and more. Measurements Governments and development agencies are spending increasing amounts of finance to support resilience-building interventions. Resilience measurement can make valuable contributions in guiding resource allocations towards resilience-building. This includes targeted identification of vulnerability hotspots, a better understanding of the drivers of resilience, and tools to infer the impact and effectiveness of resilience-building interventions. In recent years, a large number of resilience measurement tools have emerged, offering ways to track and measure resilience at a range of scales - from individuals and households to communities and nations. Efforts to measure climate resilience currently face several technical challenges. Firstly, the definition of resilience is heavily contested, making it difficult to choose appropriate characteristics and indicators to track. Secondly, the resilience or households or communities cannot be measured using a single observable metric. Resilience is made up of a range of processes and characteristics, many of which are intangible and difficult to observe (such as social capital). As a result, many resilience toolkits resort to using large lists of proxy indicators. Most of the recent initiatives to measure resilience in rural development contexts share two shortcomings: complexity and high cost. USAID published a field guide for assessing climate resilience in smallholder supply chains. Most objective approaches use fixed and transparent definitions of resilience and allow for different groups of people to be compared through standardized metrics. However, as many resilience processes and capacities are intangible, objective approaches are heavily reliant on crude proxies. Examples of commonly used objective measures include the Resilience Index Measurement and Analysis (RIMA) and the Livelihoods Change Over Time (LCOT). Subjective approaches to resilience measurement take a contrasting view. They assume that people have a valid understanding of their resilience and seek to factor perceptions into the measurement process. They challenge the notion that experts are best placed to evaluate other people's lives. Subjective approaches use people's menu of what constitutes resilience and allow them to self-evaluate accordingly. An example is the Subjectively-Evaluated Resilience Score (SERS) History The theoretical basis for many of the ideas central to climate resilience have actually existed since the 1960s. Originally an idea defined for strictly ecological systems, resilience in ecology was initially outlined by C.S. Holling as the capacity for ecological systems and relationships within those systems to persist and absorb changes to "state variables, driving variables, and parameters." This definition helped form the foundation for the notion of ecological equilibrium: