The legitimacy of leadership in international climate change negotiations

Leadeship is an essential ingredient in reaching international agreements and overcoming the collective action problems associated with responding to climate change. In this study, we aim at answering two questions that are crucial for understanding the legitimacy of leadership in international climate change negotiations. Based on the responses of the three consecutive surveys distributed at COPs 14-16, we seek first to chart which actors are actually recognized as leaders by climate change negotiation participants. Second, we aim to explain what motivates COP participants to support different actors as leaders. Both these questions are indeed crucial for understanding the role, importance, and legitimacy of leadership in the international climate change regime. Our results show that the leadership landscape in this issue area is fragmented, with no one clear-cut leader, and strongly suggest that it is imperative for any actor seeking recognition as climate change leader to be perceived as being devoted to promoting the common good.     

Urban aerosol evolution and particle formation during wintertime temperature inversions

Aerosol temporal and spatial distributions during wintertime temperature inversions in Gothenburg, Sweden, have been characterized by ground-based and airborne particle measurements combined with lidar measurements. Ground inversions frequently developed during evenings and nights with stable cold conditions, and the low wintertime insolation often resulted in near neutral boundary layer conditions during day-time. Under these conditions ground level aerosol concentrations peaked during morning rush hours and often remained relatively high throughout the day due to inefficient ventilation. The particle number concentrations decreased slowly with increasing altitude within the boundary layer, and measurements slightly above the boundary layer suggested limited entrainment of polluted air into the free troposphere. High concentrations of ultrafine particles were observed throughout the boundary layer up to altitudes of 1100 m, which suggested that nucleation took place within the residual layer during the night and early morning. Recently formed particles were also observed around midday when the layer near ground was ventilated by mixing into the boundary layer, which indicated that ultrafine particles were either transported down from the residual layer to ground level or formed when the polluted surface layer mixed with the cleaner air above.