Third IMO Greenhouse Gas Study 2014
GHG3%20Executive%20Summary%20and%20Report
GHG3%20Executive%20Summary%20and%20Report
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3<br />
Scenarios for shipping emissions<br />
2012–2050<br />
3.1 Introduction<br />
This chapter presents emissions scenarios for all six GHGs (CO 2 , CH 4 , N 2 O, HFCs, PFCs, SF 6 ) and for other<br />
relevant substances as defined in this study (NO x , NMVOC, CO, PM, SO x ).<br />
Emissions scenarios present possible ways in which emissions could develop, building on plausible<br />
socioeconomic, energy and policy scenarios. The emissions scenarios can inform policymakers, scientists<br />
and other stakeholders about the development of the environmental impacts of shipping, its drivers and the<br />
relevance of possible policy instruments to address emissions.<br />
3.1.1 Similarities with and differences from Second <strong>IMO</strong> GHG <strong>Study</strong> 2009<br />
The emissions scenarios have been developed using a similar approach to that of the Second <strong>IMO</strong> GHG<br />
<strong>Study</strong> 2009, i.e. by modelling the most important drivers of maritime transport and efficiency trends in order<br />
to project energy demand in the sector. For most emissions, the energy demand is then multiplied by an<br />
emissions factor to arrive at an emissions projection. More detail about the methods and modelling can be<br />
found in Section 3.2.<br />
Even though the approach is similar, the methods have been improved in important ways, taking into account<br />
advances in the literature and newly developed scenarios. Some of the most important improvements are<br />
highlighted below.<br />
Socioeconomic and energy scenarios<br />
In the Second <strong>IMO</strong> GHG <strong>Study</strong> 2009, a range of transport and corresponding emissions projections to 2050<br />
were presented. The underlying overall basis for these projections were the IPCC Special Report on Emissions<br />
Scenarios (SRES) (based upon the IPCC 2000 SRES, which were widely in use at the time). There has been<br />
increased recognition across the climate-scenario-modelling community that there is a need for an updated<br />
set of scenarios, but also recognition of the need to circumvent the time and expense associated with another<br />
IPCC-focused exercise. Thus, the relevant community itself developed the concept of RCPs. Since these are<br />
now in use across the climate community, they have been adopted for this study (see Section 3.2.2). Outside<br />
the climate research community, other long-term scenarios exist (e.g. IEA, 2013; OECD, 2012; IMF, <strong>2014</strong>; RTI,<br />
2013).<br />
Previously, shipping emissions scenarios were based more loosely on a consortium consensus approach,<br />
the so-called Delphi method. This study adopts a more disaggregated numerical approach with explicit<br />
improvements to the projection methodology by splitting the projections by ship type, using a non-linear<br />
regression model of a type widely adopted in the econometric literature (as opposed to simple linear models),<br />
and decoupling the transport of fossil fuels from GDP. In the previous report, there was no such discrimination<br />
by type, or consideration of future worlds where fossil fuel energy demand is decoupled from GDP. More<br />
details are provided in Section 3.2.2 and Annex 7.