Anthropogenic nitrogen plays a double role in climate change

Aug 04, 2011
Since the mid 1900s, human activities, especially the application of fertilizers in agriculture, have doubled nitrogen inputs to terrestrial ecosystems such as agriculturally used areas, but also forests and wetlands. This has two opposing effects on the climate system: on the one hand, ecosystems  are thus able to absorb more carbon dioxide from the atmosphere, which lessens the greenhouse effect. On the other hand, the nitrogen-rich soils emit more "laughing gas", which is significantly more detrimental to the climate than carbon dioxide, thus cancelling out the carbon benefits of anthropogenic reactive nitrogen. Credit: Pixelio

Human nitrogen additions to the soil may reinforce the greenhouse effect.  Nitrogen additions tend to boost plant growth, so that terrestrial ecosystems absorb more carbon dioxide from the atmosphere. But recent studies have shown that they also stimulate nitrous oxide release from the fertisilied soils – a much stronger greenhouse gas than carbon dioxide.

According to a new paper by researchers around the team of Sönke Zaehl from the Max Planck Institute for Biogeochemistry, nitrogen's detrimental effects on the climate roughly correspond to its climactic benefits. In fact, the scientists' findings suggest that the negative impacts of nitrogen may even slighty prevail.

Human activities have more than doubled nitrogen inputs to the terrestrial biosphere since the 1860s through increased atmospheric nitrogen deposition and the application of fertilizers in agriculture. Nitrogen is an essential nutrient for plant and microbial growth, and one of the key limiting nutrients in many natural ecosystems. But  anthropogenic perturbations of the nitrogen cycle through the additions of fertilisers are known to affect the terrestrial sources and sinks of greenhouse gases such as carbon dioxide (CO2) and (N2O), better known as "laughing gas".  An international research team lead by  Soenke Zaehle,  researcher at the Max Planck Institute for Biogeochemistry, has now determined the magnitude of such effects on the two greenhouse gases.

“When added to nitrogen-limited ecosystems, it [nitrogen] can stimulate plant growth and/or suppress soil respiration, thereby leading to increased ecosystem carbon storage” explains Sönke Zaehle. However, there are also potentially negative consequences for adding nitrogen to ecosystems, as increasing nitrogen availability may enhance nitrogen losses from ecosystems, and eventually even have damaging effects on plant health. Particularly relevant for climate are elevated emissions of nitrous oxide, a long-lived greenhouse gas that is emitted from fertilised fields, as well as nitrogen-rich forest and grassland ecosystems.

Drawing on reconstructions of past and present anthropogenic nitrogen deposition and fertiliser applications, Sönke Zaehle and colleagues used a global computer model of the coupled terrestrial carbon and nitrogen cycles to better understand the consequences of this anthropogenic nitrogen perturbation for the climate system. Their results confirm that the anthropogenic nitrogen perturbation has profoundly affected terrestrial and nitrous oxide fluxes. Human nitrogen additions are the principle cause for the increase in terrestrial nitrous oxide emission since 1960, and contribute to about one fifth of the current global net carbon uptake (1996-2005).

Sönke Zaehle and colleagues then determined the effect of anthropogenic nitrogen on the atmospheric concentrations of the greenhouse gases CO2 and N2O, and assessed the resulting consequences for present-day climate. The key finding is that the climatic effects of the anthropogenic nitrogen perturbation from both gases are very substantial but of opposite signs. The cooling effect due to enhanced carbon uptake of the terrestrial biosphere is more than compensated for by the warming effects from enhanced terrestrial N2O emissions.

However, “the fact that in our study the N2O effect appears stronger than the CO2 effect should not be over-interpreted” cautions Zaehle. Rather, the study highlights the relevance of anthropogenic nitrogen in the climate system and the need to consider the effects of carbon and cycling jointly. “I hope that this study fosters further research to better understand the effects of human N on ecosystem dynamics through joint observational and modelling studies”, Zaehle adds.

