Eduardo Zorita

Helmholtz-Zentrum Hereon | HZG · Paleoclimatology Research Unit

In Southern Africa, precipitation is a crucial variable linked to agriculture and water supply. In addition, extreme precipitation causes devastating flooding, and heavy rainfall events are a significant threat to the population in this region. We analyse here the spatial patterns of extreme precipitation and its projected changes in the future. We...

The southern African climate is strongly impacted by climate change. Precipitation is a key variable in this region , as it is linked to agriculture and water supply. Simulations with a regional atmospheric model over the past decades and the 21st century display a decrease in the past precipitation over some coastal areas of South Africa and an in...

We have designed a machine-learning method to predict the occurrence of extreme sea-level at the Baltic Sea coast with lead times of a few days. The method is based on a Random Forest Classifier and uses sea level pressure, surface wind, precipitation, and the prefilling state of the Baltic Sea as predictors for daily sea level above the 95 % quant...

South of 15o S, Southern Africa has a subtropical climate, which is affected by temperate and tropical weather systems and comes under the influence of the Southern Hemisphere high-pressure systems. Most rainfall occurs in austral summer, but the southwest experiences winter rainfall. Much of the precipitation in summer is of convective origin forc...

Three different climate field reconstruction (CFR) methods are employed to reconstruct spatially resolved North Atlantic–European (NAE) and Northern Hemisphere (NH) summer temperatures over the past millennium from proxy records. These are tested in the framework of pseudoproxy experiments derived from two climate simulations with comprehensive Ear...

A paleodelta ("Hainan Delta") was discovered in the Beibu Gulf, located at the northern continental shelf of the South China Sea southwest of the Island of Hainan, by the interpretation of seismic survey data. An interdisciplinary and unique data-set was acquired by studying a sediment core ZBW drilled by the China Geological Survey at a position s...

Intense drought has occurred in the United States Southwest this century, causing unprecedented stress to water resources. Here we use paleoclimate and instrumental records to establish that the recent temperature rise is incompatible with random draws from past fluctuations, including the current period of warming. Consistent with and extending pr...

Southern African climate is strongly impacted by climate change. Precipitation is a key variable in this region as it is linked to agriculture and water supply. An analysis of simulations with a regional atmospheric model over the last decades and the 21st century shows that in the past precipitation has decreased in some coastal areas of South Afr...

We present an off-line paleo-data assimilation methodology that formally combines the analog assimilation method (AA) and the Kalman Filter (KF), utilizing the KF as a post-processor of the AA output. This methodology can be applied to reconstruct climate fields that are spatially separated from proxy-based reconstructions by using the spatial co-v...

We present a new framework for the reconstruction of climate indices based on proxy data such as tree rings. The framework is based on the supervised learning method Gaussian Process Regression (GPR) and designed to preserve the amplitude of past climate variability and to adequately handle noise-contaminated proxies and variable proxy availability...

We combine a machine learning method and ensemble climate predictions to investigate windows of opportunity for seasonal predictability of European summer climate associated with the North Atlantic jet stream. We particularly focus on the impact of North Atlantic spring sea surface temperatures (SST) on the four dominant atmospheric teleconnections...

Based on the Baltic Earth Assessment Reports of this thematic issue in Earth System Dynamics and recent peer-reviewed literature, current knowledge of the effects of global warming on past and future changes in climate of the Baltic Sea region is summarised and assessed. The study is an update of the Second Assessment of Climate Change (BACC II) pu...

Three different climate field reconstruction (CFR) methods employed to reconstruct North Atlantic-European (NAE) and Northern Hemisphere (NH) summer season temperature over the past millennium from proxy records are tested in the framework of pseudoproxy experiments derived from three climate simulations with Earth System Models. Two of these metho...

Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are strongly affected by human activities. A multitude of human impacts, including climate change, affect the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Asse...

Until now, proxy records have been the primary tool for quantitative reconstructions of the physical world of the ancient and late antique Mediterranean. This chapter demonstrates the combined use of proxy datasets and the hitherto underutilized potential of earth system models in the scientific and historical study of past environmental variations...

