Impact of climate change on New Zealand s frozen water resources

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Impact of climate change on New Zealand s frozen water resources A. Mackintosh 1, N. Cullen 2, B. Anderson 1, J. Conway 3, R. Dadic 1, H. Horgan 1, T. Kerr 4, H. Purdie 5, P. Sirguey 2, C.

1 Impact of climate change on New Zealand s frozen water resources A. Mackintosh 1, N. Cullen 2, B. Anderson 1, J. Conway 3, R. Dadic 1, H. Horgan 1, T. Kerr 4, H. Purdie 5, P. Sirguey 2, C. Zammit 6 1 Victoria University of Wellington 2 University of Otago 3 Bodeker Scientific 4 Aqualinc Research Ltd 5 University of Canterbury 6 NIWA Brewster Glacier (A. Mackintosh) Impacts & Implications

2 Malcom Taylor, Contact Energy Snow and ice is important for our organisation. A good idea of the amount of snow and its spatial distribution would be of great assistance in forward planning for water storage. Stefan Beaumont, Hydrologist, West Coast Regional Council Our issues are mostly with flooding, and some of the flood events are hard to understand without thinking about a snow melt component, like in October 2010 when there was a 1:20 year flood in Greymouth, but 1:200 year flood in the Ahaura tributary. Lawrence Kees, Water Scientist, Environment Southland Water quality is our focus in Southland and a key question is how clean alpine surface water, largely a product of snow melt, is partitioned into surface and groundwater flows in the lowlands, which results in different sensitivities for nutrient loading. Communication and Engagement

2014) and index glacier locations, where end-of-summer snowlines are

3 Figure 5.12 Glacier distribution across the South Island and on Mt Ruapehu in the North Island (inset). Outline data from the Randolph Glacier Inventory (Arendt et al. 2014) and index glacier locations, where end-of-summer snowlines are measured, from Willsman et al. (2015). Franz Josef Glacier (A. Mackintosh) Tasman Glacier (G. Denton) Anderson et al Snow and ice is an important resource in New Zealand

4 Kerr, 2013 Fitzharris 2004 Snow and ice is an important resource in New Zealand

5 Figure 5.8 Estimated snow depth following the June snowfall in Canterbury. (From Hendrikx (2007) with permission of the Journal of Hydrology (NZ).) Snow and ice is an important resource in New Zealand

6 Derived from downscaled CMIP5 models, A. Sood, NIWA. Figure by B. Anderson The magnitude, timing, and distribution of changes in snow, ice and meltwater is unclear

3428 3126 Brewster Melt [mm we], DOY: 1-120 2825 2523 2222 Brewster Glacier modelled ablation 1921 1619 Figures by Ruzica Dadic Accumulation = Precipitation if T < 1 C.

7 Brewster Melt [mm we], DOY: Brewster Glacier modelled ablation Figures by Ruzica Dadic Accumulation = Precipitation if T < 1 C. Melt (if temperature > 0 C) = (DDF Tair)+(RF Q (1 α)) Inputs: Temperature (Tair), Shortwave Radiation (Q, both direct and diffuse) Parameters: degree day factor (DDF), radiation factor (RF) Allows: explicit calculation of surface albedo (α), and incoming radiation terms (Q) Snow and ice melt model; progress to date

8 P. Sirguey, J. Conway, unpublished Evaluation of snow model at national scale; to come

9 Timelapse footage of Tasman Glacier by Brian Anderson, Victoria University of Wellington Mechanisms of iceberg calving in lacustrine settings (Dykes, 2013) New Zealand glaciers; the problem of surface debris and iceberg calving

10 Progress We are enhancing snow and glacier models for New Zealand When implemented in the hydrological model TOPNET, this will allow national assessment of changing snow and ice, and downstream impacts on water resources Quality of these assessments will depend on climate model inputs Opportunities New Zealand interannual climate variability means that we will continue to have some good snow seasons and positive glacier mass balance years (e.g. Mackintosh et al. Nature Communications) Less snow storage and more rain might improve hydropower efficiencies during peak usage periods Higher glacier melt might buffer summer drought in New Zealand s most important hydropower catchments for decades to a century Our findings will allow New Zealanders to adapt, manage and thrive in our changing environment

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Tourism, the weather and future changes Susanne Becken Jordy Hendrikx Jude Wilson Ken Hughey 8 June 2010, Wanaka Today s presentation Overview Current Weather and Tourism Climate Change in NZ Ski fields