Rising [CO.Sub.2], Climate Change, and Public Health: Exploring the Links to Plant Biology

Article excerpt

BACKGROUND: Although the issue of anthropogenic climate forcing and public health is widely recognized, one fundamental aspect has remained underappreciated: the impact of climatic change on plant biology and the well-being of human systems.

OBJECTIVES: We aimed to critically evaluate the extant and probable links between plant function and human health, drawing on the pertinent literature.

DISCUSSION: Here we provide a number of critical examples that range over various health concerns related to plant biology and climate change, including aerobiology, contact dermatitis, pharmacology, toxicology, and pesticide use.

CONCLUSIONS: There are a number of clear links among climate change, plant biology, and public health that remain underappreciated by both plant scientists and health care providers. We demonstrate the importance of such links in our understanding of climate change impacts and provide a list of key questions that will help to integrate plant biology into the current paradigm regarding climate change and human health.

KEY WORDS: aerobiology, contact dermatitis, food security, pharmacology, toxicology. Environ Health Perspect 117:155-158 (2009). doi:10.1289/ehp.11501 available via http://dx.doi.org/[Online 19 September 2008]

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The concentration of atmospheric carbon dioxide has increased by 22% since 1960 to a current background level of approximately 385 [micro]mol/mol (Intergovernmental Panel on Climate Change 2007). Recent evidence that the growth rate if [CO.sub.2] emissions may have jumped from 1.3% to 3.3% per year from the 1990s to 2000-2006, potentially as a result of declining global sinks and increased economic activity, emphasizes the critical need to characterize the probable impacts of this impending climate forcing on human systems (Canadell et al. 2007).

Because [CO.sub.2] absorbs heat leaving the earth's atmosphere, there is widespread agreement that increasing [CO.sub.2] is projected to result in increasing surface temperatures and wider swings in weather. The extent to which temperatures increase and weather patterns shift and the potential consequences for human health, from heat-related deaths to the spread of vector-borne diseases, have been addressed in the scientific literature (Epstein 2005; Gamble et al. 2008; Patz and Kovats 2002). Here we describe additional dimensions of global environmental change: the response of terrestrial plants to the buildup of atmospheric [CO.sub.2], potential climatic forcing with respect to temperature on plant growth, and the implications for human health and nutrition.

Plant biology is directly affected by rising [CO.sub.2] because [CO.sub.2] is the sole supplier of carbon for photosynthesis. Because approximately 95% of all plant species are deficient in the amount of [CO.sub.2] needed to operate at maximum efficiency, recent increases in [CO.sub.2] have already stimulated plant growth, and projected future increases will continue to do so (e.g., Poorter 1993), with the degree of stimulation being at least potentially temperature dependent (Long 1991). Critics of the potential of [CO.sub.2] as a greenhouse-warming gas have stressed that [CO.sub.2]-induced stimulation of plant growth will result in a lush plant environment (Idso and Idso 1994); indeed, much of the literature has focused on agronomically important species (see, e.g., Ainsworth et al. 2002; Kimball 1993). However, [CO.sub.2] does not discriminate between desirable (e.g., wheat, rice, and forest trees) and undesirable (e.g., ragweed, poison ivy) plant species with respect to human systems.

Objectives

What aspects of plant biology currently affect public health? How have, or will, changing levels of [CO.sub.2] and increasing surface temperature change those aspects? For many health care professionals, the role of plant biology has not been fully elucidated, yet it has a number of self-evident impacts, such as nutrition, and perhaps more subtle interactions, such as the spread of narcotic plant species, that deserve for consideration and attention. …