Rising emissions of carbon dioxide and other greenhouse gases from human populations and industries are causing the global climate to change, profoundly affecting the world’s ecosystems . Increasing human populations, increasingly intensifying industries and agricultural production, deforestation and land use practices, and increasing fossil fuel based energy production all contribute to rising greenhouse gas emissions and concentrations [5; Figure 1]. Rising emissions continue to reach record levels each year, despite the year to year attempts of some nations to take up alternative energies and seek lower carbon solutions to their energy needs (2016 Global Carbon Budget). The increase in emissions is consistent with the increase in global average temperatures (Figure 4). Globally, the year 2016 and 2017 were the warmest two years on record (from NASA , and the U.S. National Oceanic and Atmospheric Administration’s 137-year time series) [4,13; Figure 5]. As carbon emissions and climate change continues largely unchecked, despite many attempts at reaching international agreements on climate change mitigation , these changes and impacts are expected to accelerate [35,36].
Anthropogenic climate change poses significant impacts and risks to both natural and human systems. Coastal regions are especially susceptible to these changes as they are affected by both marine and terrestrial impacts. Climate change impacts on coastal regions include increasing ocean temperatures, rising sea levels, changing ocean circulation patterns, precipitation, and water chemistry (ocean acidification and decreasing dissolved oxygen), and increases in the frequency and intensity of storms. Globally, much of the human population (>39%) lives within 100km of the sea, and are therefore dependent upon marine-derived resources for their social, cultural, and economic needs . Coastal communities are closely connected with their adjacent natural systems and are already affected by environmental and social stressors. Climate change impacts can affect coastal social-ecological systems: species, food webs, and associated fisheries and aquaculture; human well-being; cultural and social structures of coastal communities; and the marine infrastructure that communities depend upon for transportation, economic activities, and other services.
The IPCC describes the diverse and complex array of threats to coastal systems worldwide, while also highlighting that the overall uncertainties in projections of impacts on coastal systems are generally still quite high .The most recent global projections of climate change impacts and vulnerabilities from the IPCC are based on models of Representative Concentration Pathways (RCPs) . The RCP scenarios specify concentrations of greenhouse gases, and are used to project impacts related to climate change (Table 1).
Table 1: Projections of global mean sea level rise in meters relative to 1986-2005 based on ocean thermal expansion calculated from climate models, shown at the four emissions scenarios used by the 5th report of the IPCC. Source: WGI AR5 Summary for Policymakers. IPCC 2014, Coastal and Low-Lying Systems
|Emission scenario||Representative Concentration Pathway (RCP)||CO2 concentration in 2100 (ppm)||Mean sea level|
rise (m) by year
|Mean sea level|
rise (m) by year
|Low||2.6||421||0.24 [0.17-0.32]||0.44 [0.28-0.61]|
|Medium low||4.5||538||0.26 [0.19-0.33]||0.53 [0.36-0.71]|
|Medium high||6.0||670||0.25 [0.18-0.32]||0.55 [0.38-0.73]|
|High (‘business as usual’)||8.5||936||0.29 [0.22-0.38]||0.74 [0.52-0.98]|
In this report, we aim to present the uncertainty in climate change projections by including the projections for climate change variables at the lowest and highest RCP scenario, or the ‘best case’ and ‘worst case’ scenario, whenever possible. Long-term projections or trends within BC are expected to align with global trends in a general sense (i.e. warmer temperatures, more acidic ocean, more marine stratification, rising sea levels), but climate changes may result in regional and sub-regional interactions with localized ocean and atmospheric conditions. The ecological complexity of the BC coast and MaPP region is high, as is the uncertainty in regionally resolved climate change projections. Understanding the ecosystem and the projections of climate effects on the various components of the MaPP social-ecological system is therefore challenging.
In some cases, the spatial data for climate projections within BC are only available for certain scenarios (e.g. sea level rise projections, available for RCP 4.5 and RCP 8.5 only). Many of the available regional and sub-regional climate projections are available through PICS who use an average set of climate models from the IPCC to conduct regional analyses for the BC region at a ‘business as usual’ level of emissions (RCP 8.5) [6,7; Figure 6]. Higher resolution projections of climate effects and impacts on important sectors in this region and within BC generally will improve in the future. The current state of uncertainty means that the present report was conducted with relatively simplified, generalizable impact statements, adaptation actions, and recommendations for climate change impact planning in mind.