This is the question that has inspired Friends of the Earth to undertake a year-long research project made up of three research reports.
The first report considered the latest science findings, concluded that global temperature increases must be kept below 1.5 degrees to avoid the most devastating effects of climate change, and identified what this means for future emissions. It found that the EU would need to reduce its emissions by 60% by 2020 from 1990 levels, the United States would need to make even deeper cuts and China would need to peak its emissions by 2013 and then reduce them by 5% per year. These are clearly eye-watering reduction targets.
The second report used an adapted DECC 2050 pathways model to see if it's possible for the UK to live within its share of remaining emissions space - what we call a carbon budget. It also considered whether it was possible to do so in a socially just way. It concluded that even with Herculean efforts across all sectors the UK cannot meet its reduction goals without deploying technologies that take carbon out of the air, so-called negative emissions technologies. It did however conclude that reductions could be made without disproportionate impact on poorer households - although it would require a very determined effort to do so.
The final report is a technical analysis of the different potential negative emissions technologies currently being researched. It found that many of the technologies are at a very early stage of development, some bring significant risks, and that the most promising technologies are likely to be extremely expensive - certainly far more costly than action to reduce carbon emissions in the first place. It also found practical limits to the contribution that negative emissions technologies can make - at best, they can only provide a supporting role to emissions reductions. It concluded that dangerous climate change can only be averted if much-accelerated carbon emissions reductions are made across the globe in addition to negative emissions.