The commitments made by governments on climate change will lead to dangerous levels of global warming because they are incommensurate with the growth of greenhouse gas emissions, according to a new report.

The United Nations Environment Programme (Unep) said that pledges put forward to cut emissions would see temperatures rise by 3C above pre-industrial levels, far above the the 2C of the Paris climate agreement, which comes into force on Friday.

At least a quarter must be cut from emissions by the end of the next decade, compared with current trends, the UN said.

The report found that emissions by 2030 were likely to reach about 54 to 56 gigatonnes of carbon dioxide equivalent a year, a long way astray of the 42 gigatonnes a year likely to be the level at which warming exceeds 2C.

What is the Paris agreement? It's a climate change accord agreed by nearly 200 countries in December 2015, which came into force on 4 November 2016. The agreement commits world leaders to keeping global warming below 2C, seen as the threshold for safety by scientists, and pursuing a tougher target of 1.5C. The carbon emission curbs put forward by countries under Paris are not legally-binding but the framework of the accord, which includes a mechanism for periodically cranking those pledges up, is binding. The agreement also has a long-term goal for net zero emissions which would effectively phase out fossil fuels.





Erik Solheim, chief of Unep, said the world was “moving in the right direction” on reducing greenhouse gas emissions and tackling climate change, but that measures should be taken urgently to avoid the need for much more drastic cuts in emissions in future. “If we don’t start taking additional action now, we will grieve over the avoidable human tragedy.”

He warned in particular that people would start being displaced from their homes by the effects of climate change, suffering from drought, hunger, disease and conflicts arising from these afflictions. Mass migration as a result of climate change is hard to separate from other causes of migration, but is predicted to become a much greater problem.

This year is “locked in” to be the hottest on record, according to Nasa, eclipsing last year’s record heat, and may show the way to future temperature rises and their accompanying problems.

Under the Paris agreement, reached last December, all of the world’s functioning governments have agreed to reduce greenhouse gases in line with the need to hold warming to no more than 2C, which scientists consider the limit of safety. That agreement has been ratified by the US, China and the European Union, and several other governments.

However, while all of the governments involved in the Paris accord have agreed their own domestic targets for curbing greenhouse gases, these are not legally binding. In addition, few countries have set out concrete plans for how they would implement the curbs.

Next week, signatories to the Paris agreement will gather in Marrakesh to flesh out some aspects of the pact reached last year. Supporters hope that some countries may come up with fuller plans for how they mean to achieve the necessary future emissions reductions, and countries that have not yet ratified the agreement will be persuaded to do so.

None are expected to announce new targets on emissions in line with the reductions that the Unep report suggests are necessary. Nations currently have domestic targets on curbing or cutting emissions by 2020, set out in 2009 at the UN meeting in Copenhagen, as well as their Paris commitments which apply from 2025 to 2030.

Asad Rehman, Friends of the Earth’s international climate campaigner, said: “This is a stark warning that cannot be ignored – tougher action on climate change is urgently needed to prevent the world speeding towards catastrophe. Governments are drinking in the ‘last chance saloon’ if the lofty goals of the Paris climate agreement are to be met.”

Richard Black, director of the Energy and Climate Intelligence Unit thinktank, said: “Unep’s report confirms that there has been remarkable acceleration towards a global low-carbon economy over the past year, but considerably more action is required if governments are to meet the target they set under the Paris agreement.”

Another significant climate agreement was signed in the last few weeks. Under the Montreal Protocol of 1987, countries agreed to phase out gases known to be harmful to the ozone layer. Some of the substitutes, however, turned out to be much more potent than carbon dioxide in warming the planet.

Under a new addition to that agreement countries around the world have agreed to remove the harmful HFCs used in some air-conditioning and refrigeration systems. If fully implemented, this could result in a 0.5C reduction in future warming. Given the goal set in Paris for limiting global temperature rises to 2C, this would make a significant difference to the world’s actions on climate change if it is fully endorsed. Phasing out the relevant chemicals may take much of the rest of the decade, however, and could face resistance in some industries.

Solheim urged countries to embark on more ambitious programmes to improve energy efficiency, increase the amount of energy coming from renewable sources, and look to meet the national targets they set in Paris.