“We’re taking carbon dioxide out of the atmosphere”

Richard Houghton

Acting President & Senior Scientist
Richard A. Houghton

The amount of carbon dioxide in the atmosphere is miniscule.  It’s 0.04%, or 400 parts per million by volume.  On the other hand, that 0.04% of the atmosphere is nearly 850 billion metric tons of carbon, which is about twice as much carbon as contained in the vegetation of the Earth – trees, grasses, mosses, crops, etc.

In 2012, humans added about 10.7 billion metric tons of carbon to the atmosphere – 90% from burning of fossil fuels, 10% from deforestation. The Kyoto Protocol was to have reduced the emissions of carbon dioxide from industrialized countries by about 5% from their 1990 levels.  And the purpose of REDD (Reducing Emissions from Deforestation and forest Degradation) is to reward developing countries for similar reductions of carbon emissions, but from land rather than from fossil fuels.  Compared to 1990, however, the total emissions of carbon have not declined by the 5% target for industrialized countries. Rather, total emissions of carbon were 40% higher in 2013 than they were in 1990, although most of that increase was from fossil fuel use in the developing world, particularly China and India.

We have failed as a world to reduce carbon emissions. They are 40% higher than when the UNFCCC first proclaimed the objective of stabilizing the concentrations of greenhouse gases in the atmosphere.  In 1990 there were 750 billion metric tons in the atmosphere; today there are 850. We still need to lower the amount of carbon we release to the atmosphere each year – by a lot.

Our plans to mitigate climate change have been based on reducing emissions of heat-trapping gases, carbon dioxide in particular because its contribution to global warming is greater than the contributions from all of the other heat-trapping gases combined.

But there’s something else we can do – and something we have to do at the same time we’re reducing emissions: we have to take carbon dioxide out of the atmosphere.

How can we do that?  There are two ways.  First, nature does it for us.  Each year about half of the carbon we emit to the atmosphere accumulates there, raising the concentration of carbon dioxide. But about half of what we emit is taken up by natural processes in the ocean and on land.  Phytoplankton in the ocean and vegetation on land take carbon dioxide out of the atmosphere naturally.  But it’s difficult to enhance these natural processes.  We can’t feasibly increase the mixing of surface and deep waters in the ocean, for example. Nor can we feasibly or safely fertilize the land or ocean to increase carbon storage.

The second way to take carbon out of the atmosphere, and the only way we can manage it cheaply and with current technology, is by managing land. We could let forests grow (i.e., reduce rates of wood harvest), and we could plant trees or let forests regenerate on lands that were forested in the past, but which are now treeless.  There are lots of degraded lands around the Earth that could be reforested.

We know how to do this, and it’s an easy fix.  We don’t have to engineer chemical or physical processes to take carbon out of the air. That would be expensive in terms of energy and dollars. Green plants already do it – for free. We simply have to provide areas for forest growth.

Expanding the areas of forest and protecting growing forests are not permanent solutions for stabilizing the concentration of carbon dioxide in the atmosphere. But they could be used to stop the build-up of carbon dioxide for the few decades it will take to replace fossil fuels with renewable forms of low-carbon energy.   Forest management could stabilize the concentration of carbon dioxide in the atmosphere for a few decades – although not much longer because as forests age, they take less carbon out of the atmosphere each year.

So, when you ask someone at WHRC what he or she does, the answer is, “We’re taking carbon dioxide out of the atmosphere.”  And there don’t seem to be many institutions that have that mission with the experience and knowledge to implement it and measure it.