Troubling Transformation In Arctic – But Little To Do With Ice!

Some of you guys doing GEOG3057 may have received an email from Anson on an event called ‘Hot and Bothered? Species Vulnerability to Climate Change’  held by ZSL. It sounded interesting and I wanted to step away from my dissertation for a bit, so I decided to go. Though it wasn’t the main focus of the talk, what captured my attention was the brief touch (literally 2 mins max.) on ‘Arctic Greening’ by Dr. Richard Pearson from UCL. Following on Tuesday’s post on shifting vegetation and biomes, I thought it would be nice to add on to it.

Dr. Richard Pearson giving his speech on Arctic Greening (Author's Photo)

Dr. Richard Pearson showing his research on present day (2013) and projected shifts (2050s onwards) in Arctic Vegetation

‘Arctic Greening’  - Most Recent Observations

The current pattern we are increasingly observing in the Arctic is ‘greening’. This trend coincides with the increase in Arctic temperatures (hence shrubs, plants, lichens are loving it!), which have rapidly risen twice as much as the global rate. Way back during the Early Holocene, increases in temperature in the Alaskan Arctic led to one or more large-scale shrub invasions in the region suggesting that vegetation in the region are most likely able to respond to climate changes very rapidly.

If you are skeptical, here are some concrete evidence of photographs showing an increase in vegetation cover in Alaskan Arctic. The first set of photographs shows an increase in density of shrub patches and an expansion of shrubs into areas that were shrub-free in the same location at Ayiyak River between 1949 and 2000.

The Ayiyak River in 1949 and 2000
Note: Point A and B are in the same location in both photographs 

The second set of photographs below shows the arrival of spruce stands (A) and an increase density of shrubs (B).

The Kugururok River in 1950 and 2000
Note: Point A and B are in the same location in both photographs 

Future Predictions

So what does the future hold for Arctic landscapes?  Well, we will never be a 100% sure, but using statistical and ecological niche models, Dr. Richard Pearson and his fellow researchers predicts that potentially more than half (48-69%) of the vegetated regions will likely result in a change of physiognomic class, and woody plantations may increase up to 52% under climate change predictions for 2050s and restricted tree dispersal. Specifically, Alaska’s North Slope that is currently dominated by graminoids (grasses) will potentially be encroached by low-shrub and dwarfshrub tundra. There will also be a massive expansion of tree cover in regions, such as Northern Siberia.

Present observed (left) and predicted distributions of vegetation in 2050s (right) near the Arctic.  

(a. showing Siberia, b. showing Alaska, c. showing Western Canada)

What will it mean?
Continued ‘greening’ in Arctic will create/enhance positive climate feedbacks. For example, increases in woody vegetation will likely enhance evapotranspiration rates and atmospheric water vapour, which will act as a positive feedback to regional heating. An increase in darker woody plantations will reduce albedo and result in positive feedback to warming. The consequences of the shift would also create impacts beyond the Arctic, as many  species migrate seasonally from the lower latitudes in search for open space, such as ground-nesting birds.  

But wait for it… there are some positives in light of all the negatives
In the arctic region, increase shading derived from the increase in shrub canopy will reduce temperatures of soils, which may potentially slow carbon release from melting of permafrost, hence, acting as a negative feedback to global warming.

Short and brief, but hope you liked it! Have a great reading week guys! :)