In simplest terms, risk is the probability that a certain consequence will happen. Probabilities are estimated based on the best available current science, with a range of uncertainty, and consequences are estimated based on expert judgment and past experience with similar events.
The concept of risk is a key aspect of how the Intergovernmental Panel on Climate Change (IPCC) and the Canadian Centre for Climate Services (CCCS) assess and communicates to decision-makers the potential adverse impacts of, and response options to, climate change. To support the use of climate data and information in climate change risk assessment and adaptation planning, CCCS refers users to relevant methodologies and links them to partners who provide such services (i.e., consulting, industry, not-for-profits, and academic and research organizations).
Risks can arise from the impacts of climate change and the human responses to climate change. Adverse consequences of climate change can affect our livelihoods, well-being and health, along with the economy, social and cultural assets, infrastructures, services, and local ecosystems and species.
The risks from rising temperatures and other ecological impacts are growing. Risk is a combination of the hazard (e.g., sea level rise), the exposure (how likely it is to impact), and the vulnerability (how sensitive a community, e.g, is to be badly impacted).
- Halifax has a high risk for sea level rise (hazard). The community is low-lying and has infrastructure in the flood risk zones (exposure). If Halifax is flooded, it is estimated there is not sufficient adaptation services to avoid severe impacts to people and infrastructures (vulnerability).
Figure: Climate impacts associated with coastal risks result from the interaction of coastal hazards and the vulnerability of exposed systems (from IPCC, 2014).
How will this risk change over time?
Risk is dynamic in nature; each of the three elements (hazard, vulnerability and exposure) is subject to change over time due to climatic changes or socio-economic change; depending on the specific variable and time frame, these changes can be natural, unintended or deliberate (for example through risk management).
Note that uncertainty could lie in climate hazards, exposure, vulnerability/sensitivity, economics, human behaviour, and technology. Each of those can change over time, either naturally, unintended or as a deliberate change.
What’s the different risks of 1.5 degrees C warming vs. 2.0 degrees?
The risk of impacts changes significantly for every rise in temperature and consequent environmental damages. This is why it is important to not only prepare and adapt to climate impacts, but to also continue mitigation strategies.
Canadian Council of Ministers of the Environment (2021). Guidance on good practices in climate change risk assessment. Retrieved from https://ccme.ca/en/res/riskassessmentguidancesecured.pdf Summary Report: https://ccme.ca/en/res/riskassessmentsummarysecured.pdf
Connelly, Angela & Carter, Jeremy & Handley, John & Hincks, Stephen. (2018). Enhancing the Practical Utility of Risk Assessments in Climate Change Adaptation. Sustainability. 10. 1399. 10.3390/su10051399. Retrieved from https://www.mdpi.com/2071-1050/10/5/1399
IPCC, 2018: Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [V. Masson-Delmotte, P. Zhai, H. O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J. B. R. Matthews, Y. Chen, X. Zhou, M. I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, T. Waterfield (eds.)]. In Press. Retrieved from https://www.ipcc.ch/sr15/
Reisinger, Andy, Mark Howden, Carolina Vera, et al. (2020). The Concept of Risk in the IPCC Sixth Assessment Report: A Summary of Cross-Working Group Discussions. Intergovernmental Panel on Climate Change, Geneva, Switzerland. pp15. Retrieved from https://www.ipcc.ch/site/assets/uploads/2021/02/Risk-guidance-FINAL_15Feb2021.pdf