Almost 14 years ago, I submitted a special report to the Legislative Assembly of Ontario entitled Climate Change: Is the Science Sound? Concerned about the debate that was ongoing at the time, I felt that – as the Environmental Commissioner of Ontario – it was incumbent upon me to review the scientific evidence and provide Ontario policymakers with my considered opinion as to the strength of the arguments that were being made. I concluded at the time that climate change is occurring and that humans play a key role.
For anyone who has been paying attention to this issue during the intervening years, it is clear that both the weight of evidence and the certainty of the science are now unequivocal. Enhanced scientific modelling, as well as improved technologies, have allowed scientific organizations such as the Intergovernmental Panel on Climate Change (IPCC), the World Meteorological Organization, and the National Aeronautics and Space Administration (NASA), to reach the same inescapable conclusion: the climate-warming trends that have been witnessed over the past century are almost certainly due to increases in greenhouse gas emissions from human activity. In my most recent report on the Ontario government’s progress in reducing greenhouse gas emissions, I discuss key conclusions reached by the IPCC, as well as others, to again present Ontario policymakers with the most up-to-date scientific information possible on Earth’s changing climate.
In our day-to-day lives, we plan what to wear, and whether to bring an umbrella, based on daily weather forecasts. One day may be warmer or rainier than the next and so we make plans according to the weather. Over a much longer time frame, however, trends in weather patterns are assessed to determine what the climate is for a particular area. In other words, the difference between weather and climate is a measure of time; typically more than a 30-year timeframe. While daily changes in the weather are clear and obvious, it is more difficult to discern whether the climate is also changing. It is only through the long-term tracking and recording of data that climate patterns, and changes associated with those patterns, become evident.
At a global level, it is through this long-term tracking that scientists have determined that global average temperatures are inexorably rising. As shown below, the longer term trend shows a clear increase, particularly when averaged over 10-year time periods. As shown in the lower portion of the diagram, the average temperature of each succeeding decade has been warmer than the one previous. The most recent data indicates that 2013 was slightly warmer than the preceding two years (source). Within the Northern Hemisphere, the last 30 year period is likely to have been the warmest period during the previous 1,400 years (source).
A key question in climate change discussions is whether or not severe weather events – such as extreme heat alerts – can be attributed to a changing climate. Over the past year, research (.pdf) has revealed that the frequency with which anomalous extreme heat events are occurring has shifted, such that they now occur more often. The graph below illustrates this for the Northern Hemisphere. The far left box shows that historic summer temperature anomalies from 1951-1980 produce a normal distribution – or bell-curve pattern. The far right tail of the curve – in the darker red that is barely visible – shows that extreme heat events occurred only very rarely; only 0.1 per cent of all temperature events during the 30-year period. Over time, however, there has been a shift in the entire distribution curve; in short, extreme hot weather events are now happening much more frequently than they have in the past.
Along with rising temperatures, other indicators clearly demonstrate that not only is the climate changing, it is doing so at an accelerated rate. For instance, the average rate at which glaciers and ice sheets are melting has increased in recent years (source). While each of these findings reveals the changes that have occurred in the past, the IPCC also provided projections that should truly give reason to pause and consider what may lie ahead for the future.
Ontario’s policy decisions matter and they can have an influence on our future. I am therefore calling upon the provincial government to show leadership and to make decisions that will help the province move toward a low-carbon economy. The costs of inaction are profound and, in my view, the benefits of taking action are compelling. It is now time for leadership on climate change.