Tatiana Ilyina - Academia.edu (original) (raw)

Papers by Tatiana Ilyina

Nature communications, Mar 7, 2017

Climate change is expected to modify ecological responses in the ocean, with the potential for im... more Climate change is expected to modify ecological responses in the ocean, with the potential for important effects on the ecosystem services provided to humankind. Here we address the question of how rapidly multiple drivers of marine ecosystem change develop in the future ocean. By analysing an ensemble of models we find that, within the next 15 years, the climate change-driven trends in multiple ecosystem drivers emerge from the background of natural variability in 55% of the ocean and propagate rapidly to encompass 86% of the ocean by 2050 under a 'business-as-usual' scenario. However, we also demonstrate that the exposure of marine ecosystems to climate change-induced stress can be drastically reduced via climate mitigation measures; with mitigation, the proportion of ocean susceptible to multiple drivers within the next 15 years is reduced to 34%. Mitigation slows the pace at which multiple drivers emerge, allowing an additional 20 years for adaptation in marine ecologica...

Biogeosciences

Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation,... more Anthropogenic climate change is projected to lead to ocean warming, acidification, deoxygenation, reductions in near-surface nutrients, and changes to primary production, all of which are expected to affect marine ecosystems. Here we assess projections of these drivers of environmental change over the twenty-first century from Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) that were forced under the CMIP6 Shared Socioeconomic Pathways (SSPs). Projections are compared to those from the previous generation (CMIP5) forced under the Representative Concentration Pathways (RCPs). A total of 10 CMIP5 and 13 CMIP6 models are used in the two multi-model ensembles. Under the high-emission scenario SSP5-8.5, the multi-model global mean change (2080-2099 mean values relative to 1870-1899) ± the intermodel SD in sea surface temperature, surface pH, subsurface

On inter-annual time scales the growth rate of atmospheric CO... more On inter-annual time scales the growth rate of atmospheric CO2 is largely driven by the response of the land and ocean carbon sinks to climate variability. Therefore, climate mitigation in terms of emission reductions can be disguised by internal variability. However, the probability that emission reductions induced by a policy change caused reductions in atmospheric CO2 growth trend is unclear. We use 100 historical MPI-ESM simulations and interpret mitigation in 2020 as a policy shift from Representative Concentration Pathway 4.5 to 2.5 in a comprehensive causation attribution framework. Here we show that five-year CO2 trends are higher in 2021-2025 than over 2016-2020 in 30% of all realizations in the mitigation scenario, compared to 52% in the non-mitigation scenario. Therefore, mitigation is sufficient or necessary to cause these trends by 42% or 31%, respectively and therefore far from certain. A stronger increase in atmospheric CO2 trends despite emission reductions is possible when the global carbon cycle triggered by internal climate variability releases more CO2 than mitigation saves. Such trends might occur for of up to ten years. Certainty that mitigation causes trend reductions is only reached after ten or fifteen years, respectively of the type of causation. Our analysis showcases the inherent uncertainty of near-term CO2 projections. Assessments of the efficacy of mitigation in the near term are incomplete without quantitatively considering internal variability.

