Implications of alternative metrics for global mitigation costs and greenhouse gas emissions from agriculture

100-year Global Warming Potentials (GWPs) are used almost universally to compare emissions of greenhouse gases in national inventories and reduction targets. GWPs have been criticised on several grounds, but little work has been done to determine global mitigation costs under alternative physics-based metrics . We used the integrated assessment model MESSAGE to compare emission pathways and abatement costs for fixed and time-dependent variants of the Global Temperature Change Potential (GTP) with those based on GWPs, for a policy goal of limiting the radiative forcing to a specified level in the year 2100. We find that fixed 100-year GTPs would increase global abatement costs (discounted and aggregated over the 21^st century) under this policy goal by 5–20 % relative to 100-year GWPs, whereas time-varying GTPs would reduce costs by about 5 %. These cost differences are smaller than differences arising from alternative assumptions regarding agricultural mitigation potential and much smaller than those arising from alternative radiative forcing targets. Using the land-use model GLOBIOM, we show that alternative metrics affect food production differently in different world regions depending on regional characteristics of future land-use change to meet growing food demand. We conclude that under scenarios of complete participation, the choice of metric has a limited impact on global abatement costs but could be important for the political economy of regional and sectoral participation in collective mitigation efforts, in particular changing costs and gains over time for agriculture and energy-intensive sectors.     

Creating a global warming implementation regime

This paper proposes a global warming implementation regime which addresses the issues of equity, flexibility, cost minimization, and population growth. Previously proposed international policy instruments, such as country by country targets, carbon taxes, and tradable permits, face major difficulties as stand alone proposals. The key element of the regime proposed here is to combine annual tradable permits which are allocated based on population in a fixed year with a small carbon tax ($5–10/tonne) on emissions in excess of permits. Both permits and carbon taxes are applied to national level governments, which in turn would use whatever mix of policies desired to reduce national emissions. It is suggested that the initial number of permits correspond to total global emissions in the base year; over time, the number of permits could be reduced and the tax rate increased if improved scientific knowledge so dictates. By allocating permits based on population the equity concerns of developing countries are addressed, while taxing emissions in excess of permit holdings removes the rigidity of a quota system and limits resource transfers by effectively capping the permit trading price, which is a major concern of industrialized countries. To accommodate the difficulties of countries which have not yet achieved the demographic transition, the permit allocation scheme could be subject to a one-time adjustment after 10–15 years based on some weighting of the initial and then-current populations. The proposed scheme is based on the premise that there is a large potential for reducing emissions in developed countries or limiting emission increases in developing countries, and the intention is to create competition between national level governments in implementing cost-effective emission reduction.     

The global climate change mitigation strategy REDD: monitoring costs and uncertainties jeopardize economic benefits

REDD (Reducing Emissions from Deforestation and Forest Degradation) has been suggested as a climate change mitigation strategy that is based on the philosophy to reward countries for reducing their deforestation and forest degradation by financial benefits via the generation of carbon credits. While the potential of REDD has been widely discussed, minor attention has been drawn to the implication of uncertainties and costs associated with the estimation of carbon stock changes. To raise awareness of these issues, we conducted a simulation study for a set of countries that show high to low deforestation rates, which demonstrates that the potential to generate benefits from REDD depends highly on the magnitude of the total error while assessment costs and the price of carbon credits play a minor role. For countries with low deforestation rates REDD is obviously not an option for generating benefits as they would need to implement monitoring systems that are able to estimate carbon stock changes with a total error well below 1 %. Total errors feasible under operational monitoring systems are only sufficient to gain revenues from REDD-regimes under high deforestation rates.     

Benchmark-based emission allocation in a cap-and-trade system

Abstract

One of the important bottlenecks for the introduction of emission trading is how allowances should be distributed among the participants in a trading scheme. Both grandfathering on the basis of historic emissions and auctioning have important drawbacks. In this paper, we propose an allowance distribution rule based on benchmarking of production processes: each company's share in the total allowance is determined by its production level and a reference emission level per product. The scheme shows some important advantages compared to other schemes.     

