Detection : e.g. Monitoring & Description Attribution: e.g. Research & Analysis

1. Potential Elements of a Conceptual Framework for approaching NW Atlantic Climate Change and Impacts Typical Components of a Climate Change Program • Detection: e.g. Monitoring & Description • Attribution: e.g.Research & Analysis • Prediction: e.g. Models & Projections • Impacts (ecological, human, infrastructural, socio-economic): e.g. Projections & Assessments • Adaptation: e.g. Management & Design • Mitigation: e.g. Policy & Technology • Other Decision- and Policy-making Science Other Sectors

2. The Nature of Climate • Atmosphere-Ice-Ocean-Biosphere • A coupled highly-nonlinear system • Pronounced geographic & temporal variability • Natural Modes of Variability • Weather: Present state or short-term (days to years) variability • Some short-term predictability (days to seasons) • Climate: Statistics of Weather over period (decades) and region • Large spatial and significant temporal variability • Multiple forcings (pressures) • Very limited predictability => Need stochastic (probabilistic) approach • Greater complexity, nonlinearity and variability • Greater anthropogenic pressures The Nature of Ecosystems (and Human Populations) Future Projection of Climate Change, Impacts & Adaptation A Formidable Challenge! - How to deal with uncertainty

3. Complexities & Semantics of Climate Change & Attribution UNFCCC & Simplest Terminology • “Climate Variability” is Natural Variability • “Climate Change” is Anthropogenic variation (typically assumed as trend or shift) But: • Natural & anthropogenic variations are inter-related & difficult to separate • “Natural modes of variability” will probably dominate over anthropogenic changes for some properties in next few decades • It is the “Natural + Anthropogenic” variations that matters IPCC & Scientific Terminology • “Climate Change” is a change of climate statistics (e.g. 30 yrs) over time • “Climate Change” can include both natural and anthropogenic variations • Anthropogenic changes can be trends, shifts, or changes in statistics (e.g. extremes) • Natural changes can be trends, shifts of changes in statistics

4. Ocean Climate of the NW Atlantic Temperature at 100m in Season • Shaped by “Regional” Factors • Labrador Current in subpolar gyre • Arctic outflows (T, S, ice, other) • Seasonality from continental lee • Freshwater run-off from St Lawrence & other • Local & advected sea ice • Proximity to Gulf Stream & subtropical gyre • Complex regional coastline & bathymetry Difficulties with “downscaling” climate change projections from coupled global models (e.g. IPCC) which don’t have good representations of some of these “regional” factors; =>Difficulties in developing regional climate change projections • Strong natural temporal variability from: • Seasonal cycle • Variable jet stream & polar-subtropical air mass boundary • Regional modes of coupled air-sea-ice system (e.g. NAO) which have rich temporal structure • Continental and subtropical influences

5. Potential Elements of Conceptual Framework for approaching Ocean Climate Change in the NW Atlantic • Strong “regional” influences on hierarchy of space scales => Stepwise Downscaling • need to identify intermediate-scale domains with similar potential changes & impacts • Strong natural variability that is likely to dominate over anthropogenic trends for many variables for next couple of decades • need to know present/recent state of variabilityand impacts • consider anthropogenic perturbations on natural variability • consider shifts or trends in spatial and temporal ranges and extremes • Identify relevant time horizons,considering potential changes & societal context • “Near Term”, e.g. 2010-2025: Perturbed natural variability? • “Mid Century”, e.g. 2040-2060: Emerging new regional climate-/eco-system? • “Late Century”: e.g. 2080-2200: A scary new world? • Triage regional ocean climate components & variables as to their likelihood & impacts of change (towards a risk assessment): • likelihood from global vs regional effects, observed & theoretical support, etc. • impacts from vulnerability, adaptive capacity, socioeconomic value, etc. • essential to consider both uncertainties & risks

6. Complexities & Semantics of Climate Change & Attribution UNFCCC & Simplest Terminology • “Climate Variability” is Natural Variability • “Climate Change” is Anthropogenic variation (typically assumed as trend or shift) But: • Natural & anthropogenic variations are inter-related & difficult to separate • “Natural modes of variability” will probably dominate over anthropogenic changes for some properties in next few decades • It is the “Natural + Anthropogenic” variations that matter IPCC & Common Scientific Terminology • “Climate Change” is a change of climate statistics (e.g. 30 yrs) over time • “Climate Change” can include both natural and anthropogenic variations • Anthropogenic changes can be trends, shifts, or changes in statistics (e.g. extremes) • Natural changes can be trends, shifts of changes in statistics

7. Complexities & Semantics of Climate Change & Attribution UNFCCC & Simplest Terminology • “Climate Variability” is Natural Variability • “Climate Change” is Anthropogenic variation (typically assumed as trend or shift) But: • Natural & anthropogenic variations are inter-related & difficult to separate • “Natural modes of variability” will probably dominate over anthropogenic changes for some properties in next few decades • It is the “Natural + Anthropogenic” variations that matters IPCC & Scientific Terminology • “Climate Change” is a change of climate statistics (e.g. 30 yrs) over time • “Climate Change” can include both natural and anthropogenic variations • Anthropogenic changes can be trends, shifts, or changes in statistics (e.g. extremes) • Natural changes can be trends, shifts of changes in statistics