Event Chains

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.

heat wave event chain — Schematic diagram of event chains triggered by heat waves: (1) Peak heating in rivers and lakes lead to decreased flow regimes and increasing concentrations of nutrients impacting negatively water quality; (2) heat waves lead to the occurrence of drought periods affecting ecosystems functioning such as gross primary production (GPP), evapotranspiration (ET) and emissions of biogenic volatile organic compounds and (3) they lead to increased concentrations in ozone and aerosols negatively impacting air quality. The arrows denote either an increase or decrease in magnitude.