Global exposure and vulnerability to multi-sector development and climate change hotspots

Published: 28th June 2018 9:57Last Updated: 29th June 2018 10:45
fig 2

Figure 2 from the paper: Multi-sector risk maps for 1.5 °C, 2 °C and 3 °C climates. Moderate and high multi-sector impacts are prevalent where vulnerable people live, predominantly in South Asia at 1.5 °C, but spreading to sub-Saharan Africa, the Middle East and East Asia at higher warming. See full text for more detail. Access a high-resolution version of this figure here.

Introduction (abridged)

The 21st century will see the global population increase from 7.5 billion in 2017 to an expected 8.5–10 billion in 2050, with much of this growth in low- and middle-income regions. Future populations will be exposed to a range of climate change-related hazards of varying intensities and locations, with some 'hotspots' exposed to more risks than others, compounding the challenges.

Risks are not just dependent on the severity of climate change and subsequent hazards but critically depend on the population's spatial distribution and their vulnerability and capacity to prepare for and manage changing risks ('exposure'). Increasingly studies are showing that the world's poorest are disproportionately exposed to changes in temperature extremes and challenging hydro-climatic complexity. Following ratification of the 2015 Paris Agreement, more work is required to understand the potential range of benefits of a 1.5 °C climate, what higher degrees of warming are projected to entail for different sectors and to what extent people of different vulnerabilities will be impacted.

Along with other factors such as institutional governance, education, social structures and safety nets, vulnerability is strongly associated with wealth, although the wealthy in volatile climates are not immune. Accounting for those that are 'vulnerable to poverty' in the event of a shock, like loss of employment or a climate hazard, is critical because much larger fractions of society exist in this precarious and transient state. Escaping (or not falling back into) poverty for this group, can be particularly difficult as the frequency of natural and climate hazards prevents asset accumulation and impacts negatively on health, prices, productivity and opportunities.

To understand the scale of this problem in the future, this paper aims to assess the potential exposure of global and vulnerable populations to overlapping multi-sectoral threats. This work investigates how multi-sector risk changes with higher levels of warming and to what extent climate mitigation, socioeconomic development and poverty reduction can reduce risks. 

This paper* was published in Environmental Research Letters (Volume 13, Number 5), and is one of a selection of BRACE1.5 (Climate Change Impacts of 1.5°C and 2°C Global Warming) papers on Climate Change Impacts of 1.5°C and 2°C Global Warming. View the original paper, watch a video abstract, and download high resolution versions of the paper's figures here. The paper can also be downloaded from the right-hand column of this page.

*A summary of the methods and key findings are provided below. Please read the full text for more detail. 

Figure 1 from the paper. Sectoral score (0–3) maps for 2 °C GMT warming scenario. In the left column the individual indicators are shown, in the right column are the sectoral scores. Note that only four of the six water indicators are shown. 

Methods and Tools (in brief)

We use established methods for aggregating climate risks, using 14 indicators across the water, energy, and land sectors (table 1, figure 1). We combine these indicators to produce multi-sector risk hotspot maps, compared for 1.5°, 2.0° and 3.0° changes in Global Meant Temperature (GMT) above pre-industrial conditions (figure 2). Critically, we investigate the exposure of the global and vulnerable population (income <$10 USD/day) using three socioeconomic projections from the Shared Socioeconomic Pathways (SSPs 1–3). Our central scenario of sectoral risks is based on a 2 °C climate with 2050 population from SSP2. For the multi-sector hotspots, we assess the global and vulnerable exposure across SSPs and GMT change dimensions for 2050, to present insights in to the dynamics between socio-economic development and risks at different levels of warming and to better understand the uncertainties.

Key Findings

The paper shows that:

  • Although global exposure to multi-sector risks will affect a relatively small fraction of global land area, the risks to human populations will be large. Global exposure to multi-sector risks approximately doubles between 1.5 °C and 2 °C global mean temperature change, doubles again with 3 °C global mean temperature change and varies by a factor of 6 between the best and worst cases (SSP1/1.5 °C vs SSP3/3 °C, 0.8–4.7bi).
  • For populations vulnerable to poverty, the exposure is an order of magnitude greater (8–32x) in the high poverty and inequality scenarios (SSP3) compared with sustainable socio-economic development (SSP1).
  • 85%–95% of global exposure consists of Asian and African regions, which hold 91%–98% of the exposed and vulnerable population (depending on SSP/GMT combination), approximately half of which is in South Asia.
  • In higher warming scenarios, African regions have growing proportion of the global exposed and vulnerable population, ranging from 7%–17% at 1.5 °C, doubling to 14%–30% at 2 °C and again to 27%–51% at 3 °C.
  • Beyond 2 °C and at higher risk thresholds, the world's poorest are disproportionately impacted, particularly in cases (SSP3) of high inequality in Africa and southern Asia.
  • Sustainable development that reduces poverty, mitigates emissions and meets targets in the water, energy and land sectors has the potential for order-of-magnitude scale reductions in multi-sector climate risk for the most vulnerable.

Further resources

  • Authors

    Edward Byers, Matthew Gidden, David Leclère, Juraj Balkovic, Peter Burek, Kristie Ebi, Peter Greve, David Grey, Petr Havlik, Astrid Hillers, Nils Johnson, Taher Kahil, Volker Krey,Simon Langan, Nebjosa Nakicenovic, Robert Novak, Michael Obersteiner, Shonali Pachauri,Amanda Palazzo, Simon Parkinson, Narasimha Rao, Joeri Rogelj, Yusuke Satoh,Yoshihide Wada, Barbara Willaarts and Keywan Riahi.

    Suggested Citation

    Edward Byers et al 2018 Environ. Res. Lett. 13 055012