How to achieve the 2030 CO2 emission-reduction targets for China's industrial sector: Retrospective decomposition and prospective trajectories

The Chinese government actively follows the low-carbon development pattern and has set the definite targets of reducing carbon emissions by 2030. The industrial sector plays a significant role in China's economic growth and CO₂ emissions. This is the first study to present a specific investigation on the retrospective decomposition (1993–2014) and prospective trajectories (2015–2035) of China's industrial CO₂ emission intensity (ICEI) and industrial CO₂ emissions (ICE), aiming at China Industrial Green Development Plan 2016–2020 targets and China's 2030 CO₂ emission-reduction targets. We introduce process carbon intensity, investment and R&D factors into the decomposition model and make a combination of dynamic Monte Carlo simulation and scenario analysis to identify whether and how the targets would be realized from a sector-specific perspective. The results indicate that investment intensity is the primary driver for the increase in ICEI, while R&D intensity and energy intensity are the leading contributors to the reduction in ICEI. Under existing policies, it is very possible for the industrial sector to achieve the 2020 and 2030 intensity-reduction targets. However, the realization of 2030 emission-peak target has some uncertainties and needs extra efforts in efficiency improvement and structural adjustment. All the five scenarios would achieve the 2020 and 2030 intensity-reduction targets, except Scenario N4 for China Industrial Green Development Plan 2016–2020 target. Nonetheless, only three scenarios would realize the 2030 emission-peak target. With strong efficiency improvement and structural adjustment, ICE would hit the peak in 2025. In contrast, with high/low efficiency improvement and weak structural adjustment, ICE would fail to reach the peak before 2035. Both ICEI and ICE have substantial mitigation potentials with the enhancement of efficiency improvement and structural adjustment. Finally, we suggest that the Chinese government should raise the baseline requirements of efficiency improvement and structural adjustment for the industrial sector to achieve China’s 2030 targets.     

Estimates of the Climate Response to Aircraft CO2 and NO x Emissions Scenarios

A combination of linear response models is used to estimate the transient changes in the global means of carbon dioxide (CO₂) concentration, surface temperature, and sea level due to aviation. Apart from CO₂, the forcing caused by ozone (O₃) changes due to nitrogen oxide (NO_x) emissions from aircraft is also considered. The model is applied to aviation using several CO₂ emissions scenarios, based on reported fuel consumption in the past and scenarios for the future, and corresponding NO_x emissions. Aviation CO₂ emissions from the past until 1995 enlarged the atmospheric CO₂ concentration by 1.4 ppmv (1.7% of the anthropogenic CO₂ increase since 1800). By 1995, the global mean surface temperature had increased by about 0.004 K, and the sea level had risen by 0.045 cm. In one scenario (Fa1), which assumes a threefold increase in aviation fuel consumption until 2050 and an annual increase rate of 1% thereafter until 2100, the model predicts a CO₂ concentration change of 13 ppmv by 2100, causing temperature increases of 0.01, 0.025, 0.05 K and sea level increases of 0.1, 0.3, and 0.5 cm in the years 2015, 2050, and 2100, respectively. For other recently published scenarios, the results range from 5 to 17 ppmv for CO₂ concentration increase in the year 2050, and 0.02 to 0.05 K for temperature increase. Under the assumption that present-day aircraft-induced O₃ changes cause an equilibrium surface warming of 0.05 K, the transient responses amount to 0.03 K in surface temperature for scenario Fa1 in 1995. The radiative forcing due to an aircraft-induced O₃ increase causes a larger temperature change than aircraft CO₂ forcing. Also, climate reacts more promptly to changes in O₃ than to changes in CO₂ emissions from aviation. Finally, even under the assumption of a rather small equilibrium temperature change from aircraft-induced O₃ (0.01 K for the 1992 NO_x emissions), a proposed new combustor technology which reduces specific NO_x emissions will cause a smaller temperature change during the next century than the standard technology does, despite a slightly enhanced fuel consumption. Regional effects are not considered here, but may be larger than the global mean responses.     

