Why Does the IPCC Want Us to Cut Down Trees?

  • Share
  • Read Later

Yesterday the U.N. Intergovernmental Panel on Climate Change (IPCC) came out with an early summary of a new report projecting the future of renewable energy. As with many international studies of the sort, readers were free to use parts of the results towards whichever conclusion they’d already reached on alternative power and climate change. Optimistic greens could be cheered by the IPCC’s promise that renewable sources could provide 77% of the world’s energy by 2050, up from 13% in 2008, as long as governments adopted the right bundle of policies. Skeptics could point to the enormous price tag of those policies—the IPCC estimates that such a shift could cost up to $15 trillion over the next couple of decades, more than the entire U.S. government debt. The bottom line: a major shift to renewables may be doable, but as IPCC economist Ottmar Edenhofer said, it would be “technically and politically very challenging.”

No real surprise there, as Andrew Revkin pointed out on Dot Earth yesterday:

The document doesn’t take readers much beyond what is already well established: that without sustained and focused climate and energy policies by governments around the world, the potential of renewable energy technologies to compete with fossil fuels remains deeply limited.

But as Nathanial Gronewold of Climatewire wrote in a smart piece today, the IPCC’s estimates may actually be much more optimistic than they seem, even with the high costs the group cites. That’s because the IPCC counts as a renewable energy source “traditional biomass”—the use of wood for heating and cooking, either as charcoal or directly burnt. As Gronewold notes:

The latest IPCC report estimates that in 2008, the renewable energy sources under their review contributed 12.9 percent of the world’s main energy supply, measured in a thermal energy output unit called an exajoule. Half of that is from traditional biomass, the IPCC admits, and the group offers little justification for including this most primitive source of energy in its calculations.

IPCC researchers say their estimates show traditional biomass usage shrinking over time, to be gradually placed by more modern biomass generation, whereby trees felled are actually replanted. But charts showing the possible scenarios of the growth of renewables’ share of energy still show biomass as the top source, even out to 2050.

The IPCC’s blending of charcoal production with modern practices like biomass cogeneration on farms or wood waste burning near cities makes it difficult to determine how much traditional practices are to be replaced by more modern ones. But the IPCC admits that traditional biomass’s share is larger, and the report suggests that its consumption will only fall slightly over the coming decades while modern biomass’s share expands gradually.

In one sense, of course, biomass can be considered a renewable fuel. If you cut down a tree and burn it for fuel, the carbon that is released can be absorbed by a replacement tree. That’s renewable in a way that oil—a finite source—would never be. But the dependence on biomass for energy is already a major component in deforestation and habitat loss for endangered species. For all the focus on logging and the clearcutting of trees for agriculture in countries like Brazil, a major source of deforestation comes from the use of trees for basic energy by those who live off the grid—whether they choose to or not. As if that’s not bad enough, traditional biomass is an incredibly inefficient source of energy, and a major cause of indoor air pollution, which is why it’s only used by the poorest populations in the world.

A future where traditional biomass remains a major source of energy is not a sustainable one—not for the climate, and not for the world’s poor. The IPCC likely knows that—the summary report cautions policymakers that any policies on biomass need to take into account the impact on existing forests and land use. But that fact shouldn’t be buried in the report. If we don’t count all biomass as renewable—and we shouldn’t—getting to a clean energy system by mid-century will likely prove even harder and more expensive than it looks today.