Lemmings 'helping keep Earth green'
Lemmings could turn out to be unsung heroes of the Earth's climate.
While governments fail to act decisively on carbon emissions, the Arctic rodents are getting on with the job of keeping their environment green. By doing so, they may be helping to protect the Earth from global warming, scientists believe.
A US study found that when lemmings are absent, the Arctic tundra is likely to be more barren and covered in lichens and moss.
Where lemmings live, on the other hand, there is a surprising increase in grass and sedge. As well as providing the animals with food, the plants act as an important "sink", soaking up carbon from the atmosphere. One reason for the trend may be the waste products of large numbers of lemmings fertilising the soil, say the researchers.
Warmer temperatures are themselves promoting the growth of grasses and shrubs which are helping to make large areas of the Arctic more habitable.
Scientists still do not know what the net effects of this greening might be on climate. There is a balance to be struck between mopping up carbon and more of the greenhouse gas being released by bacteria responsible for plant decomposition. Lemmings could be helping to tip the scales in favour of carbon capture.
Dr David Johnson, from the University of Texas at El Paso, lead author of the study published in the journal Environmental Research Letters, said: "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 Arctic regions where lemmings are present and go through dramatic population cycles.
"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."