The impacts of economic structure on China’s carbon dioxide emissions: an analysis with reference to other East Asian economies

A change in economic structure influences the total energy consumption as well as CO₂ emissions of a country, given the inherent difference in levels of energy intensity and energy fuel mix of different economic sectors. Its significance has been recognized in recent literature on China’s emission mitigation which could arguably raise China’s mitigation potential and thus the possibility of keeping the 2-degree trajectory on track. This article utilizes the past trend of economic structural change of five East Asian developed economies to project the energy consumption and CO₂ emissions of China in the coming decades. A special delineation of the economic sector is made, putting private consumption together with the three typical economic production sectors, to resolve the mismatch between the statistical data of energy consumption and economic production, in that residential energy consumption is typically merged into the tertiary sector, although it does not directly correspond to gross domestic product (GDP) output. Results suggest that the level of CO₂ emissions would be lower if China followed a development pathway emphasizing the development of the tertiary sector and continuously shrinking her secondary sector, making it possible for China to contribute more to global carbon mitigation. The impact from the rise of private consumption would be relatively insignificant compared to deindustrialization. In addition to continuous improvement in technology, economic structural change, which reduces carbon emission intensity, would be essential for China to be able to achieve the carbon emission level pledged in the Paris Agreement.

Key policy insights

• For China, significant economic structural reform, particularly deindustrialization, is necessary to achieve the goal of ‘peak emission by 2030’.

• Any additional contribution from China to the global effort to maintain a 2-degree trajectory would be limited – from a ‘fair-contribution’ perspective based on share of population or GDP – because the implied mitigation targets would be almost impossible to achieve.

• If developing countries follow the pathway of developed economies, particularly in developing energy-intensive industries, energy consumption and CO₂ emissions would significantly increase, reducing the possibility of keeping global temperature rise within the 2-degree Celsius benchmark.

     

Exploring optimal mitigation and adaptation investment strategies in China

After the successful conclusion of the Paris Climate Conference (Conference of the Parties (COP) 21), countries are now attempting to identify implementation measures. An important consensus has been reached on the necessity of putting in place both mitigation and adaptation measures. In this context, this article builds a three-sector China and rest of the world model based on the DE-carbonization Model with Endogenous Technologies for Emission Reductions (DEMETER) and World Induced Technical Change Hybrid (WITCH) models. It assesses China’s mitigation and adaptation investment strategies by 2050 with an optimization including climate externalities. By making the 450?ppm target and China’s 2030 CO₂ emissions peak exogenous, it assesses two scenarios: (1) investment only in mitigation and (2) investment in both mitigation and adaptation. The article finds the following: First, the policy package with investment in both mitigation and adaptation can ensure lower CO₂ emissions and avoid more climate damage. Second, investment in adaptation should be massively injected by around 2040, whereas mitigation efforts should be continuous. Third, the CO₂ emissions peak in the tertiary sector should come prior to 2030 while the emissions pathway of the secondary sector could be allowed to increase slowly until 2035.

POLICY RELEVANCE

• The necessity of engaging in both mitigation and adaptation has been widely accepted since the Paris Climate Conference (COP21), yet few studies exist in this regard concerning China.

• Substantial investment in adaptation needs to be introduced by 2040 while the investment on mitigation should peak by 2030.

• The CO₂ emissions peak in the tertiary sector would be reached prior to 2030 while the peak in the secondary sector is achieved around 2035.

• This provides an alternative in China to the existing argument of an earlier peak in the secondary sector.

