1.5°C temperature limit - key facts


Since 2009 over a hundred Small Island Developing States, Least Developed Countries and many others have been calling for limiting global temperature rise to below 1.5°C above pre-industrial levels. Placing the 1.5°C limit alongside the legally binding goal to hold global temperatures “well below 2°C above pre-industrial levels” in the Paris Agreement was a major victory for vulnerable countries. This page is an information pool for material around the 1.5°C temperature limit. It covers these questions:

  • Why 1.5°C? Science, impacts and risks
  • What will it take to limit warming to 1.5°C?
  • What are the emissions reduction targets and 1.5°C pathways?


17 Dec 2015
Turning up the heat: how the diplomatic push for 1.5°C unfolded in Paris
The inclusion of a 1.5°C temperature limit in the new Paris climate agreement was a major victory for the poorest countries and island nations who came to Paris saying they wanted the world to act.
By placing the 1.5°C limit alongside the legally binding goal to hold global temperatures “well below 2°C above pre-industrial levels”, the deal offered hope to the many who had begun to despair about the prospects of an ambitious enough global climate agreement ever being reached.

Why 1.5°C? Science, impacts and risks

1.5°C risks and feasibility – key points

This fact sheet provides key points on risks to ecosystems, food security and sustainable development associated with 1.5°C warming. It also provides responses to arguments commonly made against 1.5°C and provides the scientific evidence for each point made.

How hot is too hot?

This blog explains the process and outcomes of the Structured Expert Dialogue (SED). It summarises the SED key messages and discusses consequences for the negotiations process.

Is it possible to return warming to below 1.5˚C within this century?

This briefing comments on the feasibility of holding warming below 1.5°C within this century and provides information on selected climate risks at 1.5°C, 2°C and 4°C warming.

Climate Impacts at 1.5°C and 2°C – A Pacific Perspective

This is short summary the key climatic risks for the Pacific region at 1.5°C and 2°C warming.

Impacts of climate change on Pacific Islands – A Science Update

This briefing paper summarises the knowledge on impacts of climate change for the Pacific region.

9 Dec 2015
Concepts for the collective long-term goal in Art 3.1
This overview discusses key concepts – “net zero“ greenhouse gas emissions, zero global greenhouse gas [anthropogenic] emissions by after the middle of the century, decarbonisation and climate neutrality – included in the current draft Paris Agreement Version 1 of 9 December 2015 at 15:00 related to the collective long-term goal as expressed in Art 3.1 and their implications to achieve a long-term global temperature goal of 1.5°C.

9 Dec 2015
Unacceptable risks posed by “climate neutrality” replacing “GHG emission reductions” in the Paris Agreement?
The term ‘climate neutrality’ is currently resonating in the climate policy arena and is included in the collective mitigation goal (Article 3.1) of the draft Paris Agreement. A close look at this relatively new and scientifically ill defined term and its potential implications reveals a fundamental risk that this term will be used to undermine efforts to reduce CO2 and other greenhouse gas emissions and be used to introduce dangerous geo-engineering approaches into the climate regime.


3 Dec 2015
Joint Contact Group on 2013-2015 Review: To make recommendations on 1.5°C
On Thursday of the first week of COP21, the Joint Contact Group that should have made recommendations to the COP on the adequacy of the 2°C temperature limit was blocked from doing so by a handful of countries. There is now a major procedural issue that is in the hands of the COP presidency if the Review is to conclude its work and COP21 take appropriate action.



For most vulnerable, 1.5°C warming limit is critical: above it, climate impacts rise rapidly
A new study by Schleussner et al. 2015 Differential climate impacts for policy-relevant limits to global warming: The case of 1.5°C and 2°C analyses the differences in impacts the world would face at 1.5°C and 2°C in a comprehensive and comparable way for the first time. The study provides an analysis of 8 relevant biophysical impacts, highlighting key differences both globally and in hot-spot regions.


Global warming reaches 1°C above preindustrial, warmest in more than 11,000 years
Global mean warming reached 1°C above preindustrial for the first time. It is a signal from the climate system that time is running out if we are to be able to reduce emissions fast enough so as to hold warming below 2°C, and ultimately below 1.5°C by 2100.

Who is concerned about 1.5°C?

A total of 104 countries called for the Paris agreement to limit warming below 1.5°C. These countries account for about 9% of global greenhouse gas emissions and about 23% of global population in 2010. This is more than at Copenhagen in 2009 where a total of 101 countries, accounting for 5% of global energy and industry related CO2 emissions and about 23% of global population in 2005 called for global temperature to stay below 1.5°C.