Based on the Baltic Earth Assessment Reports of this thematic issue in Earth System Dynamics and recent peer-reviewed literature, current knowledge about the effects of global warming on past and future changes in climate of the Baltic Sea region is summarized and assessed. The study is an update of the Second Assessment of Climate Change (BACC II)...

There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. This, along with the outstanding number of long data records, makes the Baltic Sea a unique lab...

Preprint: https://www.sciencedirect.com/science/article/pii/S0377026521000385 Abstract Inspired by the Charney-and-de Vore hypothesis, Hansen and Sutera in 1986 came forward with the claim of having detected a fingerprint of the presence of two preferred state in the tropospheric circulation at northern Hemisphere mid-latitudes. Shortly after, Nit...

Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are stongly affected by human activities. A multitude of human impacts, including climate change, affects the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Asse...

Statistical climate prediction has sometimes demonstrated higher accuracy than coupled dynamical forecast systems. This study tests the applicability of springtime soil moisture (SM) over Europe and sea surface temperatures (SSTs) of three North Atlantic (NA) regions as statistical predictors of European mean summer temperature (t2m). We set up two...

Arabian Sea upwelling in the past has been generally studied based on the sediment records. We apply two earth system models and analyze the simulated water vertical velocity to investigate coastal upwelling in the western Arabian Sea over the last millennium. In addition, two models with slightly different configurations are also employed to study...

We investigate the effects of solar forcing on the North Atlantic (NA) summer climate, in climate simulations with Earth System Models (ESMs), over the preindustrial past millennium (AD 850–1849). We use one simulation and a four-member ensemble performed with the MPI-ESM-P and CESM-LME models, respectively, forced only by low-scaling variations in...

We use a neural network-based classifier, i.e. self-organising maps to evaluate the Max Planck Institute Earth System Model seasonal prediction system. We focus on the model performance in representing the dominant atmospheric teleconnections linked to the North Atlantic Jet Stream, and their impact on European summer climate predictability. We fur...

Inferences about climate states and climate variability of the Holocene and the deglaciation rely on sparse paleo-observational proxy data. Combining these proxies with output from climate simulations is a means for increasing the understanding of the climate throughout the last tens of thousands of years. The analogue method is one approach to do...

There are a large number of geophysical processes affecting sea level dynamics and coastal erosion in the Baltic Sea region. These processes operate on a large range of spatial and temporal scales and are observed in many other coastal regions worldwide. Together with the outstanding number of long data records, this makes the Baltic Sea a unique l...

Year-to-year extreme alterations in California (CA) precipitation, denoted here as flips, present significant challenges to resource managers, emergency management officials, and the state’s economy and ecosystems generally. We evaluate regional (north, central, and south) and statewide flip behavior since 1571 CE utilizing instrumental data and pa...

The document is a supplementary material to the paper in the Ecolgy Letters: Kirdyanov A.V., Krusic P.J., Shishov V.V., Vaganov E.A., Fertikov A.I., Myglan V.S., Barinov V.V., Browse J., Esper J., Ilyin V.A., Knorre A.A., Korets M.A., Kukarskikh V.V., Mashukov D.A., Onuchin A.A., Piermattei A., Pimenov A.V., Prokushkin A.S., Ryzhkova V.A., Shishik...

Although the effect of pollution on forest health and decline received much attention in the 1980s, it has not been considered to explain the 'Divergence Problem' in dendroclimatology; a decou-pling of tree growth from rising air temperatures since the 1970s. Here we use physical and bio-geochemical measurements of hundreds of living and dead conif...

Sea-level (SL) data from the Last Glacial Cycle (LGC) have been superimposed on to digital elevation models of the South China Sea (SCS) and adjacent areas, to generate regional paleogeographic scenarios related to 4th- to 5th-order Milankovitch climate cycles. These scenarios—at 123, 65, 60.5, 56, 20, and 0.5 kyr BP—showed that the SCS functioned...

Combining proxy information and climate model simulations reconciles these sources of information about past climates. This, in turn, strengthens our understanding of past climatic changes. The analogue or proxy surrogate reconstruction method is a computationally cheap data assimilation approach, which searches in a pool of simulated climate state...

Abstract. Inferences about climate states and climate variability of the Holocene and the deglaciation rely on sparse paleo-observational proxy data. Combining these sparse proxies with output from climate simulations is a means for increasing the understanding of the climate throughout the last ~ 21 millennia. The analogue method is one approach t...

