2 www.georgianbay.ca GBA UPDATE Spring 2023 (2019-20) water levels we experienced and how much these differed from the average historical water level (red line). The green section and green arrows illustrate the most likely future range of water levels as described on page 1. The right-hand section (grey arrows) illustrates the potential range of extreme water levels that might be seen over the next 70 years, using the worst-case scenario presented in the report. This last scenario assumes that very little is done globally to reduce emissions, and by the 2090s average global temperatures could increase by 3.2 to 5.4°C compared to 1986-2005. The potential extreme high water level could be 10.3 feet higher than average (7 feet higher than was seen in 2019/2020), while the potential extreme low water level could be 6.4 feet lower than average (2.7 feet lower than in 2013). What this means is that one of the major expected impacts of climate change on our water levels is an expansion in the potential range of Michigan-Huron water levels from the historic 6.33 feet to a potential range as high as 16.73 feet – a 164 per cent increase. Again, please remember that there is a low probability of ever reaching these extreme levels, but, nonetheless, there is a risk of this happening. The most likely scenario described above has a much higher probability of occurring. Why this report? GBA has focused on this study because other water levels projection models have not been subjected to the same degree of independent scientific peer review and/or they haven’t examined the issue in the context of climate change, which we believe is crucial. Are the report’s projections reliable/accurate? There are no actual water levels projections in the study, only expected ranges of future water levels, subject to probability rankings. In those rankings, the extreme highs and lows have a lower probability of occurring than do the values in the middle of the projected ranges. The projected ranges are as accurate as they can be, given the uncertainty of climate change impacts, against the thoroughness of the modeling and methodology, and the inclusion of information and analysis from many reputable scientific research sources. What can you do? 1. The predictions in the study are based on the reality of minimal global climate change mitigation. However, everyone can take steps to reduce carbon emissions, including taking transit more often, choosing electric vehicles when possible, or eating more local, plantbased foods. For some practical tips on everyday and longer-term steps to take, the David Suzuki Foundation has compiled a list of four ways you can cut your carbon footprint: https://davidsuzuki.org/what-you-can-do/ four-places-cut-carbon/. 2. We recommend that you consider the predicted variability in water levels very carefully before making any investment in shoreline infrastructure and consider how you might be proactive in preparing for potential extreme water level events. As we go to press on this issue of UPDATE, we are trending towards an extreme low (low ice cover and high evaporation levels are expected this winter), but this a best guess, as the report also highlights future uncertainty around predicting water levels. Over the longer term, it may make sense to switch from crib docks to floating docks and adjustable ramps. 3. If you have a low-lying septic system, it may also be prudent to consider how you can protect your system from flooding and to consult an experienced contractor. Climate change is increasing the energy in storm systems, bringing greater storm surge frequency and severity. 4. Generally, we recommend that you think about ways to adapt to extreme high and low water levels on your property. Is there a solution? Adjustments at the existing control structures can do very little to mitigate extreme variability in water levels because control boards must balance the interests of all the lakes, while keeping the St. Lawrence River open for shipping most of the time, and not allowing Montreal to flood. Even if new control structures were put in place at the mouths of the St. Clair and Niagara rivers, as they should be, the ability to mitigate water levels would still be very limited and would not be resilient to significant climate change. However, there may come a time when the annual cost of water level adaptation increases to a point where it makes more sense for governments to invest in systems-wide solutions that can balance extreme highs and lows. This would be extremely expensive and more than likely very challenging to implement, requiring significant political will in both the US and Canada. However, now that the ECCC report has made it quite clear what we are potentially facing, perhaps the time has come to have a serious look at solutions, rather than focusing entirely on adaptive measures. The GBA will continue to communicate with policy makers on these matters, monitor the situation, and report regularly. We will also work with other like-minded organizations on both sides of the border, as GBA cannot resolve this issue alone. Continued from page 1 RETRACTED 4. Generally, we recommend that you think about ways
RkJQdWJsaXNoZXIy NDA3MzU4