Emissions cuts of 16% by 2030 needed to have at least 70% chance of avoiding climate catastrophe, says Friends of the Earth

Governments are gambling recklessly with human lives by wilfully underestimating the depth of the emission cuts they must makein the next 40 years, a new study has found.

Governments have so far based their calculations for cutting emissions on only a 50:50 chance of holding temperature rises to 2C, the point that many scientists consider to be the threshold for catastrophic climate change which, once passed, will leave millions exposed to drought, hunger and flooding. This constitutes an unacceptable risk, says the report from Friends of the Earth.

It suggests that to have any reasonable chance – 70% rather than 50% – of avoiding dangerous climate change emissions will need to fall 16% by 2030 worldwide, based on 1990 levels.

The research, reviewed by Kevin Anderson, director of the Tyndall Centre for Climate Change research, comes just days after 193 governments at the UN climate summit in Cancún agreed to make emission cuts –but the biggest emitters declined to raise their ambitions.

Friends of the Earth says that if the maximum amount of global emissions the world could allow – what is called the remaining "carbon budget" – were shared out equally on the basis of average populations between now and 2050, the US would need to slash its emissions by as much as 95% by 2030, the EU by 83%, and the UK by 80%. Just a week ago, the government's climate advisers said the UK should aim for a 60% cut by 2030.

China would need to peak its emissions by 2013 and then reduce them by 5% per year, today's report said. If historical, cumulative emissions are counted, the US and EU have already used more than their share of the global carbon budget. Emissions in these countries would need to cease immediately.

The group argues that the longer action to reduce emissions is delayed, the harder it will become to make deep enough cuts. If the world had cut emissions by just 1.5% a year even 15 years ago, a yearafter countries ratified the UN climate change convention, there would have been a good chance of avoiding a 2C rise in global temperatures, it says.

It called for further research to identify whether these cuts are possible using existing technologies and which new ones need to be developed as a matter of urgency.

"To make the cuts necessary, developing countries need to be provided with finance and technology. Cancún made tiny steps in dealing with these issues but we are a million miles from what is necessary. Countries are paying lip-service to two degrees. Urgent action and research are needed to see just how much emissions can be cut. It may even need geo-engineering [manipulating the world's climate]", said Mike Childs, head of climate change at Friends of the Earth.

"This report is uncomfortable but essential reading for all policymakers. It shows that the remaining global carbon budget for even a 2C temperature rise is small and diminishing," said Anderson.

"It's astonishing that the UK, EU and G8 have adopted policies based on a 50:50 chance of avoiding a two-degree rise in global temperatures – this is a reckless gamble with the lives and livelihoods of millions of people on the planet," said Andy Atkins, direcor of Friends of the earth.