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Statue of climbers Horace-Benedict de Saussure and Jacques Balmat (R) pointing at Mont Banc in Chamonix, French Alps, France, Europe
© Jon Boyes/incamerastock/Corbis
4 December 2015 8:36

Explainer: The long-term goal of the Paris climate deal

Simon Evans


Simon Evans

04.12.2015 | 8:36am
COP21 ParisExplainer: The long-term goal of the Paris climate deal

World leaders are committed to keeping warming below 2C, yet their climate pledges fall short.

They hope to signal their collective determination to follow through, by inscribing a long-term goal into the Paris climate deal.

This could firmly anchor the agreement to the latest science; or it could be vague and aspirational.

As negotiators start to grind through the latest 50-page draft text, a range of options remain on the table. Carbon Brief runs through the science and politics of the long-term goal.

Political support for a long-term goal

The world’s major powers all support a long-term goal, according to the conclusions of informal talks held by UN secretary general Ban Ki-moon in September.

The lunchtime talks hosted top-level representatives of the EU and 31 nations including China, the US, India, France, Germany and the UK.

The goal should “reaffirm, clarify, and operationalise” the 1.5 or 2C temperature limits, the conclusions say. To do this, the Paris deal “must” have a “common goal for collective action”.

A long-term goal is needed because current climate pledges put the world on track for around 3C of warming. Combined with a ratchet mechanism to raise ambition over time, a collective goal could help close the gap to 2C.

Groups have proposed various options for a collective long-term goal. Before exploring these in more detail, however, it’s worth looking at the scientific basis for a long-term goal.

The science of the long-term goal

The aim of the 1992 UN Framework Convention on Climate Change is to avoid “dangerous anthropogenic interference with the climate system”. Since 2010, the UN climate talks have translated this into a warming limit of no more than 2C.

Yet temperature limits are abstract. Policies and targets to tackle greenhouse gas emissions are much more tangible and easier to grasp. Moreover, scientists have found a direct link between emissions and temperatures, with a fixed carbon budget for any chosen warming limit.

Once this budget has been spent, CO2 emissions “have to be zero”, says Dr Joeri Rogelj, energy and climate modeller at Austrian research institute IIASA.

Reaching zero CO2 emissions is critical, Rogelj says, because it accumulates in the atmosphere. In contrast, other greenhouse gases, such as methane, have relatively short lifetimes.

The Intergovernmental Panel on Climate Change suggests greenhouse emissions should fall to zero around 2080-2100, though it does not account for the slow pace of current climate pledges.

Professor Chris Field, until recently the co-chair of the IPCC’s Working Group II, tells Carbon Brief:

Eventually, CO2 emissions need to go to zero…Most of the analysis indicates that if we are trying to reach 2C or less, we’ll need to bring emissions of CO2 down to zero, some time in the second half of the 21st century. That’s going to be a big challenge and it’s going to require quick ambition, increased above where we are currently. There are many different terms that are being used to describe where we’re headed eventually and I think that the key thing for people to understand is that where we’re headed is zero net CO2 emissions at the global scale. Any term being considered for the convention that doesn’t mean that, it’s a distortion of what we need to get.

From a scientific perspective, the path to zero emissions is also important. If emissions cuts are delayed, as with current pledges, more rapid reductions will be needed later to stay below 2C.

Current pledges imply the need for zero CO2 emissions between 2060 and 2070, Rogelj tells Carbon Brief, based on his recently published research.

Zero greenhouse gas emissions would need to be reached slightly later, perhaps by around 2090, Rogelj’s research suggests.

Carbon Capture and Storage: Where factories or power stations use technology to capture some of their CO2 and store it underground, reducing emissions. Read More

Without early efforts, negative emissions technologies might be needed later this century to correct a budget overspend. Negative emissions could be achieved through afforestation or biomass with carbon capture and storage (BECCS), explains the Met Office’s Dr Andy Wiltshire.

A forthcoming Stockholm Environment Institute paper says relying on negative emissions is risky. BECCS is unproven, and needs large areas of land that could conflict with nature or food production.

Definitions of a long-term goal

The scientific imperative, then, is for a long-term goal of zero CO2 emissions soon after 2050. For the atmosphere, it doesn’t matter if emissions are actually zero, or if they are balanced out by CO2 absorbed by trees or other means.

This is why some have proposed “net-zero” emissions targets or “carbon neutrality”. These are generally considered synonymous, and for the atmosphere they amount to the same as zero CO2.

From a societal perspective, there might still be differences, however. For instance, “net-zero” might imply using negative emissions or carbon offsets, and some people object to these for other reasons.

“Carbon neutral” does not carry carbon trading connotations, according to the World Resources Institute. It does have alternative interpretations, however, with some countries using it to mean stabilised emissions.

The way emissions are reduced — for instance using carbon capture and storage (CCS) — might also involve societal choices, though again it does not matter for the atmosphere.

Some groups have favoured the phrase “decarbonisation”, which implies a shift away from burning carbon-containing fossil fuels. This can be made firmer with “full decarbonisation”.

Jennifer Morgan, director of the World Resources Institute’s global climate program, tells Carbon Brief that “decarbonisation” is seen to give more clarity to investors than other formulations. If giving investors clarity is the aim, then the choice of language is important, she adds.

The long-term goal could also be framed around targets of zero or net-zero greenhouse gas emissions, which extends the concept to methane and other warming gases. Yet another option is “climate neutral”, though this could have potentially unwanted interpretations.

“Climate neutrality can mean very different things,” Rogelj tells Carbon Brief. It might mean net-zero emissions of the basket of greenhouse gases covered by the Kyoto Protocol, for instance, and this would not cause undue problems, he says.

