The physical science parts of this chapter draw mostly from existing datasets, complemented by the findings of the state of the climate reports and the series of reports of the Intergovernmental Panel on Climate Change (IPCC). The report of Working Group I of the IPCC Sixth Assessment Report was released in August 2021 and was available to be used in this chapter; the reports of Working Groups II and III are not due for release until early 2022. Since the 2016 state of the environment report, the IPCC has also produced a number of subject-specific special reports that are used in this chapter. Many of the datasets used for physical phenomena are maintained and updated operationally in close to real-time. These include (land) temperature and rainfall data maintained by the Bureau of Meteorology, greenhouse gas concentration data reported by CSIRO and various international institutions, and global-scale ocean temperature and sea level datasets maintained by a number of global institutions. The World Meteorological Organization also plays a significant reporting role for global variables. Greenhouse gas emissions are reported quarterly by the Australian Government. Some states and territories also do their own reporting, which broadly parallels national reporting but may differ in definitions (e.g. whether emissions associated with electricity generation are attributed to the place of generation or the place of consumption). The reported data also allow an assessment of progress towards emissions reduction targets; the adequacy of these targets can be considered in the context of the IPCC special report on global warming of 1.5 °C (IPCC 2018). The most complex part of the chapter deals with climate risk and adaptation. Documented plans and strategies by governments at all levels form the foundation of this part of the chapter, along with progress reviews of these where a process exists to undertake regular reviews (as it does in some jurisdictions). However, some part of this section will necessarily be subjective. Indigenous approach (Leech & Onwuegbuzie 2009) Indigenous people’s knowledge of climate in Australia lacks quantitative data according to a western concept of capture and record. But the direct impacts of climate variables and change sit within a lived experience – Indigenous people observe and feel changes to their Country, and most of the conversation in this space is from an observational knowledge viewpoint and oral transmission. This is a dataset that is not always shared or transferrable. Some data are recorded by universities and partners on projects where the knowledge becomes the centre of a case study. Case studies are important because they tell the story of knowledge and its people in a culturally appropriate way. Indigenous knowledge in this space can be referred to as a type of ‘mixed methods’ data or research, where quantitative and qualitative data can be merged – that is, the research involves collecting, analysing and interpreting quantitative and qualitative data in a single study or in a series of studies. Our statements in this report are based on the collection of knowledge through our networks around Australia with Indigenous people and their traditional lands; this knowledge is oral and is listening to the many common and unique stories where cultural indicators are predicting change. These cultural and environmental changes are felt through observing the change of behaviour of flora and fauna species, and interactions in the processes that lead to seasonal change and contribute to traumas. When assessing the impacts of climate and climate change on Indigenous people within their own traditional lands, we need to know not just how Country is changing, but why it is happening and how we deal with it. For example, we need to have an understanding of the role management practices have played in the harm to Country. For Indigenous people, it is the unknown that scares them the most, forcing them to ask questions and invoke change. The lack of knowledge and understanding of what has happened, coupled with climate change where little knowledge and climate services are available for First Nations people, puts them at a real disadvantage. This makes Indigenous assessments for this state of the environment report almost impossible. We need to have traditional ecological knowledge and western science working in parallel to build better policy and strategies around adapting to, and managing, climate change.