Thermal regime in the Rybinsk Reservoir under global warming

Presented are the results of studying the water temperature changes in the Rybinsk Reservoir during the ice-free period caused by the climate warming. Linear trends are revealed and estimated. The trend is observed for the period of 1976?C2008 towards the increase in the average water surface temperature during all months at the maximum rise rate of 0.89°C/10 years in July. It is demonstrated that the average water temperature in the reservoir in May?COctober has been above the norm since 1995.     

Greenhouse gas mitigation co-benefits across the global agricultural development programs

Global agricultural development programs aim to support smallholder farmers and farming communities by strengthening sustainable and resilient food production systems – which can also promote climate change mitigation as a co-benefit by reducing the emissions and enhancing removals of greenhouse gases (GHG). This study presents estimated GHG emissions reductions of almost 100 agricultural development projects over 51 low- and middle-income countries supported by the International Fund for Agriculture Development (IFAD), USAID-Feed the Future (FTF) Initiative, and Foreign, Commonwealth and Development Office (FCDO, previously DfID). Together, these projects promoted a net GHG emissions reduction of 6.5 MtCO₂e per year. The forest management and promotion of improved agroforestry systems in the project areas contributed the most to the total mitigation co-benefits of the investment portfolios (∼3.9 MtCO₂e/y). Improved crop management with minimum tillage practices, residue incorporation, water management in paddy rice, and the use of organic fertilizers also made a large contribution to the GHG emissions reduction (∼1.5 MtCO₂e/y). Grass and pasture land management across the selected projects account for a net emission reduction of 0.2 MtCO₂e/y. The implementation of improved agricultural practices in combination proves more effective for improving productivity and generating mitigation co-benefits than used in isolation. However, the aggregate impacts of soil organic carbon (SOC) sequestration should be interpreted carefully, which quickly can be lost quick. The interventions promoted by the global agricultural development programs have shown immense potential in reducing net GHG emissions or emission intensity in agriculture and allied sectors. For moving forward to achieve the net-zero and 1.5 °C goals including food security, the global agriculture development programs need to prioritize working on agriculture policy development and implementation so that agriculture expansion does not continue to drive land-use change. This needs to move from the traditional agriculture development programs to transformational changes.     

Rainfall distribution and regime in Central America

Summary Seasonal variations of the atmospheric circulation on the western flanks of the North Atlantic Anticyclone imply upward motion over the Caribbean Sea during the summer half-year, with a secondary minimum in July and August, while ascending motion decreases from November onward, and a strong subsidence develops towards the end of the winter half-year. This is associated with variations in the persistence of the trade inversion and the development of the Easterly Waves.The precipitation regime over the Caribbean Sea follows closely the seasonal variations in the field of large-scale vertical motion. A large variety in rainfall distribution and regime is found, on the other hand, on the Central American Isthmus. In qualitative terms, this is controlled by the orientation of mountain ranges and the configuration of coast lines relative to the seasonal flow patterns, that is orographic and stress-differential induced divergence and convergence effects. Due to the latitudinal variation of the Coriolis parameter, stress-differential induced divergence effects should be particularly pronounced in the tropics. The causes for the regional variations in the beginning of the rainy season and the secondary rainfall minimum in midsummer are discussed particularly.An altitudinal belt of maximum rainfall below the 1,000 m level is found in large parts of the Central American mountains. Recent climatic fluctuations display regional differences which appear to be greatly due to orographic and stressdifferential induced divergence effects.

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Zusammenfassung Jahreszeitliche Zirkulationsschwankungen auf der Westflanke der Nordatlantischen Hochdruckzelle sind verbunden mit aufsteigender Bewegung über dem Karibischen Meer während des Sommerhalbjahrs, mit einem sekundären Minimum im Hochsommer; von November an wird die Aufwärtsbewegung geringer, und ein starkes Absinken entwickelt sich gegen Ende des Winterhalbjahres. Änderungen der großräumigen Vertikalbewegung gehen mit Schwankungen in der Intensität der Passatinversion und der Ausbildung der Easterly Waves einher.Das Niederschlagsregime über dem Karibischen Meer folgt im wesentlichen den jahreszeitlichen Schwankungen der großräumigen Vertikalbewegung. Starke Gegensätze in Niederschlagsverteilung und-regime prägen sich andererseits auf der mittelamerikanischen Landbrücke aus. Sie sind im wesentlichen bestimmt durch Orientierung der Gebirge und des Küstenverlaufes in bezug zum jahreszeitlich veränderlichen Strömungsfeld. Orographische Effekte und Schubspannungs-unterschiede zwischen Land und Meer haben eine große Bedeutung für horizontale Strömungsdivergenzen in der Reibungsschicht. Wegen der Breitenabhängigkeit des Coriolis-Parameters sollten sich diese Effekte besonders stark in den Tropen auswirken. Die Ursachen für die ausgeprägten regionalen Unterschiede im Beginn der Regenzeit sowie das sekundäre Niederschlagsminimum im Hochsommer werden besonders diskutiert.In weiten Teilen der mittelamerikanischen Gebirge kann eine Höhenstufe maximalen Niederschlags unterhalb des 1000 m-Niveaus festgestellt werden. Klimaschwankungen der letzten Jahrzehnte zeigen regionale Unterschiede, die vor allem durch orographische Effekte und Schubspannungsunterschiede bedingt zu sein scheinen.

