Energy systems will require “far reaching” changes in order to prevent the kind of increases in global temperatures that would lead to runaway climate change, according to a landmark new UN report.

A new report by the Intergovernmental Panel on Climate Change (IPPC), published this morning (8 October) in South Korea, says that “unprecedented” changes in society will be required to limit worldwide temperature increases to 1.5 above the pre-Industrial Revolution average.

The report assesses the impact of rising temperatures and the steps that can be taken to mitigate them.

It says global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 per cent from 2010 levels by 2030 in order to prevent bigger temperature rises.

And they should drop to “net zero” around 2050, meaning that any remaining emissions would need to be balanced by removing CO2 from the air.

The report says: “While transitions in energy efficiency, carbon intensity of fuels, electrification and land use change are underway in various countries, limiting warming to 1.5C will require a greater scale and pace of change to transform energy, land, urban and industrial systems globally.”

“Limiting warming to 1.5C is possible within the laws of chemistry and physics but doing so would require unprecedented changes,” said Jim Skea, co-chair of IPCC Working Group III.

“The good news is that some of the kinds of actions that would be needed to limit global warming to 1.5C are already underway around the world, but they would need to accelerate,” said Valerie Masson-Delmotte, co-chair of Working Group I.

The report estimates that $1.6 to 3.8 trillion worth of investment per annum will be required in energy supply systems before the middle of the century in order to keep temperature increases below 1.5C.

This would include up to $1 trillion, $350 billion and $250 billion worth of annual investment in solar, wind and nuclear respectively.

Investments in networks and storage also need to increase to $0.3 – $1.3 trillion per annum.

Allowing the global temperature to temporarily exceed or “overshoot” 1.5C would mean a greater reliance on techniques, such as carbon, capture and storage, which remove CO2 from the air to return global temperatures to below 1.5C by 2100.

According to the assessment, a number of climate change impacts could be avoided by limiting global warming to 1.5C compared to 2C or more.

For instance, by 2100, global sea level rise would be 10cm lower with global warming of 1.5C compared with 2C.

And the likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5C, compared with at least once per decade with 2C, according to the IPCC.

Coral reefs would decline by 70-90 per cent with global warming of 1.5C, whereas virtually all would be lost with 2C.

Commenting on the report’s publication, Solar Trade Association chief executive Chris Hewett, said: “The IPCC report today amplifies already very widespread calls for the UK government to get behind low-cost solar and wind. The message couldn’t be clearer; time is running out.

“Our industry stands ready to roll out solutions which are extremely popular with the public, and no longer require subsidy, but government has put too many barriers in the way. Let’s be clear, a smart, flexible, renewables pathway is now the cheapest pathway. All we need to deliver that is fair tax treatment, fair market access and level playing fields. We’ve been repeating this message for years – action is now needed.”

Following the submission of the IPCC report, the government has said it will invite advice from the Committee on Climate Change (CCC) about strengthening the UK’s greenhouse gas cuts targets.

Chris Stark, chief executive of the CCC, said: “We now look forward to a formal request from UK ministers to begin our assessment of the appropriate statutory framework for climate change in the UK in light of the UK’s obligations under the global Paris Agreement.”