The quiet crossing of ocean tipping points
Anthropogenic climate change profoundly alters the ocean’s environmental conditions, which, in turn, impact marine ecosystems. Some of these changes are happening fast and may be difficult to reverse. The identification and monitoring of such changes, which also includes tipping points, is an ongoing and emerging research effort. Prevention of negative impacts requires mitigation efforts based on feasible research-based pathways. Climate-induced tipping points are traditionally associated with singular catastrophic events (relative to natural variations) of dramatic negative impact. High-probability high-impact ocean tipping points due to warming, ocean acidification, and deoxygenation may be more fragmented both regionally and in time but add up to global dimensions. These tipping points in combination with gradual changes need to be addressed as seriously as singular catastrophic events in order to prevent the cumulative and often compounding negative societal and Earth system impacts.
Dispatch from the Pacific. When Tropical Cyclone Harold meets the Novel Corona Virus
COVID-19 began to manifest in the Pacific Islands by early March 2020, starting in the US and French territories, spreading slowly to the independent countries of Fiji, Papua New Guinea and Timor-Leste. All of the independent Pacific countries responded with aggressive measures, closing borders and establishing curfews. Against this background, Tropical Cyclone Harold, formed on April Fool’s Day, began its devastating path through four Pacific countries: Solomon Islands with 27 dead in a ferry accident; Vanuatu whose northern islands, including Santo and Malekula were devastated by the cyclone with wind speeds greater than 200 km/h. The devastation continued in Fiji, with two tornadoes and devastation particularly in Kadavu and the southern Lau group. Tropical Cyclone Harold struck Tonga at the height of the king tide. COVID-19 continues to complicate relief efforts, particularly in Vanuatu. As of May 3, 2020, sixteen Pacific countries and territories had yet to report their first confirmed case of COVID-19: American Samoa, Cook Islands, Federated States of Micronesia, Kiribati, Nauru, Niue, Palau, Pitcairn, Republic of the Marshall Islands, Samoa, Solomon Islands, Tokelau, Tonga, Tuvalu, Vanuatu and Wallis and Futuna. The Pacific continues to lead by example motivated by collective stewardship with actions and policies based on science. Pacific leaders continue to work with the World Health Organisation (WHO) to implement COVID-19 management recommendations.
Meta-analysis of factors influencing population differentiation in yellowfin tuna (Thunnus albacares)
Decades of study have attempted to describe the population genetic structure of tuna species, including a significant number of studies focused on yellowfin (Thunnus albacares). Very often, analyses do not agree on how many stocks exist per species, and where their boundaries lie. This is possibly because studies vary so much across numerous variables, such as the geographic range covered in a study, the number and type of genetic markers used, and the number of sites sampled. This meta-analysis of 22 yellowfin studies attempts to standardize and isolate the key variables to assessing the strength of correlation with the resulting number of populations a study observes. Overall trends across the studies suggest that genetic markers with a high probability of being under selective constraints, or are located in coding regions, are more or less likely to sense population structure depending on geographic range coverage. Alternatively, when assessing neutral or non-coding genomic regions, studies also benefit from (i) more polymorphic and numerous loci, and (ii) increasing the number of sampling locations analyzed, both of which increase the statistical power of an analysis. Finally, trends were clearest when groups of accurately identified coding and non-coding, or neutral and non-neutral, studies were further subdivided by whether they used mitochondrial or nuclear DNA, confirming that analyses of the two genomes should not be compared directly. Our meta-analysis provides concrete support for long held assumptions about the relationships between population genetics study parameters and outcomes, and provides guidance for future studies on how to maximize the likelihood of identifying population structure where it exists.
Air temperature trends, variability and extremes across the Solomon Islands: 1951-2011
Past climatological studies .use only one or two local stations to describe the full climate of Solomon Islands. In this paper, we examined all available daily minimum and maximum surface air temperature data between 1951 and 2011 for all seven weather stations operated by the Solomon Islands Meteorological Service. Taro has the highest mean temperature (Tmean) at 27.5°C, owing its warmer climate to its proximity to the equator than other stations. Henderson at the central region averaged the least at 26.9°C during the same period. Honiara has the warmest Tmean on average from June through October due to its elevation. The overall annual Tmean for the country was 27.3°C with the maximum at 30.8°C and the minimum at 23.7°C. All seven stations show significant trend in Tmean, ranging from 0.14 to 0.39 °C/decade. Over three decades, the frequency of warm days (warm nights) increased by 2.2 days/decade (0.8 nights/decade) with a corresponding decrease of cool days (cool nights) by 0.4 days/decade (1.4 nights/decade). The climate of the Solomon Islands has warmed significantly between 1951 and 2011 with more warm days and nights, and fewer cool days and nights.