Heinrich events: Massive late Pleistocene detritus layers of the North Atlantic and their global climate imprint

Abstract. Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet and sailed across the Atlantic where they melted and released freshwater, as well as detritus, that formed characteristic layers on the seafloor. Heinrich events are known for cold climates in the North Atlantic region and global climate changes. We study these events in a fully coupled complex ice sheet–climate model with synchronous coupling between ice sheets and oceans. The ice discharges occur as an internal variability of the model with a recurrence period of 5 kyr, an event duration of 1–1.5 kyr, and a peak discharge rate of about 50 mSv, roughly consistent with reconstructions. The climate response shows a two-stage behavior, with freshwater release effects dominating the surge phase and ice sheet elevation effects dominating the post-surge phase. As a direct response to the freshwater discharge during the surge phase, deepwater formation in the North Atlantic decreases and the North Atlantic deepwater cell weakens by 3.5 Sv. With the reduced oceanic heat transport, the surface temperatures across the North Atlantic decrease, and the associated reduction in evaporation causes a drying in Europe. The ice discharge lowers the surface elevation in the Hudson Bay area and thus leads to increased precipitation and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the jet stream widens to the north, which contributes to a weakening of the subpolar gyre and a continued cooling over Europe even after the ice discharge. This two-stage behavior can explain previously contradicting model results and understandings of Heinrich events.

Download Full-text

Marine productivity response to Heinrich events: a model-data comparison

Climate of the Past ◽

10.5194/cp-8-1581-2012 ◽

2012 ◽

Vol 8 (5) ◽

pp. 1581-1598 ◽

Cited By ~ 23

Author(s):

V. Mariotti ◽

L. Bopp ◽

A. Tagliabue ◽

M. Kageyama ◽

D. Swingedouw

Keyword(s):

North Atlantic ◽

General Circulation ◽

Circulation Model ◽

Global Ocean ◽

Biogeochemical Model ◽

Heinrich Events ◽

The North ◽

Heinrich Event ◽

The North Atlantic ◽

Marine Productivity

Abstract. Marine sediments records suggest large changes in marine productivity during glacial periods, with abrupt variations especially during the Heinrich events. Here, we study the response of marine biogeochemistry to such an event by using a biogeochemical model of the global ocean (PISCES) coupled to an ocean-atmosphere general circulation model (IPSL-CM4). We conduct a 400-yr-long transient simulation under glacial climate conditions with a freshwater forcing of 0.1 Sv applied to the North Atlantic to mimic a Heinrich event, alongside a glacial control simulation. To evaluate our numerical results, we have compiled the available marine productivity records covering Heinrich events. We find that simulated primary productivity and organic carbon export decrease globally (by 16% for both) during a Heinrich event, albeit with large regional variations. In our experiments, the North Atlantic displays a significant decrease, whereas the Southern Ocean shows an increase, in agreement with paleo-productivity reconstructions. In the Equatorial Pacific, the model simulates an increase in organic matter export production but decreased biogenic silica export. This antagonistic behaviour results from changes in relative uptake of carbon and silicic acid by diatoms. Reasonable agreement between model and data for the large-scale response to Heinrich events gives confidence in models used to predict future centennial changes in marine production. In addition, our model allows us to investigate the mechanisms behind the observed changes in the response to Heinrich events.

Download Full-text

Changes of weather conditions in Ukraine under climate changes

Ukrainian hydrometeorological journal ◽

10.31481/uhmj.17.2016.04 ◽

2017 ◽

pp. 31-37

Author(s):

V.M. Khokhlov ◽

H.O. Borovska ◽

O.V. Umanska ◽

M.S. Tenetko

Keyword(s):

Wavelet Analysis ◽

North Atlantic ◽

Climate Changes ◽

Global Climate ◽

Weather Conditions ◽

Global Climate Changes ◽

The North ◽

Regional Feature ◽

The North Atlantic ◽

The North Atlantic Oscillation

The paper analyzes spatiotemporal features the indices of hot, cold and precipitation that are related to weather conditions. The temperature in Ukraine tends to be higher, which is the main regional feature of global climate changes. The North Atlantic Oscillation had an influence on the precipitation in Ukraine – weather is rainier during its negative phases. Also, colder night and hotter days were more frequent during negative phases of the NAO. This fact can be explained by enhancing meridional flows in Ukraine. The wavelet analysis also revealed an impact of the NAO on temperature anomalies – positive phases determined increasing monthly minimum temperatures before the 1980s and decreasing ones after 1980s. Also, the wavelet analysis showed that the Nor-th Atlantic Oscillation influenced the precipitation in northern and southern parts of Ukraine in different ways.

Download Full-text

Were the North Atlantic Heinrich events triggered by the behavior of the European ice sheets?