This study evaluates the performance of statistical models applied to the output of numerical models for short-term (1–24 h) hourly wind forecasts at three locations in the Basque Country. The target variables are horizontal wind components and the maximum wind gust at 3 h intervals. Statistical approaches such as persistence, analogues, linear reg...

The westerlies and trade winds over the South Atlantic and Indian Ocean are important drivers of the regional oceanography around southern Africa, including features such as the Agulhas Current, the Agulhas leakage, and the Benguela upwelling. Agulhas leakage constitutes a fraction of warm and saline water transport from the Indian Ocean into the S...

We investigate the effects of solar forcing during summer on the North Atlantic climate in comprehensive simulations of the preindustrial last millennium. We use two Earth System Models forced only by variations in Total Solar Irradiance (TSI). Specifically, we examine how different statistical techniques commonly used in current literature, namely...

We investigate the potential of using artificial neural networks (ANN) for the prediction of sea surface temperature anomalies (SSTA) at seasonal time scales in the North Atlantic. Even with major development in the last years, seasonal prediction systems still show low predictive skill in most of North Atlantic, in particular over the subtropics....

Summer precipitation in the north fringe of East Asian Summer Monsoon (NFEASM) accounts for the majority of annual regional precipitation and plays an important role in regional climatology and agriculture development. Here we analyze variations in summer precipitation in the NFEASM over the past millennium using several simulations with Earth Syst...

The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations. This lack of understanding is particularly critical with regard to projected drought and flood risks. Here we assess warm-season co-variability patterns...

Climate reconstructions are means to extract the signal from uncertain paleo-observations, so-called proxies. It is essential to evaluate these reconstructions to understand and quantify their uncertainties. Similarly, comparing climate simulations and proxies requires approaches to bridge the temporal and spatial differences between both and to ad...

This study focuses on mean sea-level variability at the West African coast in the observational period (1993–2013) and its offshore waters, investigating its decadal variability, long-term trends and the large-scale climate patterns that are connected to its variability. To achieve this objective, statistically analyses is performed on several avai...

Combining proxy information and climate model simulations allows reconciling both sources of information about past climates. This, in turn, strengthens our understanding of past climatic changes. The analogue or proxy surrogate reconstruction method is a computationally cheap data assimilation approach to benefit from the advantages of both data s...

Estimates of climate sensitivity from general circulation model (GCM) simulations still present a large spread despite the continued improvements in climate modeling since the 1970s. This variability is partially caused by the dependence of several long-term feedback mechanisms on the reference climate state. Indeed, state-of-the-art GCMs present a...

After the publication in 1999 of a reconstruction of the Northern Hemisphere temperature popularly known as “the hockey‐stick,” climate scientists and Internet bloggers engaged in a heated and often stalemated public debate on the validity of paleoclimate reconstructions and on their implications for the wider question of anthropogenic climate chan...

The westerlies and trade winds over the South Atlantic and Indian Ocean are important drivers of the regional oceanography around Southern Africa, including features such as the Agulhas current, the Agulhas leakage and the Benguela upwelling. The Agulhas leakage is the transport of warm and saline water from the Indian Ocean into the South Atlantic...

We aim to investigate the potential of using artificial neural networks (ANN) for the prediction of sea surface temperature anomalies (SSTA) at seasonal time scales in the North Atlantic. At these time scales, SSTAs have been linked to the intensity and genesis of extreme weather events and fluctuations of marine resources, which have the potential...

Moisture delivery in California is largely regulated by the strength and position of the North Pacific jet stream (NPJ), winter high-altitude winds that influence regional hydroclimate and forest fire during the following warm season. We use climate model simulations and paleoclimate data to reconstruct winter NPJ characteristics back to 1571 CE to...

The history of ideas, which lead to the now matured concept of empirical downscaling, with various technical procedures, is rooted in two concepts, that of synoptic climatology and that of spatial interpolation in a phase space. In the former case, the basic idea is to estimate from a synoptic weather map the regional details, and to assemble these...

