Geoscience Reference
In-Depth Information
Figure 5.1
Key chemical and physical changes in the atmosphere and oceans as a result
of climate change
Source: Poloczanska et al., 2007
afforded land-based ecosystems (Richardson and Poloczanska, 2008), there is
now a growing literature describing changes in the distribution and abundance of
marine species and communities, the loss of habitat forming species such as coral
reefs and mangroves, and changes to marine ecosystem structures and processes
(Hoegh-Guldberg and Bruno, 2010). These changes are largely consistent with
the expected direction and intensity of climate change (
Figure 5.2
). Impacts
relating to climate change have been observed via the responses of hundreds
of different species and numerous fundamental ecosystem processes, such as
primary productivity and the flow of energy and nutrients through trophic levels.
Organisms as different as phytoplankton, zooplankton, fish and seabirds have
shifted their distributions polewards and advances in reproductive timing during
spring have been observed in many systems (Poloczanska et al., 2007). Warming
of the upper ocean layers has also led to an increase in stratification (with a
corresponding reduction in nutrient availability), which has further reduced
the primary productivity of the least productive areas of the ocean. As a result,
oligotrophic (low nutrient) gyres in the Pacific and Indian Ocean have increased
by 6.6 million km² or 15 per cent over the period 1998 to 2006 (Polovina et al.,
2008). The changes that are being seen throughout out the world's oceans are
extensive and fundamental (
Figure 5.2
).
Australian marine ecosystems are revealing an increasing number of biological
responses to changes in ocean temperature and ocean chemistry (for details
