This document discusses using long-term ecosystem measurement data to detect the effects of increasing atmospheric CO2 and a changing environment. It analyzes data from the Fluxnet 2015 dataset and finds that: 1) Only coniferous forests showed a significant positive trend in maximum annual GPP that was stronger than expected from CO2 alone, possibly due to other drivers like temperature. 2) Maximum GPP varied more over time and between plant functional types than annual GPP. 3) Uncertainty in the data was generally low but higher for annual GPP in some plant types. It also outlines plans to optimize the ICOS ecosystem observation network to better detect future impacts by targeting key variables, minimizing data uncertainty, and