2016 SoE Marine Chapter - Pressures - Climate Change - Nutrient supply and cycling

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "Pressures on the marine environment associated with climate change - nutrient supply and cycling". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.----------------------------------------DESCRIPTION OF THE PRESSUREMacronutrient concentrations (e.g. nitrate and phosphate) in the surface ocean play an important role in controlling the ocean’s primary productivity. The oceans account for about half of the earth’s total primary productivity. Surface ocean waters around Australia typically have low macronutrient concentrations for nitrate and phosphate. The key physical processes supplying nutrients to the upper ocean are the seasonal deepening of the ocean surface mixed layer, the upwelling and vertical mixing associated with ocean eddies, and wind-driven coastal upwelling. In the Australian region, the first two processes dominate because conditions that cause wind-induced upwelling are confined to a few regions (e.g. Bonney upwelling off South Australia). As the ocean warms around Australia (Lenton et al, 2015) the upper ocean will become more stratified and the vertical supply of nutrients to the surface ocean could decline (Bopp et al, 2013) reducing primary productivity. However, increased eddy activity due to strengthening of the East Australian Current may compensate for a decline in the vertical nutrient supply in the Tasman Sea and cause an increase in primary productivity with climate change (Matear et al., 2013). DATA STREAM(S) USED IN EXPERT ASSESSMENTOffshore data from around Australia from the latest CARS compilation (CARS2009a v1.1, as of 12 July 2010). See http://www.marine.csiro.au/atlas/----------------------------------------2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]• 2016 •Assessment grade: High impactAssessment trend: UnclearConfidence grade: Evidence and consensus too low to make an assessmentConfidence trend: Evidence and consensus too low to make an assessmentComparability: Grade and trend not comparable to the 2011 assessment• 2011 •Assessment grade: Very goodAssessment trend: StableConfidence grade: Limited evidence or limited consensusConfidence trend: Limited evidence or limited consensus----------------------------------------CHANGES SINCE 2011 SOE ASSESSMENTUnclear what data were used in the 2011 assessment; the 2016 assessment is based on the latest CARS compilations and so includes observations added to CARS 2011-2016.2016年《环境状况报告》（State of the Environment，简称SoE）的海洋章节整合了多套基于海洋数据流开发的专家模板。本元数据记录对应专家评估报告《气候变化相关的海洋环境压力——养分供给与循环》。完整的专家评估报告（含附图与附表，如已提供）已附于本记录中。如需获取生成该专家评估报告所用的数据流，可通过本记录的“在线资源”板块查阅。 压力源说明 表层海洋中的大量营养素（如硝酸盐与磷酸盐）浓度是调控海洋初级生产力的关键因素。海洋贡献了全球约50%的总初级生产力。澳大利亚周边海域表层水体的硝酸盐、磷酸盐等大量营养素浓度普遍偏低。为上层海洋输送养分的核心物理过程包括：海洋表层混合层的季节性加深、与海洋涡旋相关的上升流与垂直混合，以及风驱动的沿岸上升流。在澳大利亚海域，前两种过程占主导地位，因为风致上升流的发生条件仅局限于少数区域（如南澳大利亚外海的邦尼上升流）。随着澳大利亚周边海域海水升温（Lenton等，2015），上层海洋层结将进一步增强，向表层海洋的垂直养分供给可能出现下降（Bopp等，2013），进而降低海洋初级生产力。不过，东澳洋流增强引发的涡旋活动增多，可能抵消塔斯曼海垂直养分供给下降的影响，进而在气候变化背景下提升该区域的初级生产力（Matear等，2013）。 专家评估所用数据流 本次评估采用澳大利亚周边海域的离岸数据，源自最新版CARS汇编数据集（CARS2009a v1.1，截至2010年7月12日）。详细信息可查阅：http://www.marine.csiro.au/atlas/ 2016年SoE评估摘要（完整细节请参阅附件中的专家评估报告） - 2016年： 评估等级：高影响 评估趋势：尚不明确 置信等级：现有证据与共识不足，无法完成评估 置信趋势：现有证据与共识不足，无法完成评估 可比性：本次评估的等级与趋势无法与2011年评估结果进行对标 - 2011年： 评估等级：极佳 评估趋势：稳定 置信等级：证据有限或共识不足 置信趋势：证据有限或共识不足 2011年SoE评估以来的变更 目前尚不明确2011年评估所用的数据集；本次2016年评估基于最新版CARS汇编数据集，纳入了2011至2016年间新增至CARS的观测数据。