|Giving Carbon Credit A brief series on the elemental substance of life Much is justifiably made about carbon and its impact on climate. But how much do you know about the much larger role carbon plays on our planet? You are what you think, and you are what you eat, and carbon is central to both. Carbon takes many forms, cycles through the environment, and is an integral part of our planet, especially the biosphere where all of our planet’s lifeforms live. Like the very air we breathe and the water we drink, carbon wears so many hats and takes on so many forms in our lives and in the life of this planet. The following short series of essays explores the myriad forms, movements and transformations of carbon through our planet and will provide additional resources if you want to find out more on your own.|
Carbon Notes from the Prairie Festival 2012
There’s a nice piece about the Land Institute’s Prairie Festival that took place September 28-30:
The pics are great and the article, while well written, barely scratched the surface of what was discussed. So here are some of my notes that I jotted down during some of the talks, that I thought might be of interest to all. Some is more of the same, some is new; these speakers are high quality and the information they presented is reliable from what I know, but when in doubt, look for corroboration. In this spirit of information sharing, I invite others who attend events of common interest to share what they took home, including links for more information–Ken Lassman
Michelle Mack, Land Institute alumnus and faculty at the University of Florida: http://people.biology.ufl.edu/mcmack/macklab/research.html
I. The Climate-Carbon connection
-while the global temp has gone up 0.8 degrees Celsius, the arctic areas have risen much faster: 3.4 degrees C annually and 7 degrees warmer in the winter.
-melting arctic sea ice has opened up traditional barriers that have restricted animal migration and limited resource exploitation.
-with disappearance of the sea ice, the Earth is losing its air conditioner.
-weather events are increasing in severity, frequency and areal coverage planet-wide.
-primary cause: greenhouse gases, primarily CO2, which has increased in atmosphere from 280 to 396ppm, or 220 gigatonnes* of formerly-buried carbon injected into the atmosphere since industrialization. -currently we’re injecting 8.4 gigatonnes/year. of that: 54% is reabsorbed by natural systems (26% by oceans, 29% by plants in tropical, temperate and boreal forests). The other 46% is retained in the atmosphere, leading to the steady rise in CO2, triggering climate change.
-Alert: the changing climate is reducing forests’ ability to absorb carbon, in some cases, changing them from net sinks (able to absorb carbon) into net emitters
II. Fire and Ice Feedbacks
-Terminology: classic term of “negative feedback” confuses some, so to clarify the relationship between climate and boreal forests, “negative feedback” will be called “stabilizing,” “cooling” or “self regulating” feedback. Example: increased CO2 leads to increased growth as a result of more available CO2, absorbing more CO2, which helps stabilize or reduce the amount of CO2, helping to cool the atmosphere.
-an example of positive feedback/destabilizing/vicious cycle type of feedback: increased CO2 warms the atmosphere so much that the increased temperatures and resulting lower humidities dry out plants, reducing their ability to grow, reducing their ability to absorb CO2. If they die and decompose, they even release CO2, so the CO2 increases even more.
The role of fire in boreal forests
-historically “carbon neutral,” meaning the CO2 released by burning is offset by vegetational growth, which absorbs CO2. Burning has been a natural part of the ecosystem with a fire burning any given spot every 100 years or so, caused primarily by lightning storms.
-recently, due to increased frequency, areal coverage and intensity, resulting in burning deeper into the peat and moss, forests have sometimes gone from net sinks or “carbon neutral” players in the carbon cycle to net carbon emitters.
-there is hope: where coniferous forests are burned and the mosses/peats are consumed, they are replaced by hardwood forests, which prefer rockier, more mineral-rich soils. Since hardwoods grow faster than conifers, they can create more biomass more quickly, increasing the tonnes/acre of CO2 absorbed when compared with coniferous ecosystems. Combine with a higher albedo (it reflects more light than the darker conifers) and more fire-resistant composition, the hardwood replacement can flip a woodland back into a net carbon sink.
