Climate Change 2001:
Working Group III: Mitigation
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Table TS.7: Balancing the near-term mitigation portfolio
Issue Favouring modest early abatement Favouring stringent early abatement
Technology development
  • Energy technologies are changing and improved versions of existing technologies are becoming available, even without policy intervention.
  • Modest early deployment of rapidly improving technologies allows learning-curve cost reductions, without premature lock-in to existing, low-productivity technology.
  • The development of radically advanced technologies will require investment in basic research.
  • Availability of low-cost measures may have substantial
    impact on emissions trajectories.
  • Endogenous (market-induced) change could accelerate development of low-cost solutions (learning-by-doing).
  • Clustering effects highlight the importance of moving to
    lower emission trajectories.
  • Induces early switch of corporate energy R&D from
    fossil frontier developments to low carbon technologies.
Capital stock and inertia
  • Beginning with initially modest emissions limits avoids premature retirement of existing capital stocks and takes advantage of the natural rate of capital stock turnover.
  • It also reduces the switching cost of existing capital and prevents rising prices of investments caused by crowding out effects.
  • Exploit more fully natural stock turnover by influencing
    new investments from the present onwards.
  • By limiting emissions to levels consistent with low CO2 concentrations, preserves an option to limit CO2 concentrations to low levels using current technology.
  • Reduces the risks from uncertainties in stabilization
    constraints and hence the risk of being forced into very
    rapid reductions that would require premature capital
    retirement later.
Social effects and inertia
  • Gradual emission reduction reduces the extent of induced sectoral unemployment by giving more time to retrain the workforce and for structural shifts in the labour market and education.
  • Reduces welfare losses associated with the need for fast changes in people’s lifestyles and living arrangements.
  • Especially if lower stabilization targets would be
    required ultimately, stronger early action reduces the
    maximum rate of emissions abatement required
    subsequently and reduces associated transitional
    problems, disruption, and the welfare losses associated with the need for faster later changes in people’s lifestyles and living arrangements.
Discounting and intergenerational equity
  • Reduces the present value of future abatement costs (ceteris paribus), but possibly reduces future relative costs by furnishing cheap technologies and increasing future income levels.
  • Reduces impacts and (ceteris paribus) reduces their
    present value.
Carbon cycle and radiative change
  • Small increase in near-term, transient CO2 concentration.
  • More early emissions absorbed, thus enabling higher total carbon emissions this century under a given stabilization constraint (to be compensated by lower emissions thereafter).
  • Small decrease in near-term, transient CO2
  • Reduces peak rates in temperature change.
Climate change impacts
  • Little evidence on damages from multi-decade episodes of relatively rapid change in the past.
  • Avoids possibly higher damages caused by faster rates
    of climate change.

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