The Alliance of Small Island States (AOSIS) and Least Developed Countries (LDC) Group called the legal objective of the Paris agreement to include the 1.5°C limit and for the agreement to be ambitious, legally binding, dynamic with 5 year commitment cycles, and include the legal foundation for dealing with loss and damage from climate change. The two negotiating groupings called for the Paris protocol to be designed to rapidly increase mitigation ambition, including for 2025 and 2030, so as to increase emission reduction action to achieving this crucial temperature goal.

The Climate Vulnerable Forum is a South-South cooperation platform for 20 participating governments to act together on climate change. The CVF has issued the Manila Communique, calling for an evidence-based strengthening of the climate goal at COP21 to 1.5°C. On the first day of the Paris climate summit COP21, leaders of 30 countries most vulnerable to climate change jointly issued a historic Manila-Paris Declaration which calls for full decarbonisation of the world economy, 100% renewable energy by 2050, and zero emissions by mid-century in order to keep the world on track for below 1.5°C degrees of warming.

Awareness campaigns

#1o5C


Campaign launched by the Climate Vulnerable Forum and CARE, calling for strengthening the long term temperature goal to 1.5°C.


#1point5toStayAlive


Caribbean climate justice initiative launched ahead of the Paris climate summit by Panos Caribbean, the Government of Saint Lucia and Caribbean Community Climate Change Centre. The website is a source of news, resources, information on actions you can join, films and music for climate justice by Caribbean artists.


External resources:

The report of the Structured Expert Dialogue

This link will take you to the full report of the Structured Expert Dialogue (SED).

10 Key Messages from the Structured Expert Dialogue

Short summary of the 10 key messages from the final report of the SED

Turn Down the Heat – Climate Extremes, Regional Impacts and the Case for Resilience

This link takes you to the World Bank´s report on climate impacts in Sub-Saharan Africa, South Asia and South-East Asia. Each regional chapter provides a table comparing impacts at 1.5°C, 2°C and 4°C warming.

Turn Down the Heat – Confronting the New Climate Normal

This link takes you to the World Bank´s report on climate impacts in Latin America and the Caribbean, Middle East and North Africa and Europe and Central Asia. Each regional chapter provides a table comparing impacts at 1.5°C, 2°C and 4°C warming.

What will it take to limit warming below 1.5°C?

Feasibility of limiting warming to below 1.5°C

This page outlines the scientific, technical and economic feasibility of holding warming well below 2°C, and below 1.5°C by 2100. It addresses the consequences of limited climate action to date, it discusses implications for the negotiations on a new climate agreement in Paris, and it reviews some critical mitigation options, like decarbonisation, renewables, bio-energy, carbon capture and storage, and the combination of the latter two – BECCS.

Technical background in Feasibility of limiting warming to 1.5°C and 2°C

This briefing note outlines the scientific conditions under which warming can be limited to well below 2°C over the 21st century, and return to below 1.5°C by 2100. It provides a scientific overview of the science on some critical mitigation technologies, like bioenergy, carbon capture and storage, and their combination – BECCS. It also contains counter arguments to claims that 1.5°C scenarios undermine food security through including large scale bioenergy deployment. The considerations in this briefing are based on the findings of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5), the 2014 UNEP Emissions Gap Report, the Report of the UNFCCC Structured Expert Dialogue (SED), as well as the recent scientific literature.

1.5°C risks and feasibility – key points

This fact sheet provides key points on risks to ecosystems, food security and sustainable development associated with 1.5°C warming. It also provides responses to arguments commonly made against 1.5°C and provides the scientific evidence for each point made.

Is it possible to return warming to below 1.5˚C within this century?

This briefing comments on the feasibility of holding warming below 1.5°C within this century and provides information on selected climate risks at 1.5°C, 2°C and 4°C warming.

The CAT emissions gap – How close are INDCs to 2 and 1.5°C pathways?

This web web page on the Climate Action Tracker (CAT) website, and the documents provided therein, show the levels of warming associated with submitted INDCs and provides an assessment of the resulting gap to meet the 1.5°C or 2°C goal.

What do the CAT, UNFCCC Synthesis Report and the UNEP 2015 Emissions Gap report say about the prospects of limiting warming to below 2°C and 1.5°C from INDC levels for 2025 and 2030?

This webpage on the Climate Action Tracker (CAT) website, and the documents provided therein, show the levels of warming associated with submitted INDCs and provides an assessment of the resulting gap to meet the 1.5°C or 2°C goal.


