Heat waves initiate complex event chains that reach from the land surface to the upper atmosphere. To investigate the impact of extended heat periods and droughts on our terrestrial ecosystems and natural resources, three overarching hypotheses shall be addressed by MOSES event-driven field campaigns:
(1) Heat waves reduce or impede the functioning of ecosystems, and their multiple recurrences may lead to irreversible changes in structure and behaviour of terrestrial and aquatic ecosystems, reducing ecosystem services and resilience for several years.
(2) Heat waves lead to a decline in air quality due to changes in atmospheric dynamics and processes at the biosphere/atmosphere interface.
(3) Heat waves lead to a decline in water quality due to low flows, nutrient increase and possible changes in the metabolic rates of organisms.