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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.

The 2015 Paris Climate Accord aims to limit global warming to at most 2°C and ideally 1.5°C relative to the preindustrial climate, to limit the impacts of anthropogenic climate change. In this Science Brief, we discuss greenhouse gas emissions budgets and pathways consistent with these warming limits.

Three recent papers in Nature Climate Change examine different aspects of these budgets and pathways:

Tokarska and Gillett (2018) use global climate model projections to calculate a new carbon budget for future emissions, relative to the 2006-2015 period, that is consistent with keeping warming to 1.5°C. They find a median remaining carbon budget of 208 billion tonnes from January 2016.

Tanaka and O'Neill (2018) use an integrated assessment model to test whether the Paris temperature limits of 2°C and 1.5°C require zero greenhouse gas emissions, whether a zero net greenhouse emissions limit implies that the temperature limits will be met and what the effect of imposing both emissions and temperature limits are. Their results suggest that meeting the  temperature limits doesn't require reducing net greenhouse gas emissions to zero, that reducing emissions to zero doesn't necessarily result in keeping temperatures under the Paris temperature limits by the end of the century, and that the effect of imposing both temperature and emissions limits is that temperatures decline after meeting the initial temperature limit.

Van Vuuren et al. also use an integrated assessment model, to develop alternative emissions scenarios that examine how the need for negative emissions may be reduced through implementing other strategies, such as making large-scale lifestyle changes, shifting to renewable energy and switching to more efficient technologies for the production of energy and materials. They find that these strategies can reduce to a small degree, but not eliminate, the need for negative emissions. They also find that these measures have co-benefits such as helping to meet other United Nations sustainability goals.

The Fraser Valley Climate Adaptive Drainage Management Forum project was initiated to generate and share the best available precipitation projections for the Fraser Valley; research collaborative climate adaptive drainage management strategies adopted in comparable settings; and host a Forum between producers, local government and agency staff, researchers and agricultural association representatives to deliberate preferred drainage management strategies to address local runoff and drainage challenges.

Three recent journal articles examine the rate of sea level rise and the ability of models to accurately simulate sea level rise at a global and regional scale.

Publishing in Geophysical Research Letters, Yi et al. (2017) examine the rate at which sea level rise is accelerating and find that the rate of acceleration over the 2005-2015 period is three times faster than it was over the 1993-2014 period and an order of magnitude larger than the acceleration over the 1920-2011 period. They also identify three primary contributors to this acceleration: the thermal expansion of sea water, reduced storage of water on land and the melting of ice on land.

In a pair of articles published in the Journal of Climate, Slangen et al. (2017) and Meyssignac et al. (2017) analyze the of climate models to simulate both global and regional sea level rise. They find that simulations can only explain about half (50% ± 30%) of the observed sea level rise. After bias corrections are included for the Greenland ice sheet and the possibility that ice sheets and the deep ocean were not in equilibrium with the 20th Century climate, the models explain about three-quarters (75% ± 38%) of the observed 20th Century sea level rise and all (105% ± 35%) of the observed sea level rise over the period from 1993-1997 to 2011-2015 period. Regionally, climate models underestimate the amount of sea level rise that occured, but do show reasonable agreement for interannual and multidecadal variability. When the same bias corrections are applied, the models come into closer agreement with observations. In addition, they find that the spatial variability in regional sea level rise is largely due to the thermal expansion of sea water and ongoing isostatic adjustment resulting from the end of the last glacial period.

Temperatures in the Cowichan Valley are warming. Global climate models project an increase in annual average temperature of almost 3°C in our region by the 2050s. While that may seem like a small change, it is comparable to the difference between the warmest and coldest years of the past. The purpose of this report is to quantify, with the most robust projections possible, the related climate impacts (including changes to climate extremes) associated with warming. This climate information will then inform regional risk assessment, decision making, and planning in the Cowichan Valley region, with a goal of improving resilience to
climate change. For this reason, this report focusses on the business-as-usual emissions scenario and the 2050s timeframe. By the end of the 21st century, projected warming and associated impacts are even larger. In addition, the amount of warming by that time depends more highly on the quantity of greenhouse gases emitted in the meantime.

Temperatures in the Capital Regional District (CRD) are warming. Global climate models project an average annual warming of about 3°C in our region by the 2050s. While that may seem like a small change, it is comparable to the difference between the warmest and coldest years of the past. The purpose of this report is to quantify, with the most robust projections possible, the related climate impacts (including changes to climate extremes) associated with warming. This climate information will then inform regional vulnerability and risk assessments, decision-making, and planning in the capital region, with a goal of improving resilience to climate change.