EXPLAINING THE EFFECTS OF CLIMATE CHANGE ON REAL ESTATE

Why is sea-level rise accelerating? Burning fossil fuels emits greenhouse gases that trap more heat in the lower atmosphere. Since preindustrial times, the planet has already warmed 0.8 C. This warming is increasing the rate of ice melt in Greenland, Antarctica and many of the world’s glaciers, adding more water to our oceans. In addition, we know that heat causes liquids to expand. Much of the heat being trapped in our atmosphere is being absorbed into oceans, causing the volume of water on Earth’s surface to thermally expand. These two factors together explain why the average global sea level has increased about 20 centimetres since 1880. How high are sea levels expected to go? Conclusions vary from 60 centimetres to more than two metres by the end of this century if we continue to burn fossil fuels at current rates. A study led by former NASA scientist James Hansen estimated three metres. One metre, however, is considered to be likely by the climate-science community. Property at Risk “If we continue on our current path, by 2050 between $66 billion and $106 billion worth of existing coastal property will likely be below sea level nationwide, with $238 billion to $507 billion worth of property below sea level by 2100,” according to a 2014 report, “Risky Business.” What’s the long-term worst outcome? The same study, published in September in the journal Proceedings of the National Academy of Sciences (PNAC), calculated that “unabated carbon emissions up to the year 2100 would commit an eventual global sea-level rise of 4.3 to 9.9 metres.” It’s important to keep in mind, however, that by “eventual” the authors don’t really know how long such a scenario might play out. What’s the best outcome? The good news is that sea-level rise is still moving slowly enough for cities and nations to plan and adapt. There is also a strong chance of avoiding worst-case scenarios by reducing — and eventually phasing out — fossil fuel use. According to the PNAC study, “Although past anthropogenic emissions already have caused sea-level commitment that will force coastal cities to adapt, future emissions will determine which areas we can continue to occupy or may have to abandon.” What do coastal communities face now? Many communities, from Alaska to Kiribati, have already been forced to relocate. Coastal communities along the Atlantic coast, from Charlottetown to Miami, are also feeling the pressure. Sea levels there are rising faster than the global average. For low-lying communities, sea-level rise isn’t the only challenge. Warming ocean waters are fuelling more intense hurricanes, which bring high winds, rain and strong storm surges.