numbers, not adjectives — D. J. C. MacKay

How good is the Paris Agreement?

by Carl Edward Rasmussen, 2023-08-10

Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change;

Properties of the Paris Agreement

• Effectiveness: When the Paris agreement came into force in 2016, the global atmospheric CO₂ growth rate was about 2.4 ppm/year, the highest ever at the time. Today, 7 years later in 2023 the growth rate is still about 2.4 ppm/year. We haven't run a controlled experiment, and don't know what the CO₂ growth rate would have been without the Paris Agreement. But stabilising temperature requires that the CO₂ growth rate is reduced to zero. This shows that the results of the agreement so far are completely inadequate.


• Consensus: The UNFCCC COP meetings are governed by consensus, which is both a virtue and a liability. The advantage is the possibly global inclusivity but the weakness is that small groups of countries can effectively block progress. In the past three decades the COP meetings have suffered from the inability to rapidly reach effective consensus. Time is running out for agreeing effective measures, we don't have a few more decades to spend on negotiation. Agreements with only partial initial consent will be preferable to no effective agreement at all. Therefore, climate clubs with broad but not necessarily immediate universal acceptance should be pursued along side consensus negotiations. The insistance on exclusively consensus driven negotiations, when the COP meetings are seen by many as the only legitimate forum for international climate negotiations, causes international paralysis.


• Responsibility: The agreement prescribes committing collectively to the 1.5°C or 2.0°C limits. Thus, no party in particular will be at fault if, or when, the commitments are broken. An effective agreement in contrast, would require specific, measurable commitments from the parties, with a clear assignment of responsibility. In its current form, the agreement invites to universal abdication of responsibility.


• Global Average Temperature Proxy: The Paris agreement targets the global average temperature. But the global average temperature is a proxy for what we really care about, which is the living conditions on the planet. Living conditions are of course difficult to quantify, so we need proxies. But is global average temperature a good proxy? Not on its own, for several resons:
  • global average temperature is not directly attributable to our actions. To be effective, an agreement must (also) target greenhouse gas emissions which are causing heating, are directly measurable and whose emissions are attributable
  • global average temperature is subject to significant natural statistical fluctuations. This means that it will take time after the smooth time averaged temperature has exceeded the 1.5°C or 2.0°C limits before we will know it with confidence
  • because of inertia in the climate system, temperature takes time to respond to our actions. If we hypothetically stopped releasing greenhouse gases today, average global temperatures would still keep increasing for a while due to what has been called global warming in the pipeline.
  These effects make is difficult to use the global average temperature proxy to govern policy.


• Commitment: According to the agreement, countries are encouraged to submit non-binding, increasingly ambitious Nationally Determined Contributions (NDCs) at regular intervals. But these are only weak incentives:
  • there is nothing, above perhaps peer pressure, pushing countries to raise their ambitions. Since weaning from fossil fuels is difficult, countries have unsurprisingly resisted
  • countries are free to water down their future NDCs or simply not implement them
  • there is no requirement of NDC immediacy. Some politicians boast impressive pledges for the far future, say 2050, when they'll no longer be active; it's not going to be their problem
  • NDCs are not legally binding, which may encourage some countries to submit pledges which they have no intention of complying with (but it will necessarily take decades before we will know how widespread this problem is).
  There is no effective pressure to ensure ambitious NDCs and no mechanisms of enforcement, so any commitments are largely vacuous in practice.

Summary

What would a better agreement look like?