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This section offers science-related news briefs as of October 2021. Topics discussed include the degradation of water quality during periods of drought in the Central Valley region of California, the possibility of manufacturing commercial monomers without greenhouse gas emissions, and the symbiotic relationship between soybean root nodules and nitrogen-fixing bacteria.

The article reports on a warning from scientists that the Great Salt Lake in Utah is at risk of collapse due to its low water level and salt concentrations exceeding a threshold at which essential microorganisms begin to die. Driven by drought and water diversion, the trends are said to threaten the base of the lake's food web. Actions taken to address the impending crisis include the signing of a landmark series of bills aimed at rescuing the lake and addressing the drought.

Ecological character displacement is a process of morphological divergence that reduces competition for limited resources.We used genomic analysis to investigate the genetic basis of a documented character displacement event in Darwin's finches on Daphne Major in the Galápagos Islands: The medium ground finch diverged from its competitor, the large ground finch, during a severe drought. We discovered a genomic region containing the HMGA2 gene that varies systematically among Darwin's finch species with different beak sizes. Two haplotypes that diverged early in the radiation were involved in the character displacement event: Genotypes associated with large beak size were at a strong selective disadvantage in medium ground finches (selection coefficient s = 0.59). Thus, a major locus has apparently facilitated a rapid ecological diversification in the adaptive radiation of Darwin's finches. [ABSTRACT FROM AUTHOR]

The western United States has been experiencing severe drought since 2013. The solid earth response to the accompanying loss of surface and near-surface water mass should be a broad region of uplift. We use seasonally adjusted time series from continuously operating global positioning system stations to measure this uplift, which we invert to estimate mass loss. The median uplift is 5 millimeters (mm), with values up to 15 mm in California's mountains. The associated pattern of mass loss, ranging up to 50 centimeters (cm) of water equivalent, is consistent with observed decreases in precipitation and streamflow. We estimate the total deficit to be ~240 gigatons, equivalent to a 10-cm layer of water over the entire region, or the annual mass loss from the Greenland Ice Sheet. [ABSTRACT FROM AUTHOR]

Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 1015 to 1.6 x 1015 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change. [ABSTRACT FROM AUTHOR]

The author reviews reports and research on the contribution of climate change to extreme events such as droughts. The author looks at the different methods used in the attribution of extreme events to climate change including couple climate model to simulate evolution of climate change, ensembles of atmosphere-only models that sample the occurrence of a rare event of interest, and circulation regime. Emphasis is given on the need for improvements in techniques for analyzing extreme events.

The article discusses the increase in salinity in the fresh water of rivers, marshes and canals in southern Iraq, including the role that the Persian Gulf plays in this regard. An overview of the impact that droughts, weakened river flow and upstream dams have on the increased salinity of fresh water in southern Iraq is provided.

The article reviews research on climate change in western North America and the western U.S. It notes areas in North America where dramatic warming has resulted in declines in seasonal snowpack and changes in winter storm patterns, drought, and vegetation mortality. The temperature of Colorado River headwaters is compared to average temperatures observed in the 20th century. The Southwest is said to be affected by warming more than other areas. Southwest water reservoirs including Lake Powell and Lake Mead are said to have lost half their volume between 1999 and 2004 due to drought.

The article discusses a two-year-long drought in southeast Brazil that has threatened a possible collapse of the area's major water supplies. Topics include a rainfall anomaly caused by persistent high pressure blocking the southward flow of water vapor from Brazil's Amazon forest, the Brazilian government's lack of preparation for such extreme climate events, and recommendations for the expansion of sanitation systems and tapping of new water resources by the Brazilian Academy of Sciences.

In this article the authors discuss aspects of a cave biodiversity project supported by the World Bank's Global Environment Facility that allowed the survey of fauna in 117 caves in 32 parts of Guangxi Autonomous Region, China, between 2005-2012 by both Chinese and international scientists. Topics include the biodiversity of cave fauna in southwestern China, the impact of severe drought in southwestern China, and its impact on the region's cave fauna.

The article presents technical comment abstracts on the article "Drought-Induced Reduction in Global Terrestrial Net Primary Production From 2000 Through 2009," by Maosheng Zhao and Steven W. Running that appeared in the August 20, 2011 issue of "Science."