Could lemmings be involved in regulating our climate?

November 18, 2011, Institute of Physics
A pedestrian walks near the scenic coastline in Anchorage, Alaska. In past years, satellite images have shown a perceptible growth in grasses and shrubs in parts of the Arctic, a phenomenon pinned on global warming.

The mention of lemmings usually evokes images of small rodents throwing themselves off the top of cliffs in acts of mass suicide; however, their reputations might no longer be determined by hearsay as a new report suggests they could be having an intricate effect on the Earth's climate.

The study, published today, in IOP Publishing's journal Environmental Research Letters, suggests that lemmings may be maintaining the biomass of certain in the Arctic at a time when the greening of this vast area is becoming more noticeable.

When lemmings are excluded from the , the researchers, from the University of Texas at El Paso, observed an increase in certain plant types called lichens and bryophytes; however when the lemmings were present there were surprising increases in grass and sedge – the plant material that lemmings actually feed on.

"Our paper confirms that we really need to be careful attributing the greening of the Arctic to global warming alone. We have shown that lemmings can promote similar greening, through the increase of grasses and sedges, as warming does in where lemmings are present and go through dramatic population cycles," said lead author of the study David Johnson.

The increase of grass and sedge could be due to changes in nutrient availability in soils from the addition of urine and faeces from the lemmings, or by simply reducing competition for space by keeping bryophyte and lichen abundance low, as well as reducing the amount of standing dead and sedge litter.

Lemming populations have historically gone through periods of highs and lows, which researchers believe have played a key role in regulating many properties and processes of tundra ecosystems.To measure these effects, the researchers measured plant cover and biomass in 50-year-old lemming exclosures and control plots in the coastal tundra near Barrow, Alaska.

Satellite imagery has already confirmed that Arctic regions are becoming increasingly populated with greenery, such as grasses and shrubs, as increasing temperatures make the areas more habitable.

As the Arctic regions continue to become populated with more plant during the summer months, the effects on the climate could tip either way. Warmer temperatures may allow plants to grow bigger and store more carbon, taking carbon dioxide out of the atmosphere and potentially reducing climate warming.

Conversely, soil decomposition increases with warmer temperatures meaning soil microbes are respiring and releasing carbon into the atmosphere and potentially increasing warming.

"We still don't know the relative magnitude of these two feedbacks to warming. A greener landscape may maintain the region as a carbon sink, however higher plant growth in a greener landscape may not be enough to offset losses of carbon from soil microbes. It is plausible that herbivores, in some situations, may provide a mechanism for higher plant growth maintaining these ecosystems as carbon sinks.

"We are not saying that lemmings are causing the greening, because greening is occurring in areas where lemmings don't occur at high densities and we are not sure how lemming populations across the Arctic are themselves responding to warmer conditions. However, it is clear from our study that lemmings, and other herbivores, are more important in some of these Arctic ecosystems than people historically give them credit for," continued Johnson.

Explore further: Climate change may be lemmings' cliff

More information: 'Exclusion of brown lemmings reduces vascular plant cover and biomass in arctic coastal tundra: resampling of a 50+ year herbivore exclosure experiment near Barrow, Alaska', D R Johnson, M J Lara, G R Shaver, G O Batzli, J D Shaw and C E Tweedie 2011 Environ. Res. Lett. 6 045507, freely available online from November 18 at

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5 / 5 (2) Nov 18, 2011
Certainly Lemmings and the lichens have a MUCH larger effect than burning billions of tons of oil per year. Let's disregard everything and focus on the lemmings (/sarcasm)
5 / 5 (1) Nov 18, 2011
Just because of air pollution alone we have to strongly consider 'green technology'. Afterall, we only breathe the stuff..

But the 'why' of climate change may be influenced by more then human activities 'only'. It is an interesting topic aslong as you do not let 'the debate' affect whether or not you act.

I think there is no question that we should move towards cleaner[more efficient] energy and fewer toxic gas emissions.
3 / 5 (4) Nov 18, 2011
Really, ya think climate change occurs by more than human activities? /sarcasm

I think there is no question that we should move towards cleaner[more efficient] energy and fewer toxic gas emissions.

Really,.. as a right-wing conservative, I'm offended. My meta-greed profits are all derived from dirty inefficient toxic gas emission based energy,... who's going to pay for maintenance of my yacht? We already have solutions on the scale necessary out back in the shed,.. it's just not as profitable. /sarcasm.

5 / 5 (1) Nov 18, 2011
Lemmings and cowfarts, I'm glad we're finally getting to the bottom of all this.
3.4 / 5 (5) Nov 18, 2011
Well, certainly the Lemmings that constitute the Conservative Movement in the U.S. are doing their best to influence the climate for the worse. Both the Earth's climate, and the U.S. financial climate.
5 / 5 (1) Nov 18, 2011
Lemmings and cowfarts, I'm glad we're finally getting to the bottom of all this.

The more I think about it, the more I realize they forgot to factor in the critical lemming fart emissions, this could have grave consequenses..
not rated yet Nov 18, 2011
I guess lemmings have a lot to teach us about the global climate.

/ambiguous joke.

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