5 November, 2018

How do we limit warming to 1.5°C: informing the Talanoa Dialogue question, “How do we get there?”

Authors

Bill Hare, Michiel Schaeffer, Carl-Friedrich Schleussner and Robert Brecha

Informing the Talanoa Dialogue question, “How do we get to 1.5°C?”

Integrated Assessment Models of climate change mitigation, assessed in IPCC Special Report on Global Warming of 1.5°C (IPCC SR1.5), show a large spectrum of 1.5°C- compatible pathways that limit warming to this level during the century, or exceed it by only a limited amount of less than 0.1°C (“low overshoot”). This Climate Analytics submission to the Talanoa Dialogue, which unpacks in some detail the implications of these pathways.

This submission unpacks in some detail the implications of 1.5°C compatible mitigation pathways assessed in the IPCC Special Report on Global Warming of 1.5°C (IPCC SR1.5). Integrated Assessment Models of climate change mitigation, assessed in IPCC SR1.5, show a large spectrum of 1.5°Ccompatible pathways that limit warming to this level during the century, or exceed it by only a limited amount of less than 0.1°C (“low overshoot”).

Where we are:

The IPCC SR1.5 assesses the state of scientific knowledge on impacts of climate change, both currently experienced and likely to be felt in a future of 1.5°C warming or more, and related global greenhouse gas emission pathways. The report shows that we will be able to limit warming to 1.5°C, if the world takes further action substantially beyond what is implied by current Nationally Determined Contributions under the Paris Agreement (PA) in aggregate. However, any
delay in near-term emissions reductions will lead to an increasing risk of greater temperature overshoot (with associated larger climate-change impacts and higher damages), a stronger reliance on uncertain mitigation options such as Carbon Dioxide Removal, and higher overall mitigation costs.

Where we want to go:

The IPCC SR1.5 has assessed global greenhouse gas emission pathwaysthat examine the technical and economic feasibility of limiting warming to 1.5°C. Simultaneously, the IPCC SR1.5 considers many dimensions of sustainable development that go beyond potential and actual impacts of climate change. The IPCC SR1.5 Summary for Policy Makers focuses on 1.5°C compatible mitigation pathways that limit global warming to 1.5°C, or below throughout the 21st century with no or limited (0.1°C) overshoot. These 1.5°C compatible pathways generally bring warming back to around 1.3°C warming by 2100 after a peak warming of 1.5°C or slightly above (less than 1.6°C) around the 2060s, and to achieve this have total greenhouse gas emissions peak around 2020 and decrease rapidly to global zero around the 2060s. Although the IPCC SR1.5 also assesses other pathways, these lead to higher warming levels. These include pathways that return warming to 1.5°C by 2100, but achieve this after an overshoot to as much as 1.9°C, which is clearly not holding warming “well below 2°C” as specified in Paris Agreement Article 2.1 and would be associated with climate risks, impacts and damages close to 2°C.

The principle part of this submission to the Talanoa Dialogue is on the question, “How do we get there?”. To this end we examine the many PA-compatible pathways toward the 1.5°C limit and highlight those that appear most likely to maximize synergies with sustainability and feasibility
criteria.

Some key conclusions from our analysis are that:

Rapid reductions in energy demand across all sectors are fundamental for 1.5°C compatible pathways that also limit negative emissions through carbon capture technologies.
A rapid and almost complete phase-out of coal by 2050 in the power sector is a universal message, with the highest agreement across scientific publications. Crucially, most of this transformation needs to happen right now, because the use of coal in the power sector needs to be reduced from currently over 35% of global electricity supply to only 3-10% by 2030.
At the same time, total coal use in energy and industry needs to be reduced to 60-80% below 2010 levels by 2030 and to up to 95% below 2010 levels by 2050.
Natural gas, even if combined with Carbon Capture and Storage (CCS) is reduced sharply as well, to 8% (3–11%) of global electricity in 2050.
With a high rate of electrification of transportation, substantial reductions in oil use are projected, with oil use by 2030 as much as 35% lower than in 2010, and 30-80% lower by 2050.
Renewable energy technologies (excluding biomass) reach a particularly high share in electricity supply of 45-65% in 2030 and 70-85% in 2050.
In addition, total primary energy needs to be supplied by renewable energy (excluding biomass) at a share of 50-65% by 2050, displacing fossil fuels from traditional markets for power generation, mobility and heating.
1.5°C compatible transformation will require significant additional investment worldwide in low-emission infrastructure as well as redirection of financial resources away from carbon-intensive investments. Global annual investments in low-carbon energy technologies overtake fossil investments already by around 2025 in 1.5°C pathways.

