The difference between ‘net zero' emissions and ‘temperature neutrality'

Irish Times

18 hours ago

Climate scientists have challenged the view that prioritising 'temperature neutrality' as a revised approach to meeting climate targets is merited. This is because insufficient reductions of greenhouse gases would be achieved.
It is considered a get-out-of-jail card for big livestock-producing countries with high methane emissions such as Ireland, they say, because it endorses an approach that shifts policy to containing 'additional global warming'.
Getting to net zero emissions is much more demanding than keeping temperatures where they are right now.
'Temperature neutrality is essentially a political choice to take current levels of warming as 'acceptable' while committing not to increase them,' said
University of Galway
researcher Dr Colm Duffy.
READ MORE
'For methane, this is particularly problematic. Because of its short atmospheric lifespan, future warming is determined by future emissions, meaning the temperature framing effectively carves out a long-term methane emissions space for the country adopting it.'
Methane is a potent short-lived climate pollutant with a much higher warming impact than CO² over 20 years, but it only lasts about a decade in the atmosphere.
'It is simultaneously a huge threat, but also our greatest lever for actually lowering temperatures. CO² is essentially up there forever,' he adds.
[
Ireland can reduce impact of extreme climate events by transforming economy, experts suggest
Opens in new window
]
In short, stabilisation is temporary due to shifting global methane background levels. 'This means the temperature neutrality [scenario] is essentially a moving target, which is not something you want to pin climate policy on.'
As Dr Róisín Moriarty of
University College Cork
's Sustainability Institute says, with less than three years of 'global carbon budget' remaining to limit warming to 1.5 degrees, and a 50 per cent chance of achieving it, countries need to do as much as they possibly can on the issue.
A carbon budget is the total amount of emissions that may be released in an effort to contain global warming. In Ireland, five-year legally binding carbon budgets are in place, applying to all sectors including agriculture.
The
Climate Change Advisory Council
put forward this new concept.
The independent body, which advises the Government, claims it is in line with the Paris Agreement. Moreover, it based carbon budget modelling and subsequent advice around future carbon budgets on it.
While the council has indicated there is nothing stopping the Government from being more ambitious, it will not advise on a higher level of ambition.
In June, the council told the Oireachtas climate committee it 'considers climate neutrality to mean that Ireland is no longer contributing to the increase in global temperatures by 2050'.
[
Move to ease climate targets criticised for allowing continued high methane emissions
]
This aligns with the national climate objective of transitioning to a climate-resilient, biodiversity-rich, and environmentally sustainable economy, it said. 'Achieving this involves balancing greenhouse gas emissions with their removal from the atmosphere, effectively stopping Ireland's contribution to rising global temperatures.'
It said improved analysis of mitigation options were used for the new proposal, targeting temperature neutrality pathways rather than an overreliance on as-yet unproven technologies such as carbon capture and storage.
The approach has not been adopted by Government, though the
Department of Agriculture
favours including temperature models in scenario planning.
The council said its Carbon Budgets Working Group assessed 1,196 scientifically based emissions scenarios that were developed for consistency with Ireland's national climate objective.
In Dr Duffy's opinion, however, temperature neutrality 'shifts the goalposts on ambition and passes the buck on climate mitigation, while essentially claiming the opposite.
'From an EU perspective, such a [scenario] could be seen as a backslide on commitments, with potential political and reputational implications,' Dr Duffy adds.