Geology ◽

10.1130/0091-7613(2000)28<123:wtnahe>2.0.co;2 ◽

2000 ◽

Vol 28 (2) ◽

pp. 123 ◽

Cited By ~ 126

Author(s):

Francis E. Grousset ◽

Claude Pujol ◽

Laurent Labeyrie ◽

Gérard Auffret ◽

An Boelaert

Keyword(s):

North Atlantic ◽

Ice Sheets ◽

Heinrich Events ◽

The North ◽

The North Atlantic

Download Full-text

Statistical Projection of the North Atlantic Storm Tracks

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-17-0348.1 ◽

2019 ◽

Vol 58 (7) ◽

pp. 1509-1522 ◽

Cited By ~ 3

Author(s):

Kajsa M. Parding ◽

Rasmus Benestad ◽

Abdelkader Mezghani ◽

Helene B. Erlandsen

Keyword(s):

North Atlantic ◽

Geopotential Height ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Storm Tracks ◽

Cmip5 Models ◽

The North ◽

The Future ◽

The North Atlantic

AbstractA method for empirical–statistical downscaling was adapted to project seasonal cyclone density over the North Atlantic Ocean. To this aim, the seasonal mean cyclone density was derived from instantaneous values of the 6-h mean sea level pressure (SLP) reanalysis fields. The cyclone density was then combined with seasonal mean reanalysis and global climate model projections of SLP or 500-hPa geopotential height to obtain future projections of the North Atlantic storm tracks. The empirical–statistical approach is computationally efficient because it makes use of seasonally aggregated cyclone statistics and allows the future cyclone density to be estimated from the full ensemble of available CMIP5 models rather than from a smaller subset. However, the projected cyclone density in the future differs considerably depending on the choice of predictor, SLP, or 500-hPa geopotential height. This discrepancy suggests that the relationship between the cyclone density and SLP, 500-hPa geopotential height, or both is nonstationary; that is, that the statistical model depends on the calibration period. A stationarity test based on 6-hourly HadGEM2-ES data indicated that the 500-hPa geopotential height was not a robust predictor of cyclone density.

Download Full-text

Rainfall Variability and Trend Analysis of Multiannual Rainfall in Romanian Plain

Annals of Valahia University of Targoviste Geographical Series ◽

10.1515/avutgs-2017-0012 ◽

2017 ◽

Vol 17 (2) ◽

pp. 124-144 ◽

Cited By ~ 3

Author(s):

Zeineddine Nouaceur ◽

Ovidiu Murărescu ◽

George Murătoreanu

Keyword(s):

North Atlantic Oscillation ◽

Central Europe ◽

North Atlantic ◽

El Nino ◽

Southern Oscillation ◽

Global Climate ◽

El Nino Southern Oscillation ◽

The North ◽

The North Atlantic ◽

The North Atlantic Oscillation

AbstractThe IPCC climate models predict, for the Central Europe, are for climate changes, being seen variability of temperature, with a growing trend of 1-2,5° C (with 1° C for alpine zone – Carpathians and 2-2,5° C for plains). Current observations in the Romanian plain are not consistent, with an existence of a multiannual variability of temperature and precipitations depending on cyclonal and anti-ciclonal activity. The research is based on calculation of reduced centered index, also the graphical chronological method in information processing (MGCTI) of „Bertin Matrix” type, to show current trends of the spatio-temporal variability of precipitation in the context of global climate change. These are in line with the movement of air masses in Europe in general, and implicitly in Romania, with particular regard to the southern region of the country where the Romanian Plain. The variability of short-term global climate is generally associated with coupling phases of oceanic and atmospheric phenomena including El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). While El Niño Southern Oscillation (ENSO) affects climate variability in the world, the North Atlantic Oscillation (NAO) is the climate model dominant in the North Atlantic region. The latter cyclic oscillation whose role is still under debate could explain the variability of rainfall in much of the, central Europe area, and support the hypothesis of a return of the rains marking the end of years of drought in Romanian plain. Faced with such great changes that today affect the central Europe region and given the complexity of spatial and temporal dimensions of the climatic signal, a more thorough research of causes and retroactions would allow for a better understanding of the mechanisms behind this new trend.

Download Full-text

Tropical Cyclones in the UPSCALE Ensemble of High-Resolution Global Climate Models*

Journal of Climate ◽

10.1175/jcli-d-14-00131.1 ◽

2015 ◽

Vol 28 (2) ◽

pp. 574-596 ◽

Cited By ~ 90

Author(s):

Malcolm J. Roberts ◽

Pier Luigi Vidale ◽

Matthew S. Mizielinski ◽

Marie-Estelle Demory ◽

Reinhard Schiemann ◽

...

Keyword(s):

Tropical Cyclones ◽

North Atlantic ◽

Global Climate ◽

Future Climate ◽

Model Resolution ◽

Central Pacific ◽

The North ◽

The Future ◽

The North Atlantic ◽

The Impact

Abstract The U.K. on Partnership for Advanced Computing in Europe (PRACE) Weather-Resolving Simulations of Climate for Global Environmental Risk (UPSCALE) project, using PRACE resources, constructed and ran an ensemble of atmosphere-only global climate model simulations, using the Met Office Unified Model Global Atmosphere 3 (GA3) configuration. Each simulation is 27 years in length for both the present climate and an end-of-century future climate, at resolutions of N96 (130 km), N216 (60 km), and N512 (25 km), in order to study the impact of model resolution on high-impact climate features such as tropical cyclones. Increased model resolution is found to improve the simulated frequency of explicitly tracked tropical cyclones, and correlations of interannual variability in the North Atlantic and northwestern Pacific lie between 0.6 and 0.75. Improvements in the deficit of genesis in the eastern North Atlantic as resolution increases appear to be related to the representation of African easterly waves and the African easterly jet. However, the intensity of the modeled tropical cyclones as measured by 10-m wind speed remains weak, and there is no indication of convergence over this range of resolutions. In the future climate ensemble, there is a reduction of 50% in the frequency of Southern Hemisphere tropical cyclones, whereas in the Northern Hemisphere there is a reduction in the North Atlantic and a shift in the Pacific with peak intensities becoming more common in the central Pacific. There is also a change in tropical cyclone intensities, with the future climate having fewer weak storms and proportionally more strong storms.

Download Full-text