     

Renewable and low-carbon energies as mitigation options of climate change for China

This article discusses how renewable and low-carbon energies can serve as mitigation options of climate change in China’s power sector. Our study is based on scenarios developed in PowerPlan, a bottom-up model simulating a countries’ power sector and its emissions. We first adjusted the model to China’s present-day economy and power sector. We then developed different scenarios based on story lines for possible future developments in China. We simulated China’s carbon-based electricity production system of today and possible future transitions towards a low-carbon system relying on renewable and low-carbon energies. In our analysis, we compare the business-as-usual scenarios with more sustainable energy scenarios. We found that by increasing the share of renewable and nuclear energies to different levels, between 17% and 57% of all CO₂ emissions from the power sector could be avoided by 2030 compared to the business-as-usual scenario. We also found that electricity generation costs increase when more sustainable power plants are installed. As a conclusion, China has two options: choosing for high climate change mitigation and high costs or choosing for moderate climate change mitigation and moderate costs. In case high climate change mitigation will be chosen, development assistance is likely to be needed to cover the costs.     

Climate change mitigation scenarios and policies and measures: the case of Kazakhstan

This article illustrates the main difficulties encountered in the preparation of GHG emission projections and climate change mitigation policies and measures (P&M) for Kazakhstan. Difficulties in representing the system with an economic model have been overcome by representing the energy system with a technical-economic growth model (MARKAL-TIMES) based on the stock of existing plants, transformation processes, and end-use devices. GHG emission scenarios depend mainly on the pace of transition in Kazakhstan from a planned economy to a market economy. Three scenarios are portrayed: an incomplete transition, a fast and successful one, and even more advanced participation in global climate change mitigation, including participation in some emission trading schemes. If the transition to a market economy is completed by 2020, P&M already adopted may reduce emissions of CO₂ from combustion by about 85 MtCO₂ by 2030 – 17% of the emissions in the baseline (WOM) scenario. One-third of these reductions are likely to be obtained from the demand sectors, and two-thirds from the supply sectors. If every tonne of CO₂ not emitted is valued up to US$10 in 2020 and $20 in 2030, additional P&M may further reduce emissions by 110 MtCO₂ by 2030.     

Consequences of Incomplete Surface Energy Balance Closure for CO2 Fluxes from Open-Path CO2/H2O Infrared Gas Analysers

We present an approach for assessing the impact of systematic biases in measured energy fluxes on CO₂ flux estimates obtained from open-path eddy-covariance systems. In our analysis, we present equations to analyse the propagation of errors through the Webb, Pearman, and Leuning (WPL) algorithm [Quart. J. Roy. Meteorol. Soc. 106, 85–100, 1980] that is widely used to account for density fluctuations on CO₂ flux measurements. Our results suggest that incomplete energy balance closure does not necessarily lead to an underestimation of CO₂ fluxes despite the existence of surface energy imbalance; either an overestimation or underestimation of CO₂ fluxes is possible depending on local atmospheric conditions and measurement errors in the sensible heat, latent heat, and CO₂ fluxes. We use open-path eddy-covariance fluxes measured over a black spruce forest in interior Alaska to explore several energy imbalance scenarios and their consequences for CO₂ fluxes.     

Energy-intensive manufacturing sectors in China: policy priorities for achieving climate mitigation and energy conservation targets

In this study, a long-range energy alternative planning (LEAP) model was built to evaluate the relative priority of three kinds of policies expected to be implemented for the energy-intensive manufacturing sectors (EIMS) in China to achieve CO₂ mitigation and energy conservation targets. These policies encourage (1) the use of more electricity instead of coal; (2) the continuous improvement of energy efficiency; and (3) a shift to other less energy-demanding sectors. The results indicate that the policy of shifting economic activity from the EIMS to other sectors is most helpful for China to achieve its targets of mitigating CO₂ emissions and conserving energy. Encouraging the EIMS to use more electricity can help China to achieve a higher proportion of non-fossil-fuel based energy in its overall primary energy consumption. No single policy will allow China to achieve all the targets, emphasizing the need for an integrated policy design that combines all types of policies.

