Image Credit: Jonas B
The soil under our feet has a complex relationship with our warming world. Microbiologist Charles Rice told EarthSky that soil helps take carbon dioxide out of the air – it absorbs millions of tons each year. But Earth is still warming, and, as it does so, microorganisms in the soil release carbon.
Charles Rice: With warmer temperatures, just like our warm bodies, the microorganisms grow faster and so they need more food, so they would feed on that organic carbon. So as they’re feeding on that, then they’re releasing that carbon back to the atmosphere as carbon dioxide.
So soil can help warm or cool the Earth – depending on how we manage it.
Charles Rice: You can increase the amount of carbon stored in soil by increasing plant inputs, and that could be by different rotations, cover crops, improving fertility. And, one way to reduce the loss of carbon of the soil is doing less tillage or stirring of the soil.
He said that keeping carbon locked in soil also keeps soil healthy and results in better crops.
Charles Rice: So there’s a multiple win situation.
Join EarthSky in celebrating The International Year of Planet Earth. Thanks to the National Science Foundation and US Geological Survey.
Our thanks to:
Charles Rice
Kansas State University
Manhattan, Kansas
As temperature increases the microorganisms subsequently release more CO2 in response to global warming. Not forgetting the oceanic C02 sink which also gives up CO2 in response to warmer temperatures, doesn’t Rice’s observations, in a significant way, help to explain why ice core proxy data shows CO2 levels lagging temperature changes in the paleoclimatic record?
I understand fossil fuels artificially contribute to the levels but the net green house effect of CO2 is an inverse logarithm of the atmospheric CO2 concentration – a case of diminishing returns. This means an enormous about of CO2 would need to sequestered to result in any measurable decrease in global temperature (if the correlation could indeed be measured). Given that tillable land is small in contribution to the total global CO2 budget, which includes both natural and anthropogenic sources, it seems that even the most proactive management of land and crops will have a negligible effect on global warming.
Irrespective of the above point, it is a common practice to turn under many crops following harvest. Doesn’t that form of tilling the soil serve to lock more CO2 into the soils as opposed to the biomass decomposing in the air and directly releasing CO2 into the atmosphere? I guess I’m wondering how we determine the net CO2 budgets in our agricultural practices.
Hank,
There is something called permaculture that could ensure that the human population is fed while also ensuring that the integrity (and quanity) of soil is kept and in fact enhanced (and not sent down The Mississippi to the tune of a 150 acre farm a day. Companion planting, vertical farming and the use of \”nitrogen fixing\” plants, are all practices that can save our soil, and us in the process. We need to move away from tilling, one-crop monocultures such as corn, which demands much of the soil and requires far more water and fertilizer. We need to start transitioning to the kind of farming that was practiced prior to the presence of cheap oil and industrial farming in the last century.
Well I just had to return after about a what, 18 month absence from offering my thoughts on global climate change. I found the article on Mr. Lornets Lorentsen particularly amusing:
“Lorents Lorentsen: There’s no doubt that the US could do more to reduce its own greenhouse gases by increasing the prices of fossil fuels, either by using taxes or trading systems, as is used in many states already.
Money from a tax on carbon – or a cap and trade system – he said, could be used to invest in renewable energy technologies – not only for the U.S., but also for India and China.”
So I ask of you Ms. Byrd and you Mr. Block, are you really a science site or are you social activists hiding behind the guise of a science site?
One wonders as the solar sunspot activity has been non-existent for the past 24 months and longer. The NASA Marshall Space Flight Center has some very intersting data on solar sunspot activity. I daily look at the SOHO, or Solar and Heliospheric Observatory’s daily image of the sun showing current solar sunspot activity. Nothing, nada, zero. Did I mention for over two years? Oh yes, I also look at the Unisys current sea surface temperature anomaly plot @
http://weather.unisys.com/surface/sst_anom.html
Please explain that if the earth is getting warmer, why is it so much of the world’s ocean’s sea surface temperatures remain BELOW normal?
If earth sky dot org was so cognizant of the earth and sky, I would be of the belief the alarm of rapid global cooling would be emanating from your site. Sadly, that is not the case.
Hello Hank, thanks for commenting.
Welcome back, Doug! No, we’re not social activists. We’re a voice for science. Congress asked the National Academy of Sciences to formulate a group of studies to inform U.S. climate policy. The NAS kicked off that effect with a meeting in Washington. Lorents Lorentsen spoke at the meeting, and we captured his voice and broadcast it. It’s our mission to broadcast the voices of scientists.
Climate is complex. There can be cooling spells of a decade or more, in a warming world.
If and when mainstream science stops believing that global warming is real and caused by humans, EarthSky will broadcast that information. Until that happens, we’ll continue to broadcast what most scientists believe to be true: that global warming is real and caused by humans.
Many thanks,
Deborah
Thank you EarthSky for being one of the prevailing “cool heads” in a warming world that waits for us to move past the protacting forces of denial and beyond the refusal to accept personal responsibility for the neccessary end products of removing massive amounts of carbon from the earth in the form of fossil fuels and releasing it into the air as no other earth-based life form as ever done.
Beyond the illusion of debate on the preponderance of scientific evidence, I always come back to the question that if we could access sunlight, wind, wave power, and geothermal possibilities more immediately and more efficiently than say waiting until 2014 to extirpate oil six and a half miles below the surface of the warming, hurricane-ready waters of the The Gulf of Mexico or say using up to nine barrels of clean water to force the Alberta Tar Sands oil soup, why wouldn’t we?
And even given that the ocean temperatures this summer were the hottest ever recorded since record-keeping began, Doug, the ineluctable question remains: if we can design, cultivate, and create more intelligently and more efficiently, why wouldn’t we?
Deborah, Lindsay, Jorge, Dan, Joel,
I couldn’t help but notice that E&S no longer allows comments on podcasts that promote global warming – mainly the climate section of your site. My concern is closing the dialog on such an incomplete and growing discipline of science seems contrary to the methods that have served science so well. I’m hoping there is an alternate explanation that doesn’t presume the science to be complete and beyond question.
Kind regards,
Hank – Las Vegas
Hi Hank, we haven’t closed the comments. The comments on this global warming post are still open as you see.
We’re about to move to a new website – due to launch mid-June – so please expect some glitchy things to happen. The new site will feature both the long and short podcasts from a single interview on one page. And it’ll be much faster to use than this site.
Your voice is welcome here.
Deborah
The alternate explanation makes perfect sense. Thank you for responding. All the best to E&S as you upgrade your site. I’m looking forward to the cool new experience.
Thanks Hank. It’ll be the same – but different. Better!
In response to Hank’s question about tilling practices – I was one of Chuck Rice’s grad students in the late 90’s, early 2000’s and my research looked at exactly this issue. I looked at soil organic matter dynamics in a long term tillage study started in 1974. Without going into mind numbing detail, I specifically looked at traditional tillage (as Hank described) where plant residue is tilled under following harvest, but before planting the next crop – and compared this to “no-tillage” where all plant residue was left in place and crops were planted directly into the soil under this easily observable layer of residue. There was a significant increase in carbon in the first 5 centimeters of no-till soil compared to the traditional tillage practice. After 5 cm there was no measurable difference. Thus no-till does sequester more carbon than traditional tillage; in Kansas, and under the specific crops we studied – this may not be the same under other climate conditions and plant input regimes.
Chuck and the soil science community as a whole would never claim that carbon sequestration in soil is the singular answer to reducing greenhouse gases, but see it instead as one of the pieces of the mitigation plans while we look for something other than fossil fuels for energy.