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A 1.5°C warmer world: A guide for policy-makers and practitioners

This BRACED guide aims to make the findings of the IPCC Special Report on the ‘impacts of global warming of 1.5°C global greenhouse gas emission pathways' more accessible.
1.5 warmer world policy guide


On 8 October 2018, the Intergovernmental Panel on Climate Change (IPCC) approved the Special Report on the ‘impacts of global warming of 1.5°C and related global greenhouse gas emission pathways’ – a.k.a. the Special Report on Global Warming of 1.5 °C. It was prepared by 91 authors and review editors from 40 countries, and is the most current and comprehensive assessment of the science for limiting warming to 1.5°C.

This guide* aims to make the findings of the Special Report more accessible to humanitarian and development practitioners and policy-makers working at global and regional scale. It provides an interpretation of the findings with a focus on the adaptation implications of the Special Report. The guide synthesises information from the report, adds case studies to illustrate key messages and points readers to additional resources where they can obtain more information.

The guide begins with a basic overview of the feasibility of limiting warming to 1.5°C, and what it would take to do this. Based on this background, it then outlines the impacts associated with 1.5°C and greater warming. This section includes possible risk hotspots, trends, and tipping points. This is followed by a section on sectoral impacts in order to inform readers on how the risks associated with warming are projected to manifest. In the context of the mitigation findings, the guide goes on to explain the adaptation implications of the report, including guidance on implementing adaptation as well as areas that need to be strengthened.

*Download the full guide from the right-hand column.

In the guide

Limiting warming to 1.5°C: what will it take? It is technically possible to limit warming to 1.5°C. Doing so will require global efforts to rapidly transform energy, land, urban areas, buildings, transport and industrial systems. This means unprecedented transitions in all aspects of society. While there are some documented examples of rapid transitions at the pace needed to make the changes, none has occurred at the scale needed to limit warming to 1.5°C.

Impacts of 1.5°C: There is no single 1.5°C warmer world, the Special Report authors conclude. A 1.5°C world is highly dependent on the choices made around managing human and natural systems, and mitigating greenhouse gases.

Uncertainty and non-linearity of risks In the Special Report, each key message is assigned a qualifier to demonstrate the level of confidence in the findings. The probability of certain outcomes is also assessed, using a calibrated language scale. There are uncertainties in the future climate and impact projections, related to inherent limitations in both the climate models and the impact models.

Selected sectoral impacts and adaptation options The Special Report provides further details on the sustainable development implications of avoided impacts between 1.5°C and 2°C for different sectors.

Key findings

1. Global warming of 1.5°C is not safe for most countries.

  • It presents serious risks to human and natural systems, with a high probability of irreversible changes, such as the complete loss of some ecosystems (e.g. coral reefs).
  • In a 1.5°C world, we can expect more extreme heat (high confidence), more heavy precipitation in several regions (high confidence) and more intense or frequent droughts in some regions (medium confidence).

2. Countries must swiftly increase ambition and action on both mitigation and adaptation.

  • Swift and aggressive mitigation action will reduce the burden to adapt, and related costs and potential damages.
  • Through effective and rapid mitigation, it is possible to reduce the need to adapt and thus the costs and complications that come with it.
  • In tandem, there is an urgent need, particularly in high-risk regions, to start planning for and investing in adaptation.

3. Half a degree matters, each year matters, each choice matters. We need to act now to avoid serious consequences.

  • The lower estimate for when we will start to see the impacts of 1.5°C is in the next 12 years – by 2030. Every single year matters in terms of emissions reductions; the faster we act and make changes, the better off we will be in terms of reaching emissions targets and avoiding the worst impacts.
  • Some powerful messages to come out of the Special Report are that half a degree matters, each year matters and each choice matters as we aim to reduce the threat of climate change through ambitious mitigation and accelerated adaptation.
  • Some of the necessary actions to tackle climate change are already underway but it is necessary to accelerate and upscale these.
  • The decisions we make today are critical to ensure a safe and sustainable world for everyone, both now and in the future.

4. The consequences of warming are not equal.

  • The Special Report integrates climate mitigation and adaptation action in the context of sustainable development and poverty alleviation efforts.
  • It notes that the impacts of warming regionally (and more locally) will depend on:
    • geographical location (small islands, low-lying coastal areas and drylands being worst affected),
    • the socio-economic status of communities and associated vulnerabilities, as well as
    • the choice of mitigation and adaptation approaches.

5. Transformational adaptation is required in high-risk regions.

  • In some regions, incremental adaptation will not be enough to adapt to effects of 1.5°C of warming.
  • Instead, transformational adaptation will be required to implement measures such as alternative lifestyles and employment for people, and new types of city planning to safeguard people and infrastructure.
  • This will require development that considers multidimensional poverty, entrenched inequalities, local culture, and local knowledge in decision-making.

6. There are limits to adaptation.

  • For certain risks there are unavoidable impacts that will occur in a 1.5°C warmer world for which there is no or limited adaptation potential.
  • These include ‘hard limits’ such as the loss of 70-90% of coral reefs by mid-century in a 1.5°C and ‘soft limits’ such as exposing millions more people to climate risks and poverty which may be overcome with carefully applied transformational adaptation.

7. The risks at 1.5°C will require humanitarian and development practitioners to adapt programming using a climate lens.

  • A climate lens should be used across work and programming should be adapted accordingly.
  • Changing climate risks need to be integrated into planning and humanitarian action across key areas of humanitarian work, including food security, health and water, in both rural and urban contexts.
  • Climate can be a risk magnifier for displacement and conflict but also pose additional risks to people already affected by conflict and displacement.

Lessons Learnt

In conclusion, this report generated the following lessons as well as some recommendations going forward:

  • The UNFCCC expects substantial ratcheting of greenhouse gas emission reduction targets and rapid and massive decarbonisation of the global energy system.
    • However, these proposed aggressive near-termreductions fail to account for fluctuations in global and national economies or potentialgeopolitical strife.
    • They will require international cooperation, and strengthened institutional capacity from national to local level, from civil society, the private sector, cities, local communities and indigenous peoples.
  • For the development and humanitarian community, the Special Report serves as both a wake-up call on the urgency of the climate problem and a scientific consensus to support what practitioners have been observing for years: that the climate is already changing and that changes are felt most acutely by the most vulnerable people.
    • While many adaptation solutions are already underway, there needs to be increased efforts to scale up adaptation and to apply a long-term lens in planning across all development and humanitarian work.

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