The project Humans on Planet Earth (HOPE) – Long-term Impacts on Biosphere Dynamics started in January 2018 and ended in June 2024. It was based in the Department of Biological Sciences, University of Bergen. The HOPE team consisted of John Birks (PI), Hilary Birks, Alistair Seddon & John-Arvid Grytnes (senior researchers), Kuber Bhatta, Vivian Felde, Suzette Flantua & Ondrej Mottl (post-doctoral research fellows), and Cathy Jenks, Linn Krüger & Arild Breistøl (assistants or computer engineer). HOPE also supported Manuel Steinbauer (Germany) and had as guest researchers Sandra Nogue (Spain) and Triin Reitalu (Estonia). It also had eight advisory mentors from the Netherlands, USA, Germany, Switzerland, and the Czech Republic - all experts on statistics, pollen analysis, computing, databases, plant geography, or human impact.
HOPE had two main objectives.
1. Test the hypothesis that prehistoric human impact altered the fundamental ecological processes that determine the assembly, ecological structure, and composition and dynamics of terrestrial plant communities. Its proponents argue the use of past ‘natural experiments’ and of the past as an analogue to our uncertain future is a “flawed strategy” and the basic concept behind Earth system science and all historical sciences, namely uniformitarianism (‘the present is the key to the past’) should be discarded. It was clearly imperative to test this hypothesis critically as it has far-reaching implications for science and society.
2. Test the associated hypothesis that inter-relationships (correlations) between estimates of ecosystem properties such as turnover, diversity, composition, and rate-of-change (RoC) during the Holocene (last 11,700 years) changed in response to prehistoric human activities.
Testing these two hypotheses is important for the modus operandi of Earth system science, global change biology, and ecological and societal predictions as a whole. If the hypotheses are not falsified, the question arises can the past be used reliably as an analogue to the uncertain future of Planet Earth and its inhabitants in the ‘Anthropocene’. If the hypotheses are not falsified, Earth today has no analogue in the past 11,700 years and the widely employed research approach of using ‘natural experiments’ in the past as a guide to predict what might happen in the future is a “flawed strategy” and should be discontinued. As almost all predictive models in global-change science rely on this approach, these hypotheses needed testing. This was the primary aim of HOPE.
HOPE’s research relied on dated pollen-stratigraphical data from lakes or mires in Europe, Asia, North America, Central & South America, and Oceania. These data were explored in a consistent manner using state-of-the-art numerical techniques to discern patterns in over 15 ecosystem properties. Temporal, spatial, and correlation patterns in these properties were compared statistically within each pollen sequence, between sequences within ecoregions (≡ biomes), between ecoregions within continents, between ecoregions on different continents, and between continents using statistical modelling techniques with human-impact events along with model-simulated climate variables as predictors.