Key policy insights

• The policy of encouraging a shift to less energy intensive industries should receive the highest priority in aiming to peak China's energy-related CO₂ emissions as early as possible, and lower overall CO₂ emissions, coal consumption and primary energy consumption in the long run.

• Encouraging a shift to electricity should go hand-in-hand with greater energy efficiency, otherwise such a policy cannot help China significantly reduce energy-related CO₂ emissions.

• Encouraging the EIMS to use more electricity should receive the highest priority in helping China achieve a higher proportion of non-fossil-fuel based energy in its overall primary energy consumption.

     

Variation in the climatic response to SRES emissions scenarios in integrated assessment models

Integrated assessment models (IAMs) have commonly been used to understand the relationship between the economy, the earth’s climate system and climate impacts. We compare the IPCC simulations of CO₂ concentration, radiative forcing, and global mean temperature changes associated with five SRES ‘marker’ emissions scenarios with the responses of three IAMs—DICE, FUND and PAGE—to these same emission scenarios. We also compare differences in simulated temperature increase resulting from moving from a high to a low emissions scenario. These IAMs offer a range of climate outcomes, some of which are inconsistent with those of IPCC, due to differing treatments of the carbon cycle and of the temperature response to radiative forcing. In particular, in FUND temperatures up until 2100 are relatively similar for the four emissions scenarios, and temperature reductions upon switching to lower emissions scenarios are small. PAGE incorporates strong carbon cycle feedbacks, leading to higher CO₂ concentrations in the twenty-second century than other models. Such IAMs are frequently applied to determine ‘optimal’ climate policy in a cost–benefit approach. Models such as FUND which show smaller temperature responses to reducing emissions than IPCC simulations on comparable timescales will underestimate the benefits of emission reductions and hence the calculated ‘optimal’ level of investment in mitigation.     

Comparative assessment of Japan's long-term carbon budget under different effort-sharing principles

This article assesses Japan's carbon budgets up to 2100 in the global efforts to achieve the 2?°C target under different effort-sharing approaches based on long-term GHG mitigation scenarios published in 13 studies. The article also presents exemplary emission trajectories for Japan to stay within the calculated budget.

The literature data allow for an in-depth analysis of four effort-sharing categories. For a 450?ppm CO₂e stabilization level, the remaining carbon budgets for 2014–2100 were negative for the effort-sharing category that emphasizes historical responsibility and capability. For the other three, including the reference ‘Cost-effectiveness’ category, which showed the highest budget range among all categories, the calculated remaining budgets (20th and 80th percentile ranges) would run out in 21–29 years if the current emission levels were to continue. A 550?ppm CO₂e stabilization level increases the budgets by 6–17 years-equivalent of the current emissions, depending on the effort-sharing category. Exemplary emissions trajectories staying within the calculated budgets were also analysed for ‘Equality’, ‘Staged’ and ‘Cost-effectiveness’ categories. For a 450?ppm CO₂e stabilization level, Japan's GHG emissions would need to phase out sometime between 2045 and 2080, and the emission reductions in 2030 would be at least 16–29% below 1990 levels even for the most lenient ‘Cost-effectiveness’ category, and 29–36% for the ‘Equality’ category. The start year for accelerated emissions reductions and the emissions convergence level in the long term have major impact on the emissions reduction rates that need to be achieved, particularly in the case of smaller budgets.

Policy relevance

In previous climate mitigation target formulation processes for 2020 and 2030 in Japan, neither equity principles nor long-term management of cumulative GHG emissions was at the centre of discussion. This article quantitatively assesses how much more GHGs Japan can emit by 2100 to achieve the 2?°C target in light of different effort-sharing approaches, and how Japan's GHG emissions can be managed up to 2100. The long-term implications of recent energy policy developments following the Fukushima nuclear disaster for the calculated carbon budgets are also discussed.     

