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Revision of Forest emissions makes meeting Ireland's carbon budgets more difficult

posted 2 Jun 2022, 10:00 by Paul Price   [ updated 3 Jun 2022, 00:46 ]
Key Points
  • This post notes increased difficulties in meeting Ireland's carbon budgets due to land use, especially forest harvest, that are now magnified by revised emission factors for forestry on peat.
  • A 2022 EPA Inventory reduction of 2 MtCO2e in Forest removals increases net land use emissions overall value for the 2018 carbon budgeting base year, but Agriculture has been revised down by 0.9 MtCO2e. Therefore there is only a minor change in the total emissions for the 2018 base year for carbon budgeting indicating that a change in the carbon budgets already approved by the Oireachtas is not warranted. 
  • Charts below show how the increased Forest land emission factor changes results decreases Forest removals and increases net land use (LULUCF) emissions in all years since 1990 by 1–2 MtCO2e.
    • These inventory changes show that forestry on upland peat soils is far less beneficial for climate action than had been indicated previously in carbon accounting. 
  • The major new issue for meeting carbon budgets revealed by the new 2022 Projections is the ongoing and increasing land emissions to 2035, due to an even bigger forest harvest "carbon cliff" than previously anticipated being magnified by the Forest emission factor change.
  • Therefore, urgent policy attention to limiting forest harvest and peat extraction in the near-term is advised otherwise other Energy, Industry and Agriculture will require even more deeper mitigation achievement.

Charting the 2022 Projections relative to meeting Ireland's carbon budgets to 2035

The new 2022 EPA Greenhouse Gas Emissions Projections note a major revision of the 1990–2022 land use emissions, stating:
Research published since last year’s projections has led to a revision to the emission factor associated with forestry on organic (peat) soils and this has led to decreased removals/increased emissions associated with forest land for all periods, with over 2 Mt CO2 eq less removals in 2019.

In addition, the new Projections (p.8) note a serious failure to meet the agreed 5-year carbon budgets given the new sectoral projections. The bar charts below (click to enlarge) summarise the projected outcome for the WEM ("with existing measures") and WAM ("with additional measures" scenarios. The projected contribution from land use is substantially higher than anticipated due to the forestry harvest and emission factor issues. These projections therefore indicate that the Climate Action Plan requires immediate revision to increase ambition and achievement to meet the agreed carbon budgets, particularly in directing greater attention to limiting land use emissions.

Charting the revised 2022 Inventory land emissions compared to the 2021 Inventory

The Inventory change can clearly be seen by comparing the 2022 Inventory values with those from 2021 – this chart uses the data as shown in the Inventory's Table 2.1. The figure below for 1990–2020 annual land use emissions shows 2022 values as solid lines and the 2021 values for Forest land and Net Total LULUCF as dashed lines. Arrows show the impact of the inventory change from 2021 to 2022: the reduction in Forest land removals resulting in an increase in Net total LULUCF emissions.  
The updated science due the revised emission factor for forestry on organic soils shows that this issue is substantially greater than had been thought and, therefore, forestry has been of far less benefit in reducing emissions than had been thought. This suggests that continued planting of forests on uplands is of far less carbon sequestration benefit and that restricting harvest of these upland plantations may be beneficial in meeting the carbon budgets to 2035.

Unusually in Europe, overall Ireland's land use is a net source of emissions, not a sink, due to the effect of organic soils for Grasslands, Wetlands, and Forest lands,. The 2022 revision substantially increases the net source value to about 6.9 MtCO2e/yr (for each of 2018. 2019, and 2020) from about 4.8 MtCO2e in 2018. 

Implications for Ireland's carbon budgeting programme

Depending on how the Climate Change Advisory Council (CCAC) and the Government view matters in the context of Ireland's 2021 amendment of the climate Act, the 2.1 MtCO2e increase in LULUCF for 2018 may have implications for Ireland's carbon budgeting as the science has changed, thereby altering the 2018 base-year value for total emissions including land use. 

The table below compares the values for 2018 national sectors as given in the CCAC Carbon Budget Technical Report (CCAC-TR, October 2021) and compared to the revised valued in the 2022 Inventory (as given in the Total from CRF tab of the Chapter 2 trends Excel file, with LULUCF from the Fig. 2.10 LULUCF tab). The tables show minor differences except for Agriculture, for which the 2022 value is 0.9 MtCO2e lower than the CCAC-TR value, and LULUCF. which is 2.0 MtCO2e higher.

2018 sector GHG totals
EPA 2022
 Energy 37.0 36.8
 Industrial Processes 3.2 3.2
 Agriculture 22.3 21.4
LULUCF Emissions
 9.6 9.7
 LULUCF Removals -4.8-2.8
 Net LULUCF4.86.8
 Waste 1.0 0.9
Total (excluding LULUCF)  63.5 62.4
Total (including LULUCF) 


The Act mandated the CCAC to provide for five-year carbon budget to provide for a 51% reduction relative to the 2018 inventory emissions. Since the CCAC thereby defined the three five-year budgets for 2021–2035 to provide for this reduction from 2018 on the basis of the 2021 Inventory, and the Oireachtas has accepted them, it would seem that the set budgets to 2030 are therefore fixed under the Act as there is no provision in the Act to revise them. However, it may be that the CCAC and Government can decide to revise the base-year value based on the revised science and may also decide to redefine the 5-year budgets accordingly. 