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Resumen Variaciones estacionales de la circulación atmosférica al lado occidental del Anticiclón del Atlántico del Norte están relacionados con el campo del movimiento vertical sobre el Mar Caribe. Hay un movimiento ascendente durante la mitad vernal del año, mostrando cierta disminución en los meses de Julio y Agosto. Una subsidencia pronunciada, por otra parte, suele desarrollarse hacia el final de la mitad invernal del año. Los cambios estacionales en el campo del movimiento vertical van junto con variaciones en la intensidad de la inversion de alísios y de las Ondas del Este.El régimen de lluvias sobre el Mar Caribe está conforme con las variaciones estacionales en el campo del movimiento vertical. En el Istmo Centroamericano, por otra parte, hay grandes contrastes en la distribucion regional y el régimen de lluvias, las cuales se deben a la orientación de las cordilleras y de las costas con respecto a los flujos atmosféricos dominantes. Diferencias en las condiciones aerodinámicas entre la superficie del mar y superficies terrestres, por otra parte, causan efectos de divergencia o convergencia en la faja costera. Debido a la variación latitudinal del parametro de Coriolis, dichos efectos deberían de ser particularmente importantes en los trópicos. Se discutan especialmente las causas para las differencias regionales que existen respecto al comienzo de la estación lluviosa.En gran parte de las montanas de Centro America hay un piso con lluvias máximas, situado debajo de 1,000 m, con una disminución pronunciada monte arriba. Las fluctuaciones climáticas de los ultimos decénios demuestran un carácter distinto en las varias partes del Istmo, lo que parece ser debido a efectos regionales de divergencia y convergencia.

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Résumé Les variations saisonnières de la circulation atmosphérique sur le flanc ouest de l'anticyclone situé sur l'Atlantique septentrional impliquent un mouvement ascendant de l'air au-dessus de la Mer des Caraïbes durant le semestre d'été. Ce mouvement est interrompu par un minimum secondaire en juillet et août. La durée de ces mouvements ascendants diminue à partir du mois de novembre et un fort courant subsident s'y développe vers la fin du semestre d'hiver. Ces mouvements sont associés aux variations de l'inversion des alizés et à l'évolution de l'ondulation de l'est.Le régime des précipitations de la Mer des Caraïbes suit étroitement les variations saisonnières du champ des mouvements verticaux à grande échelle. On recontre par contre une grande diversité dans les régimes et la distribution des précipitations en Amérique Centrale. Cette constatation se contrôle qualitativement par l'orientation des chaînes de montagne et la configuration des côtes par rapport aux modèles d'écoulement saisonnier. C'est à dire que cette diversité est due à des effets de divergence et de convergence provenant des conditions orographiques et des conditions de frottement différencié entre la terre et la mer. Du fait de la variation du paramètre de Coriolis avec la latitude, les effets de divergence provoquée par le dit frottement différencié doivent être spécialement prononcés sous les tropiques. On discute ici en particulier les causes des variations régionales du début de la saison des pluies et du minimum secondaire des précipitations au milieu de l'été.Une ceinture du maximum des précipitations se retrouve au-dessous de 1000 m d'altitude dans la plus grande partie des montagnes de l'Amérique Centrale. Des fluctuations climatiques récentes présentent des différences régionales qui semblent dues principalement à des effets orographiques et à la divergence produite par le frottement différencié de l'air sur la terre et la mer.

