Integrated assessment models can help quantifying the implications of international climate agreements and regional climate action. This paper reviews scenario results from model intercomparison projects to explore different possible outcomes of post 2020 climate negotiations, recently announced pledges and their relation to 2°C. We provide key information for all the major economies such as the year of emission peaking, the regional carbon budgets and emissions allowances. We highlight the distributional consequences of climate policies, and discuss the role of carbon markets for financing clean energy investments, and achieving efficiency and equity.So far, international climate policy has been ineffective in curbing the rise of global greenhouse-gas emissions. Still, ambitious climate targets such as the 2°C target require a phase-out of global emissions by the end of the century, and an active participation of all world regions in climate policy 1 . Given the many obstacles to global cooperative action on climate change, the question remains how diverse national climate policies can be coordinated and strengthened globally. Within the United Nations Framework Convention on Climate Change (UNFCCC), the Durban Platform for Enhanced 2 Action 2 provides an important platform for a post-2020 international climate agreement. It contains several innovative elements, most notably a focus on the major economies that goes beyond the traditional divide between Annex I and non-Annex I countries. The Durban platform calls for a new climate treaty to be agreed in 2015 and implemented as early as 2020. The recently announced USChina climate deal and the EU climate framework provide encouraging steps forwards, but aligning the incentives of the major emitters in pursuing stringent climate policies remains a challenge. In this paper, we aim at assessing the implications of post 2020 climate policies with specific reference to the major economies. We provide quantitative estimates of regional emission budgets, timing of emission peaking, and distribution of mitigation costs. We examine the role of carbon markets and different burden sharing schemes to alleviate distributional inequalities and finance the investment needs in low carbon mitigation technologies. In order to quantify these policy relevant variables, we resort to global models.Integrated assessment models (IAMs) are tools designed to investigate the implications of achieving climate and other objectives in an integrated and rigorous framework. They are numerical models that account for major interactions among energy, land-use, economic and climate systems. Model differ in the economic, technological and sectoral representation and in the way they are solved, with some models maximizing an inter-temporal objective function (such as economic activity) and others simulating a set of equilibria (see the SOM for individual model description and references to documentation). Models generate global long-term scenarios for a number of regions or countries that ca...

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Available online xxxx JEL classification: H23 Q40 Q54 C61 C68 O57In this paper we investigate CO 2 emission scenarios for Colombia and the effects of implementing carbon taxes and abatement targets on the energy system. By comparing baseline and policy scenario results from two integrated assessment partial equilibrium models TIAM-ECN and GCAM and two general equilibrium models Phoenix and MEG4C, we provide an indication of future developments and dynamics in the Colombian energy system. Currently, the carbon intensity of the energy system in Colombia is low compared to other countries in Latin America. However, this trend may change given the projected rapid growth of the economy and the potential increase in the use of carbon-based technologies. Climate policy in Colombia is under development and has yet to consider economic instruments such as taxes and abatement targets. This paper shows how taxes or abatement targets can achieve significant CO 2 reductions in Colombia. Though abatement may be achieved through different pathways, taxes and targets promote the entry of cleaner energy sources into the market and reduce final energy demand through energy efficiency improvements and other demand-side responses. The electric power sector plays an important role in achieving CO 2 emission reductions in Colombia, through the increase of hydropower, the introduction of wind technologies, and the deployment of biomass, coal and natural gas with CO 2 capture and storage (CCS). Uncertainty over the prevailing mitigation pathway reinforces the importance of climate policy to guide sectors toward low-carbon technologies. This paper also assesses the economy-wide implications of mitigation policies such as potential losses in GDP and consumption. An assessment of the legal, institutional, social and environmental barriers to economy-wide mitigation policies is critical yet beyond the scope of this paper.

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a b s t r a c t Available online xxxx JEL classification: H23 C88 Q40 Q54 C61 C63 C68 O57 Keywords: Climate policy Low-carbon energy scenarios Mitigation alternatives BrazilThis paper assesses the effects of market-based mechanisms and carbon emission restrictions on the Brazilian energy system by comparing the results of six different energy-economic or integrated assessment models under different scenarios for carbon taxes and abatement targets up to 2050. Results show an increase over time in emissions in the baseline scenarios due, largely, to higher penetration of natural gas and coal. Climate policy scenarios, however, indicate that such a pathway can be avoided. While taxes up to 32 US$/tCO 2 e do not significantly reduce emissions, higher taxes (from 50 US$/tCO 2 e in 2020 to 162US$/tCO 2 e in 2050) induce average emission reductions around 60% when compared to the baseline. Emission constraint scenarios yield even lower reductions in most models. Emission reductions are mostly due to lower energy consumption, increased penetration of renewable energy (especially biomass and wind) and of carbon capture and storage technologies for fossil and/or biomass fuels. This paper also provides a discussion of specific issues related to mitigation alternatives in Brazil. The range of mitigation options resulting from the model runs generally falls within the limits found for specific energy sources in the country, although infrastructure investments and technology improvements are needed for the projected mitigation scenarios to achieve actual feasibility.

The feasibility of achieving climate stabilization consistent with the objective of 2°C is heavily influenced by how the effort in terms of mitigation and economic resources will be distributed among the major economies. This paper provides a multi-model quantification of the mitigation commitment in 10 major regions of the world for a diversity of allocation schemes. Our results indicate that a policy with uniform carbon pricing and no transfer payments would yield an uneven distribution of policy costs, which would be lower than the global average for OECD countries, higher for developing economies and the highest, for energy exporters. We show that a resource sharing scheme based on long-term convergence of per capita emissions would not resolve the issue of cost distribution. An effort sharing scheme which equalizes regional policy costs would yield an allocation of allowances comparable with the ones proposed by the Major Economies. Under such a scheme, emissions would peak between 2030 and 2045 for China and remain rather flat for India. In all cases, a very large international carbon market would be required.

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Climate change is likely to affect water availability and therefore hydropower generation in many regions of the world. In drying regions, hydropower generation may be impaired, creating a need for new power investments that would otherwise have been unnecessary. In this study we apply two partial equilibrium models (GCAM and TIAM-ECN) and two general equilibrium models (MEG4C and Phoenix) to identify possible pathways of power sector adaptation for Colombia under climate change. We adopt two GCM projections that deteriorate hydropower generation over the next three decades, and simulate each for two radiative forcing scenarios (RCP8.5 and RCP4.5). Relative to Colombia's projected power demand growth over the coming decades, losses in hydropower generation are marginal. Nonetheless, climate-driven losses in hydropower must be compensated by alternative technologies´expansion, which vary significantly across models. When climate policy is implemented (RCP4.5), three distinct expansion pathways emerge: increased solar and wind energy (TIAM-ECN); significant power demand reductions (Phoenix and MEG4C); and increased fossil resources with carbon dioxide capture and storage (GCAM). We show the need to explore the tradeoffs/synergies among alternative expansion pathways and their potential impacts on other sectors (e.g. water and land), and for effective policies to incentivize their adoption in Colombia.