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Last edited 14 Jan 2019
What we need for the journey to net-zero carbon emissions
|Net-zero carbon dioxide emissions must be achieved to ensure that climate change is kept within tolerable levels. ICE's Energy Panel discusses the 'net-zero' concept and the innovations needed to move from rhetoric to realisation.|
The concept of “net zero” carbon dioxide emissions became a key discussion topic during 2018. The core idea is simple enough – net zero emissions are achieved when the global economy takes out as much carbon dioxide (and other greenhouse gases) from the atmosphere as it emits into the atmosphere.
 Nearer date for net zero emissions
It’s been clear for many years that, at some future date, net zero emissions must be achieved if we’re to keep climate change effects within tolerable limits. That future date has generally been considered to be at some time towards the end of this century.
That changed in 2018, when many stakeholders started calling for the net zero target date to be much sooner, with 2050 most frequently mentioned as the new deadline.
One of the main drivers for an earlier date was the release of an Intergovernmental Panel on Climate Change (IPCC) report on the impacts of global warming of 1.5 °C above pre-industrial levels. The report found that the difference between the impacts of global warming of 1.5 °C and of 2.0 °C (or higher) were significant and could justify the further actions needed to ensure that warming is limited to 1.5 °C.
This lower limit would go considerably further than the central objective of the Paris Agreement on climate change, which has a long-term goal to hold the global average temperature increase to “well below 2°C above preindustrial levels”. Although there’s a further reference in the Agreement to “pursue efforts” to limit the temperature increase to 1.5°C, there’s no consensus on whether this should be a firm target.
Modelling carried out for the IPCC 1.5°C report indicates that CO2 emissions must reach net zero by 2050 to deliver a 1.5°C limit, compared to 2070 for 2°C, prompting the recent discussions. The report is very clear that this will not be easy, commenting that “pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems”.
The report goes on to say that “these systems transitions are unprecedented in terms of scale, but not necessarily in terms of speed, and imply deep emissions reductions in all sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those options”.
In response to these caveats, a number of governments have already raised concerns over the scale of change – and the associated costs – to deliver a 1.5°C limit and net zero by 2050. At the 24th UN Conference of Parties on climate change in Poland in December 2018 (“COP24”), the US, Russia, Saudi Arabia and Kuwait persuaded the conference to issue only a commendation of the timing of the scientists’ report, rather than a positive statement of welcome for the report.
However, the EU, together with many developing nations, affirmed at COP24 that they would strive to meet the IPCC’s advice on limiting warming to no more than 1.5°C. This debate will continue through the international climate change negotiations in 2019 and beyond.
 UK’s Committee on Climate Change (CCC) response
The UK government response to the 1.5°C report included a request for the Committee on Climate Change (CCC) to complete a review by March 2019 and provide advice on when the UK should reach net zero emissions of carbon dioxide. The CCC has just completed a call for evidence on its review.
 CCC found that carbon dioxide removal (CDR) is needed
An important technical finding of the 1.5°C report was that reaching the 1.5°C target would require the extensive use of “carbon dioxide removal” (CDR) in almost all scenarios. This presents a major challenge, as the only established techniques for CDR are afforestation, reforestation and land restoration.
The global capacity for these fall far short of the required tonnages in the IPCC scenarios, so one or more of the potential CDR techniques would need to be developed at scale for CDR to play a significant role in practice.
Potential CDR techniques include soil carbon sequestration, Bioenergy with carbon capture and storage (BECCS), direct air carbon capture and storage (DACCS), enhanced weathering and ocean alkalinisation. All of these are being considered with renewed interest as a result of the 1.5°C report.
 UK government plans for carbon capture, use and storage
In parallel (and after something of a hiatus in UK carbon capture policy for several years), in November 2018 the UK government launched an action plan on carbon capture, use and storage (CCUS) to set out “the next steps government and industry should take in partnership in order to achieve the government’s ambition of having the option to deploy CCUS at scale during the 2030s, subject to costs coming down sufficiently”.
All of which indicates that 2019 will be a very active year for the net zero concept and the innovations needed to enable this.
This article was originally published by the Institution of Civil Engineers on 7 January 2019 at https://www.ice.org.uk/news-and-insight/the-civil-engineer/january-2019/the-journey-to-net-zero-carbon-emissions
 Related articles on Designing Buildings Wiki
- Carbon emissions.
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- The Carbon Plan: Delivering our low carbon future.
- The Institution of Civil Engineers.
- The Low Carbon Transition Plan: National strategy for climate and energy.
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