Ending greenhouse gas emissions 'may not stop global warming'
A science journal has U-turned on its claim that we are past the 'point of no return' and global warming cannot be stopped after British experts disputed the findings. The study claims that if humans ended greenhouse gas emissions tomorrow we would still see global temperatures continuing to rise for several centuries. Leading journal Scientific Reports was strongly criticised by British scientists after they published a press release titled: 'Ending greenhouse gas emissions may not stop global warming' to publicise the paper, which is still . Following the backlash, the journal revised its press release, admitting the prediction was based on a particular computer model and results should be tested on 'alternative models'. Richard Betts, a professor of climate impacts at the University of Exeter, was among those who criticised the study. Speaking with newspaper, he said: 'While the press release suggests that global warming may now be unstoppable for centuries, the model result in this paper is not convincing as support for that message. 'The paper itself does not actually claim to be a prediction of the real world, it just reports the behaviour of one model but the press release goes a big step further and presents it as a prediction. 'The model, which is not one used in the main Intergovernmental Panel on Climate Change projections, has not been shown to be credible enough to support confident predictions, and is contradicted by more established and extensively evaluated [models] in many of its physical processes. 'This paper clearly may be cited in support of a misleading message that it is now "too late" to avoid catastrophic climate change, which would have the potential to cause unnecessary despair. 'However, the study is nowhere near strong enough to make such a frightening message credible.' Sir Brian Hoskins, a climatologist at Imperial College London, who was also not involved with the study, questioned the team's 'toy' model. 'This is the sort of investigation with a toy model that should be done and is fun, but should not be given this sort of publicity until the processes involved have been investigated using more complex models and representations,' he said. Andrew Watson, a Royal Society research professor at the University of Exeter, said that he did not agree with the press release describing global warming as potentially catastrophic, 'given that it occurs over 500 years'. The study authors include Professor Jorgen Randers, a respected Norwegian academic from the BI Norwegian Business School in Oslo. Professor Randers told MailOnline: 'As I see it, [Scientific Reports] have, in a most helpful manner, published what we called for in our paper, namely a report on what happens in the big climate models when they stop emissions in 2020.' Some scientists hailed the findings as significant and worth taking note of, however. 'This study provides evidence for what we don't want to hear that global heating may have already become self-reinforcing, and that we have therefore passed the point of no return for halting long-term climate change,' Phillip Williamson of the University of East Anglia said. Scientists used a computer model called ESCIMO to simulate the effect of different greenhouse gas emission reductions on changes in the global climate between now and they year 2500, based on records spanning all the way back to 1850. Even if all human-made greenhouse-gas emissions were reduced to zero this year, global temperatures would still be around 5.4F (3C) warmer in 2500 than on 1850, the model found. Sea levels, meanwhile, would rise by around eight feet (2.5 metres) by 2500, compared to 1850, submerging glaciers and flooding land. 'Recently, there have been warnings that some of these tipping points are coming closer and are too dangerous to be disregarded,' say the scientists, from BI Norwegian Business School in Oslo in their research paper. 'In this paper we report that in the ESCIMO climate model the world is already past a point-of-no-return for global warming.' The team tried another scenario, stretching out the date at which humanity theoretically brings greenhouse gas emissions to zero. Under this scenario, where human-made greenhouse gas emissions peak during the 2030s and decline to zero by 2100, global temperatures will be 5.4F (3C) warmer and sea levels 10 feet (three metres) higher by 2500 than they were in 1850 an even greater sea level rise. The authors suggest continued melting of Arctic ice and carbon-containing permafrost ground that's continuously frozen may increase the amount water vapour, methane and carbon dioxide in the atmosphere. This would also reduce the area of ice that reflects heat and light from the Sun, causing more short-wave radiation to be absorbed by the Earth, heating the planet. This could mean humanity will need to create more white buildings to reflect more sunlight back into space to compensate for the loss of ice. To prevent the projected temperature and sea level rises, the authors suggest that all human-made greenhouse gas emissions would have had to be reduced to zero between 1960 and 1970. As it is, humans will have to take proactive measures to remove at least 33 gigatonnes of carbon dioxide from the atmosphere each year from 2020 onwards through carbon capture and storage methods, according to the authors. This may help to limit the potentially catastrophic impacts of this on Earth's ecosystems and human society, who may have to evacuate entire cities when rising sea levels cause severe flooding. 'The findings should not be misinterpreted as saying that we are doomed, with nothing that can be done to make any difference,' Professor Williamson said. 'On the contrary, the differences between their scenarios net-zero by the end of the century and net-zero now are dramatic, giving the choice of climate catastrophe within our children's lifetimes or keeping future temperature increases below 1.5C for at least a century.' Professor Mark Maslin, a climate change expert at University College London, said the results need to be confirmed by more complex climate models used by the Intergovernmental Panel on Climate Change (IPCC). The latest round of climate model simulations run by IPCC show that if greenhouse gas emissions were to stop immediately, there is likely to be very little further increase in temperatures and no sign of warming resuming in future. 'These results come from one model which has not undergone the rigorous cross checking and testing that is usual for climate models,' Professor Maslin said. The authors of the study encourage other researchers to explore their results using alternative models.