Marine aggregates are the vector for biogenically bound carbon and nutrients from the euphotic zo... more Marine aggregates are the vector for biogenically bound carbon and nutrients from the euphotic zone to the interior of the oceans. To improve the representation of this biological carbon pump in the global biogeochemical HAMburg Ocean Carbon Cycle (HAMOCC) model, we implemented a novel Microstructure, Multiscale, Mechanistic, Marine Aggregates in the Global Ocean (M 4 AGO) sinking scheme. M 4 AGO explicitly represents the size, microstructure, heterogeneous composition, density and porosity of aggregates and ties ballasting mineral and particulate organic carbon (POC) fluxes together. Additionally, we incorporated temperature-dependent remineralization of POC. We compare M 4 AGO with the standard HAMOCC version, where POC fluxes follow a Martin curve approach with (i) linearly increasing sinking velocity with depth and (ii) temperatureindependent remineralization. Minerals descend separately with a constant speed. In contrast to the standard HAMOCC, M 4 AGO reproduces the latitudinal pattern of POC transfer efficiency, as recently constrained by Weber et al. (2016). High latitudes show transfer efficiencies of ≈ 0.25 ± 0.04, and the subtropical gyres show lower values of about 0.10 ± 0.03. In addition to temperature as a driving factor for remineralization, diatom frustule size co-determines POC fluxes in silicifier-dominated ocean regions, while calcium carbonate enhances the aggregate excess density and thus sinking velocity in subtropical gyres. Prescribing rising carbon dioxide (CO 2) concentrations in stand-alone runs (without climate feedback), M 4 AGO alters the regional ocean atmosphere CO 2 fluxes compared to the standard model. M 4 AGO exhibits higher CO 2 uptake in the Southern Ocean compared to the standard run, while in subtropical gyres, less CO 2 is taken up. Overall, the global oceanic CO 2 uptake remains the same. With the explicit representation of measurable aggregate properties, M 4 AGO can serve as a test bed for evaluating the impact of aggregate-associated processes on global biogeochemical cycles and, in particular, on the biological carbon pump.

Proceedings of the National Academy of Sciences

Measurements show large decadal variability in the rate of CO2 accumulation in the atmosphere tha... more Measurements show large decadal variability in the rate of CO2 accumulation in the atmosphere that is not driven by CO2 emissions. The decade of the 1990s experienced enhanced carbon accumulation in the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. These variations are driven by natural sources and sinks of CO2 due to the ocean and the terrestrial biosphere. In this study, we compare three independent methods for estimating oceanic CO2 uptake and find that the ocean carbon sink could be responsible for up to 40% of the observed decadal variability in atmospheric CO2 accumulation. Data-based estimates of the ocean carbon sink from pCO2 mapping methods and decadal ocean inverse models generally agree on the magnitude and sign of decadal variability in the ocean CO2 sink at both global and regional scales. Simulations with ocean biogeochemical models confirm that climate variability drove the observed decad...

Geophysical Research Letters

Termination effects of large-scale artificial ocean alkalinization (AOA) have received little att... more Termination effects of large-scale artificial ocean alkalinization (AOA) have received little attention because AOA was assumed to pose low environmental risk. With the Max Planck Institute Earth system model, we use emission-driven AOA simulations following the Representative Concentration Pathway 8.5 (RCP8.5). We find that after termination of AOA warming trends in regions of the Northern Hemisphere become ∼50% higher than those in RCP8.5 with rates similar to those caused by termination of solar geoengineering over the following three decades after cessation (up to 0.15 K/year). Rates of ocean acidification after termination of AOA outpace those in RCP8.5. In warm shallow regions where vulnerable coral reefs are located, decreasing trends in surface pH double (0.01 units/year) and the drop in the carbonate saturation state (Ω) becomes up to 1 order of magnitude larger (0.2 units/year). Thus, termination of AOA poses higher risks to biological systems sensitive to fast-paced environmental changes than previously thought. Plain Language Summary Climate engineering (CE) methods are intended to alleviate the environmental perturbations caused by climate change and ocean acidification. However, these methods can also lead to environmental issues. Among all the different CE techniques, the method of artificial ocean alkalinization (AOA) is commonly discussed. AOA involves the release of processed alkaline minerals into the ocean, which enhances the uptake of atmospheric carbon by the ocean while reducing the acidification of seawater. We study the impacts caused by the termination of AOA on environmental properties that are relevant for organisms and ecosystems because they are sensitive not only to the magnitude of environmental change but also to its pace. We analyze the rate at which the environment changes after termination of this method using an Earth system model that simulates the response of our climate to CE. We found that the abrupt termination of large-scale implementation of AOA leads to regional rates of surface warming and ocean acidification, which largely exceed the pace of change that the implementation of AOA was intended to alleviate. This enhanced rate of environmental change would restrict even more the already limited adaptive capacity of vulnerable organisms and ecosystems.

