Chapter ?. Biodiversity and Global Climate Change ………..…………....… Amanda Isbell
Introduction
Biodiversity is defined as the genes, species, habitats, and ecosystems of a planet
(Sell, 1996; Feehan, 2009). These collective ecosystems are important to mankind,
because they provide necessary products and services that have become integral to human
society. Such resources include, but are not limited to: pest control, climate regulation,
food supply, and recreational aesthetics. Species and their ecosystems have had a variety
of responses to rising global temperatures, including migration patterns, decreasing range
sizes, and a change in host organisms (Feehan, 2009). This leads many scientists to
believe that the changing climate could play a direct role in biodiversity changes (Pimm,
2009). This chapter focuses on the impact of climate change on biodiversity, and specific
species that are sensitive to the environmental changes.
Biodiversity
According to the Millennium Ecosystem Assessment report, biodiversity is the
variability among living organisms from all sources, including terrestrial, marine, and
other aquatic ecosystems and the ecological complexes of which they are part. This
includes diversity within species, between species, and of ecosystems. This is an
important definition to understand, because it demonstrates how many factors must be
considered when accounting for the biodiversity of a certain space. Each of these aspects
is inherently significant to the success of the species and habitats contained within a
system, and thus, the biodiversity of the system. Biodiversity is responsible for things
such as timber products, the preservation of exotic species, food supply, the protection of
water sources, and the variety of genetic material in an ecosystem. These are resources
that have become vital to mankind. And yet, as essential as they are to a functioning
society, recent studies suggest that extinction rates are high and increasing, and
populations and habitats are declining in number (Millennium Ecosystem Assessment,
MEA, 2006). Figure 1. shows the decline in the populations of vertebrate species since
1970 (MEA, 2006).
Figure 1 The Living Planet Index (Source: Millennium Ecosystem Assessment, 2006)
Although this figure is not an accurate representation for non-vertebrates, it
demonstrates the trend of decreasing species numbers in recent decades. This presents a
problem for society. Biodiversity is usually associated with animal and plant species,
which has caused its role in everyday human life to become overlooked. But this trend of
decline could affect the quality of human life as well. For example, in a 2000 report, 25%
of medical prescriptions acquired their active ingredients from plant systems (Waldman
and Shevah, 2000). Should the projected decreases of species happen, we could
potentially lose some of these ingredients in their natural state.
Causes of Biodiversity Change
There are numerous sources that influence biodiversity change. Some
anthropogenic factors include increased urbanization, the modification of river systems,
habitat fragmentation due to infrastructure expansion, and the destruction of ecosystems
for economic and resource usage (Feehan, 2009). The most common theme between the
causes listed is that they fit under the category of land-use change. Land-use change has
been accepted as the most important factor of biodiversity change in the current century
(Sala and Jackson, 2006). A quantitative analysis completed in 1997 by Wilcove et al.
showed that 85% of listed species they examined were threatened by habitat change
(Beatley, 2000). This is concerning, because the regions most affected by land-use
change also tend to be the most biologically diverse. For example, tropical forests along
the equator contain somewhere between 50-90% of the species of the world (Sell, 1996).
Projections of vascular plant species show that these same regions will lose the most
biodiversity, with Tropical-Africa sustaining the most losses and Indo-Malayan the
second-most (MEA, 2006).
Another significant cause of biodiversity change is nutrient loading. Nutrient
loading is defined by
the Millennium
Ecosystem
Assessment as
anthropogenic
increases in nitrogen,
phosphorus, sulfur,
and other nutrientassociated pollutants.
In recent decades,
nitrogen loading has
become increasingly
popular due to its
agricultural
production benefits
(MEA, 2006). Figure
2. shows nitrogen
Figure 2. Source: Millennium Ecosystem Assessment
released into the
atmosphere per year and the rising usage. This graph demonstrates that current trends
carry projected nitrogen emissions past the range that ecosystems can convert into
beneficial products. Once this level has been reached, harmful effects can occur that
negate any beneficial crop yield. Such effects include: eutrophication of freshwater
ecosystems, hypoxia in coastal marine ecosystems, as well as nitrous oxide emissions that
pollute the atmosphere and contribute to global climate change (MEA, 2006).
The Millennium Ecosystem Assessment considers land-use change and nutrient
loading to be two of the three most significant drivers of biodiversity change. The third is
climate change, which will be discussed in detail in the next section.
The Impact of Global Climate Change
Climate change may not be the largest cause of biodiversity change on its own,
but it has been shown exacerbate the effects of other factors, and vice versa. For
example, fragmented populations are more susceptible to the effects of climate
change than non-fragmented populations (de Chazal, 2009). Fragmented
populations are already vulnerable to ecosystem change due in part to a lack of
genetic diversity that limits the ability of these populations to adapt to a new
environment (MEA, 2006). When combined together, these factors increase the
potential of extinction for at-risk species (de Chazal, 2009) and those that have
small habitat ranges (Feehan, 2009).
Although climate change is the largest threat to biodiversity when in
consideration with other factors, it does present issues of its own. In general, these
are range shifts, range losses, and population declines (Thuiller et all, 2005). More
specifically, climate change is expected to decrease water availability, increase the
risk of floods and wildfires, and increase the transmission of vector-borne diseases
in areas previously unaffected (MEA, 2006).
In the next addition, this chapter will delve into more specific details of the
impact that climate change has on global biodiversity. I will also chose example species
that are thought to be the most sensitive to global climate change and briefly discuss why.
References:
Beatley, T. “Preserving Biodiversity.” Journal of the American Planning Association;
Winter 2000; 66, 1.
de Chazal, Jacqueline, and Mark D.A. Rounsevell, “Land-use and climate change within
assessments of biodiversity change: A review”, Global Environmental Change,
Volume 19, Issue 2, May 2009, Pages 306-315, ISSN 0959-3780,
10.1016/j.gloenvcha.2008.09.007.
Feehan, Jane, Mike Harley, and Jell van Minnen. "Climate Change In Europe. 1. Impact
On Terrestrial Ecosystems And Biodiversity. A Review." Agronomy For
Sustainable Development (EDP Sciences)29.3 (2009): 409-421. Academic Search
Complete. Web. 3 Feb. 2012
Millennium Ecosystem Assessment, MEA, Millennium Ecosystem Assessment Synthesis
Reports. 2006
Pimm, S. L., “Climate Disruption and Biodiversity”, Current Biology, Volume 19, Issue
14, 28 July 2009, Pages R595-R601, ISSN 0960-9822,
10.1016/j.cub.2009.05.055.
Sala, E. and Robert B. Jackson. “Determinants of Biodiversity Change: Ecological Tools
for Building Scenarios”, Ecology , Vol. 87, No. 8 (Aug., 2006), pp. 1875-1876
Sell, S. “North-South environmental bargaining: Ozone, climate change, and
biodiversity”. Global governance 2.1 01 Jan 1996: 97-118. Lynne Rienner
Publishers, Inc. 31 Jan 2012
Thuiller, et al. “Potential Impacts Of Future Land Use And Climate Change On The Red
List Status Of The Proteaceae In The Cape Floristic Region, South
Africa.” Global Change Biology 11.9 (2005): 1452-1468. Environment Complete.
Web. 17 Feb. 2012.
Waldman, M., and Y. Shevah. "Biological Diversity - an Overview. " Water, Air and Soil
Pollution 123.1-4 (2000): 299. ABI/INFORM Global, ProQuest. Web. 3 Feb.
2012