Explore further: Food shortages could be most critical world issue by mid-century

More information: Sönke Zaehle,  et al. Carbon benefits of anthropogenic reactive nitrogen offset by nitrous oxide emissions, Nature Geoscience, 31 July 2011; doi 10.1038/NGEO1207

Related Stories

Greenhouse gases from forest soils

Apr 12, 2011

Reactive nitrogen compounds from agriculture, transport, and industry lead to increased emissions of the greenhouse gas nitrous oxide (N2O) from forests in Europe. Nitrous oxide emission from forest soils is at least twice ...

Waterways contribute to growth of potent greenhouse gas

Dec 20, 2010

Nitrous oxide, a potent greenhouse gas, has increased by more than 20 percent over the last century, and nitrogen in waterways is fueling part of that growth, according to a Michigan State University study.

Can biochar help suppress greenhouse gases?

Mar 18, 2011

Nitrous oxide is a potent greenhouse gas and a precursor to compounds that contribute to the destruction of the ozone. Intensively managed, grazed pastures are responsible for an increase in nitrous oxide ...

Can biochar help suppress greenhouse gases?

Apr 20, 2011

Nitrous oxide is a potent greenhouse gas and a precursor to compounds that contribute to the destruction of the ozone. Intensively managed, grazed pastures are responsible for an increase in nitrous oxide emissions from grazing ...

Recommended for you

More, bigger wildfires burning western US, study shows

5 hours ago

Wildfires across the western United States have been getting bigger and more frequent over the last 30 years – a trend that could continue as climate change causes temperatures to rise and drought to become ...

User comments : 14

Adjust slider to filter visible comments by rank

Display comments: newest first

mtc123
2.5 / 5 (16) Aug 04, 2011
I see....
Now nitrogen is bad.
We should probably ban ALL fertilizers.
This nonsense is the latest in the leftist paradigm.
antialias_physorg
2.9 / 5 (13) Aug 04, 2011
This nonsense is the latest in the leftist paradigm.

What has a scientific finding got to do with politics?

This is from one of the Max Planck institutes. They are not affiliated with any party or ideology.
Dokudango
3.2 / 5 (9) Aug 04, 2011
It didn't take long for the crazies to hit this one. Nobody is calling for a ban on fertilizers; this article has nothing to do with politics. Read the last paragraph once again.
antialias_physorg
2.9 / 5 (11) Aug 04, 2011
Honestly, more and more I'm getting the impression that there are industry-paid 50cent drones at work, here.

(like in China where some people get paid a small fee for each pro-government blog/forum comment they write in an attempt to make it look like stuff that doesn't fit the party world view isn't true)

I'll take my tinfoil hat off now...
Plankton333
3.4 / 5 (7) Aug 04, 2011
This article is very interesting but it doesn't seem to factor in the carbon footprint from creating the fertilisers. About 5% of world wide natural gas is consumed making ammonia for fertiliser.
ted208
2.1 / 5 (21) Aug 04, 2011

The CO2 Hoax is not working out to well, the Climate models are a compete sham and in disarray. So lets expand the list to an even more potent green house gas Nitrogen.

The good and the bad of Nitrogen!

I have known for years that Fertilizers are a two edge sword good for crop growth but bad for the rivers and oceans that help to create dead zones. This to me is part of the real problem facing the ecosystem not global warming or CO2. It is Chemical and hormonal release and a massive growth in population, over fishing amongst others that are the real problems. It's a pity that Warmist organizations and followers have boxed themselves into a corner with the CO2 CAGW theory and they can't bear to look at the real world climate situation, or the fact that the worlds population are growing weary of the doom and glum the endlsee CO2 tax scams and the weekly scandals from the IPPC contributor's.
It leaves no room, money or time to devote to the real issues facing our planet!

jamesrm
2 / 5 (12) Aug 04, 2011
"This nonsense is the latest in the leftist paradigm.

