Arctic soils emit a greenhouse gas called nitrous oxide.  Nitrous oxide is 300 times more powerful than carbon dioxide in warming the planet.  In addition to its potential to warm the planet, nitrous oxide is one way that Arctic soils lose nitrogen.  This is important because nitrogen limits plant growth in the Arctic. Thus, the less nitrogen there is, fewer plants grow and then fewer caribou, muskox, rabbits, etc can live in the Arctic.

The release of nitrous oxide from soil typically increases as the soil temperature increases.  As the Arctic grows warmer, it will begin to contribute to greenhouse gas production.  This is one example of a positive feedback loop. Ecosystems that currently help control our temperature will begin to help increase our global temperature creating a runaway train that may destroy our civilization.  In addition, as these ecosystems grow warmer, they will begin to lose more and more nitrogen to the atmosphere and we do not know if they will then also increase their nitrogen fixation ability.  So, Arctic scientists are very interested in how Arctic soils will respond to temperature increases.

We’ve been investigating this issue at a place called Truelove Lowland which is a beautiful spot on Devon Island in Canada’s Arctic

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Stream on Truelove Lowland

.  We found that, yes, as soils warm, they do indeed emit more nitrous oxide.  However, surprisingly we found that this increase in emission dependended on the form of nitrogen available in the soil.  There are two major forms of inorganic nitrogen in soil, nitrate and ammonia.  Typically, nitrate is the form that is readily available to animals, plants and bacteria.  But in the Arctic, this is not always the case and normally when we do our analyses, we find that the amount of ammonia is the best predictor of how much nitrous oxide the soil is going produce.  In this experiment, when we fertilized with nitrate we saw large increases in nitrous oxide production with increasing temperature but when we fertilized with ammonia, we didn’t see this large increase.   This surprised us because in the field, we knew that the primary source of nitrous oxide was ammonia and not nitrate.  Using chemicals that inhibit certain groups of organisms, here is what we think is going on:

In the Arctic soil, fungi compete so strongly for nitrate that the only form of nitrogen available for release as nitrous oxide is ammonia.   So, this explains our field results, that is, ammonia dominates in the field settings because fungi suck up all the nitrate.

However, in some parts of the Arctic, in the bits that are soggy and wet, a group of organisms called denitrifiers will rapidly respond to climate change, if they have nitrate. They normally can’t get nitrate so this isn’t a problem, unless…

Many other Arctic scientists have found that nitrate levels can rapidly increase if snow depth increases.  It sounds counter-intuitive, but if the Arctic warms, then snow depth will likely increase.  So, people have been investigating what happens when snow depth increases as well as when the ecosystem warms.  Our results, suggest that Arctic soils that are currently unresponsive to increases in temperature, will suddenly become very responsive.

Is this a problem?  We don’t know yet.  How important is nitrous oxide contribution from Arctic soils to the world’s nitrous oxide budget?  Not really that important.  What will happen to nitrogen levels in these soils as they warm?  No one really knows.  We care about this because 50% of Canada’s carbon is safely stored in the Arctic soils.  If climate change was to suddenly release this carbon, very, very bad things would happen to our planet.

Approximately 50 soil scientists were brought together by Greg Henry to participate in the International Polar Year Project, Climate Change Effects on Canadian Arctic Tundra Ecosystems; Interdisciplinary and Multi-Scale Assessments.  Our goal in this project was to provide an assessment of Canadian Arctic soils.

About half Canada has permafrost, permanently frozen soil, and this permafrost dramatically changes how soils, plants and animals respond and contribute to climate change. We are investigating how these soils differ from one another in their responses and why they differ.  A key response is the storage of carbon because these permafrost soils hold 25% of the carbon sequestered in the terrestrial biosphere.  As a group, we have explored how these soils store, release and process carbon.  We knew that these carbon storage processes were controlled by nitrogen and thus, we also explored how nitrogen processing differed.  Our work in 2008, highlighted the ultimate importance of water for these soils.  Water affected how plants provided nitrogen to the soil; water affected how large organisms in the soil freed up this nitrogen and carbon for further storage and water affected how these soils released greenhouse gas back to the atmosphere.  Most surprisingly, we found that soils that had little water were most susceptible to climate change.  Our work highlighted that the vast desert that sits on the top of Canada, the Polar Desert, may be rapidly changing in response to climate change.  The sustainability of this change is not yet known and we worry that many fragile Arctic soils, such as the dunes and deserts, may be under threat.

The nitrogen cycle, controls carbon sequestration.  A key component of the nitrogen cycle in the Arctic is bryophytes which provide ammonia, which in turn is transformed to nitrate and used by plants.  As expected, bryophytes were controlled by moisture and needed phosphorus for maximum efficiency.  However, the normal organisms convert the nitrogen provided by bryophytes to a form available to the rest of the ecosystem, were absent.  The organisms, autotrophic ammonia oxidizers, were found at very low levels across the Arctic.  Instead, it appears that heterotrophic or archael ammonia oxidizers are the critical organisms in Canada’s Arctic.  This is important because heterotrophic and archael oxidizers respond very rapidly to increases in temperature whereas autotrophic oxidizers do not.  Thus, work in 2009 will focus on identifying what is the key group as this will be essential for predictions on how Arctic systems respond to climate change.

Most of Canada’s carbon is locked in the Arctic soils.  A key activity in 2008 was the collection of samples we need to estimate the Arctic soil carbon storage and if it was declining or increasing over the last 20 years.  This was a two step process, first we estimated soil carbon losses and/or gains over a long time period and then we estimated the variability associated with carbon storage in these soils.  These results are currently being linked to the Canadian Soil Carbon project.

All of our research teams report the same dependency in Arctic systems.  Response and contribution to climate change is highly dependent on plant species present in that soil. In other words, while moisture and temperature are important and have over the long term altered plant communities and soil types.  Current responses are linked intimately to the plant present at the sampling location.  As a group, we wish to highlight this observation as it suggests that invasive species in Arctic climes may have a significant influence on carbon cycling in Canada’s Arctic.

The budget on Tuesday was not a good one for Canadian Science.  The Conservative government has followed its past policy of not supporting Canadian Science.  They renewed the Canadian Foundation for Innovation and supported University infrastructure.  However, the Foundation for Innovation and Infrastructure do not support laboratory operations.  Without this money, science activity withers and fewer students get trained.

For the North, it was a special disaster.  The International Polar Year is winding up.  Most northern researchers are looking at 80-90% reduction in operating funds in the 2010/11 polar year.  Yet, there is nothing in the budget to address this. Without funds available in 2009 to support 10/11 activity, we can count on 2010/11 being a dismal year for Northern research.

The commitment to build a northern research station is welcome but once again, what use is infrastructure if there are no funds to use it.  The Conservatives transferred money to Indian and Northern Affairs Canada for northern reseach but INAC’s mandate is not innovation and much of northern research is not directly linked to INAC’s mandate.

The Conservative budget is even more disappointing because of its missed human resource opportunity.  As has been pointed out to them, there are a wide range of peer-reviewed research projects that were not funded because of a lack of funds.  These projects have been vetted by the Tri-Councils and peers.  These projects all had the goal of training Canadians in the knowledge economy.  If funds had been provided in this budget, Science activity could have exploded in 2009 providing 1000’s of training positions for laid off knowledge workers.  This would have provided Canada with a cohort of highly trained individuals who would be ready to re-enter the economy in 2011.

Instead, we will have empty buildings and our best and brightest will once again be leaving for Obama land.