Publications Library

As the climate warms, the Earth's cryosphere, comprised of snow, ice and frozen soil, including permafrost, has been shrinking. Changes in snow cover, depth and the timing of snow melt can have impacts on ecosystems and human communities. Data on snow cover and depth is used to identify historical trends and provides a baseline with which to compare projected future changes.

Recent research published in Atmosphere-Ocean examines trends in snow cover as measured at observing stations by ruler and sonic sensors, looking at how snow cover has changed over the 1955-2017 period and comparing the two methods of measurement. In this Science Brief we discuss what these results tell us about snow cover in Canada's changing climate.

The state of the future climate depends on human actions, primarily the emission of greenhouse gases and other industrial pollutants. This raises the questions: "What path are recent historical emissions following?" "What path would we be on, if we continue with business-as-usual, in the absence of further mitigation action?" And, "Are these paths reliable guides to future emissions?" One scenario that is commonly used in the scientific literature, RCP 8.5, is often referred to as "business-as-usual." Recently, some scientists have taken issue with this description, saying it is unrealistic and may hinder the goal of emissions reductions policy. Others argue that, in fact, RCP 8.5 is the scenario that most closely tracks cumulative emissions to date, that it is thus of the most use for planning out to the middle of the century. In this Science Brief, we unpack each of these arguments and evaluate what these differing perspectives can tell us about the ultimate objective of emissions scenarios as tools for exploring future climate change.

This Science Brief covers a paper in the Proceedings of the National Academy of Sciences, by Xu et al. (2020), who use global climate model (GCM) output, weather station data, estimates of historical global population density, and data on global gross domestic product (GDP), crop and livestock production, to determine if there has been a human climate niche. They determine that such a niche has existed. For the past 6000 years, human populations have lived largely in a fairly narrow range of climates and populations clustered around two temperature ranges, with most people living in a range of about 11°C to about 15°C for mean annual temperature and a smaller, but significant portion living in a range around 20°C to about 25°C.
They then examine how this niche may change in the future. They find that, under a high emissions scenario, this niche is projected to shift spatially more in the upcoming 50 years than it has in the past 6000, leaving a third of the projected future human population in regions where the mean annual temperature is greater than 29°C.

This report places the conditions in British Columbia (BC) over 2019 into climatological context. It finds that: a moderate El Niño likely contributed to a slightly warmer than normal 2019 in BC; anomalous warmth peaked in spring, forcing rapid melt of a near-normal winter snowpack; precipitation in summer and fall was above-to-much-above normal across the province; trends in temperature are positive for the period 1950 – 2019 with minimum temperatures (Tmin) increasing faster than maximum temperatures (Tmax), and that precipitation shows no significant trend over the same period.

As the Arctic warms, the rate at which microbes in Arctic soil digest soil organic matter increases and, with it, the release of carbon dioxide into the atmosphere also increases. The amount of carbon released into the atmosphere from permafrost in this region is significant and so it is important to measure it accurately and be able to make credible projections of it.

Publishing in Nature Climate Change, Natali et al. (2019) use observations of CO₂ flux from Arctic and Boreal permafrost soil to create a model that allows them to estimate winter (October through the end of April) soil carbon flux over the 2003-2017 period. They also drive their model with global climate model output, to make projections of future CO₂ flux in the region. They estimate that approximately 1.7 gigatonnes of carbon (GtC) were released each winter over the 2003-2017 period. The authors also find that, of the variables that they tested, soil temperature had the largest relative influence on CO₂ flux. Their projections show future winter Arctic soil fluxes of about 2.0 GtC per year by 2100, for a moderate emissions scenario, and about 2.3 GtC per year, assuming a high-emissions scenario.

Understanding how human influences are affecting different parts of the climate system allows us to improve future climate projections. Due to the relative sparsity of precipitation data and the large amount of internal variability that it exhibits, detecting and attributing the human influence on precipitation is difficult. This Science Brief covers recent research that uses information about the physical processes responsible for precipitation in order to detect the anthropogenic influence on winter precipitation over North America and Eurasia over the 1920-2015 period.

Publishing in Geophysical Research Letters, Guo et al. (2019) use a technique known as "dynamical adjustment," to estimate the atmospheric circulation and thermodynamic contributions to observed precipitation over Eastern North America and Northern Eurasia over the 1920-2015 period. They find that the thermodynamic component, due to anthropogenic emissions, contributes to increases in precipitation in both regions. They then compare the spatial pattern and magnitude of these components to those obtained from global climate models driven with anthropogenic forcings. They find strong agreement between the thermodynamic components of precipitation obtained from the observational data and those obtained from climate model output.

Climate change is challenging industry and communities across the Northeast region of the province. Wildfires, hail storms, and floods have already challenged local infrastructure and posed health risks to communities. Projected climate change for the region includes increases in frequency and intensity of extremes. Ensuring the region is as prepared as possible for future climate events is critical to maintaining a thriving community, robust natural environment, and vibrant economy. As prepared as possible means the region understands how the climate is changing, and is working together to increase resiliency, and to improve natural and physical infrastructure. Early efforts will reduce the reliance on emergency management and support the ability to thrive over time. Local governments in the region are taking a proactive approach to understanding how climate change will pose risks to Northeast communities and are planning together to build resiliency across the region.

This document is intended to offer science-based information on how the Northeast’s climate is changing and expected to change over the 21st century. Designing to current and future climate parameters is anticipated to be markedly more cost effective than reacting to climate shocks and stresses over time. In the report, climate projections for the 2020s are offered to represent current climate conditions; projections for the 2050s illustrate the trajectory of change regardless of global emissions reductions; and projections for the 2080s illustrate our likely “business as usual” future climate scenario by late century. The 2020s projections are useful as they more accurately depict the current state of climate than historical observed baseline data. The 2050s projections are useful for medium-term planning and infrastructure purposes, while the 2080s provide guidance for long-term infrastructure decisions.

A forward-thinking group at Nanaimo Hospital developed a comprehensive climate risk assessment matrix which is becoming an integral part of their organizational decision-making. Future hospital retrofits will potentially include increased cooling capacity, enhanced air filtration, and other measures to reduce costs, greenhouse gas emissions, and protect the facility and its patients from the potential effects of climate change.