28 August 2017, VOX, The “500-year” flood, explained: why Houston was so under prepared for Hurricane Harvey. It’s the city’s third “500-year” flood in the past three years. It’s difficult to comprehend the scale of the flooding and devastation that Hurricane Harvey and its aftermath are wreaking on the Houston area. Weather experts call the storm unprecedented, and note that it’s gone beyond even the most pessimistic forecasts. In the final reckoning, it’s certain that Harvey will be classified a 500-year flood — and maybe even a 1,000-year flood. But those terms can be a bit misleading — especially when high-profile people, like the president of the United States, confuse the issue by calling Harvey “a once in 500 year flood.” In theory, a 500-year flood is something that has a 1-in-500 shot of happening in any given year — in other words, the sort of event that’s so rare that it might not make sense to plan around the possibility of it happening. The problem is that 500-year floods are happening more often than probability predicts — especially in Houston. And, especially in Houston, prevention planning hasn’t evolved to acknowledge that a “500-year” flood isn’t really a 1-in-500 chance anymore. “500-year” floods are based not on history, but on probability. The severity of floods tends to get put in terms of years: a 100-year flood, a 500-year flood, a 1,000-year flood. But this isn’t an assessment of “the worst flood in” that time — places like Houston don’t actually have detailed weather records going back to 1017 AD, after all. Read More here
Category Archives: Impacts Observed & Projected
28 August 2017, The Conversation, Is Hurricane Harvey a harbinger for Houston’s future? Over the past week we have seen two major tropical storms devastate different parts of the world. First Typhoon Hato struck Hong Kong and Southern China killing at least a dozen people. And over the weekend Hurricane Harvey made landfall from the Gulf of Mexico, bringing extremely heavy rain to southern Texas and causing devastating floods in Houston. Tropical cyclones are, of course, a natural feature of our climate. But the extreme impacts of these recent storms, especially in Houston, has understandably led to questions over whether climate change is to blame. How are tropical cyclones changing? Tropical cyclones, called typhoons in the Northwest Pacific and hurricanes in the North Atlantic, are major storm systems that initiate near the Equator and can hit locations in the tropics and subtropics around the world. Read More here
28 August 2017, Climate Home, Link between Hurricane Harvey and climate change is unclear. Reports the devastating storm was made worse by humanity’s carbon emissions fail to grasp climate change is not just about warming. The unprecedented amount of rainfall accompanying Hurricane Harvey immediately raised the question whether and to what extent climate change is to blame. In a warming world the vapour capacity of the atmosphere increases, and more extreme rainfall, like Texas is witnessing right now, is to be expected as a result. This leads many to conclude that climate change exacerbated the impacts of hurricane Harvey. It is very appropriate to highlight that this is the kind of event we expect to see more of in a warming world. However, to apply this argument directly and attribute (and quantify) the impacts from Harvey itself to human-induced climate change, neglects that climate change is not just about warming. In a changing climate, two effects come together: not only does the atmosphere warm up (thermodynamic effect) but the atmospheric circulation, which determine where, when, and how weather systems develop, can change as well (dynamic effect). Read More here
28 August 2017, Desmog, 12 Years After Katrina, Hurricane Harvey Pummels Gulf Coast and Its Climate Science-Denying Politicians. As the remnants of Hurricane Harvey (now a tropical storm) continue to flood Houston — just days before the 12th anniversary of Hurricane Katrina — I visited Shannon Rainey, whose house was built on top of a Superfund site in the Upper Ninth Ward of New Orleans. Rainey is worried about family members in Houston. She knows all too well how long it can take to get back what is lost in a storm. “I still live with Katrina every day,” she told me. New Orleans remains threatened by bands of rain extending from Harvey, causing many residents with fierce memories of Katrina to remain on edge. Earlier this month, the city proved it was ill-prepared for hurricane season nearly a year after Baton Rouge’s 1,000-year flood. Rain inundated New Orleans, with more than nine inches falling in only three hours, exposing that the city’s pump system could not operate at full capacity. The city is still scrambling to make the needed repairs and clean the sewer system’s catch basins, which remain clogged in many places. Read More here