External resources:

What would it take to limit climate change to 1.5°C?

This link will take you to the press release of the International Institute for Applied Systems Analysis´ (IIASA) on the publication “Energy system transformations for limiting end-of-century warming to below 1.5°C” by Rogelj et al. in Nature Climate Change.

What is needed in the Paris Agreement for 1.5°C?

Info sheet: Timetables for Zero Emissions and 2050 Emissions Reductions: State of the Science for the ADP Agreement

This info sheet provides the numbers on emission reductions and time tables for zero global emissions that are in line with holding warming below 1.5°C and 2°C, based on IPCC scenarios.

Timetables for zero emissions and 2050 emission reductions: State of the Science for the ADP Agreement

This briefing note outlines suggested time frames for reaching zero global CO2 and total greenhouse gas emissions for the ‘below 2 °C’ and ‘below 1.5 °C by 2100’ limits based on the findings of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) and the 2014 UNEP Emissions Gap Report.

Timing of zero emissions, deep emission reductions and full decarbonisation for 1.5 and 2°C limits

The UNFCCC Synthesis Report and the latest UNEP Emissions Gap Report both build on a set of pathways that limit warming to either 1.5°C or 2°C relative to preindustrial levels. This page provides a visual comparison of the timing of zero emissions, deep emission reductions and full decarbonisation for 1.5 and 2°C temperature limits.

The Climate Action Tracker’s emission pathway and infographic

This web page provides an infographic illustrating the gap between current INDC estimates and the 1.5°C and 2°C goal.

Five year commitments for the Paris Agreement: A fundamental issue for below 2°C and 1.5°C

This technical paper provides key points and explains why initial and successive 5 year commitment periods for all Parties are a necessary element of the new agreement to help ensure that the 1.5/2°C goal is met. It steps through evidence from scientific, economic, regulatory and political perspectives.

Voices in the media

Richard Branson and a group of high-profile business leaders back limiting warming to below 1.5°C.

“We believe that net zero by 2050 would at least get us to 2 degrees, leaving the door open for further reduction to 1.5, which should be something we should be looking at in the future. We believe the business case for net zero in 2050 is irrefutable.” Jochen Zeitz, the former chief executive of Puma.
Coalition of business leaders challenges 2C climate change target, The Guardian, 6 December 2015 http://www.theguardian.com/environment/2015/dec/06/paris-climate-change-summit-richard-branson

James Fletcher, St. Lucia’s Minister for Sustainable Development, Energy, Science, and Technology

“It’s a fight that really should not be focused on numbers, 1.5, 2, 2.5. It should be focused on lives. We’re not fighting for numbers, we’re fighting for lives.”
Matter of degree: Temperature goal an issue in climate talks, Associated Press, 4 December 2015

Thoriq Ibrahim, Environment and Energy Minister of the Maldives and chairman of the Alliance of Small Island States (AOSIS).

“A long-term temperature goal of well below 1.5 degrees must be reflected in the Paris agreement, along with an indicative pathway for achieving it, including urgent peaking and deep mid-century emissions reductions.”
Paris climate talks: vulnerable countries demand 1.5C warming limit, The Guardian, 30 November 2015

Open Letter from Academics to World Leaders ahead of the Paris Climate Conference 2015

“…more extinctions of species and loss of ecosystems; increasing vulnerability to storm surges; more heatwaves; more intense precipitation; more climate related deaths and disease; more climate refugees; slower poverty reduction; less food security; and more conflicts worsened by these factors. Given such high stakes, our leaders ought to be mustering planet-wide mobilization, at all societal levels, to limit global warming to no more than 1.5 degrees Celsius.”
More than 2,000 academics call on world heads to do more to limit global warming, The Guardian, 23 November 2015

Ronny Jumeau, Seychelles Climate Change Ambassador

“It’s not just about the islands, it’s about New York, it’s about New Orleans, it’s about London, it’s about Venice. There is no way we can compromise on 1.5.”
The Forgotten U.N. Climate Goal: 1.5°C, Climate Central, 19 November 2015

Tony de Brum, Marshall Islands Foreign Minister

“The Paris Agreement must explain to the world what a below 1.5 or 2 degree economic transformation looks like in practical terms. In our view, the agreement should say that we’re aiming to fully de-carbonize, or achieve net zero emissions, by mid-century.”
I’m fighting for the survival of my country in the battle against climate change, PRI, 30 October 2015