Investigating the causes of the response of the thermohaline circulation to past and future climate changes

The Atlantic thermohaline circulation (THC) is an important part of the earth's climate system. Previous research has shown large uncertainties in simulating future changes in this critical system. The simulated THC response to idealized freshwater perturbations and the associated climate changes have been intercompared as an activity of World Climate Research Program (WCRP) Coupled Model Intercomparison Project/Paleo-Modeling Intercomparison Project (CMIP/PMIP) committees. This intercomparison among models ranging from the earth system models of intermediate complexity (EMICs) to the fully coupled atmosphere-ocean general circulation models (AOGCMs) seeks to document and improve understanding of the causes of the wide variations in the modeled THC response. The robustness of particular simulation features has been evaluated across the model results. In response to 0.1-Sv (1 Sv equivalent to 10^6 ms^3 s^-1) freshwater input in the northern North Atlantic, the multimodel ensemble mean THC weakens by 30% after 100 yr. All models simulate sonic weakening of the THC, but no model simulates a complete shutdown of the THC. The multimodel ensemble indicates that the surface air temperature could present a complex anomaly pattern with cooling south of Greenland and warming over the Barents and Nordic Seas. The Atlantic ITCZ tends to shift southward. In response to 1.0-Sv freshwater input, the THC switches off rapidly in all model simulations. A large cooling occurs over the North Atlantic. The annual mean Atlantic ITCZ moves into the Southern Hemisphere. Models disagree in terms of the reversibility of the THC after its shutdown. In general, the EMICs and AOGCMs obtain similar THC responses and climate changes with more pronounced and sharper patterns in the AOGCMs.

A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration

As part of the Coupled Model Intercomparison Project, integrations with a common design have been undertaken with eleven different climate models to compare the response of the Atlantic thermohaline circulation ( THC) to time-dependent climate change caused by increasing atmospheric CO2 concentration. Over 140 years, during which the CO2 concentration quadruples, the circulation strength declines gradually in all models, by between 10 and 50%. No model shows a rapid or complete collapse, despite the fairly rapid increase and high final concentration of CO2. The models having the strongest overturning in the control climate tend to show the largest THC reductions. In all models, the THC weakening is caused more by changes in surface heat flux than by changes in surface water flux. No model shows a cooling anywhere, because the greenhouse warming is dominant.

Dynamic sea level changes following changes in the thermohaline circulation

Using the coupled climate model CLIMBER-3α, we investigate changes in sea surface elevation due to a weakening of the thermohaline circulation (THC). In addition to a global sea level rise due to a warming of the deep sea, this leads to a regional dynamic sea level change which follows quasi-instantaneously any change in the ocean circulation. We show that the magnitude of this dynamic effect can locally reach up to ~1m, depending on the initial THC strength. In some regions the rate of change can be up to 20-25 mm/yr. The emerging patterns are discussed with respect to the oceanic circulation changes. Most prominent is a south-north gradient reflecting the changes in geostrophic surface currents. Our results suggest that an analysis of observed sea level change patterns could be useful for monitoring the THC strength.

Populismos y democracias defectuosas en El Ecuador (1996-2012): continuidades y diferencia

From 1995 to 2015, Ecuador experienced one of its longest periods of deep political, social and economic crisis. During this interval, three democratically elected governments (Bucaram, 1997; Mahuad, 2000 and Gutiérrez, 2005) were overthrown and a critical juncture arose in 2006 as a result. Since 2007, and as a consequence of these chaotic circumstances, new populist strongmen ascended and, amid the biggest bonanza of oil revenues in Ecuadorian history, established a defective democracy. The gradual escalation of authoritarian tendencies during the three consecutive terms in which Rafael Correa has acted as President, have resulted in the severe weakening of the country’s democratic institutions, since Correa’s has strived to perpetuate himself in power through continual re-election into office, instead of building an institutional quality-democracy. This study aims to clarify the historical foundations of the recurrence of caudillistas, populist and authoritarian governments in Ecuador, revealing the basis of the specific path dependence of Ecuadorian politics. We also explore the Jungian theory, specifically the “pseudo-hero myth”, as the political narrative which Correa’s regime successfully employed to establish its hegemony. Additionally, we perform a psychological-political case analysis by examining the social psychology components underlying the Ecuadorian path dependence towards authoritarian and populist caudillos: Specifically, our case study is framed within historical institutionalism, which focuses on methodological individualism to attend various political science and psychological-political theories...