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BackgroundIn preparation for the 2015 international climate negotiations in Paris, Parties submitted Intended Nationally Determined Contributions (INDCs) to the United Nations Framework Convention on Climate Change (UNFCCC) expressing each countries’ respective post-2020 climate actions. In this paper we assess individual Parties’ expected reduction of emissions/removals from land use, land use change, and forest (LULUCF) sector for reaching their INDC target, and the aggregate global effect on the INDCs on the future development of emission and removals from the LULUCF sector. This has been done through analysis Parties’ official information concerning the role of LULUCF mitigation efforts for reaching INDC targets as presented in National Communications, Biennial Update Reports, and Additional file 1.ResultsOn the aggregate global level, the Parties themselves perceive that net LULUCF emissions will increase over time. Overall, the net LULUCF emissions are estimated to increase by 0.6 Gt CO2e year−1 (range: 0.1–1.1) in 2020 and 1.3 Gt CO2e year−1 (range: 0.7–2.1) in 2030, both compared to 2010 levels. On the other hand, the full implementation of the INDCs is estimated to lead to a reduction of net LULUCF emissions in 2030 compared to 2010 levels. It is estimated that if all conditional and unconditional INDCs are implemented, net LULUCF emissions would decrease by 0.5 Gt CO2e year−1 (range: 0.2–0.8) by 2020 and 0.9 Gt CO2e year−1 (range: 0.5–1.3) by 2030, both compared to 2010 levels. The largest absolute reductions of net LULUCF emissions (compared to 2010 levels) are expected from Indonesia and Brazil, followed by China and Ethiopia.ConclusionsThe results highlights that countries are expecting a significant contribution from the LULUCF sector to meet their INDC mitigation targets. At the global level, the LULUCF sector is expected to contribute to as much as 20% of the full mitigation potential of all the conditional and unconditional INDC targets. However, large uncertainties still surround how Parties estimate, project and account for emissions and removals from the LULUCF sector. While INDCs represent a new source of land-use information, further information and updates of the INDCs will be required to reduce uncertainty of the LULUCF projections.Electronic supplementary materialThe online version of this article (doi:10.1186/s13021-016-0068-3) contains supplementary material, which is available to authorized users.

The Paris Agreement is based on emission scenarios that move from a sluggish phase-out of fossil fuels to large-scale late-century negative emissions. Alternative pathways of early deployment of negative emission technologies need to be considered to ensure that climate targets are reached safely and sustainably. The historic climate summit in Paris in 2015 galvanized global commitments to an ambitious yet vaguely defined goal of climate stabilization. At the same time some scientists argue that the model-based scenarios with 1.5-and even 2-degree temperature change targets seem unattainable and detached from current political realities 1,2. Here we scrutinize the dominant climate mitigation scenario archetype that projects low global decarbonization rates in the first half of this century followed by large negative emissions in the second half, thanks to Carbon Dioxide Removal (CDR) technologies 3. We call this approach to mitigation timing the "Late Century CDR" scenario archetype (Figure 1a). This archetype is consistent with nearly all of 2-degree scenarios covered by the Fifth Assessment Report (AR5) by the Intergovernmental Panel on Climate Change (IPCC) 4 , 87% of which deploy CDR technologies in the second half of the century 5. Following this predominant archetype might not only turn out to be a risky strategy, but also lead to significant environmental damages and may be economically inefficient. In "Late Century CDR" scenarios, CDR mostly in the form of bioenergy with Carbon Capture and Storage (BECCS) typically removes the equivalent of 20 years of current GHG emissions to reverse the temporary GHG budget overshoot that is tolerated earlier on 6. The challenges and uncertainties associated with CDR are well described in the scientific literature 5,7 , yet the scientific and political debate addressing the consequences of large-scale and late deployment of CDR as a "backstop" strategy is only at an early stage. We argue that a new set of scenarios needs to be generated and analyzed to inform the policy process on robust timing of climate mitigation with the aim of avoiding negative side effects. Essentially, three attributes characterize such budget-constrained scenarios: the timing and magnitude of global peak net emissions and its speed of decline thereafter; the maximum amount of allowable deployment of biomass-based CDRs; and an admissible risk threshold associated with a temperature overshoot.

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