Three ERC Starting Grants for OCCR members

Heli Huhtamaa: “Climatic impact and human consequences of past volcanic eruptions” (VolCOPE)

Large volcanic eruptions can have a substantial impact on climate and these climatic disturbances can, in turn, have severe human consequences far away from the eruption location. In order to assess the possible long-range societal impacts of future large eruptions, we need to understand the eruption-climate-society causalities better. Since our recent past has witnessed only a limited number of large eruptions, we have to look back into history to study these causalities.

Recent research has connected several historical crises to volcanic-induced cold summer extremes. However, less is known about how climatic effects over the winter season influenced human well-being. Moreover, alt- hough many studies have identified human calamities that coincide with known eruption events, previous research has rarely investigated why some societies were able to cope with the cold pulses better than others.

The VolCOPE project will investigate the climatic and societal effects of past volcanic eruptions in 1500– 1850 CE Europe, by using rigorous historical source criticism, geospatial analysis, and paleoclimatological state-of-the-art methods. The spatiotemporal winter temperature responses will be investigated with a novel climate field reconstruction created within the project. The project will utilize a variety of historical sources in order to quantify the possible livelihood, socioeconomic, and demographic effects with high temporal and spatial precision. The project will also investigate to what degree the detected societal effects can be at- tributed to volcanic-induced climatic disturbances, and to what degree existing socio-environmental condi- tions and emerging human actions explain these events. With the results gained in the project, my team will develop an eruption-climate-society causality model, which will help to identify the so-called “components of coping” – the various factors that influence the exposure, vulnerability, and resilience to climatic disturbances.

Charlotte Laufkötter: «Mechanistic model simulations of the marine biological carbon pump» (MOANA)
 

The marine biological carbon pump is a key component of the global carbon cycle, significantly regulates Earth's past and present climate and provides the main source of energy for organisms living in the mesopelagic and deep ocean. Changes in the organic carbon transport to the deep sea may have significant consequences for the future climate, for fisheries and ecosystem services, and may be related to past atmospheric CO₂ concentration changes. Yet, our current understanding of the biological pump is incomplete and simplistic, and consequently it's response to anthropogenic stressors, in particular climate change, remains highly uncertain. The reasons for this poor understanding include: the ocean is chronically undersampled, hampering the understanding of key mechanisms; the sensitivity of future projections towards individual mechanisms and parameter choices are not understood; and additionally, recently discovered carbon export mechanisms due to zooplankton behaviour are not included in model simulations.

MOANA will utilize state-of-the-art ocean observations measured by biogeochemical Argo floats (BGC-Argo), fast Earth System models of intermediate complexity and high-end marine biogeochemistry models to create reliable estimates of the marine biological carbon pump. The proposed work is organized in three work packages and a synthesis. Work package A will focus on the carbon flux through the mesopelagic. I will utilize BGC-Argo measurements to constrain implementations of the sinking particle flux, followed by model studies to constrain the sensitivity of the particle flux to future global warming and during the past 20,000 years. Work package B will focus on the dissolved organic carbon generation in the upper ocean, building on recent laboratory constraints. Work package C will focus on the active carbon transport by zooplankton, namely the effects of diel vertical migration and seasonal hibernation at depth. 

A final synthesis will combine the findings into a model that for the first time includes all known components of the marine biological carbon cycling.  Limiting and mitigating climate change is one of humanity's biggest challenges in the 21st century. A mechanistic understanding of the marine biological carbon cycling is crucial to understand future feedbacks to the climate, assess the response of marine ecosystems to global warming and estimate the consequences of potential geoengineering activities for marine ecosystem services. MOANA will create mechanistic representations of key processes, combined with individual uncertainty envelopes, resulting in a significant step forward in our understanding of the biological pump.

Madhav Thakur: «Food Webs and Biodiversity Change in an Extreme World» (FoBEx)

Anthropogenic climate change has increased the frequency and severity of climate extremes, which pose serious threats to native biodiversity and ecosystem functioning across the biosphere. Yet, we know little about how food webs respond to climate extremes (e.g., periodic heat waves and extreme droughts) that occur in combination with gradually changing climate (e.g., mean temperature rise).

In this project, my team and I aim to investigate how the combination of gradually changing climate and climate extremes alter the structure and function of terrestrial food webs associated with native and alien plants. Terrestrial food webs are composed of green food webs above the ground and brown food webs below the ground, between which mass and energy flow mainly via plants. Interactions between green and brown food webs are crucial determinant of numerous ecosystem functions ranging from primary production to carbon sequestration. Because of the higher frequency of specialized interactions in green food webs than in brown food webs, theory predicts that climate change will have stronger impacts on green food webs. I recently proposed that such a mismatch in green and brown food web response would lead to an imbalance in mass and energy flow between the two food webs- the “green-brown imbalance hypothesis”.