Earth's Future

To contribute to a quantitative comparison of climate engineering (CE) methods, we assess atmosph... more To contribute to a quantitative comparison of climate engineering (CE) methods, we assess atmosphere-, ocean-, and land-based CE measures with respect to Earth system effects consistently within one comprehensive model. We use the Max Planck Institute Earth System Model (MPI-ESM) with prognostic carbon cycle to compare solar radiation management (SRM) by stratospheric sulfur injection and two carbon dioxide removal methods: afforestation and ocean alkalinization. The CE model experiments are designed to offset the effect of fossil-fuel burning on global mean surface air temperature under the RCP8.5 scenario to follow or get closer to the RCP4.5 scenario. Our results show the importance of feedbacks in the CE effects. For example, as a response to SRM the land carbon uptake is enhanced by 92 Gt by the year 2100 compared to the reference RCP8.5 scenario due to reduced soil respiration thus reducing atmospheric CO 2. Furthermore, we show that normalizations allow for a better comparability of different CE methods. For example, we find that due to compensating processes such as biogeophysical effects of afforestation more carbon needs to be removed from the atmosphere by afforestation than by alkalinization to reach the same global warming reduction. Overall, we illustrate how different CE methods affect the components of the Earth system; we identify challenges arising in a CE comparison, and thereby contribute to developing a framework for a comparative assessment of CE.

Earth System Science Data

Accurate assessment of anthropogenic carbon dioxide (CO 2) emissions and their redistribution amo... more Accurate assessment of anthropogenic carbon dioxide (CO 2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere-the "global carbon budget"-is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. CO 2 emissions from fossil fuels and industry (E FF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (E LUC), mainly deforestation, are based on land-cover change data and bookkeeping models. The global atmospheric CO 2 concentration is measured directly and its rate of growth (G ATM) is computed from the annual changes in concentration. The ocean CO 2 sink (S OCEAN) and terrestrial CO 2 sink (S LAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (B IM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2007-2016), E FF was 9.4 ± 0.

ABSTRACT During the Paleocene-Eocene Thermal Maximum (PETM; 55 million years ago) the climate und... more ABSTRACT During the Paleocene-Eocene Thermal Maximum (PETM; 55 million years ago) the climate underwent significant changes within short geological timescales. The atmosphere, ocean and land system was affected by a massive carbon release which caused an intense global warming, indicated by a negative δ13C-carbon isotope excursion and carbonate dissolution in the ocean. In terms of released carbon and concomitant changes in ocean carbon cycle, the PETM probably serves as the most analogous event in Earth's history for ongoing ocean acidification. However the dimensions of the changes in ocean carbon cycle during the PETM are still uncertain based on the ambiguous amount and time scale of the carbon release. We use the fully coupled Earth System Model of the Max Planck Institute for Meteorology (MPI- ESM) which includes ocean and atmospheric general circulation models (MPI-OM & ECHAM respectively) and models of ocean biogeochemistry (HAMOCC) and land vegetation (JSBACH). Such modeling system enables us to simulate the closed carbon cycle in the oceanic, land and atmospheric compartments. Moreover, by using a three-dimensional ESM we get a more detailed representation of the ocean biogeochemistry and the underlying physical processes. After initializing the ocean biogeochemistry within Late Paleocene (pre-PETM) boundary conditions in an ocean standalone setup, we ran the model into a steady state under 2x pre-industrial atmospheric CO2 concentrations (560 ppmv). Starting from this climate state we compute different carbon release scenarios for the onset of the PETM. Within these model-runs of several 1000 years duration we prescribe a carbon release of up to 1.5 Gt a-1, which is at the upper limit of estimations for the PETM. We focus on how ocean biogeochemistry is affected, but also highlight the interactions between the different compartments of the carbon cycle. First model results and modifications implemented in HAMOCC for application to the PETM will be presented.

