Sometimes it appears that climate change issues cannot be realistically grasped without attaching signs. Not the positive or negative signs associated with radiative forcing but the $$$$ signs. We need to reduce emissions and there is a cost associated with it. Indicated are some key pointers from the Stern Report. Although these quotes are from the Stern Report, the message is general.

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Climate change could have very serious impacts on growth and development.

There is still time to avoid the worst impacts of climate change, if we take strong action now.

The costs of stabilising the climate are significant but manageable; delay would be dangerous and much more costly.

Action on climate change is required across all countries.

A range of options exists to cut emissions; strong, deliberate policy action is required to motivate their take-up.

Climate change demands an international response, based on a shared understanding of long-term goals and agreement on frameworks for action.

The expected annual cost of achieving emissions reductions, consistent with an emissions trajectory leading to stabilisation at around 500-550ppm CO2e, is likely to be around 1% of GDP by 2050, with a range of +/- 3%.

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Now these estimates of the cost can vary depending on the models used to project them. The reason we need to start thinking of what action we may take becomes more important as time goes by.

Here is a graph from the Stern Report (Chapter 9) that shows costs if fossil-fuel (energy) emissions were cut from 24 GtCO2e/year in 2002 to 18 GtCO2e/year in 2050.

The picture shows the average cost of reducing fossil fuel emissions to 18 GtCO2 in 2050*

*The red lines give uncertainty bounds around the central estimate. These have been calculated using Monte Carlo analysis. For each technology, the full range of possible costs (typically ± 30% for new technologies, ±20% for established ones) is specified. Similarly, future oil prices are specified as probability distributions ranging from $20 to over $80 per barrel, as are gas prices (£2-6/GJ), coal prices and future energy demands (to allow for the uncertain rate of uptake of energy efficiency). This produces a probability distribution that is the basis for the ranges given.

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Costs are likely to rise significantly as mitigation efforts become more ambitious or sudden, suggesting that efforts to reduce emissions rapidly are likely to be very costly.

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