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With 16 Figures

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A financial support by the University of Wisconsin Research Committee during the writing stage of this work is gratefully acknowledged.     

Climate agreements based on responsibility for global warming: Periodic updating,policy choices,and regional costs

It has been suggested that calculations of historical responsibility for global warming should be used to distribute mitigation requirements in future climate agreements. For a medium-term mitigation scenario, we calculate regional mitigation costs resulting from global allocation schemes based on the Brazilian Proposal that solely incorporate historical responsibility as a burden sharing criterion. We find that they are likely to violate ability-to-pay principles. In spite of less stringent abatement requirements, developing country regions experience cost burdens (as a percentage of GDP) in the same range as those of developed countries. We also assess the policy options available for calculating historical responsibility. The periodic updating of responsibility calculations over time, concerns over the robustness and availability of emissions data, and the question of whether past emissions were knowingly harmful, may lead to policy choices that increase the relative historical responsibility attributed to developing countries. This, in turn, would increase their mitigation cost burden.     

National climate change mitigation legislation,strategy and targets: a global update

Global climate change governance has changed substantially in the last decade, with a shift in focus from negotiating globally agreed greenhouse gas (GHG) reduction targets to nationally determined contributions, as enshrined in the 2015 Paris Agreement. This paper analyses trends in adoption of national climate legislation and strategies, GHG targets, and renewable and energy efficiency targets in almost all UNFCCC Parties, focusing on the period from 2007 to 2017. The uniqueness and added value of this paper reside in its broad sweep of countries, the more than decade-long coverage and the use of objective metrics rather than normative judgements. Key results show that national climate legislation and strategies witnessed a strong increase in the first half of the assessed decade, likely due to the political lead up to the Copenhagen Climate Conference in 2009, but have somewhat stagnated in recent years, currently covering 70% of global GHG emissions (almost 50% of countries). In comparison, the coverage of GHG targets increased considerably in the run up to adoption of the Paris Agreement and 89% of global GHG emissions are currently covered by such targets. Renewable energy targets saw a steady spread, with 79% of the global GHG emissions covered in 2017 compared to 45% in 2007, with a steep increase in developing countries.

Key policy insights

• The number of countries that have national legislation and strategies in place increased strongly up to 2012, but the increase has levelled off in recent years, now covering 70% of global emissions by 2017 (48% of countries and 76% of global population).

• Economy-wide GHG reduction targets witnessed a strong increase in the build up to 2015 and are adopted by countries covering 89% of global GHG emissions (76% not counting USA) and 90% of global population (86% not counting USA) in 2017.

• Renewable energy targets saw a steady increase throughout the last decade with coverage of countries in 2017 comparable to that of GHG targets.

• Key shifts in national measures coincide with landmark international events – an increase in legislation and strategy in the build-up to the Copenhagen Climate Conference and an increase in targets around the Paris Agreement – emphasizing the importance of the international process to maintaining national momentum.

     

National contributions to climate change mitigation from agriculture: allocating a global target

Globally, agriculture and related land use change contributed about 17% of the world’s anthropogenic GHG emissions in 2010 (8.4 GtCO₂e yr^?1), making GHG mitigation in the agriculture sector critical to meeting the Paris Agreement’s 2°C goal. This article proposes a range of country-level targets for mitigation of agricultural emissions by allocating a global target according to five approaches to effort-sharing for climate change mitigation: responsibility, capability, equality, responsibility-capability-need and equal cumulative per capita emissions. Allocating mitigation targets according to responsibility for total historical emissions or capability to mitigate assigned large targets for agricultural emission reductions to North America, Europe and China. Targets based on responsibility for historical agricultural emissions resulted in a relatively even distribution of targets among countries and regions. Meanwhile, targets based on equal future agricultural emissions per capita or equal per capita cumulative emissions assigned very large mitigation targets to countries with large agricultural economies, while allowing some densely populated countries to increase agricultural emissions. There is no single ‘correct’ framework for allocating a global mitigation goal. Instead, using these approaches as a set provides a transparent, scientific basis for countries to inform and help assess the significance of their commitments to reducing emissions from the agriculture sector.

