Jochen Harnisch

Multi-gas assessment of the Kyoto Protocol

The Kyoto Protocol allows reductions in emissions of several ‘greenhouse’ gases to be credited against a CO2-equivalent emissions limit, calculated using ‘global warming potential’ indices for each gas. Using an integrated global-systems model, it is shown that a multi-gas control strategy could greatly reduce the costs of fulfilling the Kyoto Protocol compared with a CO2-only strategy. Extending the Kyoto Protocol to 2100 without more severe emissions reductions shows little difference between the two strategies in climate and ecosystem effects. Under a more stringent emissions policy, the use of global warming potentials as applied in the Kyoto Protocol leads to considerably more mitigation of climate change for multi-gas strategies than for the—supposedly equivalent—CO2-only control, thus emphasizing the limits of global warming potentials as a tool for political decisions.

Uncertainty in emissions projections for climate models

Future global climate projections are subject to large uncertainties. Major sources of this uncertainty are projections of anthropogenic emissions. We evaluate the uncertainty in future anthropogenic emissions using a computable general equilibrium model of the world economy. Results are simulated through 2100 for carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6), sulfur dioxide (SO2), black carbon (BC) and organic carbon (OC), nitrogen oxides (NOx), carbon monoxide (CO), ammonia (NH3) and non-methane volatile organic compounds (NMVOCs). We construct mean and upper and lower 95% emissions scenarios (available from the authors at 11 � 11 latitude–longitude grid). Using the MIT Integrated Global System Model (IGSM), we find a temperature change range in 2100 of 0.9 to 4.01C, compared with the Intergovernmental Panel on Climate Change emissions scenarios that result in a range of 1.3 to 3.61C when simulated through MIT IGSM. r 2002 Elsevier Science Ltd. All rights reserved.

Tropospheric trends for CF4 and C2F6 since 1982 derived from SF6 dated stratospheric air

The stratosphere can be used as an archive of past tropospheric conditions. Measurements of the long-lived trace gases CF4, C2F6, and SF6 have been carried out on stratospheric air samples obtained by balloon borne cryosampling from altitudes of up to 34 km between 1987 and 1995. SF6 observations were used to ‘date’ the air samples. Above 25 km height the SF6 concentrations are lagging the tropospheric ones by several years: 4.5 years for the tropics, 6 years for mid-latitudes and up to 10 years for the arctic winter vortex. The high ages of stratospheric air found inside the upper polar vortex may indicate that the lag of the peak halogen burden between the troposphere and the polar stratosphere is longer than previously assumed. The age information from SF6 allows to reconstruct tropospheric trends for CF4 and C2F6 since 1982. Accordingly, for the period 1982 to 1995, concentrations increased from 62 to 75 ppt for CF4 and from 1.5 to 2.6 ppt for C2F6. Mean increase rates of 1.00 ppt yr−1 for CF4 and 0.084 ppt yr−1 for C2F6 translate into annual injection rates of about 14,600 t yr−1 and 1,900 t yr−1 respectively. With aluminium production as the only major source, average emissions per ton of primary aluminium are thus calculated to be 0.77 kg for CF4 and 0.10 kg of C2F6 in 1994.

Natural CF4 and SF6 on Earth

The occurrence of CF4 and SF6 in natural fluorites (CaF2) is reported. Contents are found to be typically 200–2000 ppt-mass for CF4 and 50–100 ppt-mass for SF6. CF4 and SF6 were also detected in granites where fluorite is an accessory mineral. CF4 and SF6 thus possess a large reservoir in the continental crust that by degassing can sustain natural atmospheric background levels of 40 ppt-mole and up to 0.01 ppt-mole, respectively. The article also discusses how natural SF6 may cause interference in hydrological tracer studies.

Natural fluorinated organics in fluorite and rocks

Results of measurements of fluorinated compounds in gasses extracted from igneous and metamorphic rocks are reported. A new extraction method analogous to a pepper mill for geological samples is described. It permits extraction at low temperatures and ensures a rapid transfer of extracted gases from active surfaces to cryogenic pre-concentration loop. Values for CF4, CF3Cl, CF2Cl2, CFCl3, CHF3, SF6 and NF3 in fluorites, granites, basalts and other igneous and metamorphic rocks are reported. It is proposed that trifluoroacetic acid (TFA) that was recently discovered in various environmental archives could also origin from similar geogenic sources.