If such a revision were to occur it would be important that at least the same percentage reduction occurs for the 2021–2025 and 2026–2030 budgets compared to five years of stable emissions at the 2018 level. Sustaining the 2018 level for 5-years would hypothetically have resulted in 342 MtCO2e. Compared to this the CCAC and Oireachtas-approved 2021-25 first carbon budget of 295 MtCO2e is a 14% emissions reduction (47 MtCO2e less). And for the 2026–2030 second carbon budget, the reduction is 41% lower (or 142 MtCO2e less) than the sustained 2018 level. 

The table below show what the resulting possible adjustments might look like by applying the same percent reduction relative to five-years at the 2018 rate.

Calculating possible CBs adjusted for revised 2018 value
2018 value x 5 years342346
CB1 for 2021–2025 defined/adjusted295299
CB2 for 2026–2030 defined/adjusted200203
CB3 for 2031–2035 defined/adjusted151153

This preliminary analysis indicates that there would be little change from the existing defined 5-year CO2e carbon budgets if the base-year data changed on the basis of the revised 2022 Inventory values for 2018. Also, the slight increase suggested by the adjusted values is not warranted for a developed nation in global equity terms, given that the effect is an increase in Ireland's claim on the remaining global carbon budget. Therefore, given the small adjustment, the time to make a change in the Oireachtas, and the potential for confusion in climate action, a change in the five-year carbon budgets as already defined does not appear to be warranted.  

However, far more importantly, as indicated by the new projections, the major new problem in meeting the defined carbon budgets appears to be a substantial increase in projected LULUCF emissions to 2030. Table 1 in the Projections report shows that projected net LULUCF emissions for WEM increase by +61.5% to 2030, or for WAM by +20.9% relative to 2018,. Moreover, these large percentage increases relate to an increased 2018 net LULUCF value of 6.8 MtCO2e/yr.  The LULUCF increases directly imply an increased LULUCF sectoral ceiling and so other sectoral ceilings must further decrease accordingly to make up for the failure to cut net land use emissions unless strong land use policy regulation is enabled. 

In short, the revised Forest GHG inventory time series raises important questions for Ireland's carbon budgeting base year emissions definition and achievement of the defined budgets. The analysis here suggest that there is insufficient basis to change the carbon budgets provided by the CCAC and confirmed by the Oireachtas. Much more important is the apparent substantial increase in the 2022 projected land use emissions up to 2035 compared to the CCAC-TR values. 

A projected increase in forest plantation harvest relative to past planting and afforestation was described in the CCAC-TR (p. 86) as the forestry "carbon cliff" given the reduction in forest CO2 removals. The 2022 Projections imply that this "carbon cliff" is even larger than previously anticipated and makes meeting the carbon budgets considerably more difficult. Therefore, limiting LULUCF emissions is now a far greater issue for climate action policy revision and requires stronger policies and measures in the 2022 Climate Action Plan. Urgent policy measures to limit forest harvest and peat extraction would appear to be required to avoid significantly increased mitigation costs in energy and agriculture if the carbon budgets are to be met.

Additional charts of land use emissions, removals and net LULUCF GHGs: annual, and cumulative from 1990

What matters for climate change temperature impact in land use are cumulative CO2 emissions. In land use CO2 is by far the largest part of the recorded or projected CO2e.

The chart below shows a digest of the 2022 Inventory annual land use time series for 1990–2020 as solid lines, separating total land use removals shown in blue (mostly due to "Forest land" and "Harvested Wood Products") and total land use emissions shown in red (mostly due to "Grasslands" and "Wetlands". The Net Total shown in black is given by emissions minus removals, reaching 6.9 MtCO2e/year in 2018. Dashed lines show the corresponding 2021 inventory analysis time series data. Arrows again show the change in 2019 value from the 2021 to the 2022 Inventory.

The chart below sums the cumulative total since 1990 based on the same time series values shown in the annual chart above. Cumulative land emissions since 1990 have reached 299 MtCO2e versus removals of 83 MtCO2e, resulting in a net source of 216 MtCO2e. The adjustment in Forest land emissions means that this value is nearly 50 MtCO2e higher than shown in the 2021 Inventory. This is a substantial net loss of carbon from Irish land use over time, showing that only if net annual land use moved from emissions to removals would these past land carbon stocks start to be refilled. In other words land carbon sequestration will not meaningfully offset ongoing emissions in other sectors, they need to achieve actual GHG emissions reductions. 

To reach net zero annual land use emissions would require a major change in land use policy particularly directed at limiting farming and forestry harvest and planting on all organic soils, and limiting peat extraction to near-zero. Without such measures any slow increases in sequestration rate through afforestation on mineral soils and rewetting of peatland will have comparatively small effect given the ongoing land carbon losses being accounted from Grasslands and Wetlands and the reduced removals from Forestland. 

The substantial reduction in inventory annual and cumulative forest removals due to the impact of past planting on organic soils indicates that any plans for further afforestation on uplands needs to be reconsidered as a matter of urgency. The need for focused land use planning to restrict activity and drainage on all organic soils is even more apparent given the revised emission factors. A land use plan backed by strong policy support could have highly beneficial environmental and climate outcomes and guide a revision to forestry and farming practices aligned with international commitments.