Key policy insights

• Meeting the Paris Agreement 2°C goal will require global mitigation of agricultural non-CO₂ emissions of approximately 1 GtCO₂e yr^?1 by 2030.

• Allocating this 1 GtCO₂e yr^?1 according to various effort-sharing approaches, it is found that countries will need to mitigate agricultural business-as-usual emissions in 2030 by a median of 10%. Targets vary widely with criteria used for allocation.

• The targets calculated here are in line with the ambition of the few countries (primarily in Africa) that included mitigation targets for the agriculture sector in their (Intended) Nationally Determined Contributions.

• For agriculture to contribute to meeting the 2°C or 1.5°C targets, countries will need to be ambitious in pursuing emission reductions. Technology development and transfer will be particularly important.

     

The regional nature of global challenges: a need and strategy for integrated regional modeling

Glaciers of the conterminous United States have been receding for the past century. Since 1900 the recession has varied from a 24 % loss in area (Mt. Rainier, Washington) to a 66 % loss in the Lewis Range of Montana. The rates of retreat are generally similar with a rapid loss in the early decades of the 20th century, slowing in the 1950s–1970s, and a resumption of rapid retreat starting in the 1990s. Decadal estimates of changes in glacier area for a subset of 31 glaciers from 1900 to 2000 are used to test a snow water equivalent model that is subsequently employed to examine the effects of temperature and precipitation variability on annual glacier area changes for these glaciers. Model results indicate that both winter precipitation and winter temperature have been important climatic factors affecting the variability of glacier variability during the 20th Century. Most of the glaciers analyzed appear to be more sensitive to temperature variability than to precipitation variability. However, precipitation variability is important, especially for high elevation glaciers. Additionally, glaciers with areas greater than 1 km² are highly sensitive to variability in temperature.     

The global distribution of methane in the troposphere

Methane has been measured in air samples collected at approximately weekly intervals at 23 globally distributed sites in the NOAA/GMCC cooperative flask sampling network. Sites range in latitude from 90° S to 76° N, and at most of these we report 2 years of data beginning in early 1983. All measurements have been made by gas chromatography with a flame ionization detector at the NOAA/GMCC laboratory in Boulder, Colorado. All air samples have been referenced to a single secondary standard of methane-in-air, ensuring a high degree of internal consistency in the data. The precision of measurements is estimated from replicate determinations on each sample as 0.2%. The latitudinal distribution of methane and the seasonal variation of this distribution in the marine boundary layer has been defined in great detail, including a remarkable uniformity in background levels of methane in the Southern Hemisphere. We report for the first time the observation of a complete seasonal cycle of methane at the South Pole. A significant vertical gradient is observed between a sea level and a high altitude site in Hawaii. Globally averaged background concentrations in the marine boundary layer have been calculated for the 2 year-period May 1983–April 1985 inclusive, from which we find an average increase of 12.8 ppb per year, or 0.78% per year when referenced to the globally averaged concentration (1625 ppb) at the mid-point of this period. We present evidence that there has been a slowing down in the methane growth rate.Presented at the Conference on the Scientific Application of Baseline Observations of Atmospheric Composition (SABOAC), Aspendale, Australia, 7–9 November 1984.     

Analyses of the global distribution of precipitation

The global distribution of area-averaged precipitation is extremely difficult to determine with precision. In this paper we will explain why satellite measurements are necessary for the production of global analyses of precipitation, summarize some of the various methods which have been used to estimate rainfall from satellite observations over the past two decades, and describe an attempt to use a mix of remotely sensed estimates and surface observations of rainfall to produce analyses of the large-scale rainfall for the globe. We will discuss the relationship between two types of satellite-derived precipitation estimates over the oceans from 40°N to 40°S, and then will conclude with a discussion of some possible physical mechanisms which might be responsible for the observed correlation between area-averaged rainfall and cloudiness.     