How to reach an elusive INDC target: macro-economic implications of carbon taxation and emissions trading in Turkey

This paper employs a computable general equilibrium model (CGE) to analyse how a carbon tax and/or a national Emissions Trading System (ETS) would affect macroeconomic parameters in Turkey. The modelling work is based on three main policy options for the government by 2030, in the context of Turkey’s mitigation target under its Intended Nationally Determined Contribution (INDC), that is, reducing greenhouse gas (GHG) emissions by up to 21% from its Business as Usual (BAU) scenario in 2030: (i) improving the productivity of renewable energy by 1% per annum, a target already included in the INDC, (ii) introducing a new flat rate tax of 15% per ton of CO₂ (of a reference carbon price in world markets) imposed on emissions originating from carbon-intensive sectors, and (iii) introducing a new ETS with caps on emission permits. Our base path scenario projects that GHG emissions in 2030 will be much lower than Turkey’s BAU trajectory of growth from 430 Mt CO₂-eq in 2013 to 1.175 Mt CO₂-eq by 2030, implying that the government’s commitment is largely redundant. On the other hand, if the official target is assumed to be only a simple reduction percentage in 2030 (by 21%), but based on our more realistic base path, the government’s current renewable energy plans will not be sufficient to reach it.

• Turkey’s official INDC is based on over-optimistic assumptions of GDP growth and a highly carbon-intensive development pathway;

• A carbon tax and/or an ETS would be required to reach the 21% reduction target over a realistic base path scenario for 2030;

• The policy options considered in this paper have some effects on major sectors’ shares in total value-added. Yet the reduction in the shares of agriculture, industry, and transportation does not go beyond 1%, while the service sector seems to benefit from most of the policy options;

• Overall employment would be affected positively by the renewable energy target, carbon tax, and ETS through the creation of new jobs;

• Unemployment rates are lower, economic growth is stronger, and households become better off to a larger extent under an ETS than carbon taxation.

     

Managing atmospheric CO2

A coupled carbon cycle-climate model is used to compute global atmospheric CO₂ and temperature variation that would result from several future CO₂ emission scenarios. The model includes temperature and CO₂ feedbacks on the terrestrial biosphere, and temperature feedback on the oceanic uptake of CO₂. The scenarios used include cases in which fossil fuel CO₂ emissions are held constant at the 1986 value or increase by 1% yr^–1 until either 2000 or 2020, followed by a gradual transition to a rate of decrease of 1 or 2% yr^–1. The climatic effect of increases in non-CO₂ trace gases is included, and scenarios are considered in which these gases increase until 2075 or are stabilized once CO₂ emission reductions begin. Low and high deforestation scenarios are also considered. In all cases, results are computed for equilibrium climatic sensitivities to CO₂ doubling of 2.0 and 4.0 °C.Peak atmospheric CO₂ concentrations of 400–500 ppmv and global mean warming after 1980 of 0.6–3.2 °C occur, with maximum rates of global mean warming of 0.2–0.3 °C decade^–1. The peak CO₂ concentrations in these scenarios are significantly below that commonly regarded as unavoidable; further sensitivity analyses suggest that limiting atmospheric CO₂ to as little as 400 ppmv is a credible option.Two factors in the model are important in limiting atmospheric CO₂: (1) the airborne fraction falls rapidly once emissions begin to decrease, so that total emissions (fossil fuel + land use-induced) need initially fall to only about half their present value in order to stabilize atmospheric CO₂, and (2) changes in rates of deforestation have an immediate and proportional effect on gross emissions from the biosphere, whereas the CO₂ sink due to regrowth of forests responds more slowly, so that decreases in the rate of deforestation have a disproportionately large effect on net emission.If fossil fuel emissions were to decrease at 1–2% yr^–1 beginning early in the next century, emissions could decrease to the rate of CO₂ uptake by the predominantly oceanic sink within 50–100 yrs. Simulation results suggest that if subsequent emission reductions were tied to the rate of CO₂ uptake by natural CO₂ sinks, these reductions could proceed more slowly than initially while preventing further CO₂ increases, since the natural CO₂ sink strength decreases on time scales of one to several centuries. The model used here does not account for the possible effect on atmospheric CO₂ concentration of possible changes in oceanic circulation. Based on past rates of atmospheric CO₂ variation determined from polar ice cores, it appears that the largest plausible perturbation in ocean-air CO₂ flux due to changes of oceanic circulation is substantially smaller than the permitted fossil fuel CO₂ emissions under the above strategy, so tieing fossil fuel emissions to the total sink strength could provide adequate flexibility for responding to unexpected changes in oceanic CO₂ uptake caused by climatic warming-induced changes of oceanic circulation.     

