Projecting climate change in Australia s marine environment Kathleen McInnes

Projecting climate change in Australia s marine environment Kathleen McInnes CSIRO Oceans and Atmosphere Flagship Centre for Australian Climate and Weather Research

Framing of the problem IMPACTS EMISSIONS and Land-use Change Source: IPCC WG2 Summary for Policy Makers

Coastal Systems are particularly sensitive to: o Ocean Temperature Over 90% of the increase in energy in the climate system has warmed the oceans over recent decades o Ocean Acidification Coastal sea surface temperatures have been increasing at a faster About rate 30% than of the ocean anthropogenic temperatures CO 2 emitted over the last Climate 200 years zones has have been moved absorbed polewards by the oceans Ocean ph has fallen 0.1 units representing a 26% increase in the hydrogen ion concentration in seawater Acidification impedes the ability of calcifying organisms to form Sea levels their have skeletons risen about 20 cm since 1900 o Sea Level Rise Relative rates may be higher due to land subsidence Impacts will be most profound during extreme events o Other factors include: Storms, winds and waves Freshwater input

New climate projections for Australia The NRM (natural resource management) project Technical Report The underpinning science behind all projections 8 x Cluster Reports Focus on regional areas with distinct future climates 8 x Cluster Brochures Easy to understand key messages about regional climate change Data Delivery Brochure Info on climate model data availability

Marine Projections 1. Regional projections of mean sea level rise 2. Allowances for extreme sea levels 3. Projections of changes in SSTs, acidification and salinity

Plausible Futures (RCPs) Taylor et al, 2010 RCP8.5 High emissions RCP4.5 Intermediate emissions RCP2.6 Low emissions

Global sea level reflects the state of the Earth s climate system Figure 13.1 Warming/cooling of the ocean (thermal expansion/contraction) Change in mass of glaciers and ice sheets Changes in terrestrial storage Relative sea level is also affected by ocean density, circulation, land movement, and distribution of mass on the Earth

Projections of Global mean sea level rise (GMSLR) Sea level rise by 2100 compared with 1986 2005 RCP2.6 0.44 [0.28 0.61] m RCP8.5 0.74 [0.53 0.98] m Scenario Likely range for sea level rise 2081-2100 relative to 1986-2005 RCP2.6 RCP4.5 RCP6.0 RCP8.5 0.26-0.55 m 0.32-0.63 m 0.33-0.63 m 0.45-0.82 m Collapse of marine-based sectors of the Antarctic Ice Sheet, if initiated, would add no more than several tenths of a meter by 2100. Figure 13.27

Trends around Australia Altimeter 1993-2012 and tide gauges (dots) Spatial patterns show large regional departures from global mean sea level rise because of other influences such as El Nino/Southern Oscillation SOI included SOI removed Source: White et al, Earth-Science Reviews, 2014

21 st century GMSLR projections Medium confidence in likely ranges. Very likely that the 21 st century mean rate of GMSLR will exceed that of 1971-2010 under all RCPs. RCP 8.5 0.53 0.98 m by 2100 8-16 mm yr -1 during 2081-2100 RCP 2.6 0.28 0.61 m by 2100 SPM Figure 8

Contributing processes lead to non-uniform SLR Glacial Isostatic Adjustment Ocean dynamical response Glacier mass loss Ice sheet mass loss SLR Sum For RCP 8.5 in 2080 2099 relative to 1986-2005 About 70% of the global coastlines are projected to experience a sea level change within 20% of the global mean sea level change.

Extreme Sea Levels: Many factors can contribute Impacts are felt during extreme events!! Wave Runup Wave Setup Storm Surge Astronomical Tides Variability (Seasonal / Interannual) Climate change can affect extreme sea levels by: 1. Increased Mean Sea Level 2. Changes to Storminess Mean Sea Level

Factoring in the nature of extremes Planning Benchmark SLR Presentation title Presenter name Page 15

So how do we prepare for Sea Level Rise? Given: 1. Uncertain Sea Level Rise 2. Characteristics of extreme sea level rise?

Sea level allowances - based on Hunter (2012) 1. Consider raising an asset (or its protection) by an amount that ensures future level of protection is unchanged from todays 2. Takes into account (1) mean sea level rise - z (2) sea level rise uncertainty - derived from 5-95% uncertainty (3) extreme sea level characteristics the slope of the extreme sea level return period curve 3. Allowance: A= z+ (Assuming a normal distribution for SLR) z

Exceedance probabilities and expected number of exceedances

1-in-100 year storm tide height (source: Haigh et al, 2014) Estimated from modelled sea levels over 66 year period Includes tides and surge but not wave effects

Observed Historical Changes Verges et al 2014 & Booth et al 2007 Porities growth rates GBR Poloczanska, et al, 2014 De ath et al 2009

Historical Changes Australian Region Lenton et al Reconstructed ph SST annual mean 2013 (C) Mauna Loa Lenton et al Reconstructed Arag (Ω AR ) HadiSST Atmospheric CO2 conc (ppm) Reconstructed SST (C)

Mean State 1986-2005 SST (C) CARS 2009 Aragonite Saturation State (Ω AR ) Observed Modelled Lenton et al

Nov_10 Feb_11 May_11 Aug_11 Nov_11 Feb_12 May_12 Aug_12 Nov_12 Feb_13 May_13 Apr_09 Aug_09 Dec_09 Apr_10 Aug_10 Dec_10 Apr_11 Aug_11 Dec_11 Apr_12 Aug_12 Dec_12 Apr_13 Apr_09 Aug_09 Dec_09 Apr_10 Aug_10 Dec_10 Apr_11 Aug_11 Dec_11 Apr_12 Aug_12 Dec_12 Apr_13 NRS Assessment 2009-2013 4.5 4 3.5 3 2.5 2 30 25 20 15 10 Maria Island Ω AR Maria Island SST (C) 4.5 4 3.5 3 2.5 2 30 25 20 15 10 Ningaloo Ω AR Ningaloo SST (C)

Projected Impacts Together these changes are expected to have significant impacts on the long-term health, diversity and viability of many marine species, and are likely to impact key sectors such as fin and shellfish fisheries, aquaculture, tourism and coastal protection. Hoegh-Guldberg et al, 2007

Summary New climate projections will soon be available for the 8 NRM regions of Australia to help underpin adaptation planning These show that in response to rising atmospheric CO 2 levels: sea levels will be higher, marine environment will be warmer and more acidic under all emissions scenarios The magnitude of the change will be proportional to the level of emissions Large heterogeneity around Australia with very large changes in some regions

Thank you For more information kathleen.mcinnes@csiro.au http://www.cmar.csiro.au/sealevel/

APPROACH USED FOR NRM Process understanding Observed trends Climate model results Model evaluation Downscaling Five key considerations used to produce qualitative and quantitative change information with confidence ratings. More traditional approach than UKCP09 - No PPE produced, primary tool is CMIP5 global climate models and offline calculations - Projections are not labelled as probabilistic No overall scenario structure produced like KNMI14 - Results presented for time slices and for different RCPs (similar to IPCC 2013 and others) - However a tailored scenario generator, the Australian Climate Futures tool is available GCM-RCM matrix not the primary tool like NARCCAP -GCMs are the primary data source, complemented by regional insights from downscaling