Economic costs of ocean acidification: a look into the impacts on global shellfish production

Ocean acidification is increasingly recognized as a major global problem. Yet economic assessments of its effects are currently almost absent. Unlike most other marine organisms, mollusks, which have significant commercial value worldwide, have relatively solid scientific evidence of biological impact of acidification and allow us to make such an economic evaluation. By performing a partial-equilibrium analysis, we estimate global and regional economic costs of production loss of mollusks due to ocean acidification. Our results show that the costs for the world as a whole could be over 100 billion USD with an assumption of increasing demand of mollusks with expected income growths combined with a business-as-usual emission trend towards the year 2100. The major determinants of cost levels are the impacts on the Chinese production, which is dominant in the world, and the expected demand increase of mollusks in today’s developing countries, which include China, in accordance with their future income rise. Our results have direct implications for climate policy. Because the ocean acidifies faster than the atmosphere warms, the acidification effects on mollusks would raise the social cost of carbon more strongly than the estimated damage adds to the damage costs of climate change.     

The contribution of future agricultural trends in the US Midwest to global climate change mitigation

Land use change is a complex response to changing environmental and socioeconomic systems. Historical drivers of land use change include changes in the natural resource availability of a region, changes in economic conditions for production of certain products and changing policies. Most recently, introduction of policy incentives for biofuel production have influenced land use change in the US Midwest, leading to concerns that bioenergy production systems may compete with food production and land conservation. Here we explore how land use may be impacted by future climate mitigation measures by nesting a high resolution agricultural model (EPIC – Environmental Policy Indicator Climate) for the US Midwest within a global integrated assessment model (GCAM – Global Change Assessment Model). This approach is designed to provide greater spatial resolution and detailed agricultural practice information by focusing on the climate mitigation potential of agriculture and land use in a specific region, while retaining the global economic context necessary to understand the far ranging effects of climate mitigation targets. We find that until the simulated carbon prices are very high, the US Midwest has a comparative advantage in producing traditional food and feed crops over bioenergy crops. Overall, the model responds to multiple pressures by adopting a mix of future responses. We also find that the GCAM model is capable of simulations at multiple spatial scales and agricultural technology resolution, which provides the capability to examine regional response to global policy and economic conditions in the context of climate mitigation.     

The effect of global climate change, population distribution, and climate mitigation on building energy use in the U.S. and China

Climate change will affect the energy system in a number of ways, one of which is through changes in demands for heating and cooling in buildings. Understanding the potential effect of climate change on heating and cooling demands requires taking into account not only the manner in which the building sector might evolve over time, but also important uncertainty about the nature of climate change itself. In this study, we explore the uncertainty in climate change impacts on heating and cooling requirement by constructing estimates of heating and cooling degree days (HDD/CDDs) for both reference (no-policy) and 550 ppmv CO₂ concentration pathways built from three different Global Climate Models (GCMs) output and three scenarios of gridded population distribution. The implications that changing climate and population distribution might have for building energy consumption in the U.S. and China are then explored by using the results of HDD/CDDs as inputs to a detailed, building energy model, nested in the long-term global integrated assessment framework, Global Change Assessment Model (GCAM). The results across the modeled changes in climate and population distributions indicate that unabated climate change would cause building sector’s final energy consumption to decrease modestly (6 % decrease or less depending on climate models) in both the U.S. and China by the end of the century as decreased heating consumption more than offsets increased cooling using primarily electricity. However, global climate change virtually has negligible effect on total CO₂ emissions in the buildings sector in both countries. The results also indicate more substantial implications for the fuel mix with increases in electricity and decreases in other fuels, which may be consistent with climate mitigation goals. The variation in results across all scenarios due to variation of population distribution is smaller than variation due to the use of different climate models.     

EU 20-20-20 energy policy as a model for global climate mitigation

The EU has established an aggressive portfolio with explicit near-term targets for 2020 – to reduce GHG emissions by 20%, rising to 30% if the conditions are right, to increase the share of renewable energy to 20%, and to make a 20% improvement in energy efficiency – intended to be the first step in a long-term strategy to limit climate forcing. The effectiveness and cost of extending these measures in time are considered along with the ambition and propagation to the rest of the world. Numerical results are reported and analysed for the contribution of the portfolio's various elements through a set of sensitivity experiments. It is found that the hypothetical programme leads to very substantial reductions in GHG emissions, dramatic increases in use of electricity, and substantial changes in land-use including reduced deforestation, but at the expense of higher food prices. The GHG emissions reductions are driven primarily by the direct limits. Although the carbon price is lower under the hypothetical protocol than it would be under the emissions cap alone, the economic cost of the portfolio is higher, between 13% and 22%.