A greener Arctic in a warming climate

Students collecting samples on the Alaskan tundra.

A new study of thirty years of satellite data shows considerable changes to the Arctic tundra. The difference between the seasons is diminishing, resulting in increasing plant growth and a less clear distinction between North and South. Vegetation is moving northwards as climatic conditions shift.

The study, conducted by an international team of 21 researchers from 17 institutions in 7 countries and funded by NASA is published in Nature Climate Change. Professor Bruce Forbes from the Arctic Centre of the University of Lapland in Rovaniemi, Finland, one of the authors, says  indigenous reindeer nomads in northern Russia are already experiencing increases in the height of deciduous shrubs.

Although conditions differ in different parts of the region, overall the growing season is beginning earlier and the autumn freeze starting later.

Climate News Network quotes Professor Forbes as saying “we are seeing more frequent and longer-lasting high pressure systems. In winter, the snow cover comes later, is deeper on average than in the 1960s, but is melting out earlier in spring”.  Forbes and his research team used dendrochronology, the science of tree-ring measurement to confirm the findings.

“In a few decades, if the current trends continue, much more of the existing low shrub tundra will start to resemble woodlands as the shrubs become tree-sized”, says Forbes.

The warming will change ecoystems considerably and also result in “feedback” effects. Melting permafrost means peat and vegetation will decompose, releasing methane and carbon dioxide into the atmosphere.

Let me close with “food for thought” from Tim Radford, the author of the Climate News Network report on the study:

“Climate is a complicated business, and there is always legitimate room for argument about the validity of one selected set of measurements, a potential bias in the observations, or the reliability of comparison data collected two generations earlier. But vegetables can’t be fooled. Plants grow where they can. If deciduous shrubs are growing taller, and colonizing sites ever further north, then conditions must be getting warmer, and staying warmer.”

It’s hard to argue with that.