The scarcity of long instrumental records, uncertainty in reconstructions, and insufficient skill in model simulations hamper assessing how regional precipitation changed over past centuries. Here, we use standardized precipitation data to compare a regional climate simulation, reconstructions, and long observational records of seasonal (March to J...

Regional climate modelling bridges the gap between the coarse resolution of current global climate models and the regional-to-local scales, where the impacts of climate change are of primary interest. Here, we present a review of the added value of the regional climate modelling approach within the scope of paleoclimate research and discuss the cur...

We analyze the contribution of the Agulhas Current on the central water masses of the Benguela upwelling system (BUS) over the last decades in a high-resolution ocean simulation driven by atmospheric reanalysis. The BUS is an Eastern Boundary Upwelling System where upwelling of cold nutrient-rich water favors biomass growth. The two distinct subreg...

Climate reconstructions are means to extract the signal from uncertain paleo-observations, i.e. proxies. It is essential to evaluate these to understand and quantify their uncertainties. Similarly, comparing climate simulations and proxies requires approaches to bridge the, e.g., temporal and spatial differences between both and address their speci...

Estimates of climate sensitivity from General Circulation Model (GCM) simulations still present a large spread despite the continued improvements in climate modeling since the 1970s. This variability is partially caused by the dependence of several long-term feedback mechanisms on the reference climate state. Indeed, state-of-the-art GCMs present a...

We investigate whether the recently observed trends in daily maximum and minimum near-surface air temperature (Tmax and Tmin, respectively) over South America (SA) are consistent with the simulated response of Tmin and Tmax to anthropogenic forcing. Results indicate that the recently observed warming in the dry seasons is well beyond the range of n...

WORKSHOP ON THE COMPARISON OF PALEOCLIMATE DATA AND SIMULATIONS OVER TIME PERIODS UP TO THE LAST GLACIAL CYCLE What: An international group of approximately 30 scientists with background and expertise in global and regional climate modeling, statistics, and climate proxy data discussed the state of the art, progress, and challenges in comparing gl...

Arabian Sea upwelling in the past has been generally studied based on the sediment records. We apply two earth system models and analyse the simulated water vertical velocity to investigate the variations of the coastal upwelling in the western Arabian Sea over the last millennium. In addition, two models with slightly different configurations are...

This article analyses high-quality hydroclimate proxy records and spatial reconstructions from the Central and Eastern Mediterranean and compares them with two Earth System Model simulations (CCSM4, MPI-ESM-P) for the Crusader period in the Levant (1095–1290 CE), the Mamluk regime in Transjordan (1260–1516 CE) and the Ottoman crisis and Celâlî Rebe...

East Asia has experienced strong warming since the 1960s accompanied by an increased frequency of heat waves and shrinking glaciers over the Tibetan Plateau and the Tien Shan. Here, we place the recent warmth in a long-term perspective by presenting a new spatially resolved warm-season (May-September) temperature reconstruction for the period 1-200...

The scarcity of long instrumental records, uncertainty in reconstructions, and insufficient skill in model simulations hamper assessing how regional precipitation changed over past centuries. Here, we use standardised precipitation data to compare global and regional climate simulations and reconstructions and long observational records of seasonal...

Spatial covariance in the simulated temperature evolution over the past millennium has been reported to exceed that of multiproxy-based reconstructions. Here we use tree ring-based temperature reconstructions and state-of-the-art climate model simulations to assess temporal changes in Northern Hemisphere intercontinental temperature covariance duri...

In response to climate change, coastal communities are expected to experience increasing coastal impacts of sea-level rise (SLR). Strategies formulated and implemented to curb these impacts can thus be more effective if scientific findings on the response to climate change and SLR impacts on coastal communities are taken into consideration and not...

The main purpose of this study is to quantify the contribution of atmospheric factors to recent off-shore sea-level variability in the Baltic Sea and the North Sea on interannual timescales. For this purpose, we statistically analysed sea-level records from tide gauges and satellite altimetry and several climatic data sets covering the last century...

Studies based on sediment records, sea-surface temperature and wind suggest that upwelling along the western coast of Arabian Sea is strongly affected by the Indian summer Monsoon. We examine this relationship directly in an eddy-resolving global ocean simulation STORM driven by atmospheric reanalysis over the last 61 years. With its very high spat...