Impacts of Climate Change on Arctic Environment, Ecosystem Services and Society (CLICHE) Jan Weckström (Consortium leader, prof.

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1 Impacts of Climate Change on Arctic Environment, Ecosystem Services and Society (CLICHE) Jan Weckström (Consortium leader, prof. Atte Korhola) 1

2 Cliché: The overall objective To improve our understanding of the impacts of climate change on Arctic ecosystems and the services that they provide through ecosystem studies, synthesis activities and societal impact assessments. More specifically the proposed research will: Investigate, map and model the past, present and future climate change-induced changes in central ecosystems of the European Arctic with unprecedented precision: Deepen our understanding of the basic principles of ecosystem and social resilience and dynamics; identify key taxa, structures or processes that clearly indicate impending or realised global change through their loss, occurrence or behaviour, using analogs from the past (e.g. HTM, MWP), experiments, observations and models; Develop adaptation and mitigation strategies to minimize the adverse effects of climate change on local communities, traditional livelihoods, fisheries, and tourism industry and promote sustainable development of local community structures and enhance the quality of life of local human populations. 2

3 Cliche comprises eight major Work Packages WP 1: on Arctic tree-lines and ecotones (Team leader: Heikki Seppä) WP2 on Arctic vegetation and biodiversity (Team leader: Miska Luoto) WP3: on peatland ecology and carbon dynamics (Team leader: Eeva-Stiina Tuittila) WP4: on snow properties and snow cover (Team leader: Matti Leppäranta) WP5 on Arctic freshwater ecosystems (Team leader: Atte Korhola) WP6 on fisheries yields (Team leader Kimmo Kahilainen) WP7 to tourism industry and local communities (Team leader: Jarkko Saarinen) WP8 on Arctic herding communities (Team leader: Hannu I. Heikkinen) 3

4 What is new in Cliche? The holistic approach covers a full range of spatial (hot spots, European Arctic, circumpolar) and temporal (past, present, future) scales; It combines observational, experimental, reconstructional, re-sampling, geospatial, modeling and socioeconomic methodologies to assess the vulnerability of northern environment and societies to climate change The multidisciplinary approach will promote a systemic understanding of the impacts of ongoing and projected climate change 4

5 Hot spots Maximum Holocene treeline Modern treeline Modern northern limit HTM northern limit No data available 5

6 Impacts of climate change on Arctic freshwater ecosystems 6

7 Work package summary This WP takes a holistic approach to examine lake responses to changes in climatic variables on different time domains (past, present, future) in order to improve our understanding of global climate change and active adaptive management and governance of resilience to sustain ecosystem states. In this context, for any specific site we need to identify: (i) its current ecological status; (ii) its previous condition (reference condition) and desired future status; (iii) how it has responded to climate change (cooling and warming); and (iv) the role of other influences, including the impact of other stressors, that might confound the expected response. 7

8 PRESENT PAST high-resolution PAST low-resolution 8

9 Used material Phytoplankton Zooplankton Fish Plant pigments Stable isotopes Lipids (fatty acids) Cladocera Diatoms Plant macrofossils Chrysophyte cysts Black carbon (SCP/shoot/puuhiili) Water chemistry Water optics Sediment analysis (LOI, grain size,magnetism) 9

10 Photo: Kimmo 10

11 Overall project setup The study lakes in the Värriö Strict Nature reserve, eastern Lapland One fishless reference lake One lake with possible fish One experimental lake with a dense brown trout (Salmo trutta) population, stocked in 1980, Paleolimnological research before and after the fish introduction Removal of the fish stock recovering back to naturally fishless lake? Fishless? Fishle ss Dense brown trout stock 11

12 We think that Fish introduction in 1980 has caused cascading top-down effects However, has it also impacted the primary producers i.e. diatoms? Gammarus Brown trout Cladocera Chaoborus Diatom 12

13 Fish versus zooplankton Cladocera accumulation ind. /cm 2 /year The density of cladoceran zooplankton has increased after the fish introduction in Fish No Fish 13

14 Conclusions Top-down effects of introduced brown trout on their prey animals were observed in the sediment record No clear changes in diatom communities can be observed in the fishless lakes However, the introduced brown trout seem to have affected the diatom community structure in Lake Kuutsjärvi The mechanism behind the impact of fish on diatom community structure in Lake Kuutsjärvi remains so far unclear 14

15 Dissolved organic matter (DOM) in high latitude lakes Why to study aquatic DOC? Lakes have proven to be active sites of transport, transformation and storage of terrestrial carbon (t-doc) Global warming is expected to increase the amount of t-doc in lakes due to increased runoff, melting and changes in cacthment vegetation DOC is an essential component in aquatic ecosystems 15

16 DOC additions & bacterial vs. algal production a PP:BP Control Subarctic Boreal DOC addition lead to a shift from dominance of primary to bacterial productivity 10 b 0 day 1 day 3 day 5 Forsström et al. 2013: Aquatic Microbial Ecology 16

17 A comparison between modern and preindustrial biota in NW Finnish Lapland Effects of the recent climate warming on subarctic and arctic freshwaters have already been documented Subarctic and arctic freshwater ecosystems are excellent sites for studying long-term environmental variability due to the low direct anthropogenic impact, and because they are vulnerable to even moderate environmental change However, it is not known if all changes are caused strictly by climate, or if local factors (e.g. catchment properties, biotic interactions) can override the climatic signal The aim of this study is to determine recent changes in subarctic Fennoscandian lakes and evaluate the impact of local versus global environmental factors. 17

18 TOP-BOTTOM APPROACH The impact of climate change on freshwater biota Smol (2008) 18

19 MATERIAL Study area in Fennoscandian subarctic with steep climatic gradients Study sites consist of 52 small, shallow, oligotrophic lakes Studied biota consists of fossil and modern diatoms (24 lakes), chironomids (17), cladoceran (32) and pediastrum (6) NOTE: not all groups were analysed from all lakes 19

20 Fig. 1. Distribution of the study lakes. Fig. 2. Yearly precipitation and mean air temperatures ( ) in Kilpisjärvi (yellow circle in Fig. 1).

21 Proxy data analysed Chironomids Diatoms Pediastrum Cladocera Head capsule 21

22 CONCLUSION No regional uniformity of changes in biota Only one lake where diatoms, chironomids and cladoceran communities have changed No clear signs of direct climate impact. Climatic changes are most probably overridden by local environmental factors i.e. differences in lake catchment characteristics and biological interactions Most of the studied lakes are still in their pre-industrial reference/natural state Local factors should be taken into account when interpreting recent changes in high latitude freshwater ecosystems 22