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Climate and Health Overview
- Average Annual
- All Climate Divisions in Michigan experienced warmer average annual temperatures during the 1981-2010 period than during the 1951-1980 period. Increases ranged from 0.6° F in southeastern parts of the state up to 1.3° F in the Northwestern Lower peninsula.
- The number of days per year exceeding 90° F and 95° F has not changed significantly for most locations in Michigan.
- Alternatively, heat waves defined by both temperature and humidity driven by weather systems such as air masses have significantly increased in Southeastern Michigan; while the number of dry, cool days during summer has significantly declined (UCS, 2012).
- Average Annual
- total precipitation has increased by about 11 % in the Great Lakes region since 1900
- total annual precipitation in Michigan increased by 4.5% (or 1.4 inches) from the 1951-1980 average to the 1981-2010 average
- precipitation is highly variable by geography and time. In Ann Arbor, we've seen a much faster change in precipitation, but across the Upper Peninsula and Northern Wisconsin, we've seen total precipitation decline or remain relatively stable
- Extreme (heaviest 1% of precipitation events)
- In the Midwest, the amount of precipitation falling in the 1% heaviest precipitation events has increased by 37%, (Walsh et al., 2014). Michigan has experienced a similar change between the time periods of 1951-1980 and 1981-2010, with most observational stations recording increased number of days with precipitation exceeding 1 inch (see Table 2.5). The average change over the twenty-two stations was 13.1% or an increase of 0.6 days per year.
Adverse health outcomes directly related to heat stress range from mild (heat cramps, heat edema, heat rash) to moderate (heat exhaustion, heat syncope characterized by dizziness and fainting) to severe heat stroke (body temperature of 1040 F or higher and complete or partial loss of consciousness), hyperpyrexia (elevated body temperature) and death (CDC, 2014). These severe outcomes can result in damage to the brain, kidneys and heart and may require hospitalization (Mastrangelo et al., 2007).
Indirectly, prolonged periods of high temperatures can have adverse effects on plant life reducing green space and tree canopy coverage. In urban environments a lack of green space exacerbates the existing urban heat island effect, which has been reported to increase the detrimental effects of heat on health outcomes (Akbari et al., 1997).
Climate change can affect respiratory diseases as air quality is impacted by changes in temperature, moisture levels, and wind patterns. For Michigan the specific changes of most concern include increased concentrations of ground level ozone, particulate matter less than 2.5 microns in diameter (PM2.5), other fine particles, and the production of aeroallergens such as pollen and mold spores (Kinney, 2008; Irfan, 2012).
The American Lung Association has published evidence linking air pollutants with respiratory symptoms, infant pneumonia mortality, lung cancer, COPD, bronchitis, all-cause mortality, cardiovascular disease and stroke (2014).
Acute ground-level ozone exposure is linked to childhood Respiratory disease, exacerbations of asthma and, more specifically, increased emergency department visits for asthma (reviewed in Sheffield et al., 2011).
PM2.5 causes worsening respiratory symptoms (mild), more frequent medication use, decreased lung function (moderate), recurrent health care utilization and increased mortality (severe) (Anderson et al., 2012; Delfino et al., 2008; Barnett et al., 2005).
In Michigan, climate change is expected to cause seasonal shifts which could lead to earlier and longer growing seasons and later first frost. This shift means plants are releasing pollen earlier and longer than in the past. In addition, as CO2 increases it signals pollen producing plants to produce three to four times more pollen, and the pollen itself may actually be more potent (EPA, 2006). Consequently the prevalence of allergic rhinitis is also rising (Shea et al., 2008).
The warming climate may be increasing the risk of some infectious waterborne diseases in Michigan. Legionella is a common bacteria found naturally in the environment, usually in warm water. Another aquatic pathogen, Naegleria fowleri, is known to cause fatal primary amebic meningoencephalitis in recreational swimmers exposed to warm freshwater in the southern U.S. However, in 2010 a fatal case occurred after swimming in freshwater in Minnesota, 550 miles further north than any other known U.S. case. On the other hand, warm temperatures may reduce the survival in water of some enteric pathogens such as E. coli, Campylobacter, and enteroviruses (Hunter, 2003).
Rising temperatures can have significant effects on algal blooms, which are a rapid increase in the population of one or a few species of algae that occur naturally in an aquatic system, freshwater or marine. Certain blooms are composed of species that naturally produce biotoxins that are harmful to human, animal, and ecosystem health; these toxin-producing blooms are called harmful algal blooms (HABs). Recent research suggests that, in addition to nutrient contamination from anthropogenic sources, the impacts of climate change may promote the growth and dominance of HABs through a variety of mechanisms including, but not limited to: warmer water temperatures, increases in atmospheric carbon dioxide concentrations, and changes in rainfall patterns (EPA, 2015).
Mosquitoes and ticks act as vectors for a variety of diseases. In the U.S. and in the Midwest, these insect vectors will likely survive in greater numbers as winters become milder and summers become longer and hotter. Climate-related changes in the vectors' habitat and host species populations will also influence future disease risk. In Michigan the primary diseases of concern are West Nile Virus (mosquito borne) and Lyme Disease (Tick borne).
Injury and CO Poisoning
As discussed previously the major summer events include extreme heat events, heavy rain, droughts, and floods. Besides these impacts, Michigan can experience tornadoes and high winds leading to systems disruptions such as infrastructure destruction, power outages, and social disruption. Health impacts include injuries, CO poisoning, mental distress and death.
Winter weather events include extremely low temperatures, heavy snowfall and ice storms. There is some evidence that lake-effect snow and ice storm events are related to climate change in Michigan and will continue to increase in frequency, at least short term; and some climatologists have linked the occurrence of extreme cold events to disruption in the arctic jet stream (see Figure 2.3) caused by melting polar ice (Kim et al., 2014). These weather events can also indirectly lead to health impacts through changes in the built environment. Health effects include the risk of CO poisoning and death from improperly used heaters and generators, hypothermia, and physical injuries from accidents due to snow and ice.