Back to search

‘Carbon law’ could lead to zero global emissions by 2050

Researchers have proposed a global roadmap for decarbonisation over the coming decades. The roadmap is based on the idea of a simple heuristic, described by the researchers as ‘carbon law’, of halving carbon dioxide (CO2) emissions every decade from 2020 to 2050. The researchers say that, if combined with the development of new technologies and efforts to reduce CO2 emissions from land use, this target could lead to a carbon-neutral global economy by 2050.

The Paris Agreement is the current international commitment to reduce greenhouse gas (GHG) emissions, which aims to limit global warming to below 2 degrees Celsius (°C). However, international commitments are often at odds with national priorities and political realities. In this study, researchers develop a global roadmap, or planning instrument, for decarbonisation over the coming decades, linking short-term targets with long-term goals.

The roadmap is based on a simple heuristic, called ‘carbon law’ by the researchers, of halving human CO2 emissions every decade. The carbon law, which would apply to all sectors of industry and countries, would need to be accompanied by the development of carbon capture and storage (CCS) technologies and the reduction of CO2 emissions from land use. The roadmap was developed by reviewing scientific research as well as gathering expert opinion from discussions among The Earth League, a network of scientists and institutions. The researchers focused on four dimensions – innovation, institutions, infrastructure and investment – that qualitatively identifiy crucial steps needed for the transformation to be realised, outlining a number of actions over the periods 2017–2020, 2020–2030, 2030–2040 and 2040–2050.

By 2020: initially the researchers suggest that fossil-fuel emissions must start falling by 2020 through measures such as carbon-tax schemes, feed-in tariffs and quota approaches. For example, fossil-fuel subsidies, currently between USD $500 and $600 billion (406 and 487 billion euros) per year, should be ended by 2020, as opposed to 2025, as agreed by the G7 (countries with the seven largest advanced economies in the world1) in 2016. All major cities and corporations should also have decarbonisation strategies in place. Emerging economies, such as South Africa, are identified as a risk to the roadmap and the researchers say that international efforts should incentivise low-carbon development. Food production also accounts for 10% of GHG emissions, so carbon management in the food system should be a major focus of investment in order to move towards more sustainable, low-meat diets, which would benefit ecosystems and human health, while reducing pollution.

2020–2030: large changes need to be made to the global economy in this decade. Carbon pricing must cover all GHG emissions starting at USD $50 (41 euros) per ton increasing to $400 (324 euros) per ton by mid-century (it is now around USD $12 (10 euros) per ton). By 2030 coal use should be almost phased out and cities such as Copenhagen and Hamburg, should be fossil-fuel free. There should be robust taxes on air transport and shipping and countries should phase out the internal combustion engine in new cars by 2030. These measures should hasten the development of non fossil-fuel technologies as well as investment in the development of technologies to mitigate climate change (e.g. energy-storage systems, CCS and smart-power grids). Major investment should also be made in afforestation to remove CO2 from the atmosphere.

2030–2050: this decade is characterised by key breakthroughs in the road map. For example, oil would be phased out for energy, and petrol and diesel cars rarely used on the roads worldwide. Aircraft should also be running on alternative fuels such as hydrogen and, therefore, should be carbon neutral. The construction industry would also become carbon neutral and CCS technologies would be able to remove large amounts (5 gigatonnes a year by 2050) of CO2 from the atmosphere. After 2040, all major European countries should be close to net-zero carbon states with North America, South America and most of Africa and Asia reaching this stage by 2050. The global economy would be powered by carbon-free energy and fed by sustainable agriculture, which sequesters carbon.

It should be noted that the study is a hypothetical exercise in order to explore how to achieve rapid decarbonisation and it is unknown how emission-reductions strategies will play out in the real world. For example, CCS technologies are still in the early stage of development — technology is not yet ready or affordable — and it is unknown whether the future sequestration amounts described in the roadmap are further from Science for Environment Policy or visit the major source:

Source: Rockström, J., Gaffney, O., Rogelj, J., Meinshausen, M., Nakicenovic, N. & Schellnhuber, H.J. (2017). A roadmap for rapid decarbonization. Science. 355 (6331): 1269-1271. DOI: 10.1126/science.aah3443.