The Dirt on Climate Change

As a collective whole, we humans are making dangerous adjustments to our planet’s thermostat. Then again, as individuals, many of us are searching for ways to reverse this trend. For now, look no farther than the patch of ground beneath your feet.


You may be standing on the second story of an office building or on a parking lot, but beneath these trappings, lies potential. As opposed to just a blank slate in which we grow our veggies, healthy soil is a living entity and a crucial carbon sink.

Plants convert CO2 into chemical energy through photosynthesis. Rather than being released back to the atmosphere, this carbon can end up in the soil thanks to the host of microbes that do business with plant roots. Essentially, living plants leak extra carbon to  bacteria and fungi in the soil in exchange for other nutrients. Soil organisms use this energy to go about their lives, and in the process, they transform decaying organic matter into humus.

k7421540_HUMMUSDespite lacking a second “m,” humus does relate to the delicious Mediterranean spread in the sense that it is extremely important to soil fertility, and thus all plants, garbanzo beans notwithstanding. Although humus is highly complex and difficult to define, there is no mystery shrouding its relative stability. Humified carbon can stick around for well over a hundred years in the soil without degrading to CO2. 1   So, we can picture high-functioning soil as a massive carbon sponge capable of storing thousands of gigatonnes of carbon.2

But, what about soil­­­ that no longer hosts an ecosystem of humus-makers? Unfortunately, there’s a lot of it underfoot. Any number of crops may soon be planted in such soils across the continent this summer. Widespread application of chemicals has largely uncoupled conventional agriculture from soil health in the modern era. In excess, fertilizers, herbicides, pesticides, and fungicides can severely alter microbial communities, rendering the soil inherently less fertile (so it requires even more inputs), and ultimately reducing its carbon-storing capacity.3


But, let’s set industrial agriculture aside, and ground this conversation closer to home. At the very least, we can all be the land managers of our own backyards. Even damaged dirt can recover if we are willing to get our hands dirty restoring soil health. As you roll up your sleeves, keep the following principles in mind:

1. Less Lawn

Let’s face it, despite being costly
to maintain in terms of cash, water, and fossil fuel, many of us still want tidy, green grass in our lives. Nevertheless, we can shrink our lawns and our carbon footprint in step. Even if you replace just the corners of your lawns with native shrubs and cover plants, you can improve soil health and streamline your  lawnmower’s trajectory. Ask around at your local plant nursery to select suitable, native vegetation that’s pleasing to the eye and to the soil microbes.Screen Shot 2016-03-13 at 10.18.41 PM

2. More Mulch

Don’t toss the grass clippings when you trim your now-svelte lawn. Use them as a “green manure” to boost the health of your yard. Let them dry for a few days, and then incorporate them as needed around flowerbeds, trees, or shrubs. Also, use mulches such as straw, leaves, or wood chips on top of your soil as a protective blanket to encourage soil moisture and to reduce weeds.

3. You till, you kill

Admittedly, this mantra is a bit of an overstatement. Tilling can be very useful; experienced gardeners routinely dig up tidy rows in the spring. But, tearing up the dirt disturbs the living soil community and the resources they depend on. Avoiding tillage can improve soil moisture, prevent soil loss, and promote soil fertility in the long run.650x360xnotilling.jpg.pagespeed.ic.eOHliNvsUc

 4. Don’t dare to bare

Perhaps the most important lesson of all is to minimize bare soil. Carbon stored in soil can rapidly escape to the atmosphere as CO2 when exposed to the air. Prevent this scenario by keeping pathways narrow, tilling less, and covering  exposed  soil with vegetation or mulch.

Additional Resources:


  1. Dungait, J. A. J., Hopkins, D. W., Gregory, A. S. and Whitmore, A. P. 2012. Soil organic matter turnover is governed by accessibility not recalcitrance. Glob Change Biol, 18: 1781–1796.
  2. Ecological Society of America. 2000. Carbon sequestration in soils.
  3. Schwartz, J. 2014. Soil as carbon storehouse: new weapon in climate fight? Yale Environment 360.
  4. Barker, D. and M. Pollan. 2015. A secret weapon to fight climate change: dirt. The Washington Post.

Look who’s talking…

What if I asked you whether human-caused climate change were a real and imminent threat? Let’s imagine you wanted to respond with a pithy idiom. You might say:

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“Does a bear poop in the woods?”

Umm, well, I suppose so…




“Does the pope wear a funny hat?” Pope_Francis

Come to think of it….

But, speaking of the pope, does Francis agree with you on the matter? He sure does, calling climate change a “global problem with grave implications” in his 184-page encyclical Laudato Si this past September. Move over Al Gore, because the pope is not the only person with star power joining the climate change discussion on the international stage.

In 2014, Arnold Schwarzenegger and six other executive directors launched a documentary TV-series on climate change with celebrity correspondents including Jessica Alba, Matt Damon, and Harrison Ford. To paraphrase Schwarzenegger’s intention to air a second season of Years of Living Dangerously later in 2016, he more or less said, “I’ll be back.”

In September 2014, Leonardo DiCaprio lent his celebrity to the UN climate summit in New York. Although he did not make mention of it in his speech, his serious concerns over rising sea levels may have first set in when he filmed the final scenes of Titanic. The 2014 UN summit also opened with a short video on climate change narrated by none other than Morgan Freeman. Climate change deniers the world over cringed at this film, well aware that when Morgan Freeman narrates something, nature makes it so.

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All jests aside, more celebrities are getting involved in climate change activism, and, in turn, hopefully engaging wider audiences on the topic. I am not sure I take heart in the fact that Han Solo and the Terminator are on board with cutting carbon emissions, but I think it is a good thing that more people are discussing the same agenda.

Or, at least tweeting about it—UVM researchers recently conducted an analysis of 1.5 million climate-related tweets, and tallied considerably more Twitter activity from climate change activists than from climate change deniers, “indicating that the twittersphere largely agrees with the scientific consensus on this issue.” 1 But, what about those near-mythical folks who dwell outside of the twittersphere?

After ducking out of the pouring rain on a 60°F day this past December, a friend of mine overheard this conversation while waiting in line at a Burlington pharmacy:

“You know, this is on account of global warning,” a man said of the weather to another woman waiting in line. “We’ll be seeing more of this as the glacier melts.”

Later, my friend and I puzzled over this conversation—is it good that people are connecting strange weather to global warming (or warning?) even if they are extremely confused by the terminology and the science behind climate change? At the very least, it’s more encouraging than politicians who deny that climate change exists.2

To me, recent stories of people taking extraordinary action against climate change are speaking more loudly than any misguided presidential candidate. For one, a growing chorus of island nations is making a powerful moral case to aggressively combat climate change on a global scale; check out Marshall Island poet Kathy Jetnil-Kijiner from the 2014 UN climate summit. 3 In another David and Goliath-type story, 21 young Americans are currently suing the U.S. government over climate change.4 They view U.S. promotion of fossil fuel as a direct affront to their right to enjoy a livable future. They may or may not win in court, but at the very least they ought to get people talking.

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  1. Cody, E., A. Regan, L. Mitchell, P.S. Dodds, C. Danforth. 2015. Climate Change Sentiment on Twitter: an Unsolicited Public Opinion Poll. Plos One.
  1. Merchant, E. 2015. News Republic. How the 2016 Presidential Candidates View Climate Change.
  1. Mooney, C. and J. Warrick. 2015. Washington Post.
  1. Taylor, D. 2015. Huffington Post.