WHOS: a Catalyst to Earth Systems Data access in Climate Change Adaptation and Implementation of Early Warning Systems for All

Multiple factors contribute to the increase in climate and weather-related hazards such as floods, droughts, landslides, and severe weather events impacting millions of lives and properties. Climate change poses threats to food, water and human security, acting as a catalyst for human induced migrations.  Despite projected intensification of these threats, hydrometeorological and Early Warning Systems, coupled with Early and Anticipatory Actions, prove effective in climate change adaptation, saving lives and reducing losses. The United Nations launched the Early Warnings for All (EW4All) initiative in November 2022 to protect every person on Earth with Early Warning Systems within five years. Water, central to climate action is also the 6th of the 17 Sustainable Development Goals (SDGs) and affects 15 SDGs, shifting the focus and increasing demand for water-related data, which is always complex to access. Despite several negotiated water agreements, access to relevant hydrological data remains a challenge, hindering their successful implementation and monitoring. Effective interoperable data exchange platforms are essential for timely data, understanding challenges, creating visibility of the data providers, improving cooperation at different scales, and demonstrating the return on investment in data collection. Open access and free exchange of valid hydrological data still faces challenges from technological, policy, political, economic, and cultural perspectives. To address these challenges, the World Meteorological Organization (WMO) launched various initiatives promoting access and exchange of Earth Systems data for effective implementation of Climate Change Adaptation Actions and EW4All. These initiatives include, WMO Unified Data Policy, WMO Integrated Global Observing Networks, Global Basic Observing Networks (GBON), WMO Information Systems (WIS2.0), WMO Hydrological Observing System (WHOS), Hydrological Status and Outlook System, and Systematic Observations Financing Facility. WIS 2.0 provides a framework for WMO data sharing, embracing the Earth system approach, enabling the WMO unified data policy, and supporting the GBON. WHOS, the hydrological component of the WIS 2.0, provides a framework for publication, discovery, access, evaluation, and exchange of hydrological data across different scales and providers, addressing complexities of such data through standardization and brokering approaches benefiting multiple uses. Furthermore, it recognizes the multi-dimensional complexities of hydrological data sharing without imposing specific tool or system platform and building on existing systems, and agreements. At the same time enables the hydrological data sharing, regardless of the specific standard or technology used by the data providers or consumers, by applying a brokering architecture where a specific component (the WHOS broker, based on the DAB technology) takes care of mediation and harmonization. WHOS aims to describe where, which, and how hydrological data exists; provide visibility of creators, publishers, and users; address challenges associated with access and sharing across different scales; consistent metadata description and ontology; integrate different data including surface water, groundwater, and water quality; break silos through consistent approach of data sharing among Cryosphere, Hydrology, Weather, Marine and Ocean. WHOS plays a central role in climate change adaptation, EW4All, and Water Resources Management and has proven valuable for flood forecasting, transboundary cooperation, joint monitoring of the data sharing and access in different cases of implementation.