers looked at the expected greenhouse gas emissions and the need for carbon removal in a scenario that limits temperature rise to 1.5 degrees C above pre-industrial levels. Although each of the alternative scenarios reduced emissions significantly, none sufficiently eliminated the need for BECCS altogether. Only if all options were combined, removing carbon from the atmosphere would no longer be required.

As previously stated, reaching the 1.5 degrees C target is unlikely to be achieved without carbon removal, but deploying alternative strategies will help minimize the need for BECCS and diversify the options, the researchers conclude. This would provide more flexibility to ensure the Paris climate goals are reached.

Moreover, many of the alternatives include benefits, the authors argue. They mention, for example, that reduced meat consumption results in healthier diets, improved energy efficiency reduces air pollution and improves energy security, while reduced population growth and agricultural intensification may benefit biodiversity conservation.


Some of the alternatives explored by Van Vuuren and co-authors may not be very realistic in the short term, according to Christopher Martius, principal scientist at the Center for International Forestry Research (CIFOR).

“For decades, we have not been able to achieve significant changes in life styles and energy efficiency at a global scale, so these may be pipe dreams,” Martius said. “Moreover, there are problems related to equity. Some of the alternatives—like limiting population growth and changing lifestyles—could be seen by developing countries as ideas that are imposed by western countries.”

Considering options to mitigate climate change, we first and foremost need to look at the role of the fossil fuel industry and oil producing countries, Martius said. “So far, we are not seeing a reduced appetite for oil and gas extraction globally. All countries that have oil or gas want to explore it to the max—the riches in the ground are just too shiny.”

Although not all alternatives may be realistic in the short term, the article by Van Vuuren and his colleagues is important, because it points at the need to look beyond BECCS, said Martius, who is based at CIFOR’s headquarters in Bogor, Indonesia.

“Relying on one untested and highly technical, engineered process like BECCS would be madness.  People tend to look for silver bullet solutions, but a mix of options will always be better and more adaptive. It will give much greater flexibility to select the most appropriate approaches in different contexts. We need to have more options and pursue them relentlessly in parallel.”

Article tags

BECCSbioenergybiofuelbiomassCIFORclimate changeIPCCrenewable energytemperatures



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