The Consequences of CO2 Stabilisation for the Impacts of Climate Change

This paper reports the main results of an assessment of the global-scale implications of the stabilisation of atmospheric CO₂ concentrations at 750 ppm (by 2250) and 550 ppm (by 2150), in relationto a scenario of unmitigated emissions. The climate change scenarios were derived from simulation experiments conducted with the HadCM2 global climate model and forced with the IPCC IS92a, S750 and S550 emissions scenarios. The simulated changes in climate were applied to an observed global baseline climatology, and applied with impacts models to estimate impacts on natural vegetation, water resources, coastal flood risk and wetland loss, crop yield and food security, and malaria. The studies used a single set of population and socio-economic scenarios about the future that are similar to those adopted in the IS92a emissions scenario.An emissions pathway which stabilises CO₂ concentrations at 750 ppmby the 2230s delays the 2050 temperature increase under unmitigated emissions by around 50 years. The loss of tropical forest and grassland which occurs by the 2050s under unmitigated emissions is delayed to the 22nd century, and the switch from carbon sink to carbon source is delayed from the 2050s to the 2170s. Coastal wetland loss is slowed. Stabilisation at 750 ppm generally has relatively little effect on the impacts of climate change on water resource stress, and populations at risk of hunger or falciparum malaria until the 2080s.A pathway which stabilises CO₂ concentrations at 550 ppm by the 2170s delays the 2050 temperature increase under unmitigated emissions by around 100 years. There is no substantial loss of tropical forest or grassland, even by the 2230s, although the terrestrial carbon store ceases to act as a net carbon sink by around 2170 (this time because the vegetation has reached a new equilibrium with the atmosphere). Coastal wetland loss is slowed considerably, and the increase in coastal flood risk is considerably lower than under unmitigated emissions. CO₂ stabilisation at 550 ppm reduces substantially water resource stress, relative to unmitigated emissions, but has relatively little impact on populations at risk of falciparum malaria, and may even cause more people to be at risk of hunger. While this study shows that mitigation avoids many impacts, particularly in the longer-term (beyond the 2080s), stabilisation at 550 ppm appears to be necessary to avoid or significantly reduce most of the projected impacts in the unmitigated case.     

Stabilizing CO2 concentrations with incomplete international cooperation

Many stabilization scenarios have examined the implications of stabilization on the assumption that all regions and all sectors of all of the world's economies undertake emissions mitigations wherever and whenever it is cheapest to do so. This idealized assumption is just one of many ways in which emissions mitigation actions could play out globally, but not necessarily the most likely. This paper explores the implications of generic policy regimes that lead to stabilization of CO₂ concentrations under conditions in which non-Annex I regions delay emissions reductions and in which carbon prices vary across participating regions. The resulting stabilization scenarios are contrasted with the idealized results. Delays in the date by which non-Annex I regions begin to reduce emissions raise the price of carbon in Annex I regions relative to the price of carbon in Annex I in an idealized regime for any given CO₂ concentration limit. This effect increases the longer the delay in non-Annex I accession, the lower the non-Annex I carbon prices relative to the Annex I prices, and the more stringent the stabilization level. The effect of delay is very pronounced when CO₂ concentrations are stabilized at 450 ppmv, however the effect is much less pronounced at 550 ppmv and above. For long delays in non-Annex I accession, 450 ppmv stabilization levels become infeasible.     