Yet “climate neutral” could also mean balancing greenhouse gas emissions with other climate agents, such as air pollution, or even geoengineering that aims to offset warming. Rogelj says:

It would be reckless to introduce language in a climate treaty that leaves such possibilities, which are in opposition to the ultimate objective of the convention…It would be almost a perversion of the aim of the convention.

Offsetting emissions through geoengineering might limit global average temperature increases, but it would not avoid local climate impacts and other types of interference, such as ocean acidification.

The World Resources Institute has a helpful glossary of long-term goal definitions.

Options for a long-term goal

Drafts for the Paris climate agreement earlier this year contained 15 different options around long-term emissions goals. The pre-Paris draft had whittled this down to three, though each of these wrapped a range of related options together.

A 50-page draft text, released this week, contains an even more condensed set of options for a collective long-term goal, shown below.

Draft Paris agreement text, published at 8am on 3 December.

Draft Paris agreement text, published at 8am on 3 December.

The options include “zero global greenhouse gas emissions by 2060-2080”, reductions of X to Y percent by 2050 and a “long-term low emissions transformation”, potentially either “over the course of this century” or “as soon as possible after mid-century”.

This final, more vague formulation could ask for a global shift towards “climate neutrality”, the ill-defined and potentially “reckless” option we looked at above. Or it could aim towards decarbonisation. Notably, however, it does not mention “full decarbonisation”.

A final option is the “equitable distribution of a global carbon budget based on historical responsibilities”.

This formulation is, perhaps, unlikely to survive, since it implies a top-down division of the remaining carbon budget. It is precisely this sort of top-down approach that climate talks have tried to move away from by allowing countries to present nationally determined pledges to cut emissions.

On top of this dedicated section of the text, other kinds of long-term goals could be sprinkled throughout the Paris agreement. These could include goals on temperature targets, on promises to scale up climate finance, or on regularly producing national climate adaptation plans.

Positions on a long-term goal

To get a sense of the language likely to win out on the long-term goal, it’s worth looking at the positions of nations and negotiating groups.

The WRI’s Morgan tells Carbon Brief:

The end of the century isn’t helpful, it’s just so far away… [Some] countries will seek to push the date or do away with this [long-term goal].

She says the debate will continue until the end of the summit: “There are still strongly held views.”

Track Zero, an NGO dedicated to zero emissions, also says a long-term goal for 2100 is too far into the future. It could be “interpreted as kicking the issue into the long grass”, the group says.

It adds that options around “low carbon” or “low-emissions transformation” are “inadequate” because they don’t specify the end goal or the end date.

At the more progressive end of debate is the Climate Vulnerable Forum, a group of 20 nations including Bangladesh and the Philippines. The forum wants full decarbonisation by 2050, zero global greenhouse gases by 2060-2080 and 100% of energy to come from renewables by 2050.

The position is similar to many mainstream NGOs. WWF calls for peak global greenhouse gas emissions by 2020, a 75-95% cut below 2010 levels by 2050 and a 1.5C warming limit.

The African group of nations says decarbonisation leaves out other greenhouse gases and wants the goal to be equitable, for instance, with developed nations peaking emissions more quickly.

The G7 of Japan, Germany, the US, UK, Canada, Italy and France backed complete decarbonisation of the global economy this century in a communique issued in June.

India opposes language on decarbonisation, however, arguing it needs cheap fossil energy to drag its poorest residents out of poverty. Meanwhile, China has previously resisted long-term global emissions goals, and is expected to oppose specific numerical emissions targets in Paris.

In a joint statement with France, China backed “[a] transition to green and low-carbon, climate-resilient and sustainable development”. This statement also endorsed the idea of countries drawing up “national low-carbon development strategies” towards 2050.

In a statement with the US, China backed a “global low-carbon transformation during the course of this century”.

Privately, the US wants a target of “climate neutrality over the course of this century”, according to Indian publication Business Standard, in an article said to be based on a confidential US note.

However, the US also signed on to the G7 communique. Decarbonisation language was added back into the draft Paris text at the US’s request, Carbon Brief understands.

The EU position says: “Global greenhouse gas emissions need to peak by 2020 at the latest, be reduced by at least by 50% by 2050 compared to 1990 and be near zero or below by 2100.”

Its three-point vision for a “credible agreement” in Paris uses less specific language, however, calling for a “shift to low-carbon economies”. There have been behind-the-scenes wrangles within the EU, with Poland thought to be pushing for less concrete language around “climate neutrality”.

A senior EU source tells Carbon Brief:

There’s lots of challenge about a 2050 number. Many parties don’t want to have to carve up global emissions by this year…’Decarbonisation’ has been very difficult. We’re still pushing for it, but may have to lose it. China find it difficult, but we don’t know yet if it’s a red line for them.


As the first week in Paris draws to a close, some observers say the long-term goal is the area of text that has seen the greatest progress. The list of options has barely been reduced, however.

These options could still provide that strong link to the science on avoiding dangerous warming — or they could set vague and aspirational goals.

Even a strong long-term goal will lack credibility if it is not backed by a ratchet to raise ambition over time, argues Rob Bailey, director of energy, environment and resources at Chatham House.

This combination of a ratchet and a long-term goal are, therefore, essential, if Paris is to be seen as a success, despite failing to secure 2C. As things stand, that success is still all to play for.

Main image: Statue of climbers Horace-Benedict de Saussure and Jacques Balmat pointing at Mont Banc in Chamonix, French Alps, France, Europe. © Jon Boyes/incamerastock/Corbis.
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