Effect of Global Warming

Malnutrition
With high confidence, Confalonieri et al. (2007) projected that malnutrition would increase due to climate change.Drought reduces variety in diets and reduces overall consumption. This can lead to micronutrient deficiencies.
The World Health Organization (WHO) (referred to by Confalonieri et al., 2007)[27] conducted a regional and global assessment to quantify the amount of premature morbidity and mortality due to a range of factors, including climate change. Projections were made over future climate change impacts. Limited adjustments for adaptation were included in the estimates based on these projections. Projected relative risks attributable to climate change in 2030 varied by health outcome and region. Risks were largely negative, with most of the projected disease burden due to increases in diarrhoeal disease and malnutrition. These increases were primarily in low-income populations already experiencing a large burden of disease.



Food supply
Main article: Climate change and agriculture
Climate change will impact agriculture and food production around the world due to: the effects of elevated CO2 in the atmosphere, higher temperatures, altered precipitation and transpiration regimes, increased frequency of extreme events, and modified weed, pest, and pathogen pressure (Easterling et al.., 2007:282).[23] In general, low-latitude areas are at most risk of having decreased crop yields (Schneider et al.., 2007:790).[10] With low to medium confidence, Schneider et al.. (2007:787) concluded that for about a 1 to 3°C global mean temperature increase (by 2100, relative to the 1990-2000 average level) there would be productivity decreases for some cereals in low latitudes, and productivity increases in high latitudes. With medium confidence, global production potential was predicted to:
• increase up to around 3°C,
• very likely decrease above about 3 to 4°C.
Most of the studies on global agriculture assessed by Schneider et al.. (2007:790) had not incorporated a number of critical factors, including changes in extreme events, or the spread of pests and diseases. Studies had also not considered the development of specific practices or technologies to aid adaptation.



Temperature rise
From 1961 to 2003, the global ocean temperature has risen by 0.10 °C from the surface to a depth of 700 m. There is variability both year-to-year and over longer time scales, with global ocean heat content observations showing high rates of warming for 1991 to 2003, but some cooling from 2003 to 2007.[21] The temperature of the Antarctic Southern Ocean rose by 0.17 °C (0.31 °F) between the 1950s and the 1980s, nearly twice the rate for the world's oceans as a whole [22]. As well as having effects on ecosystems (e.g. by melting sea ice, affecting algae that grow on its underside), warming reduces the ocean's ability to absorb CO2.


Oceans
The role of the oceans in global warming is a complex one. The oceans serve as a sink for carbon dioxide, taking up much that would otherwise remain in the atmosphere, but increased levels of CO2 have led to ocean acidification. Furthermore, as the temperature of the oceans increases, they become less able to absorb excess CO2. Global warming is projected to have a number of effects on the oceans. Ongoing effects include rising sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean surface, leading to increased temperature stratification. Other possible effects include large-scale changes in ocean circulation.