Campaigners have accused the National Grid of failing to live up to the Paris Agreement on climate change after it published a report about how energy supplies might develop in the future.

In the report, the private company which runs Britain’s high-voltage electricity network considered four possible scenarios including one called 'Two Degrees', saying this was based on the historic Paris accord's target for the maximum amount of global warming.

The other three scenarios sounded grim for those hoping Britain will play its part in the international efforts to prevent the worst effects of climate change. A business-as-usual approach was the “least affluent of the scenarios and the least green”; another scenario contemplated “low economic growth” competing with the “desire to become greener and decrease carbon emissions”; while the fourth foresaw consumers with “more money available to spend” but “little inclination to become environmentally friendly”.

Environmental group WWF criticised the company for its lack of ambition, saying it had failed to consider the actual target laid out in the historic Paris Agreement on climate change. This committed signatories to “holding the increase in the global average temperature to well below 2C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5C … recognising that this would significantly reduce the risks and impacts of climate change”.

Gareth Redmond-King, head of climate and energy policy at WWF, said: “[The] assessment by the National Grid is disappointing and shows that the UK needs a better and more ambitious plan for how we meet increased energy demand whilst cutting emissions.

“The UK can't possibly be left answering ‘two degrees’ to a question about how we plan to meet our international commitments to tackle climate change.

“It just fails to set the level of ambition necessary to deliver what we signed up to under the Paris Agreement – the answer needs to be 1.5 degrees.”

Previously scientists thought that particularly dangerous effects of climate change would begin after 2C of warming, but concern is growing that this figure is too high, particularly because of fears allowing this much would lock in major sea level rise over the next few centuries.

To date, the world has warmed by just under 1C because of greenhouse gas emissions caused by humans.

The UK Government has committed to ambitious targets to cut emissions, but it has repeatedly delayed its Clean Growth Plan, which is meant to set out how these will actually be achieved. Ministers have said the plan will be published in September, about a year late.

Mr Redmond-King said: “We are already feeling the impact of climate change and this forecast comes hard on the heels of the Committee on Climate Change report which challenges the UK Government to step up to the challenge.

“We need their commitment to support and grow low-carbon industries and solutions – particularly in the building and transport sectors where emissions are rising, not falling, and we need this quickly.

“The Government's Clean Growth Plan needs to prove these forecasts wrong when it is published in September.”

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Responding to the criticism, a National Grid spokesman said: “National Grid is not responsible for setting the Paris climate change targets or the Government’s own aspirations. The scenario is titled ‘Two Degrees’ because that was the target set by the Paris Agreement.

"However the report refers on a number of occasions to limiting warming to two degrees or less because we recognise there is an aspiration to go beyond that.”

The report, called Future Energy Scenarios, said under its ‘Two Degrees’ scenario “increased investment ensures the delivery of high levels of low carbon energy” and “consumers make conscious choices to be greener and can afford technology to support it”.

“With highly effective policy interventions in place, this is the only scenario where all UK carbon reduction targets are achieved,” it said.

“We see the highest economic growth of all the scenarios. There is a collective ambition to decarbonise the economy.

“High taxes are levied on those who continue to use carbon intensive options, such as conventional gas for heating. Policy and incentives are in place to reduce demand and increase renewable generation.”

Under the business-as-usual scenario, the focus is on “ensuring security of supply at a low cost for consumers”.

“This is the least affluent of the scenarios and the least green. There is little money or appetite for investing in long-term low carbon technologies. Steady State sees the slowest economic growth and subsequently there is the least investment in the longer-term future,” it says.

“There is little ambition to move to a low-carbon world, with policies that focus on the affordability of energy. No taxes are levied on the use of gas.

“The emphasis remains on ensuring security of supply at the lowest cost. Consumers are very cost conscious and try to limit their spending and reduce their bills.

“They have no desire to move to a low-carbon world. Innovation continues as it does today. Businesses and consumers take a low risk, short-term value approach.”

Writing in the report’s foreword, Marcus Stewart, the Grid’s head of energy insights, said it was designed to provide “a range of credible futures” to help develop an energy system “that is robust against a range of outcomes”.