Corrigendum: Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy.

[This corrects the article DOI: 10.1093/biosci/bix133.].

Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy.

Increasing surface temperatures, Arctic sea-ice loss, and other evidence of anthropogenic global warming (AGW) are acknowledged by every major scientific organization in the world. However, there is a wide gap between this broad scientific consensus and public opinion. Internet blogs have strongly contributed to this consensus gap by fomenting misunderstandings of AGW causes and consequences. Polar bears (Ursus maritimus) have become a "poster species" for AGW, making them a target of those denying AGW evidence. Here, focusing on Arctic sea ice and polar bears, we show that blogs that deny or downplay AGW disregard the overwhelming scientific evidence of Arctic sea-ice loss and polar bear vulnerability. By denying the impacts of AGW on polar bears, bloggers aim to cast doubt on other established ecological consequences of AGW, aggravating the consensus gap. To counter misinformation and reduce this gap, scientists should directly engage the public in the media and blogosphere.

Scientists' views about attribution of global warming.

Results are presented from a survey held among 1868 scientists studying various aspects of climate change, including physical climate, climate impacts, and mitigation. The survey was unique in its size, broadness and level of detail. Consistent with other research, we found that, as the level of expertise in climate science grew, so too did the level of agreement on anthropogenic causation. 90% of respondents with more than 10 climate-related peer-reviewed publications (about half of all respondents), explicitly agreed with anthropogenic greenhouse gases (GHGs) being the dominant driver of recent global warming. The respondents' quantitative estimate of the GHG contribution appeared to strongly depend on their judgment or knowledge of the cooling effect of aerosols. The phrasing of the IPCC attribution statement in its fourth assessment report (AR4)-providing a lower limit for the isolated GHG contribution-may have led to an underestimation of the GHG influence on recent warming. The phrasing was improved in AR5. We also report on the respondents' views on other factors contributing to global warming; of these Land Use and Land Cover Change (LULCC) was considered the most important. Respondents who characterized human influence on climate as insignificant, reported having had the most frequent media coverage regarding their views on climate change.

Evidence for the role of organics in aerosol particle formation under atmospheric conditions.

New particle formation in the atmosphere is an important parameter in governing the radiative forcing of atmospheric aerosols. However, detailed nucleation mechanisms remain ambiguous, as laboratory data have so far not been successful in explaining atmospheric nucleation. We investigated the formation of new particles in a smog chamber simulating the photochemical formation of H(2)SO(4) and organic condensable species. Nucleation occurs at H(2)SO(4) concentrations similar to those found in the ambient atmosphere during nucleation events. The measured particle formation rates are proportional to the product of the concentrations of H(2)SO(4) and an organic molecule. This suggests that only one H(2)SO(4) molecule and one organic molecule are involved in the rate-limiting step of the observed nucleation process. Parameterizing this process in a global aerosol model results in substantially better agreement with ambient observations compared to control runs.

Alpha-pinene oxidation in the presence of seed aerosol: estimates of nucleation rates, growth rates, and yield.

A recently developed inverse-modeling procedure has been applied to a case study of particle nucleation and growth following alpha-pinene and SO2 oxidation in a smog chamber. With the use of only the measured aerosol size distributions as input, the condensational growth rate is obtained by regression analysis of the general dynamic equation, taking into account coagulation and wall losses. The growth rate provides an indirect measure of the concentration of the condensing species, offset by their vapor pressures. Assuming a particle density of 1.0 g cm(-3), an aerosol yield of 7 +/- 1% is obtained for an initial alpha-pinene concentration of 14 ppbv and a final organic aerosol mass of 4 microg m3. Using the estimated vapor concentration, we show that the time-dependence of the yield is at least partly due to the time needed for condensation. Such a kinetic limitation to secondary organic aerosol formation may have implications for our understanding of gas-particle partitioning. The measured size distributions are also used to determine the empirical nucleation rate; it appears to be enhanced by the presence of organics.