Nature communications, Jan 30, 2016

As a major CO2 sink, the North Atlantic, especially its subpolar gyre region, is essential for th... more As a major CO2 sink, the North Atlantic, especially its subpolar gyre region, is essential for the global carbon cycle. Decadal fluctuations of CO2 uptake in the North Atlantic subpolar gyre region are associated with the evolution of the North Atlantic Oscillation, the Atlantic meridional overturning circulation, ocean mixing and sea surface temperature anomalies. While variations in the physical state of the ocean can be predicted several years in advance by initialization of Earth system models, predictability of CO2 uptake has remained unexplored. Here we investigate the predictability of CO2 uptake variations by initialization of the MPI-ESM decadal prediction system. We find large multi-year variability in oceanic CO2 uptake and demonstrate that its potential predictive skill in the western subpolar gyre region is up to 4-7 years. The predictive skill is mainly maintained in winter and is attributed to the improved physical state of the ocean.

Geoscientific Model Development Discussions, 2016

Coordinated experimental design and implementation has become a cornerstone of global climate mod... more Coordinated experimental design and implementation has become a cornerstone of global climate modelling. So-called Model Intercomparison Projects (MIPs) enable systematic and robust analysis of results across many models to identify common signals and understand model similarities and differences without being hindered by ad-hoc differences in model set-up or experimental boundary conditions. The activity known as the Coupled Model Intercomparison Project (CMIP) has thus grown significantly in scope and as it enters its 6th phase, CMIP6, the design and documentation of individual simulations has been devolved to individual climate science communities. The Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP) takes responsibility for design, documentation and analysis of carbon cycle feedbacks and interactions in climate simulations. These feedbacks are potentially large and play a leading order contribution in determining the atmospheric composition...

Hamburg Studies on Maritime Affairs, 2000

ABSTRACT Persistent toxic substances (PTS) are organic chemicals that are environmentally persist... more ABSTRACT Persistent toxic substances (PTS) are organic chemicals that are environmentally persistent and harmful to human health and to the environment. Bioaccumulation or increase in concentration of a pollutant from the environment to the first organism in a food chain refers to how pollutants enter a food chain. They can be released into the environment in various ways including during their production, application (e.g., pesticides), or combustion (e.g., dioxins). Whether produced by natural or anthropogenic processes, PTS have a particular combination of physical and chemical properties allowing them to remain intact for exceptionally long periods after release into the environment. PTS migrate between different environmental compartments and undergo long-range transport (LRT) by natural processes in both the atmosphere and oceans, thus becoming ubiquitous global contaminants. PTS are distributed throughout the oceans as a consequence of atmospheric deposition and direct introduction into aquatic systems. Scientific and political interest in the fate and behaviour of PTS in the environment arises from concern over human exposure to these chemicals and their discovery in pristine environments far from source regions. There is international interest in reducing and (possibly) eliminating releases of PTS, and in reducing risks to regional and global environments. International agreements, such as the UNEP Stockholm Convention on Persistent Organic Pollutants, the UNECE Convention on Longrange Transboundary Air Pollution, and the OSPAR Convention, require assessment criteria of the environmental risks posed by PTS based on sound scientific knowledge and models.

Journal of Climate, 2015

Surface waves in the ocean respond to variability and changes of climate. Observations and modeli... more Surface waves in the ocean respond to variability and changes of climate. Observations and modeling studies indicate trends in wave height over the past decades. Nevertheless, it is currently impossible to discern whether these trends are the result of climate variability or change. The output of an Earth system model (EC-EARTH) produced within phase 5 of the Coupled Model Intercomparison Project (CMIP5) is used here to force a global Wave Model (WAM) in order to study the response of waves to different climate regimes. A control simulation was run to determine the natural (unforced) model variability. A simplified fingerprint approach was used to calculate positive and negative limits of natural variability for wind speed and significant wave height, which were then compared to different (forced) climate regimes over the historical period (1850–2010) and in the future climate change scenario RCP8.5 (2010–2100). Detectable climate change signals were found in the current decade (201...

Oceanic uptake of man-made CO2 leads to a decrease in the ocean pH and carbonate saturation state... more Oceanic uptake of man-made CO2 leads to a decrease in the ocean pH and carbonate saturation state. This processes, known as ocean acidification is expected to have adverse effects on a variety of marine organisms. A surprising consequence of ocean acidification, which has gone widely unrecognized, is its effect on underwater sound transmission. Low-frequency sound absorption in the ocean occurs