SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Morrill, Carrie; Ward, Ellen M.; Wagner, Amy J.; Otto-bliesner, Bette L.; Rosenbloom, Nan.

The 8.2ka event is a key test case for simulating the coupled climate response to changes in the Atlantic Meridional Overturning Circulation (AMOC). Recent advances in quantifying freshwater fluxes at 8.2ka from the proxy record have improved the realism of the forcing magnitude in model simulations, yet this forcing is still generally applied in an unrealistic geographic manner, across most of the Labrador Sea rather than just along the Labrador coast. Previous simulations with eddy- resolving ocean models have come to conflicting conclusions regarding the ability of such a coastally confined flow to impact the AMOC. These simulations have also not incorporated full atmosphere models nor have they used the new meltwater forcing values for 8.2ka. We use...

Tipo: Text

Palavras-chave: Atlantic Meridional Overturning Circulation; Abrupt climate change; Deglaciation; 8; 2 ka event; Freshwater forcing; Coupled climate model simulation.

Ano: 2014

URL: https://archimer.ifremer.fr/doc/00496/60735/65213.pdf

Agulhas salt-leakage oscillations during abrupt climate changes of the Late Pleistocene

Rapid reductions and millennial-scale variability in Nordic Seas sea ice cover during abrupt glacial climate changes

Marino, Gianluca; Zahn, Rainer; Ziegler, Martin; Purcell, Conor; Knorr, Gregor; Hall, Ian R.; Ziveri, Patrizia; Elderfield, Henry.

An ensemble of new, high-resolution records of surface ocean hydrography from the Indian-Atlantic oceanic gateway, south of Africa, demonstrates recurrent and high-amplitude salinity oscillations in the Agulhas Leakage area during the penultimate glacial-interglacial cycle. A series of millennial-scale salinification events, indicating strengthened salt leakage into the South Atlantic, appear to correlate with abrupt changes in the North Atlantic climate and Atlantic Meridional Overturning Circulation (AMOC). This interhemispheric coupling, which plausibly involved changes in the Hadley Cell and midlatitude westerlies that impacted the interocean transport at the tip of Africa, suggests that the Agulhas Leakage acted as a source of negative buoyancy for...

Tipo: Text

Palavras-chave: Agulhas Leakage; Abrupt climate change; Millennial-scale variability; AMOC; Bipolar seesaw; Southern Hemisphere atmospheric circulation.

Ano: 2013

URL: https://archimer.ifremer.fr/doc/00264/37493/35791.pdf

Timing of massive ‘Fleuve Manche’ discharges over the last 350 kyr: insights into the European ice-sheet oscillations and the European drainage network from MIS 10 to 2

Sadatzki, Henrik; Maffezzoli, Niccolò; Dokken, Trond M.; Simon, Margit H; Berben, Sarah M. P.; Fahl, Kirsten; Kjær, Helle A.; Spolaor, Andrea; Stein, Ruediger; Vallelonga, Paul; Vinther, Bo M.; Jansen, Eystein.

Constraining the past sea ice variability in the Nordic Seas is critical for a comprehensive understanding of the abrupt Dansgaard-Oeschger (D-O) climate changes during the last glacial. Here we present unprecedentedly detailed sea ice proxy evidence from two Norwegian Sea sediment cores and an East Greenland ice core to resolve and constrain sea ice variations during four D-O events between 32 and 41 ka. Our independent sea ice records consistently reveal a millennial-scale variability and threshold response between an extensive seasonal sea ice cover in the Nordic Seas during cold stadials and reduced seasonal sea ice conditions during warmer interstadials. They document substantial and rapid sea ice reductions that may have happened within 250 y or...

Tipo: Text

Palavras-chave: Sea ice; Nordic Seas; Dansgaard-Oeschger events; Abrupt climate change.

Ano: 2020

URL: https://archimer.ifremer.fr/doc/00659/77066/78374.pdf

The Mesolithic-Neolithic transition in southern Iberia

Toucanne, Samuel; Zaragosi, S.; Bourillet, Jean-francois; Cremer, M.; Eynaud, Frederique; Van Vliet-lanoe, B.; Penaud, A.; Fontanier, C.; Turon, J. L.; Cortijo, E.; Gibbard, P. L..

Continuous high-resolution mass accumulation rates (MAR) and X-ray fluorescence (XRF) measurements from marine sediment records in the Bay of Biscay (NE Atlantic) have allowed the determination of the timing and the amplitude of the ‘Fleuve Manche’ (Channel River) discharges during glacial stages MIS 10, MIS 8, MIS 6 and MIS 4–2. These results have yielded detailed insight into the Middle and Late Pleistocene glaciations in Europe and the drainage network of the western and central European rivers over the last 350 kyr. This study provides clear evidence that the ‘Fleuve Manche’ connected the southern North Sea basin with the Bay of Biscay during each glacial period and reveals that ‘Fleuve Manche’ activity during the glaciations MIS 10 and MIS 8 was...

Tipo: Text

Palavras-chave: Northern north sea; Late weichselian glaciation; Western iberian margin; Abrupt climate change; C 14 YR BP; Deep sea; Heinrich events; Norwegian margin; Millennial scale; English channel.

Ano: 2009

URL: http://archimer.ifremer.fr/doc/00011/12261/9037.pdf

Cortes Sanchez, Miguel; Jimenez Espejo, Francisco J.; Simon Vallejo, Maria D.; Gibaja Bao, Juan F.; Carvalho, Antonio Faustino; Martinez-ruiz, Francisca; Rodrigo Gamiz, Marta; Flores, Jose-abel; Paytan, Adina; Lopez Saez, Jose A.; Pena-chocarro, Leonor; Carrion, Jose S.; Morales Muniz, Arturo; Rosello Izquierdo, Eufrasia; Riquelme Cantal, Jose A.; Dean, Rebecca M.; Salgueiro, Emilia; Martinez Sanchez, Rafael M.; De La Rubia De Gracia, Juan J.; Lozano Francisco, Maria C.; Vera Pelaez, Jose L.; Llorente Rodriguez, Laura; Bicho, Nuno F..

