Assessing Temporary Carbon Storage in Life Cycle Assessment and ...

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With reduced uptake the atmospheric CO 2 content trends upwards again, and 20 years after the initial removal, the atmospheric content is lowered by only about half as much as the initial amount removed. Extra sink (tC) Temperature difference (10 -12 K) 0.0 -0.5 -1.0 0 -1 -2 2000 2020 2040 2060 2080 2100 2000 2020 2040 2060 2080 2100 0.5 0.0 -0.5 -1.0 Difference in atmospheric carbon content (tC) Extra sink (tC) Temperature difference (10 -12 K) 0.0 -0.5 -1.0 0 -1 -2 2000 2020 2040 2060 2080 2100 2000 2020 2040 2060 2080 2100 0.5 0.0 -0.5 -1.0 Difference in atmospheric carbon content (tC) Figure 7.4.2: The effect of sink activity on atmospheric CO2 concentration and resultant temperature. The Figure on the left shows the effect of a permanent sink, and the Figure on the right, the effect of a sink created in 2000 and reversed again in 2020. All curves show the change as a consequence of the sink activity. These changes are therefore additional to any CO2 or temperature changes that may be occurring due to other factors (such as fossil-fuel emssions). If carbon storage is only temporary and is reversed after 20 years (the pink line in Figure 7.4.2, right panel) then the atmospheric carbon content increases by 1 tonne again at the time of the carbon release. However, because the atmospheric content has increased over the time with reduced ocean uptake, the ultimate CO 2 content is greater than it would have been if there had been no temporary storage. That elevation in atmospheric carbon content is most pronounced immediately after the re-release of stored carbon and then trends back down towards the 0 line. Changes in CO 2 concentration then have radiative forcing properties and affect global temperatures. Because of thermal inertia, temperature does not follow radiative forcing immediately, but only with some further delay. That has been modelled here with a simple 10-year time constant. The effect of different thermal delay constants has been explored to some extent by Kirschbaum (2003a). Importantly, following establishment of permanent carbon sinks, temperature is reduced the most about a decade after the sink activity and diminishes thereafter. Following the establishment of temporary sinks, temperature is reduced while carbon is stored, but temperature then increases again and ultimately is higher than it would have been without the use of temporary carbon sinks. The ultimate warming effect is greatest about 20 years after the re-release of carbon, and increases with the length of carbon storage. 41
7.4.3 Climate Change Impacts So, is temporary carbon storage a useful strategy? Or for permanent carbon storage, what would be the best time for establishing carbon sinks? To address this question, it is necessary to explicitly quantify climate-change impacts, and various possibilities have been suggested in past work. In general, impacts can occur in at least three different ways: 1) by the direct and instantaneous effect of elevated temperature; 2) through the rate of temperature increase; 3) through the cumulative impact of increased temperatures. The direct and immediate effect of temperature is the relevant measure for impacts such as heat waves and other extreme weather events. This metric is essentially the same as the Global Temperature Potential. The rate of temperature increase is a concern because many aspects of a warmer world may not be inherently worse than current conditions, but the change from the current to a future, warmer world will be difficult for both natural and socio-economic systems. If change is slow enough then systems can be moved or adapted, but faster change may be too rapid for such adjustments. The third type of impact relates to the cumulative impact of raised temperatures. This is the critical issue for impacts such as sea-level rise. The extent of sea-level rise is related to both the magnitude of warming and the length of time over which oceans and glaciers are exposed to increased surface temperatures. This metric is essentially the same as Greenhouse Warming Potentials. These three impacts can then be calculated under any emissions scenario. This was done here for the SRES A2 scenario (Figure 7.4.3). It shows that under this (Business-as-usual) scenario, all three types of impacts are expected to increase through to the end of the 21 st century and beyond. One can then ask the specific question by how much the experience of the same climatic changes can be delayed (or hastened) by specific land-use options. One can ask specifically how much ‘time trees can buy’. Hence, if the same threshold value in terms of climatic impacts would be reached on 1 February 2100, say, instead of 1 January 2100, it would constitute 31 days of time having been bought. Figure 7.4.4 shows the difference in time for the experience of the same climatic changes by the use of either permanent (top panel) or temporary (bottom panel) carbon sinks. This is shown separately for the three types of climatic impacts, instantaneous temperature (T), rate of temperature changed (Δ) and cumulative temperature (Σ). The units are given in days (to experience a given climatic change) per GtC stored in a biosphere sink. 42
Page 1 and 2: Assessing Temporary Carbon Storage
Page 3 and 4: This report summarises the presenta
Page 5 and 6: Table of Contents 1 Introduction ..
Page 7 and 8: LCA and CF. Other standards and met
Page 9 and 10: then pushed back from a certain num
Page 11 and 12: The first issue was the setting of
Page 13 and 14: 2 The role of temporary carbon sink
Page 15 and 16: time frames. The impact of delaying
Page 17 and 18: In the inventory, a delayed emissio
Page 19 and 20: impact category in LCA, for consist
Page 21 and 22: atmospheric sink to another (from a
Page 23 and 24: etween the linear approximation (op
Page 25 and 26: Finally, the dynamic LCA approach (
Page 27 and 28: 6 References [1] European Commissio
Page 29 and 30: 7.2 Treatment of carbon storage and
Page 31 and 32: oundary for data collection is not
Page 33 and 34: It is very difficult to make such a
Page 35 and 36: The stored amount of carbon is mult
Page 37 and 38: 7.2.8. Annex 3: Methodology propose
Page 39 and 40: To overcome some of the problems of
Page 41 and 42: References 1. Fuglestvedt JS, Bernt
Page 43 and 44: 7.4 Temporary Carbon Sequestration
Page 45: Figure 7.4.1: Diagrammatical repres
Page 49 and 50: Time savings in terms of reducing i
Page 51 and 52: The use of biosphere sinks to ‘bu
Page 53 and 54: and a high exponent (4) of the impa
Page 55 and 56: The two currently most used and dis
Page 57 and 58: enefits. They are: 1.) it buys time
Page 59 and 60: 7.6 ILCD Handbook recommendations M
Page 61 and 62: For fossil carbon dioxide this flow
Page 63 and 64: 7.8 ISO 14067 Carbon footprint of p
Page 65 and 66: 7.10 Biogenic CO2 emissions and the
Page 67 and 68: • Additional fellings for bioener
Page 69 and 70: It is very likely that accounting s
Page 71 and 72: Furthermore, the expansion of bioen
Page 73 and 74: The result is highly sensitive to t
Page 75 and 76: For the neutral scenario, where we
Page 77 and 78: How to obtain EU publications Our p

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