We examine the relative impact of population increases and climate change in affecting future water demand for Sydney, Australia. We use the Weather and Research Forecasting model, a water demand model and a stochastic weather generator to downscale four different global climate models for the present (1990–2010), near (2020–2040) and far (2060–2080) future. Projected climate change would increase median metered consumption, at 2019/2020 population levels, from around 484 GL under present climate to 484–494 GL under near future climate and 495–505 GL under far future climate. Population changes from 2014/2015 to 2024/2025 have a far larger impact, increasing median metered consumption from 457 to 508 GL under the present climate, 463 to 515 GL under near future climate and from 471 to 524 GL under far future climate. The projected changes in consumption are sensitive to the climate model used. Overall, while population growth is a far stronger driver of increasing water demand than climate change for Sydney, both act in parallel to reduce the time it would take for all storage to be exhausted. Failing to account for climate change would therefore lead to overconfidence in the reliability of Sydney's water supply.

我们研究了人口增长和气候变化对澳大利亚悉尼未来用水需求的相对影响。我们使用天气和研究预测模型、需水模型和随机天气发生器来缩小当前（1990-2010）、近期（2020-2040）和远（2060-2080）未来四种不同的全球气候模型。预计的气候变化将使 2019/2020 年人口水平的计量消费中值从目前气候下的 484 GL 增加到近期气候下的 484-494 GL 和远未来气候下的 495-505 GL。2014/2015 年至 2024/2025 年的人口变化产生的影响要大得多，在当前气候下，计量消费中位数从 457 GL 增加到 508 GL，在近期气候下从 463 GL 增加到 515 GL，在远未来气候下从 471 GL 增加到 524 GL。消费的预计变化对所使用的气候模型很敏感。总体而言，虽然人口增长是悉尼用水需求增长的一个比气候变化更强大的驱动力，但两者同时采取行动，以减少所有储存用完所需的时间。因此，不考虑气候变化会导致对悉尼供水可靠性的过度自信。