Ocean acidification and climate change: synergies and challenges of addressing both under the UNFCCC

Ocean acidification and climate change are linked by their common driver: CO₂. Climate change is the consequence of a range of GHG emissions, but ocean acidification on a global scale is caused solely by increased concentrations of atmospheric CO₂. Reducing CO₂ emissions is therefore the most effective way to mitigate ocean acidification. Acting to prevent further ocean acidification by reducing CO₂ emissions will also provide simultaneous benefits by alleviating future climate change. Although it is possible that reducing CO₂ emissions to a level low enough to address ocean acidification will simultaneously address climate change, the reverse is unfortunately not necessarily true. Despite the ocean's integral role in the climate system and the potentially wide-ranging impacts on marine life and humans, the problem of ocean acidification is largely absent from most policy discussions pertaining to CO₂ emissions. The linkages between ocean acidification, climate change and the United Nations Framework Convention on Climate Change (UNFCCC) are identified and possible scenarios for developing common solutions to reduce and adapt to ocean acidification and climate change are offered. Areas where the UNFCCC is currently lacking capacity to effectively tackle rising ocean acidity are also highlighted.     

REGIONAL CLIMATE CHANGE SCENARIOS UNDER GLOBAL WARMING IN KAZAKHSTAN

The aim of this paper is to report on the development of regional climate change scenarios for Kazakhstan as the result of increasing of CO₂ concentration in the global atmosphere. These scenarios are used in the assessment of climate change impacts on the agricultural, forest and water resources of Kazakhstan. Climate change scenarios for Kazakhstan to assess both long-term (2× CO₂ in 2075) and short-term (2000, 2010 and 2030) impacts were prepared. The climate conditions under increasing CO₂ concentration were estimated from three General Circulation Models (GCM) outputs: the model of the Canadian Climate Center Model (CCCM), the model of the Geophysical Fluid Dynamics Laboratory (GFDL) and the 1% transient version of the GFDL model (GFDL-T). The near-term climate scenarios were obtained using the probabilistic forecast model (PFM) to the year 2010 and the results of GFDL-T for years 2000 and 2030. A baseline scenario representing the current climate conditions based on observations from 1951 to 1980 was developed. The assessment of climate change in Kazakhstan based on the analysis of 100-years observations is given too. As a result of comparisons of the current climate (based on observed climate) the 1× CO₂ output from GCMs showed that the GFDL model best matches the observed climate. The GFDL model suggests that the minimum increase in temperature is expected in winter, when most of the territory is expected to have temperatures 2.3–4.5 °C higher. The maximum (4.3 to 8.2 °C) is expected to be in spring. CCCM scenario estimates an extreme worming above 11 °C in spring months. GFDL-T outputs provide an intermediate scenario.     

The danger of overvaluing methane’s influence on future climate change

Minimizing the future impacts of climate change requires reducing the greenhouse gas (GHG) load in the atmosphere. Anthropogenic emissions include many types of GHG’s as well as particulates such as black carbon and sulfate aerosols, each of which has a different effect on the atmosphere, and a different atmospheric lifetime. Several recent studies have advocated for the importance of short timescales when comparing the climate impact of different climate pollutants, placing a high relative value on short-lived pollutants, such as methane (CH₄) and black carbon (BC) versus carbon dioxide (CO₂). These studies have generated confusion over how to value changes in temperature that occur over short versus long timescales. We show the temperature changes that result from exchanging CO₂ for CH₄ using a variety of commonly suggested metrics to illustrate the trade-offs involved in potential carbon trading mechanisms that place a high value on CH₄ emissions. Reducing CH₄ emissions today would lead to a climate cooling of approximately ~0.5 °C, but this value will not change greatly if we delay reducing CH₄ emissions by years or decades. This is not true for CO₂, for which the climate is influenced by cumulative emissions. Any delay in reducing CO₂ emissions is likely to lead to higher cumulative emissions, and more warming. The exact warming resulting from this delay depends on the trajectory of future CO₂ emissions but using one business-as usual-projection we estimate an increase of 3/4 °C for every 15-year delay in CO₂ mitigation. Overvaluing the influence of CH₄ emissions on climate could easily result in our “locking” the earth into a warmer temperature trajectory, one that is temporarily masked by the short-term cooling effects of the CH₄ reductions, but then persists for many generations.     

