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10. The Future of Coral Reefs in a
Rapidly Changing World
O. Hoegh-Guldberg
Coral reefs are renowned for their breathtaking beauty
and the bounty of diverse life forms that live within
their carbonate structures. This book is a testimony to
this splendour and variety. Unfortunately, coral reefs
are changing due to the influence of humans on the
marine environment. These changes are coming about
due to the exploitation of coral reef organisms and
through insidious changes to the condition of the waters (increased sediments and nutrients) that surround
them. While these changes are having a very large impact on coral reefs (Chapter 9), changes to important
atmospheric components called greenhouse gases are
driving even larger impacts due to rapid changes to
global climate, including the seas in which coral reefs
live. These effects of climate change have impacted
coral reefs in a spectacular fashion, with thousands of
square kilometres of often remote coral reefs becoming
stressed, with often large numbers of reef-dwelling
organisms dying. While the impacts on coral reefs are
only a small subset of the ecosystem changes that are
happening across the planet as a result of climate
change, coral reefs have grabbed public attention. This
is because they are the first iconic ecosystem to demonstrate that biological systems, rather than changing
gradually, may change abruptly and substantially as a
result of climate change.
In this chapter, the issue of climate change is outlined
and discussed, particularly with references to past, current and future climate change. There are several major
issues. The first is the unusual nature of the current
changes in our climate system. The second is the response of coral reef organisms to our rapidly warming
and acidifying ocean. The last concerns possible options
we have for minimising the impacts of greenhouse
driven change on coral reefs. Discussion of these issues
leads us to several conclusions. First, coral reefs are unable to sustain atmospheric concentrations of carbon dioxide of more than 450 parts per million (ppm); efforts to
reduce emissions must therefore be intensified. Second,
efforts to reduce local stresses (e.g. declining water quality, over-exploitation of coral reef fish stocks; see Chapter 9) must be increased as coral reefs enter a period of a
rapidly shifting oceanic climate. Addressing these two
aspects aggressively over the next decade represents the
last chance we have of preventing the loss of coral reefs
for hundreds, if not thousands, of years.
N THE ENHANCED GREENHOUSE EFFECT
Radiation from the sun heats terrestrial, oceanic and
atmospheric components of the Earth. About 30% of
incoming energy is eventually reradiated back into
10. The Future of Coral Reefs in a
Rapidly Changing World
O. Hoegh-Guldberg
Coral reefs are renowned for their breathtaking beauty
and the bounty of diverse life forms that live within
their carbonate structures. This book is a testimony to
this splendour and variety. Unfortunately, coral reefs
are changing due to the influence of humans on the
marine environment. These changes are coming about
due to the exploitation of coral reef organisms and
through insidious changes to the condition of the waters (increased sediments and nutrients) that surround
them. While these changes are having a very large impact on coral reefs (Chapter 9), changes to important
atmospheric components called greenhouse gases are
driving even larger impacts due to rapid changes to
global climate, including the seas in which coral reefs
live. These effects of climate change have impacted
coral reefs in a spectacular fashion, with thousands of
square kilometres of often remote coral reefs becoming
stressed, with often large numbers of reef-dwelling
organisms dying. While the impacts on coral reefs are
only a small subset of the ecosystem changes that are
happening across the planet as a result of climate
change, coral reefs have grabbed public attention. This
is because they are the first iconic ecosystem to demonstrate that biological systems, rather than changing
gradually, may change abruptly and substantially as a
result of climate change.
In this chapter, the issue of climate change is outlined
and discussed, particularly with references to past, current and future climate change. There are several major
issues. The first is the unusual nature of the current
changes in our climate system. The second is the response of coral reef organisms to our rapidly warming
and acidifying ocean. The last concerns possible options
we have for minimising the impacts of greenhouse
driven change on coral reefs. Discussion of these issues
leads us to several conclusions. First, coral reefs are unable to sustain atmospheric concentrations of carbon dioxide of more than 450 parts per million (ppm); efforts to
reduce emissions must therefore be intensified. Second,
efforts to reduce local stresses (e.g. declining water quality, over-exploitation of coral reef fish stocks; see Chapter 9) must be increased as coral reefs enter a period of a
rapidly shifting oceanic climate. Addressing these two
aspects aggressively over the next decade represents the
last chance we have of preventing the loss of coral reefs
for hundreds, if not thousands, of years.
N THE ENHANCED GREENHOUSE EFFECT
Radiation from the sun heats terrestrial, oceanic and
atmospheric components of the Earth. About 30% of
incoming energy is eventually reradiated back into