New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in...

Tipo: Text

Palavras-chave: Abrupt climate change; Mesolithic-Neolithic transition; South Iberia; Holocene; Migration; Hunter-fisher-gatherers; Paleoceanography.

Ano: 2012

URL: https://archimer.ifremer.fr/doc/00266/37678/35767.pdf

Ice-shelf collapse from subsurface warming as a trigger for Heinrich events

Climate Policy When the Distant Future Matters: Catastrophic Events with Hyperbolic Discounting

Marcott, Shaun A.; Clark, Peter U.; Padman, Laurie; Klinkhammer, Gary P.; Springer, Scott R.; Liu, Zhengyu; Otto-bliesner, Bette L.; Carlson, Anders E.; Ungerer, Andy; Padman, June; He, Feng; Cheng, Jun; Schmittner, Andreas.

Episodic iceberg-discharge events from the Hudson Strait Ice Stream (HSIS) of the Laurentide Ice Sheet, referred to as Heinrich events, are commonly attributed to internal ice-sheet instabilities, but their systematic occurrence at the culmination of a large reduction in the Atlantic meridional overturning circulation (AMOC) indicates a climate control. We report Mg/Ca data on benthic foraminifera from an intermediate-depth site in the northwest Atlantic and results from a climate-model simulation that reveal basin-wide subsurface warming at the same time as large reductions in the AMOC, with temperature increasing by approximately 2 C over a 1-2 kyr interval prior to a Heinrich event. In simulations with an ocean model coupled to a thermodynamically...

Tipo: Text

Palavras-chave: Paleoceanography; Paleoclimatology; Abrupt climate change.

Ano: 2011

URL: https://archimer.ifremer.fr/doc/00227/33819/32479.pdf

Karp, Larry S.; Tsur, Yacov.

Low probability catastrophic climate change can have a significant influence on policy under hyperbolic discounting. We compare the set of Markov Perfect Equilibria (MPE) to the optimal policy under time-consistent commitment. For some initial levels of risk there are multiple MPE; these may involve either excessive or insufficient stabilization effort. These results imply that even if the free-rider problem amongst contemporaneous decision-makers were solved, there may remain a coordination problem amongst successive generations of decision-makers. A numerical example shows that under plausible conditions society should respond vigorously to the threat of climate change.

CLIMATE POLICY WHEN THE DISTANT FUTURE MATTERS: CATASTROPHIC EVENTS WITH HYPERBOLIC DISCOUNTING

Palavras-chave: Abrupt climate change; Event uncertainty; Catastrophic risk; Hyperbolic discounting; Markov Perfect Equilibria; Environmental Economics and Policy; Risk and Uncertainty; C61; C73; D63; D99; Q54.

Ano: 2007

URL: http://purl.umn.edu/7186

Karp, Larry S.; Tsur, Yacov.

Low probability catastrophic climate change can have a signifcant influence on policy under hyperbolic discounting. We compare the set of Markov Perfect Equilibria (MPE) to the optimal policy under time-consistent commitment. For some initial levels of risk there are multiple MPE; these may involve either excessive or insufficient stabilization effort. These results imply that even if the free-rider problem amongst contemporaneous decision-makers were solved, there may remain a coordination problem amongst successive generations of decision-makers. A numerical example shows that under plausible conditions society should respond vigorously to the threat of climate change.

Endogenous Discounting and Climate Policy

Palavras-chave: Abrupt climate change; Event uncertainty; Catastrophic risk; Hyperbolic discounting; Markov Perfect Equilibria; Environmental Economics and Policy; C61; C73; D63; D99; Q54.

Ano: 2007

URL: http://purl.umn.edu/7181

Tsur, Yacov; Zemel, Amos.

Under risk of abrupt climate change, the occurrence hazard is added to the social discount rate. As a result, the social discount rate (i) increases and (ii) turns endogenous to the global warming policy. The second effect bears profound policy implications that are magnified by economic growth. In particular, we find that greenhouse gases (GHG) emission should be terminated at a finite time so that the ensuing occurrence risk will vanish in the long run. Due to the public bad nature of the catastrophic risk, the second effect is ignored in a competitive allocation and unregulated economic growth will give rise to excessive emissions. In fact, the GHG emission paths under the optimal and competitive growth regimes lie at the extreme ends of the range of...

Climate change policy in a growing economy under catastrophic risks

Palavras-chave: Abrupt climate change; Hazard rate; Discounting; Economic growth; Emission policy; H23; H41; O13; O40; Q54; Q58.

Ano: 2008

URL: http://purl.umn.edu/37944

Tsur, Yacov; Zemel, Amos.

Under risk of catastrophic climate change, the occurrence hazard is added to the social discount rate. As a result, the social discount rate (i) increases and (ii) turns endogenous to the global warming policy. The second effect bears profound policy implications that are magnifed by economic growth. In particular, it implies that green- house gases (GHG) emission should gradually be brought to a halt. Due to the public bad nature of the catastrophic risk, the second effect is ignored in a competitive allocation and unregulated economic growth will give rise to excessive emissions. We find that the GHG emission paths under the optimal and competitive growth regimes lie at the extreme ends of the range of feasible emissions. We derive the Pigouvian hazard...