Kirchberger, 2021). These recent experiences, coupled with the increasing demand for more and better data on migration and the growing interest of scholars and policy makers in the climate-migration relationship, make this a very opportune time to rethink the role of household surveys in this domain and identify potential areas of improvement.

Building on recent insights from Letta et al. (2023), this paper proposes a three-part solution for advancing the climate migration agenda by leveraging the use of household surveys. First, it offers a critical reflection on the current challenges and opportunities for household surveys to fill data gaps and contribute to shedding light on some crucial aspects of the climate-migration nexus and its implications for household and individual welfare. Second, it proposes a conceptual framework that identifies key relationships, focusing on burning issues such as the direct and indirect contribution of climate change to cross-border mobility, and assesses the corresponding data needs to operationalize this empirically and the potential of multi-topic household surveys to address these needs. Third, the paper provides practical empirical guidelines for researchers interested in leveraging existing household surveys to investigate the climate-migration nexus, with special emphasis on how to assess and reduce the rare event problem, explore the migration-adaptation relationship, and address issues related to migration definition, variable construction, and identification strategy. For the sake of concreteness, we tailor our recommendations to one of <mark>the largest and longest-running household survey programs worldwide,</mark> namely, the Living Standards Measurement Study (LSMS) of the World Bank. Among academics, LSMS surveys are often referred to as vested candidates for contributing to an increasing demand for migration data (Bilsborrow, 2016). Using LSMS surveys as an example, the paper identifies priority entry points for enhancing the value of household surveys as a source for accurate and reliable climate migration data and proposes some concrete actions that can be undertaken for achieving this goal in the short- and medium-term.

The remainder of the paper is organized as follows. Section 2 provides essential information on data sources and characteristics of climate-related migration, summarizes the most recent findings of the empirical literature, and assesses the main remaining data gaps hindering further understanding of the climate-migration nexus. Section 3 proposes an empirically-oriented conceptual framework on climate migration and outlines a methodological agenda that serves as a guide to maximize and boost the potential of household surveys for the study of climate related migration. Section 4 puts forward empirical guidelines for the use of existing surveys. Section 5 concludes.

# **2. Assessing the climate migration data landscape: Gaps, limitations, and the quest for doing better**

# **2.1 Definitions, metrics, and data sources: Navigating an imperfect (but promising) world**

Measuring migration is a long-standing thorny issue. In general, data on any type of migration is difficult to collect precisely. The intrinsic complexity associated with the concept of migration, its dynamic nature (across space and time), and the lack of universally-accepted definitions represent a challenge in the development of appropriate data collection systems on migration. This applies especially where national statistical systems are weak, which is more common in low- and lower-middle-income countries. In such cases, regular, systematic 5