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Why is CCS important?

world CO2 emissions, 1990 - 2035 Rising CO2 concentrations in the atmosphere from pre-industrial levels of 280ppm to a present day value of 365ppm has lead to increasing ocean acidification and may be contributing to climate change and a rising of global temperatures. A doubling of man-made CO2 emissions since the 1970's coupled with geological evidence, which shows that changes of this magnitude usually occur over timescales of 5,000 to 10,000 years, suggests that it is likely that man-made CO2 is contributing significantly to this rise in atmospheric CO2. If fossil fuel combustion is allowed to continue to grow unabated then it is projected that CO2 emissions will reach 35.4 Gt a year by 2035. This is inline with the worst case scenario in the IPCC 2007 Climate Change report which couples CO2 rises to a world average temperature increase from 2.4-6.4C by 2100. If the world is to maintain its current dependance on fossil fuels then CCS is a necessary technology for tackling rising atmospheric CO2.


UK CO2 emissions, pre-industrial revolution to present Rising CO2The UK emits more than 500 millions of tonnes of carbon dioxide every year. The quantity has steadily increased since the start of the industrial revolution (1800's). We are not the country that uses the most CO2 per member of the population - but our usage is still high. Worldwide, emissions are still rising. UK CO2 emissions since before the industrial revolution. The image to the right shows data compiled by G. Marland, T. A. Boden and R. J. Andres of ORNL.

How does CO2 affect the climate?

Global temperatures and atmospheric CO<sub>2</sub> levels, 1880 to 2010 The effects of carbon dioxide in the atmosphere are controversial. However, the average temperature of the Earth is rising, especially when measured at the poles. Note that the average Earth surface temperature correlates well with the amount of CO2 in the atmosphere (i.e. as the CO2 levels in the atmosphere have increased, the surface temperature has gone up at the same time).

For more general climate change information click here, and for more on the science behind climate change prediction click here.

How does CO2 affect the oceans?

predicted increases in ocean acidity, 1750 to 3000
Caldeira, K. & Wickett, M.E. (2003) Nature, v. 425. p. 365
About half of the extra CO2 from the atmosphere will dissolve in the oceans, making the water more acidic. The diagram shows how acidic the oceans will become in the future, up to the year 3000. To work this out, it was necessary to:
  1. predict how CO2 emissions will change in the future (the top of the diagram)
  2. calculate how this will change the amount of CO2 in the atmosphere (middle part of the diagram)
  3. finally work out how acidic the oceans will become (bottom part of the diagram)
The acidity is shown as a change in pH units. The effects of this change on marine life is unknown, but could be disastrous.


Surface ocean acidity The effects of making the ocean more acid are absolutely inevitable, and are easy to predict, as it relies on simple chemistry, not on complex computer models of climate. The ocean already holds 400 Billion tons of fossil fuel CO2. Consequently, the ocean is already 0.1 pH units more acid than before industrial CO2 emissions. This means nutrients for plankton in the North Sea, and all shallow ocean waters, are changing rapidly. This is the base of the food chain for invertebrates, shells and, eventually, economic fishing. By 2050 the ocean will be five times more acid than at any time since glaciation (change pH 8.4 to pH 7.8). More information on ocean acidification.

Image adapted from Wolf-Gladrow et al. (1999).
Last modified: 21 Mar, 2012
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