Climate and chemistry effects of a regional scale nuclear conflict

Previous studies have highlighted the severity of detrimental effects for life on earth after an assumed regionally limited nuclear war. These effects are caused by climatic, chemical and radiative changes persisting for up to one decade. However, so far only a very limited number of climate model simulations have been performed, giving rise to the question how realistic previous computations have been. This study uses the coupled chemistry climate model (CCM) SOCOL, which belongs to a different family of CCMs than previously used, to investigate the consequences of such a hypothetical nuclear conflict. In accordance with previous studies, the present work assumes a scenario of a nuclear conflict between India and Pakistan, each applying 50 warheads with an individual blasting power of 15 kt ("Hiroshima size") against the major population centers, resulting in the emission of tiny soot particles, which are generated in the firestorms expected in the aftermath of the detonations. Substantial uncertainties related to the calculation of likely soot emissions, particularly concerning assumptions of target fuel loading and targeting of weapons, have been addressed by simulating several scenarios, with soot emissions ranging from 1 to 12 Tg. Their high absorptivity with respect to solar radiation leads to a rapid self-lofting of the soot particles into the strato- and mesosphere within a few days after emission, where they remain for several years. Consequently, the model suggests earth's surface temperatures to drop by several degrees Celsius due to the shielding of solar irradiance by the soot, indicating a major global cooling. In addition, there is a substantial reduction of precipitation lasting 5 to 10 yr after the conflict, depending on the magnitude of the initial soot release. Extreme cold spells associated with an increase in sea ice formation are found during Northern Hemisphere winter, which expose the continental land masses of North America and Eurasia to a cooling of several degrees. In the stratosphere, the strong heating leads to an acceleration of catalytic ozone loss and, consequently, to enhancements of UV radiation at the ground. In contrast to surface temperature and precipitation changes, which show a linear dependence to the soot burden, there is a saturation effect with respect to stratospheric ozone chemistry. Soot emissions of 5 Tg lead to an ozone column reduction of almost 50% in northern high latitudes, while emitting 12 Tg only increases ozone loss by a further 10%. In summary, this study, though using a different chemistry climate model, corroborates the previous investigations with respect to the atmospheric impacts. In addition to these persistent effects, the present study draws attention to episodically cold phases, which would likely add to the severity of human harm worldwide. The best insurance against such a catastrophic development would be the delegitimization of nuclear weapons.

Age affects the adjustment of cognitive control after a conflict: evidence from the bivalency effect

Age affects cognitive control. When facing a conflict, older adults are less able to activate goal-relevant information and inhibit irrelevant information. However, cognitive control also affects the events after a conflict. The purpose of this study was to determine whether age affects the adjustment of cognitive control following a conflict. To this end, we investigated the bivalency effect, that is, the performance slowing occurring after the conflict induced by bivalent stimuli (i.e., stimuli with features for two tasks). In two experiments, we tested young adults (aged 20-30) and older adults (aged 65-85) in a paradigm requiring alternations between three tasks, with bivalent stimuli occasionally occurring on one task. The young adults showed a slowing for all trials following bivalent stimuli. This indicates a widespread and long-lasting bivalency effect, replicating previous findings. In contrast, the older adults showed a more specific and shorter-lived slowing. Thus, age affects the adjustment of cognitive control following a conflict.

Third party assessments in trust problems with conflict of interest: An experiment on the effects of promisesm

Is it possible to elicit reliable assessment from an assessor having a conflict of interest (e.g. a professor that writes a recommendation letter for a formal PhD student)? We propose an experimental test and show that compared to a not-incentivized assessment, a promise to give a truthful assessment reduces misreporting to the same extent as an incentivized assessment (i.e. when the assessor gains higher payoff if the assessment is correct).