Expect the unexpected with climate change

An increasingly common fallback position once climate change "skeptics" accept that the planet is warming and humans are the dominant cause is the myth that climate change won't be bad. In fact, this particular myth comes in at #3 on our list of most used climate myths. It's an ideal fallback position because it allows those who reject the body of scientific evidence to believe that if they are wrong on the science, it's okay, because the consequences won't be dire anyway. One of my colleagues, Molly Henderson recently completed a Masters Degree program class on scientific research which focused on climate change, which she aced (way to go, Molly!). For her final research paper, she examined the consequences of climate change on the prevalence of water-borne diseases in the US Great Lakes region. Molly states the problem as follows. "Many cities that surround the Great Lakes are equipped with sewer systems that capture and combine sanitary sewage and stormwater as they are conveyed to wastewater treatment plants (McLellan et al., 2007). The EPA estimates that 150 communities within the Great Lakes drainage basin are serviced by combined sewer systems (CSS) (U.S. EPA, 2012). Extreme precipitation events can overcome the conveyance capacity of CSS and cause overflows, known as combined sewer overflows (CSO). These overflow events result in untreated sanitary sewage and stormwater discharges into receiving waters (i.e, rivers, streams, lakes, etc.). Urban stormwater and sewage overflow water contains human pathogens including viruses, protozoans, and pathogenic bacteria that can cause adverse health effects if ingested. The Great Lakes provide drinking water for an estimated 40 million people and there are more than 500 recreational beaches along lake shores (Great Lakes Legislative Caucus, 2012). Waterborne disease outbreaks result when water supplies are contaminated with pathogens that infect humans. It is well known that extreme precipitation events that cause CSO in the Great Lakes Region can lead to waterborne disease outbreaks, as seen in the 1993 outbreak of intestinal illness in Milwaukee, Wisconsin which affected an estimated 403,000 people (Curriero et al., 2001). Observed and projected climate changes due to global warming infer that more frequent extreme precipitation events are on the horizon for this region, thus potentially leading to a higher incidence of waterborne disease outbreaks if mitigation measures are not taken to improve existing CSS infrastructure and reduce greenhouse gas emissions." Combined Sewer Overflow (CSO) Plume in Lake Michigan (Milwaukee Harbor) credit Macalester College.