The role of fire in tundra ecosystems
-there has been an unprecedented increase in the frequency, intensity and areal coverage of fires in tundra ecosystems as well.
-fire is not a natural part of the tundra ecosystem—it degrades it.
-traditional cultures do not have a historic memory of tundra fires and soil sampling does not reveal a record of tundra fires in the past 5-7,000 years.
-bunch grasses grow in clumps, or “tussocks” which do bounce back after a fire. But the surrounding moss/peat build-up that is burned in the fire releases 2 kilograms of carbon per square meter.
-the carbon released from one large tundra fire turned the entire planetary tundra ecosystem from a net carbon sink to a net emitter in one summer!
-The story of boreal tundras and fire is not complete until you look at what is underneath it: permafrost. When a tundra burns, it turns black, increasing its ability to absorb heat. This, combined with warmer weather, accelerates melting of the permafrost.
-Permafrost stores huge amounts of carbon: best estimates indicate 1374 Gigatonnes, or more than what the other forested soils store on the rest of the planet combined.
-We are witnessing accelerated ice melt under boreal tundras. The huge concern of climatologists is that this could result in the release of approximately 100 Gigatonnes of carbon into the atmosphere per year. Remember, humans are releasing 8.4 Gigatonnes. Needless to say this would be much more than what existing natural sinks could absorb.
-Not only does melting permafrost have the capacity to release huge amounts of carbon, it destabilizes the entire landscape, resulting in what is called “thermal karst” topography. This is a landscape of sinkholes, unstable ground that shifts buildings, roads and everything else. This is a huge burden on any human habitation, including traditional cultures.
The role of agriculture in the future
-It’s probable that there will be a 3-6 degree Celsius increase in combined land-sea global temperatures by 2100.
-This translates to a poleward shift of weather and climate patterns. Hadley cells** could expand northward, spreading desert climate northward into what is currently productive agricultural regions, including places like Kansas.
-Current estimates are that there will be a 10% decrease in dryland precipitation with every degree increase in global temps.
-There is a real possibility of droughts that last a decade or longer—perhaps even a century.
-Perennial crops such as what the Land Institute is working on can obviously help confer resilience to the agricultural ecosystems, improve soil health, and buffer from the extremes on the microclimate scale, not only helping plants, but also soil life.
-Can produce a kinder, gentler type of agriculture that might be able to better adapt to northward migration into what are now boreal ecosystems.
*A gigatonne is a billion metric tonnes, or 109 tonnes. What’s a tonne? It’s 1000 kilograms, or 2204.6 lbs, slightly more than a US or “short” ton. A simple way to convert Gigatons to US tons can be found here: http://www.convertunits.com/from/gigaton/to/ton+%5Bshort,+US%5D
So 220 Gigatons of carbon translates to 242.5 billion tons (US) of carbon. That’s a LOT of carbon! But wait: a tonne of carbon translates to 3.67 tonnes of CO2, because carbon dioxide has two oxygen atoms (atomic weight 16) for every atom of carbon (atomic weight 14). That’s why a gallon of gasoline produces 20 lbs of CO2! http://www.fueleconomy.gov/feg/co2.shtml
**Hadley cells are zonal atmospheric circulation patterns, characterized by low pressure around the equator, then as you go north (in the northern hemisphere) easterly prevailing winds, transitioning to a primarily high pressure/dry/desert zone around 30 degrees north, prevailing westerlies north of that up to about 60 degrees north, where there is another low pressure zone, followed by prevailing easterlies in the polar arctic. Check out a pretty good video depiction here: http://www.youtube.com/watch?v=DHrapzHPCSA The concern is that with increased global temps, the prevailing desert zone currently located around 30 degrees north (think northern Mexico, the Sahara desert) will shift northward. With Kansas and much of the productive agricultural are of North America located only 5-10 degrees north, this could be a real problem!