Geoscience Reference
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notably with earlier maturity, particularly in potatoes (Arteca
et al., 1979), sweet potatoes (Bhattacharya et al., 1985) and
increases in biological nitrogen fixation in soya beans (Hardy
and Havelka, 1975; Phillips et al., 1976; Finn and Brun, 1982;
Lamborg et al., 1983). Elevated CO
2
concentration may increase
carbohydrates, but may reduce chlorophyll, proteins, amino
acids, carotene and mineral nutrients (Bhattacharya and Geyer,
1993). Despite the potential positive effects on yield quantities,
elevated CO
2
may be detrimental to the yield quality of certain
crops, as in wheat through protein content reduction (Sinclair
et al., 2000).
Elevated CO
2
, besides affecting the crop, also affects the
environment, which in turn may have either beneficial or damag-
ing effects on agricultural production (Lemon, 1983; Morison,
1987; Peiris et al., 1996; Rosenzweig and Hillel, 1998). The pro-
jection of global-scale yields can be determined through the
strength of CO
2
fertilisation (Parry et al., 2004; Nelson et al.,
2009). North America and Europe will benefit from climate
change with strong CO
2
fertilisation but Africa and India will
lose 5% even with strong CO
2
fertilisation. These projected
losses will be up to 30% if the CO
2
fertilisation effects are not
considered. The crop response to elevated CO
2
may be actu-
ally lower than previously thought with consequences for crop
modelling and projections of food supply (Long et al., 2004,
2009). This is because of many limiting factors such as pests
and weeds, nutrients, competition for resources, soil water and
air quality, which are neither well understood at large scale nor
well implemented in leading models. The science, however, is
far from certain on the benefits of carbon fertilisation (Cline,
2008).
However, the nature of the biophysical effects and human
responses to agriculture are complex and uncertain (Adams
et al., 1998). There are large uncertainties to uncover; partic-
ularly, because there is lack of information on many specific
local regions and include the uncertainties on the magnitude
of climate change, the effects of technological changes on pro-
ductivity, water and fertiliser application strategies, changes
in pest and disease occurrence, global food demands and the
numerous possibilities of adaptation (Cannon, 2003; Engvild,
2003; Fuhrer, 2003). Most agronomists believe that agricul-
tural production will be mostly affected by the severity and
pace of climate change, not so much by gradual trends in cli-
mate. If change is gradual, there may be enough time for biota
adjustment. Rapid climate change, however, would harm agri-
culture in many countries, especially those that are already
