Figure 1. The meteorological value chain: All links in the chain must operate effectively to yield success Figure 2. Downscaling of weather and climate information via nesting

5. Weather and climate information services are delivered to users, including national and local authorities, businesses, media, academia and the general public. 6. Effective decisions in response to weather and climate information are made by authorities, agents in all economic sectors, and individuals.

Observations from the entire globe International exchange of observations

Global Numerical Weather Prediction

Weather and climate-related infrastructure - must be designed and coordinated globally

Last-mile activities undertaken primarily at regional, national and local level

Effective decision-making and action Delivery of hydromet services Local data processing, forecast, warning and advisory products

Figure 1. The meteorological value chain: All links in the chain must operate effectively to yield success. Source: WMO Secretariat, 2021

The global nature of weather and climate implies that unless the first three links of the value chain are functioning, the last three links will be missing needed

input and will not be able to deliver the expected outcomes. The first three links in the value chain (shown in red) constitute the global meteorological infrastructure and rely on a global implementation approach (box 1). In contrast, the last three links (in blue) are typically implemented nationally. The importance of the global nature of the first three links cannot be overstated. For a prediction horizon beyond 24 to 36 hours, the use of global observational data and global models to underpin the predictions in any location is needed, even if the target area for a given prediction is very small and local (box 2). Conversely, without local efforts everywhere to make and exchange observations, the models cannot generate the data needed for effective forecasting at the national and local levels. All countries, therefore, share an interest in the first three links in the chain, while they handle the last three primarily individually. “Last-mile” projects predominantly invest in the last three links, due to the perception that this is where the value is created. However, without complementary investments in the first three links, investments in the last three will often not have the expected benefits.