Economic Evaluation of Sectoral Emission Reduction Objectives for Climate Change

Publisher Summary This paper summarizes a study that identifies a least-cost allocation of objectives for different sectors and greenhouse gases so that the European Union would meet its Kyoto target of –8% in 2008–2012 compared to 1990 emissions. For the purposes of the study, it was assumed that the EU would comply with its Kyoto target without the “Kyoto mechanisms.” The study concludes that the marginal abatement cost amounts to € 99 42/tCO 2 -eq if each Member State fulfils their Kyoto “burden sharing” target individually. However, the cost would be reduced to € 99 20/tCO 2 -eq if the EU Member States fulfill their Kyoto obligations jointly, allowing to take measures where they are most cost-effective. In this least cost case, the annual compliance cost in 2010 is estimated at € 99 3.7 billion. The compliance cost would be fairly small in most sectors. This approach will fully maintain the environmental integrity of the Kyoto Protocol, while identifying those policies and measures that achieve the Kyoto target in a manner that minimizes the cost. Simply, the intention is to identify a least-cost allocation so that the cost of production of energy and other goods would increase as little as possible.

Comparison of emissions estimates derived from atmospheric measurements with national estimates of HFCs, PFCs and SF6

This paper assesses the feasibility of using atmospheric measurement of fluorinated greenhouse gases (HFCs, PFCs and SF6) for the review and verification of greenhouse gas inventories provided by national governments. For this purpose, available data were compiled. It was found that atmospheric measurements of these gases are available and provide an indication of global annual emissions with sufficient certainty to reach the following conclusions: Within the uncertainty of the method, it was found that emissions of HFC-23, a by-product of HCFC-22 production, as obtained from atmospheric measurements did not decrease as fast, as the countries have reported. In contrast, SF6 concentrations in the atmosphere suggest higher emissions than reported by countries. Regional emission estimates from atmospheric measurements are still in a more pioneering state and cannot be compared to national estimates. Intensified efforts to measure HFCs, PFCs and SF6 in the atmosphere are recommended.

CF4 and the age of mesospheric and polar vortex air

A chronology of tropospheric CF4 mixing ratios is reported for the northern hemisphere. A decline of global emissions of CF4 from 16,000 to 11,000 metric tons yr−1 is found for the periods 1978–1990 and 1992–1998, respectively. The atmospheric chronology of CF4 is applied to determine the age of air of cryogenic air samples collected on rocket and balloon platforms. Age values of 7 years are found inside the polar vortex between 25–44 km altitude and of 11 years between 56 and 61 km altitude, which is significantly higher than predicted by most models currently used to assess the effects of high-flying aircraft. The results suggest that the mesosphere is more isolated from below than previously believed. A comparison of age values derived from CF4 and SF6 relative to predicted deviations constrains the atmospheric lifetime of SF6 to >5,000 years.

Multiple gas control under the Kyoto agreement

Under the Kyoto Protocol, reductions in emissions of several radiative gases can be credited against a carbon equivalent emissions cap. We investigate the economic implications of including other greenhouse gases and sinks in the climate change control policy using our revised and updated version of the Emissions Prediction and Policy Analysis (EPPA) model. In addition we amended our methane abatement curves based on different interpretations of estimates that substantial abatement of methane can be obtained at no cost. The inclusion of other greenhouse gases and CO2 sinks reduces the costs of achieving CO2 emissions reductions specified under the agreement.

A stratospheric excess of CO2‐due to tropical deep convection?

The age of stratospheric air is a measure that characterizes the time scales of stratospheric transport. In this work we present and compare age-values as determined from measurements of CO 2 and SF 6 on air-samples obtained between 1987 and 1995 on six flights of our balloon-borne cryo-sampler. In the middle stratosphere for five out of six flights we find age-values that are up to three years lower for CO 2 than for SF 6 . This CO 2 -age anomaly corresponds to an excess of 4-5 ppm CO 2 . Evidence is presented that this excess-CO 2 originates from rapid convective transport of near surface air. Additionally, we show that globally no compact relationship exists between the age of air and mixing-ratios of N 2 O.