Knowledge and implications of global change in the oceans for biology, ecology, and ecosystem services - Ocean Sustainability in the 21st Century - page 124

4.1 Introduction
There is an increasing awareness that the Earth is changing, but it is still unknown whether
these changes occur cyclically, stochastically, episodically, or are long-term trends. The con-
temporary global climate change is a reality and a result of human activities that annually
release gigatonnes of carbon into the Earth's atmosphere (IPCC, 2007 ; Hansen et al., 2007 ) .
Direct consequences of cumulative post-industrial emissions include increasing global tem-
perature, perturbed regional weather patterns, rising sea levels, acidifying oceans, decreas-
ing oxygen concentration, changed nutrient loads, and altered ocean circulation (Brierley
and Kingsford, 2009 ). All of these factors cause climate change to have different effects on
marine ecosystems, their function, biodiversity, and on the goods and services that they can
provide. These contribute to human welfare, both directly and indirectly, and represent part
of the total economic value of the planet (Costanza et al., 1997 ); therefore, the loss of these
goods and services has important social and economic implications. Also deep-sea ecosys-
tems, which have long been thought to be extremely stable in terms of physico-chemical
conditions, may experience abrupt change and climate-driven temperature shifts as a dir-
ect consequence of the prevailing surface climate conditions (Smith et al., 2009 ; Masuda et
al., 2010 ; Fahrbach et al., 2011 ) . Contemporary climate change has the potential to perturb
ocean circulation on a time-scale far shorter than that of continental drift. For example, a re-
ductionintheNorthAtlantic Currentcouldhavemajorimplications fornorthernEuropeand
beyond during this century (Cunningham et al., 2007 ) . This emphasizes the importance of
regional considerations versus global generalization of the 'global warming' paradigm (Bri-
erley and Kingsford, 2009 ) . Climate-induced changes strongly differ across the globe, espe-
ciallyalongalatitudinalgradient.Warmingappearsmorepronouncedatthepolesthanatthe
equator, and the responses of climate change are expected to differ for different marine hab-
itats (Hoegh-Guldberg and Bruno, 2010 ; McGinty et al., 2011 ) . For example, whilst open
oceans are more affected by the influence of wind on the timing and strength of stratifica-
tion, coastal areas are expected to be more vulnerable to the effects of wind due to storms.