Climate Changes

Several stories on the science and politics of global warming caught our attention this week:

Temperature increases resulting from climate change in the southwestern U.S. will likely eliminate Joshua trees from 90 percent of their current range in 60 to 90 years, according to a new study led by U.S. Geological Survey ecologist Ken Cole. The research team used models of future climate, an analysis of the climatic tolerances of the species in its current range, and the fossil record to project the future distribution of Joshua trees. The study concludes that the species could be restricted to the northernmost portion of its current range as early as the end of this century. The Joshua tree, a giant North American yucca, occupies desert grasslands and shrublands of the Mojave Desert of California, Nevada, Arizona, and Utah.

Regions in relative high latitudes – China, Russia and the U.S. – could see a significant increase in arable land in coming years, but Africa, Europe and India and South America could lose land area, according to a study published in the journal Environmental Research Letters. “The possible gains and losses of arable land in various regions worldwide may generate tremendous impacts in the upcoming decades upon regional and global agricultural commodity production, demand and trade, as well as on the planning and development of agricultural and engineering infrastructures,” said study author and civil and environmental engineering professor Ximing Cai.

When icebergs cool and dilute oceans, they also raise chlorophyll levels in the water that may in turn increase carbon dioxide absorption in the Southern Ocean, according to research published in the journal Nature Geosciences. “The latest findings document a persistent change in physical and biological characteristics of surface waters after the transit of an iceberg, which has important effects on phytoplankton populations, clearly demonstrating that icebergs influence oceanic surface waters and mixing to greater extents than previously realized,” said Ronald Kaufmann, associate professor of marine science and environmental studies at the University of San Diego and one of the authors of the paper.

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