Our planet is constantly changing, driven by slow tectonic motions of the Earth’s interior, by the cycles in the Earth’s rotation around its axis and orbiting around the sun, by catastrophic impacts of asteroids, and by the appearance of ever new life forms some of which have fundamentally changed the chemistry of the Earth’s surface. Modern humans, aided by technology which distinguishes them from any other life form on Earth, are drivers of global change on a scale that is alarming even in a geological perspective. In just 150 years of modern industrial development, fossil organic carbon that lay buried in geological deposits for hundreds of millions of years has been unearthed and returned to the atmosphere as CO2. The effects on global climate, well-established by measurements from around the world, are manifested in the ocean as rising sea surface temperature and changes in circulation. Increased CO2 uptake in the ocean’s surface waters leads to acidification, affecting calcifying marine organisms. Seasonal stratification of coastal seas under pressure from anthropogenic eutrophication results in expanding zones where bottom waters become depleted of oxygen. The urgent need to put a brake on global climate change, through a transition from fossil to renewable energy sources, has initiated a rush on critical metals. To satisfy demands from industry, even the remote deep-sea floor is currently being explored for mineral resources. This will bring ocean ecosystems even further under pressure. Understanding of the mechanisms and consequences of human disturbances is urgently needed.Read more +
Coastal seas of densely populated regions have been receiving excess nutrients derived from agriculture and urban wastewater. Algal blooms resulting from this eutrophication, combined with seasonal stratification of the water column, intensified by global warming, increasingly lead to deoxygenation in bottom waters. We investigate how release of phosphorus from the anoxic seabed may aggravate eutrophication and deoxygenation.
Concerns about future access to critical raw materials for high-tech industry has spurred a race to the bottom of the ocean, in pursuit of valuable mineral resources hidden in its depths. Scientific knowledge necessary to assess the impacts of mineral extraction on delicate deep-sea ecosystems is still scarce. We study the physical effects of mining on the deep-sea environment, as well as the resilience of deep-sea fauna to disturbance.
Acidification of the ocean as a result of increasing atmospheric CO2 will affect calcifying marine organisms from tiny pelagic coccolithophores to reef-building corals. How these organisms may be impacted is the focus of our lab experiments with modern calcifying organisms and investigation of fossil life forms from past high-CO2 periods. This will help to determine the feedback that calcifying organisms have on atmospheric CO2.
Changing ocean circulation
Ocean currents act much like a conveyer belt. They are important for the transport of heat, nutrients, and dissolved gases such as CO2. Warming of the ocean - and input of freshwater from Arctic Sea-ice and melting polar icecaps is affecting the ocean circulation. Sustained observations of basin-wide transports provide insight into the changing circulation and helps to validate and improve climate models.