Choose your own priorities on our interactive table

Issues: conflict l global warming l disease l hunger l terrorism

The Challenge

There is unequivocal evidence that humans are changing the planet’s climate. We are already committed to average temperature increases of about 0.6°C, even without further rises in atmospheric carbon dioxide concentration.

An introduction to the Copenhagen Consensus

Economists battle it out to rank possible solutions for the great challenges in global stability and security

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• Make your own rankings on our interactive table

BACKGROUND

• Copenhagen Consensus: conflict

• Copenhagen Consensus: disease

• Copenhagen Consensus: global warming

• Copenhagen Consensus: hunger

• Copenhagen Consensus: terrorism

The world has focused on mitigation — reducing carbon emissions — a close look at the costs and benefits suggests that relying on this alone is a poor approach.

Option One: Continuing focus on mitigation

Even if mitigation — economic measures like taxes or trading systems — succeeded in capping emissions at 2010 levels, then the world would pump out 55 billion tonnes of carbon emissions in 2100, instead of 67 billion tonnes.

It is a difference of 18 per cent: the benefits would remain smaller than 0.5 per cent of the world’s GDP for more than 200 years. These benefits simply are not large enough to make the investment worthwhile.

The Numbers

Spending $800 billion over 100 years solely on mitigating emissions would lose money overall.

When you add up the benefits of that spending — from the slightly lower temperatures that would result — the returns are only $685 billion. For each dollar spent, we would get 90 cents of ‘good’ back. Mitigation alone will clearly not 'solve' the climate problem.

Option Two: Combining mitigation with other policies

In addition to mitigation, policy-makers must ensure that we adapt to climate change. Adaptation can mean doing things like growing drought tolerant crops, spending more on irrigation, developing rainwater storage systems, or proactively preventing the health issues that climate change poses.

But to make a real difference, the world needs to increase its research and development into carbon saving and sequestering technology.

The Numbers

Instead of spending $800 billion (in total present-day terms) solely on mitigation, we could keep the investment the same size but direct a small amount to adaptation policies, and $50bn each year to research into greener technology.

This research spend would add up to about 0.1 per cent of global GDP.

As the gap between the cost of carbon-free and carbon-emitting technology decreases, any tax on emissions should become smaller. This allows the research and development essentially to pay for itself.

With research and development in the mix, the total benefits from this $800bn investment would add up to more than $2,129bn. That is a more respectable $2.70 return on each dollar spent.

Other Options

Mitigation plus Research & Development: Investing immediately in R&D to make low-carbon energy options available more quickly, and to increase the effectiveness of mitigation in the longer term

Research & Development Only: Focusing investment on research and development to stimulate the shift to low-cost, low-carbon energy technologies

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