Winter snow melt events in the Eurasian Arctic:

consequences analysed from scientific and indigenous knowledge

Terry V Callaghan1, Stef Bokhorst, Ross Brown, Pavel Y. Groisman, Cecilia Johansson, Margareta Johansson, Niklas Labba, Vladimir Radionov, Jan Åge Riseth

1R l S di h A d f S i St kh l S d1Royal Swedish Academy of Sciences, Stockholm, Sweden

Data presented from:-

a) the SWIPA (snow, water, ice and permafrost in the Arctic) Assessment to be released in May 2011 by AMAP (Callaghan et al in Press)AMAP (Callaghan et al., in Press)

b) the International Polar Year ”Back to the Future” Assessment of multi-decadal changes in the A ti t b bli h d i S t b 2011 bArctic to be published in September 2011 by AMBIO (Callaghan and Tweedie, in press) and

c) Several already published papers: the Russian ) y p p ppapers are made available through the SWIPA report

Snow cover is changing in Eurasia and beyond

mean February snow depth

number of days with snow cover > 50% from November to May

winter temperature (November–May)

Long-term variability in snow cover in Northern Eurasia 1936-2004: Solid lines indicate linearLong term variability in snow cover in Northern Eurasia 1936 2004: Solid lines indicate linear trends the red ad hoc line denotes the recent decrease in snow cover duration from 1980.

Kitaev et al., 2005 in SWIPA

Changes to the cryosphere are rapid and are accelerating

mm

Juliandayday

Julianday

Julianday

y

mm

Callaghan et al., 2010 Kohler et al., 2006Callaghan et al., 2010 Kohler et al., 2006

Changes in snow conditions have numerous consequences from local tonumerous consequences from local to global scales. Changes in snow affect:-

•Feedbacks to climate: e.g. albedo

•Feedbacks to other cryosphere components such as permafrost

•Hydrology and water use such as hydro power

•Plant productivity and CO2 drawdown through timing and duration of the growing season and soil moisture contentof the growing season and soil moisture content

•Biodiveristy by habitat destruction and preventing access to food plants

•Local livelihoods through effects on tourism (ski industry) and indigenous peoples’ land use such as reindeer herding

Scientists have a limited understanding of snow conditions whereas Indigenous Peoples have a vocabulary of ca. 200 g p ywords based on generations of experience: this adaptive

knowledge has enabled their survival.

A multidisciplinary team of scientists has worked with Saami reindeer herders to learn about their terminology and recent

changes in snow conditions (Riseth et al 2010, Polar Record)

Most terms focus on snow conditions that affect movement ofaffect movement of people and animals over the snow (density and weight-bearing) and access to food plants by reindeer (ice crusts)

Snowpack profiles are ”read” by the Saami. They indicate how the land can be used but they also give a history of weather conditions and land useuse.

Ice-crusts –incomplete melt: surface crust =

l t lt

History of weather events

complete melt

Compacted by grazing

Riseth et al., 2010, Polar Record

Snowpack characteristics are changing: the thicknesses of very hard snow layers are increasing, particularly in relation to the snowpack depth, and they are more often at the base of the snowpack denoting complete melt events

Time period

Cumsum very hard

( )

Cumsum very hard

/ fil

Cumsum very hard

Cumsum very hard

/ fil

Number of profiles

are more often at the base of the snowpack denoting complete melt events

snow (m) snow /profile(m)

snow relative to snowpack thickness

snow /profile relative to snowpack thickness

1961- 3.81 0.022 9.15 0.055 16876

1977-92

5.39 0.026 11.17 0.054 207

1993-2009

6.46 0.033 20.60 0.104 1982009

Cumulative amount of very hard snow in layers relative to total snow depth

(Johansson et al., in press).

Snow conditions (e.g. Hardness) affect lemming cycles (Kausrud et al., Nature, 2008) with effects that cascade onto vegetation and predators

Fewer lemmings = fewer arctic foxes, snowy owls

etc.

Fewer lemmings = more vegetation = faster response to

climate warming (Olofsson et al., 2005)

Harder snow = Fewer lemming peaks

Extreme winter warming and snow-on-rain events are well-known by Saami as events damage vegetation, kill animals, and affect land use

< 10th January

2001, temp. -15 0C

17th January 2001, temp.

+50C >

”Typical event” in Northernmost Sweden: courtesy of TR Christensen

November weather

”Typical event” in Northernmost Sweden: courtesy of TR Christensen

1961-1996 1993

Temp oC

-7.0 -2.8

Precip mm

69 230

On Svalbard, freezing rain harms plants, reindeer and voles; Aanes et al., 2000

The impacts of the events are geographically widespread

Rare Canadian Peary reindeerpopulations are in dramatic p pdecline largely because of events (Barry et al., 2007; Miller and Barry 2009)

20,000 muskoxen were killed in the high Arctic in 2003 through rain on snow events; Rennert et al., 2009

Reindeer were killed in an icing event covering

e e s; e e e a , 009CAFF

Reindeer were killed in an icing event covering 6,000 km2 in Yamal in 2007; Forbes 2008; Forbes and Stammler 2009

Extreme warming events - experiments

controlcontrol

treatmentRESULTS

Species specific damage including:-

Bokhorst et al., 2008; 2009;2010 etc

Species specific damage including:Reduced berry productionDeath of shootsEarly bud burst and death

A natural event was identified in May 2008 in northern Norway: a few warm days in winter 2007 had long-lasting effects.

MODIS-derived NDVI values at 0 25NDVI values at 0.25 km2 resolution show 26% reduction over >1424 k 2>1424 km2

Bokhorst et al., in press

The number of warming events in winter is variable in time and space. We need better predictive power.

50

60

70

20 40 60 80 100 120 140 160 18040

-3 0 3 6 9 12

Sum of rain (mm) exceeding 4 mm per day falling on snow deeper than 3 cm: change in 1989 2006

Thickness of the basal ice layer has been

Sum of rain (mm) exceeding 4 mm per day, falling on snow deeper than 3 cm: change in 1989-2006 as compared to 1951-1980. Insignificant changes are shown in white (Shmakin, 2010 in SWIPA).

Thickness of the basal ice layer has been measured at 958 Russian stations since 1966. Dangerous events for reindeer husbandry (DER) are reported when the basal ice layer is thicker than 5 mm over 10 yconsecutive days. The number of sites reporting DER decreased by ~5%/decade mainly in response to a shorter and more intense snowmelt season. Bulygina et al., 2010 in SWIPA2010 in SWIPA

Conclusions

R hResearchers measure relatively few snow variables that are relevant to ecology and land use

Discourse with Indigenous Peoples provides new perspectives to both researchers and land users

Generally observed and predicted changes in snow conditions underestimate important impacts e.g. step changes and regime shifts

Our predictive power related to events is limited: there will be surprises!

Thank you for your attention