Publications

What good looks like: G7 climate policy 2024 update

This brief outlines seven key policy recommendations for this June’s G7 summit that, if adopted, would demonstrate the ambition and leadership needed to keep the Paris Agreement’s 1.5°C limit in sight.

The 1.5°C limit and risks of overshoot

This briefing looks at what the 1.5°C limit means in terms of adaptation and loss and damage for the most vulnerable countries and regions. It finds that slowing down warming is critical to buy us time to adapt and also to avoid irreversible loss and damage. Even if warming rises above 1.5°C (overshoot) we can bring it down again with ambitious emissions reductions.

Le seuil de +1,5°C et le risque de dépassement de ce seuil

Ce rapport examine ce que la limite de 1,5 °C signifie en termes d'adaptation et de pertes et dommages pour les pays et régions les plus vulnérables. Il constate qu'il est essentiel de ralentir le réchauffement pour nous donner le temps de nous adapter et pour éviter des pertes et des dommages irréversibles. Même si le réchauffement dépasse 1,5 °C, nous pouvons le faire baisser à nouveau en réduisant les émissions de manière ambitieuse.

Climate justice and loss and damage: perspectives from the global south

This article outlines the loss and damage debate through a climate justice lens with particular emphasis on Small Island Developing States and Least Developed Countries. It examines the latest developments of the new loss and damage fund including operationalisation.

Kipppunkte und kaskadische Kippdynamiken im Klimasystem

Dieser im Auftrag des deutschen Umweltbundesamtes erstellte Bericht befasst sich mit Kippelementen - sensible Komponenten des Erdsystems, die bei Überschreiten kritischer Schwellenwerte (Kipppunkte) irreversiblen Veränderungen ausgesetzt werden können. Er unterstreicht, dass selbstverstärkende Mechanismen zwischen diesen Elementen zu schnellen, irreversiblen Veränderungen führen können.

Limited reversal of regional climate signals in overshoot scenarios

This peer-reviewed paper analyses what happens in an 'overshoot scenario' - where temperature rise peaks just above 1.5°C, but then return below it by the end of the century. It concludes that despite a drop in warming, regional climate changes may only be partially reversed in the decades after peak warming, demonstrating the value of limiting peak temperatures to as low as possible.

Advisory opinion on "Climate emergency and human rights"

This Amicus Curiae is an advisory opinion requested by the republics of Chile and Colombia on "Climate emergency and human rights". It was presented by Climate Analytics Caribbean to the Inter-American Court of Human Rights. It outlines the intricate intersections of climate change, human rights, and state obligations, with a specific emphasis on the unique challenges faced by Caribbean nations.

Unabated: the Carbon Capture and Storage 86 billion tonne carbon bomb aimed at derailing a fossil phase-out

The climate talks at COP28 have centred around the need for a fossil fuel phase-out. Our analysis quantifies the risk posed by restricting a phase-out commitment to only ‘unabated’ fossil fuels.

No change to warming as fossil fuel endgame brings focus onto false solutions

The CAT's annual warming estimate has risen by 0.1˚C to 2.5˚C. The estimate is largely influenced by weak existing targets rather than shifts triggered by updated Nationally Determined Contributions.

Adjusting 1.5°C climate change mitigation pathways in light of adverse new information

This study uses an integrated assessment model to explore how 1.5°C pathways could adjust in light of new adverse information, such as a reduced 1.5°C carbon budget, or slower-than-expected low-carbon technology deployment.

The effects of political knowledge use by developing country negotiators in Loss and Damage negotiations

This article traces how developing country negotiators used knowledge to further their interests in loss and damage negotiations from 2003 to 2013.

2030 targets aligned to 1.5°C: evidence from the latest global pathways

Our new method applies sustainability limits and minimises the need for carbon dioxide removal to set key 2030 global targets for renewables, fossil fuels and emissions.

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Decarbonisation targets and 1.5℃ pathways

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