Zero emissions needed before 2040

HUMANS must reduce net greenhouse gases emissions to zero “well before 2040” to ensure global warming does not go above 1.5°C by the end of the century, scientists have warned.

They gave the alert after carrying out a study using a sophisticated new computer model.

The analysis suggests that efforts to prevent temperatures rising to potentially dangerous levels may have to rely heavily on “negative emissions” technology that is still in its infancy.

Commenting on the study, Professor Richard Betts, head of climate impacts at the UK’S Met Office Hadley Centre, said the “important” research spelled out the “enormous challenge” ahead.

The new study, described in a paper in the journal Nature Communications, is one of the first to use the new Felix computer model, which includes social and economic factors along with environmental ones.

One of the researchers, Dr Michael Obersteiner, of the International Institute for Applied Systems Analysis near Vienna, said: “The Felix model... provides a unique systemic view of the whole carbon cycle, which is vital to our understanding of future climate change and energy.

“The study shows that the combined energy and landuse system should deliver zero net anthropogenic emissions well before 2040 to assure the attainability of a 1.5°C target by 2100.”

This does not necessarily mean that humans would have to stop burning fossil fuels in little over 20 years, as the researchers included natural carbon sinks – such as forests – and the use of carbon-capture technology in their calculations.

In the Nature Communications paper, the researchers wrote: “Roughly speaking, and based on current technologies, energy sector emissions will need to peak within the next decade.

“By 2100, the market share of fossil fuels will need to fall to less than a fourth of total primary energy demand to preserve the possibility of meeting the (Paris Agreement) targets.”

They said “full de-carbonisation” would probably have to rely on the combined use of carbon-capture technology, which is still being developed, and the burning of biofuels.

The idea is that trees and other plants would absorb carbon and then be burnt in power plants with the emissions prevented from getting back into the atmosphere by carbon-capture, creating a giant machine to suck CO2 from the air. However some doubt this will be possible on a large scale, given the need to use land to grow crops and raise animals.

And the paper said: “If coupling of (carbon-capture-and-storage) technology with bioenergy production is ultimately found to be unfeasible, uneconomical or unacceptably burdensome on ecosystems, then alternative negative emissions technologies will need to be substituted.

Betts, who has played a leading role in the Intergovernmental Panel on Climate Change’s work, said the research should help world leaders establish what they have to do.

“This important paper provides much-needed detail on how the countries of the world might meet their commitments under the Paris Agreement,” he said. “It is clear that it is an enormous challenge, especially if we do not develop ways to remove carbon dioxide from the atmosphere and put these into practice.”

Gareth Redmond-king, head of climate and energy policy at conservation group WWF, said the paper showed just how pressing the need was to take action.

“Once again, climate scientists are sounding an alarm to remind us of the urgent need to act now to tackle climate change,” he said.

“Melting ice caps, dying coral reefs, plummeting wildlife populations, rising sea levels and extreme weather – they all get worse and worse as the Earth’s temperature rises.

“Similar analysis recently showed that, on current levels of emissions, we’ll have reached enough to warm by 1.5°C as soon as four years’ time!”

The Felix model is freely available to be downloaded and used by anyone. – The Independent