5 minute read

Mikaël J. A. Maes (mikael.MAES@oecd.org) & Ivan Haščič (ivan.HASCIC@oecd.org), Environment Directorate (OECD)

Why monitor climate-related hazards? 

The natural environment is essential for people and their livelihoods to thrive. Throughout history, climate-related hazards and damaging natural disasters have impacted and shaped societies around the world. However, climate change poses a growing threat to people’s livelihoods by influencing the intensity and the frequency of climate-related hazards, resulting in more regular and more intense natural disasters ​(IPCC, 2021)​. One report estimated that natural disasters caused USD 280 billion in global losses in 2021, making it the second-costliest year ever recorded for the insurance sector ​(Munich RE, 2022)​. Considering the severe socio-economic losses, better understanding the exposure and vulnerability to climate-related hazards on a global scale is vital to effectively mitigate and adapt to future hazards. 

The OECD has developed a new database using high-resolution geospatial data to produce indicators for monitoring exposure to climate-related hazards, focusing on seven climate hazard domains (Figure 1). The data and methods are described in a recently published OECD Working Paper. These new indicators can help countries, regions and communities monitor past impacts of climate-related hazards and inform countries on the development and application of national climate change mitigation and adaptation plans. 

Several key features make this work unique. The indicators are internationally comparable with global geographic coverage on a national level; additional subnational detail is available for a subset of IPAC countries. They also provide time series generally starting in 1979, permitting trend analysis and anomaly calculation. The underlying geospatial data sources were selected considering the frequency of their updates and their timeliness, thus allowing for annual updates of the set of indicators.  

Figure  1: OECD indicator set on climate-related hazards 

Source: ​Maes, et al. (2022).

Key trends for climate-related hazards 

Analysis over the past four decades shows that temperatures around the world are rising and the associated extreme heat events are impacting more and more people. Over the past five years, average temperatures are +0.92°C higher compared to the baseline period 1981-2010, indicating average global temperatures are fast increasing (Figure 2). On average, 68% of the world’s population was potentially exposed to extreme temperatures over the past five years, representing an estimated 5.3 billion people (Figure 2). Compared with the 1979-1984 average, an additional 13.5% of the global population was exposed to extreme temperatures over the past five years, highlighting that an increasingly larger share of the world’s population is exposed to extreme temperatures (Figure 2). Considering that average and extreme temperatures are expected to further increase, extreme temperature risks are likely to further worsen over the coming decades. This calls for countries and the international community to accelerate climate action and strengthen measures to protect their populations from exposure to extreme temperatures. 

Croplands are increasingly affected by droughts with potentially disruptive effects on the global food supply. Over the past five years, the average cropland soil moisture content decreased by -1.9% across OECD countries’ croplands (Figure 2). Some of the IPAC countries most affected include Argentina, South Africa and Brazil, which experienced a cropland soil moisture decline of -6% or more over the past five years compared to the baseline period 1981-2010. These national averages can hide even more severe local declines of cropland soil moisture such as in the Portuguese regions of Algarve and Madeira, which experienced cropland soil moisture declines below -10%. Drought events vary widely across regions within countries but are expected to worsen in many countries because of climate change. Urgent action to secure the global food supply will be essential over the coming decades. 

Figure 2: Extreme temperatures and droughts are increasingly common around the world 

How do we measure climate-related hazards? 

Known data sources such as the EM-DAT database for international disasters track the occurrence of natural disasters around the world. However, there is a dearth of readily available indicators at the national and subnational levels that allow to assess the exposure and vulnerability to climate-related hazards. To address this data gap, this working paper examined in detail data sources to construct national and subnational exposure indicators for climate-related hazards, developing a specific methodology for each of these hazards. Methodologies are informed by standards from the World Meteorological Organization, the US National Oceanic and Atmospheric Administration, latest research and standards developed by well-recognised organisations, and builds on international frameworks for assessing climate-related hazards.  

By assessing the suitability of datasets during a quality review, the paper identified geospatial data sources with high spatio-temporal resolution that are frequently updated and have a global geographic coverage. The underlying geospatial datasets are often complex, requiring specific expertise for meaningful analysis. This required OECD to deploy statistical programming techniques in R and Python software and running these analyses in parallel, involving large volumes of data that require long processing times. Through these computing techniques, this paper facilitates the use of such data by summarising the underlying information into indicators accessible to non-expert audiences and suitable to support policy analyses and government decision-making. 

Key challenges for the future 

Fully characterising the risks from climate-related hazards would require considering the vulnerability of exposed people and assets to such hazards (see ​(IPCC, 2022)​ for a conceptual model). All three of these dimensions – hazard, exposure, vulnerability – imply integrating the physical and socio-economic drivers that influence the risk. However, measuring all three of these dimensions in a consistent way is difficult due to current data limitations. There are, for example, little to no geospatial data sources for assessing components of vulnerability on a global scale, particularly concerning data with high spatio-temporal resolution to allow analysing countries nationally and subnationally. 

Modelling the change in exposure to climate-related hazards could help countries better understand what further climate policy actions are needed to future-proof a countries’ population and its economic and natural assets. This set of indicators focuses mostly on understanding historical exposure to climate-related hazards. Applying climate projection models such as Representative Concentration Pathways or Shared Socioeconomic Pathways to predict the change in climate-related hazards under different greenhouse gas trajectories would help countries understand what climate-related exposures will be further worsening over time. Follow-up OECD work will seek to expand in this direction. 

Collaboration is underrated. Yet, collaboration is paramount for addressing measurement challenges to advance our understanding of how to monitor exposure and vulnerability to climate-related hazards, both based on historical events or under different future climate scenarios. This set of indicators required months of data analysis using big data sources and coding techniques. These indicators were prepared by building collaborations across different teams within the OECD and jointly with the IEA. Building partnerships between different institutions, academia and the private sector will be key to addressing measurement challenges. 

​​References 

• IPCC. (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change, Geneva. 
• IPCC. (2022). Climate Change 2022: Impacts, Adaptation and Vulnerability. Intergovernmental Panel on Climate Change. Retrieved 03 10, 2022, from IPCC_AR6_WGII_FullReport.pdf
• Maes, M., Gonzales-Hishinuma, A., Haščič, I., Hoffmann, C., Banquet, A., Veneri, P., . . . Quadrelli, R. (2022). Monitoring exposure to climate-related hazards: Indicator methodology and key results. Paris: OECD Publishing. doi:10.1787/19970900 
• Munich RE. (2022). Hurricanes, cold waves, tornadoes: Weather disasters in USA dominate natural disaster losses in 2021. Retrieved 06 10, 2022, from https://www.munichre.com/en/company/media-relations/media-information-and-corporate-news/media-information/2022/natural-disaster-losses-2021.html