The importance of reduced meat and dairy consumption for meeting stringent climate change targets

For agriculture, there are three major options for mitigating greenhouse gas (GHG) emissions: 1) productivity improvements, particularly in the livestock sector; 2) dedicated technical mitigation measures; and 3) human dietary changes. The aim of the paper is to estimate long-term agricultural GHG emissions, under different mitigation scenarios, and to relate them to the emissions space compatible with the 2 °C temperature target. Our estimates include emissions up to 2070 from agricultural soils, manure management, enteric fermentation and paddy rice fields, and are based on IPCC Tier 2 methodology. We find that baseline agricultural CO₂-equivalent emissions (using Global Warming Potentials with a 100 year time horizon) will be approximately 13 Gton CO₂eq/year in 2070, compared to 7.1 Gton CO₂eq/year 2000. However, if faster growth in livestock productivity is combined with dedicated technical mitigation measures, emissions may be kept to 7.7 Gton CO₂eq/year in 2070. If structural changes in human diets are included, emissions may be reduced further, to 3–5 Gton CO₂eq/year in 2070. The total annual emissions for meeting the 2 °C target with a chance above 50 % is in the order of 13 Gton CO₂eq/year or less in 2070, for all sectors combined. We conclude that reduced ruminant meat and dairy consumption will be indispensable for reaching the 2 °C target with a high probability, unless unprecedented advances in technology take place.     

The Present, Past, and Future Contributions to Global Warming of CO2 Emissions from Fuels

The objective of this paper is to emphasize theresponsibility of developed countries to implement the Climate Convention, as well as the role ofdeveloping countries in CO₂ emissions controlwhile sustaining their rights to increase energyconsumption per capita during the development process. Itis shown that the growth in CO₂$ emissions fromfossil fuel consumption in North America, excludingMexico, from 1990 to 1996 was 3.7 times higherthan that of Latin America in absolute terms. Thecumulative contribution to global warming, expressedas the mass of the gas multiplied by time (GtCy), can becalculated as the integration of the atmosphericconcentration of the emitted gas along time, witha weight function in the integrand to simulate theclimate response. To simulate climate response,we used the superposition of exponential decay functions with different decay constants. Thehistorical contributions of the OECD countries,the Eastern European countries and theex-Soviet Union, and from all developingcountries are considered. The future contributionsare computed in three scenarios. All of them showthat emissions from Non-Annex I countrieswill become higher than those of Annex I countriessoon after 2010, while the curves of atmosphericconcentration will cross one another later, not muchbefore 2050, and the respective contributions toglobal temperature increase will cross about 2090.     

CO2 emission clusters within global supply chain networks: Implications for climate change mitigation

Production and consumption of goods and services are interlinked through complex global supply-chain networks; so are the greenhouse gas emissions associated with them. Using a model that represents global supply-chain networks, we identified supply-chain clusters with high CO₂ emissions within more than 300 million individual supply chains. We distinguished 4756 significant CO₂ clusters and found that in 2008, global supply-chain networks associated with U.S. transport equipment and construction demand included relatively large CO₂ clusters in China, accounting for 17% and 10%, respectively, of the U.S. CO₂ footprint. Of added importance is the fact that these two clusters in China had annual growth rates of 42% and 58%, respectively, during the period 1995–2008. Our results show the importance for climate policy of monitoring these CO₂ clusters that dominate CO₂ emissions in global supply chains, and they offer insights on where climate policy can be effectively directed.