Smithsonian's perspective on impact of global warming on biodiversity
As an extremely diverse region of rainforest and coral reefs, the tropics may have the most to lose as a result of global warming. Some disagree, arguing that tropical organisms will be favored as their ranges expand into temperate areas. Few empirical studies provide specific answers to help us choose conservation and mitigation measures.
Science asked Jens Svenning, University of Aarhus, Denmark and Richard Condit of the Smithsonian's Global Earth Observatory Network to review two papers about species range change.
In a range analysis for plants and insects on a mountain slope in Costa Rica, Colwell et al. show that a 3.2˚ C increase in temperature threatens 53 percent of the area's species with lowland extinction and 51 percent with range shift gaps, meaning that they have nowhere else to go.
The other study they reviewed, by Moritz et al., follows historical range expansions and contractions for small mammals in Yosemite National Park in California, USA and shows that ranges may contract dangerously as they are pushed further and further up mountain slopes:
energy :: sustainability :: biodiversity :: tropics :: extinction :: ecosystem :: species :: global warming :: climate change ::
To provide the proper perspective for this work Svenning, who held a postdoctoral fellowship with the Smithsonian's GEO network in 2000-2002 and Condit cite empirical work by colleagues at the Smithsonian and others.
In a 2001 Science article by STRI staff scientist Carlos Jaramillo et al., plant pollen diversity in rock cores from northern South America revealed that warming events in the tropics over 60 million years were not particularly detrimental, with the caveat that warming in fragmented landscapes or crossing a temperature threshold could cause severe extinctions in the future.
Extant species that evolved in warmer climates should retain the ability to tolerate warmer climates in the future, as argued in a 2001 issue of Science by Eldredge Bermingham, director of STRI and Christopher Dick, professor of ecology and evolutionary biology at the University of Michigan at Ann Arbor.
It is not clear which factors (temperature, moisture, competition with other species, habitat limitation) are the primary causes of tropical extinctions. Drought tolerance, however, definitely limits tropical plant distributions. This was reported in the May 2007 issue of Nature by Bettina Engelbrecht, research associate and lecturer at San Francisco State University, and colleagues.
Condit and Svenning also cite their own studies from the tropics and temperate areas where other drivers of extinction are at work. They call for more discoveries of the sort that often result when researchers are brought together in places like STRI's facilities in Panama, where camaraderie fuels critical ecological research within an intellectual context that encourages a deep time and wide world perspective.
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.
Picture: How will a warmer world affect seasonal behavior such as the flowering of these Cuipo trees in Panama? Credit: Marcos Guerra, STRI
References:
Jens-Christian Svenning and Richard Condit, "Biodiversity in a Warmer World", Science 10 October 2008: Vol. 322. no. 5899, pp. 206 - 207, DOI: 10.1126/science.1164542
2 Comments:
Is THIS what you're so het up about?
Come on guys, get a grip. There's a whole world of serious, grown-up stuff to talk about. Don't destroy you credibility with fairy-tales.
Over the past several hundred million years, atmospheric CO2 levels have varied wildly. During that time, plants and animals evolved and adapted to the changing levels of CO2.
Some plants are optimised to higher levels than at present, some to lower, depending upon their evolutionary history. Some plants that evolved for higher levels than at present are essentially CO2 starved.
You should understand that the competition for advantages within environmental niches is ongoing, and will never stop while life exists.
Rather than reducing this discussion to the one-dimensional framework of "catastrophic anthropogenic global warming", intelligent people would expand the framework to look more deeply and broadly.
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