You Cannot Save the Climate Without Trees

Clearing tropical rainforests will not stop climate change. (credit: Dan Klotz)

The People’s Climate March that trumpeted its way through the streets of Manhattan yesterday was led by communities on the front lines of climate change—and Indigenous Peoples were at the forefront of this group.  The tropical forests where they live are not only getting hammered by changing weather patterns, drug traffickers, invasive pests, and massive fires, but these woodlands are also being cleared at an alarming rate, making way for cropland, pastureland, strip mines, and other ventures that extract natural resources from the Earth.

The United Nations Food and Agriculture Organization rang the alarm bell on the world’s forests in April of this year.  Working off of its own data as well as the most recent reports from the Intergovernmental Panel on Climate Change—a group of 2,000 scientists from around the world—the FAO declared that 13 million hectares of tropical forests are now cleared every year, an area larger than half the countries in the world.  The process of this “conversion” releases an estimated 4 billion tons of carbon dioxide annually, almost twice the amount produced by urban transportation (cars, trucks, buses, et. al.) throughout the world.

The reason deforestation releases so much carbon dioxide is that trees store an incredible amount of carbon in their trunks, roots, and limbs.  The FAO also estimated that the world’s forests remove approximately two billion tons of carbon dioxide from the atmosphere every year.

One of the questions often raised by those seeking to clear out the forests is whether chopping away the old growth and planting young trees helps the planet. In the past, the rapid growth of young trees was thought to absorb more carbon than the slower growth of stately larger trees, or even the oldest found in old growth forests.

But that question was laid to rest in a thorough literature review from scientists at the US Geological Survey. In looking at 403 tropical and temperate tree species, the researchers found that “…large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree.”

So forests are valuable to nature, storing billions of tons of carbon at a point in time where the amount of carbon that human beings produce is radically changing our planet’s atmosphere.  Forests are also valuable, obviously, to the people whose lives and livelihoods depend on the forests remaining upright and living. We should do more to conserve the forests that remain, right?

Wrong, according to a researcher from the Yale School of Forestry and Environmental Studies.

In a controversial opinion piece that ran in the New York Times, the Yale professor presented a new argument for chopping down trees. The massive amounts of forest loss since the mid nineteenth century have supposedly cooled the planet by reducing the biogenic volatile organic compounds (BVOCs) released by forests, compounds that exacerbate the climate impacts of ozone, methane, and other industrial pollutants. Trees are also darker colored, and thus absorb more sunlight than light colored cropland.

The op-ed and its theories, however, don’t hold up under scrutiny. According to forest ecologist Michael Wolosin, the piece’s underlying research establishes that the impact of forests on carbon is three times larger than the impact of forests on BVOCs. Many more variables need to be included, he argues, before calculating whether forests should be devalued in any climate equation.

Steve Schwartzmann, PhD, who directs Environmental Defense Fund’s Tropical Forestry Work, notes that the clouds produced by rainforests reflect more light and heat than the trees absorb.  These clouds are also vital to global weather patterns. Large scale deforestation causes massive disruptions of precipitation, and he points to research from Princeton last year that connected deforestation in the Amazon to weather patterns over California.

Whether the last stands of our planet’s once-vast forests should remain standing is not a question to be tossed about lightly, in print or in real life.  Just ask those from Brazil or Indonesia or elsewhere who led the climate march.  They came to lend their voices to the outcry and hear what solutions the world might offer. We can only hope that they and their forests can be considered part of the answer.

Changing Planet

Dan Klotz is a veteran writer and advocate on conservation efforts and the health and sustainability of our food systems. Dan's career has spanned a wide range of policy issues, including protecting sharks around the world, securing the land rights of indigenous communities, addressing the sustainability and research needs of agriculture both domestically and internationally, advocating for smoke-free workplaces, cleaning up toxic waste sites, and preserving wild areas on land and in the ocean.