The rise of global surface temperatures slowed during the last decade. The northern hemisphere saw a spate of harsh winters. The 2012/2013 winter, for example, saw extremely cold temperatures and high snowfalls across Europe and eastern North America, and one of the driest March in Western Norway since reliable observations started around 1900. At the same time the Arctic experienced extreme warming and accelerated sea ice loss, culminating in the record-low of September 2012.
Anthropogenic global warming may explain much of the persistent changes over the northern hemisphere, but not the large year-to-year variations. Nor may it entirely explain the strong decadal fluctuations in northern hemisphere climate observed over the last century.
The ultimate test of understanding
Will it be possible to predict such weather conditions in seasonal and longer time scales?
Noel Keenlyside, professor at the Geophysical Institute, UoB and the Bjerknes Centre hopes so. He is coordinating the new project EPOCASA, (Enhancing seasonal-to-decadal Prediction Of Climate for the North Atlantic Sector and Arctic). As the project name tells, they are aiming to develop a dynamical climate prediction system on longer timescales focused on the North Atlantic Sector and the Arctic.
Today the ability to predict climate in our region is far from established. However, there is mounting observational and modeling evidence that different parts of the climate system – like the Tropics, the North Atlantic, Arctic sea ice, Eurasian snow cover, and the stratosphere – provide a basis for skillful climate prediction in the North Atlantic Sector.
"Prediction is the ultimate test of understanding", according to Keenlyside. "For example we hope by performing retrospective decadal predictions (hindcasts) over the last century, to shed light on the relative importance of internal and external influences on natural climate variability, including the significance of feedback mechanisms. Furthermore, the hindcasts will allow us to better disentangle the relationship between human influence and natural variability in the climate system”.
From the kick-off meeting for EPOCASA January 30.: From left Yonqi Gao, Anne Britt Sandø, Mao-Lin Shen, Francois Counillon, Mats Bentsen, Noel Keenlyside, Tor Eldevik, Mahaut de Vareilles, Øystein Skagseth, Camille Li, Kjell Arne Mork, Ingo Bethke, Yvan Orsolini, Retish Senan, Thomas Toniazzo, Marius Årthun, Frode Stordal. Foto: Kjartan Mæstad, IMR
Visit the EPOCASA project page here
Paving way for operational predictions
The climate prediction system which will be developed in EPOCASA, couples an advanced data assiliation method developed at the NESRC, to the Norwegian Earth System Model (NorESM). This coupling builds upon the developments initiated in the earlier Bjerknes Centre strategic thematic project PRACTICE.
The innovative approach to data assimilation methods represents something new in the Bjerknes Centre. The combination of data assimilation experts with atmospheric, ocean and climate scientists is a new constellation of cooperation in Norway.
”The climate prediction capability we are developing will be paving the way for operational climate prediction, that will be of direct benefit to Norwegian society and economy” Keenlyside says.
But also, the scientific research carried out in EPOCASA will furthermore lead to a deeper understanding of the factors controlling climate in our region, and its predictability on timescales from seasons to a decade.