What has a scientific finding got to do with politics?"

You have to wonder why they bother coming to these sights, much better off at Faux News or Tea/Racist party forums, etc.
Strange thing is hes likely to believes in Niberoo, the Rapture and the Illuminati but not in humanities ability to change the world in a negative way through ignorance, go figure?

rgds
James
LordOfRuin
2.6 / 5 (5) Aug 05, 2011
Nothing new here though. I'd always been under the impression that the nitrogen cycle was as important as other more widely published / reported climate change influences. The impact of fertiliser run off on our water ways and sea life is profound. In fact, I seem to remember reading somewhere that there is more nitrogen in todays rainfall than we used to put on our fields fifty odd years ago. (Mmm, now that I've said that, I'm going to have to go looking for that aren't I?)
DeadCorpse
1.3 / 5 (13) Aug 05, 2011
If they used the old IPCC data, along with the now faulty and discredited heat retention numbers, then any conclusion they could draw from their global model is WRONG.

First Carbon, now Nitrogen... How long before they come up with a "study" that H and O are bad for the environment as well?
antialias_physorg
3.7 / 5 (6) Aug 05, 2011
What dou you mean by 'bad'? They just say it has an effect. (and yes: H and O, especially when combined to water vapor - like in airplain contrails - very likely do have a noticeable effect on global warming)
Serendipity_Seraph
1.1 / 5 (8) Aug 07, 2011
I am scratching my head a bit on this one. Earth's atmosphere is neary 79% nitrogen. It is difficult to believe that fertilizer usage is significantly change the nitrogen levels or the levels of nitrous oxide since the other most significant atmospheric gas is oxygen and nitrous oxide is create naturally by many processes.
omatumr
1 / 5 (10) Aug 08, 2011
Anthropogenic nitrogen is bad, bad!


UN's Big Brother knows.

AGW (Anthropogenic Global Warming) blindly assumes the validity of a foolish decision reached at the Bilderberg on 17-21 April 1967 [1]:

The Sun "is homogeneous and in hydrostatic equilibrium."

1. O. Gingerich and C. De Jager, Solar Physics 3, 5-25 (1968):

http://adsabs.har....3....5G

That foolishness is the fundamental assumption of AGW propaganda.

Every solar cycle, solar flare, and solar eruption falsifies Bilderberg's SSM and AGW.

Earth's heat source is obviously not constant [2], but Al Gore, Big Brother, UN, and associates pretend that their propaganda is "scientific."

They are getting desperate now because the public has realized that government scientists have manipulated data and observations for research funds.

2. "Earth's heat source - the Sun", E & E 20 (2009) 131-144

http://arxiv.org/pdf/0905.0704

With kind regards,
Oliver K. Manuel
Former NASA PI for Apollo
Howhot
3 / 5 (4) Aug 09, 2011
"f they used the old IPCC data, along with the now faulty and discredited heat retention numbers, then any conclusion they could draw from their global model is WRONG."

How do you people talk to your kids when you are so full of pseudoscience crap. I'm sorry the only thing discredited was your comment on AGW. (Same goes for the spectacular psuedo-science of Oli (shame oli)).

Howhot
3 / 5 (2) Aug 13, 2011
So the anti-AGW people need more to chew on regarding nitrogen in the atmospheric soup of man made gasses. Here is one easy to read puff piece;

http://chem.ku.dk...thethic/

More news stories

There's something ancient in the icebox

Glaciers are commonly thought to work like a belt sander. As they move over the land they scrape off everything—vegetation, soil, and even the top layer of bedrock. So scientists were greatly surprised ...

Clean air: Fewer sources for self-cleaning

Up to now, HONO, also known as nitrous acid, was considered one of the most important sources of hydroxyl radicals (OH), which are regarded as the detergent of the atmosphere, allowing the air to clean itself. ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...