Climate changes and the local environment:
As the amount of carbon dioxide in the atmosphere continues to increase due to human emissions, average annual temperatures in Marion County, Indiana are expected to rise from an annual average of about 63.5°F in 2007 to an average of 69°F by 2100 under “low emission” predictions, or an average of 73.5°F under “high emission” predictions.
Low emission conditions are estimated by assuming that we will at least moderately decrease our emissions in the near future, while high emission conditions assume that we will do nothing to change our current behavior. Without immediate action to reduce emissions, we can expect to have almost twenty times as many extreme heat days in Marion County. Extreme heat days are days when the highest temperatures rise above 95°F. Likewise, Marion County is expected to experience three to four times as many high heat nights, defined by temperatures 68°F or above, in the coming century under low and high emission scenarios respectively.
Another consequence of climate change that Marion County will face in the coming years is a likely increase in rainfall. Average annual precipitation has been increasing since 1895 in Indiana, and is expected to continue to increase in the future, possibly by 6-8% within the next half century. Most of this rain is expected in the winter and spring, leaving the summer and fall months possibly drier than they are now. With increased precipitation, we also expect to see heavy downpours more often followed by more frequent flooding.
How we know:
The projections of future climate change presented in this article come mainly from the Indiana Climate Change Impacts Assessment compiled by Purdue University and the National Oceanic and Atmospheric Administration’s (NOAA) Climate Explorer tool. Both of these tools rely on temperature and precipitation data gathered at weather stations on the ground around the county and state. These historical values are then compared to predictions for the future compiled by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). The IPCC creates future predictions with advanced computer models that evaluate the climate under different emissions scenarios.
Rising temperature and changes in rain patterns will likely have serious consequences for the health of people in Marion County. Scientists expect higher rates of dehydration, heat stroke, and death. Extreme heat can worsen pre-existing conditions, such as heart disease and diabetes, especially among children and the elderly. The number of deaths that can be linked to temperature extremes is expected to rise from 33 in 1990 to between 43 and 71 per year by 2050.
As temperatures rise in Marion County, air quality may also decline. Ozone particles stay near the ground in hot weather, triggering asthma attacks and exacerbating high blood pressure. Since cold winters currently control populations of mosquitoes and ticks, warming trends could well promote a sharp increase in the number of both pests, which could in turn allow the disease they carry to infect more people. It is likely that the emissions cuts that would reduce global warming would save more lives in Indiana than in most other states.
The growing season in Marion County has already lengthened significantly. By the 2050s, it is expected to lengthen by at least thirty days under high emission scenarios. The longer growing season will likely increase crop productivity in Marion County, though not as much as one might expect. The increasing number of high heat days will likely damage some crops, and the increase in precipitation during winter and spring, together with the rise in extreme precipitation events, should increasingly wash fertilizer and nutrients from the soil into nearby watersheds. Nevertheless, Indiana is likely to remain the top producer of corn and soybeans.
Marion County will therefore growing increasingly uncomfortable and unhealthy for many of its residents, yet a key sector of its economy - agricultural production - may in fact benefit from at least modest warming. These benefits will likely decline sharply in high emissions scenarios, and it is therefore in the interest of Marion County residents to contribute to a lower-carbon future.
2014 EPA Clean Power Plan. EPA.
Impacts of Climate Change for the State of Indiana. EPA.
Indiana’s Past and Future Climate. Purdue University.
Article author: Eve Kelly, Georgetown University
Article editor: Dr. Dagomar Degroot, Georgetown University