New high-resolution climate models are projecting that, in the not-too-distant future, America could face frequent and extreme temperatures that would take a significant toll on the nation's water resources and agricultural efforts. On the brighter side, the advanced climate models are so detailed that they could one day be used by policy makers to plan mitigation strategies on a local level.

Many of the computer models used by scientists to predict Earth's shifting climate focus on global trends, and so often have a spatial resolution of hundreds of kilometers. While these broad-stroke models are extremely useful for looking at the big picture, they can lack the ability to delve into the localized effects of climate change.

The new, American-led model has a different set of strengths to its globally focused cousins. With a spatial resolution of just 7.5 miles (12 km), it is capable of projecting localized climate events that affect, for example, a single county, rather than a state. The team asserts that it can use the tool to predict and examine the implications of atmospheric events on this scale across the entirety of the continental US.

"The high resolution of our models can capture regional climate variables caused by local landforms like mountains, valleys and bodies of water," said Zach Zobel, University of Illinois atmospheric sciences researcher, and one of the co-developers of the new climate model. "That will allow policymakers to tailor response actions in a very localized way."

The localized approach could also help make climate change more tangible to the public by making it more obvious just how the damaging the effects could be to their town or city.

However, whilst the climate model allows researchers to probe certain aspects or land and weather events in impressive detail, it also has its blind spots. The new model focuses on temperature projections and does not yet take into account the impact of other events, such as regional precipitation patterns, that could impact the current results.

The researchers used the model to produce data for the periods 2045 – 2054, and 2085 – 2094, and looked at two scenarios. In one projection the team simulated a "business as usual scenario," wherein fossil fuel use sticks to current projections, and another more positive scenario, in which there is a significant drop-off in its use by the end of the century. The results were then compared to historical data covering the period between 1995 – 2004 to provide context.

The projections, should they be accurate, paint a grim picture for parts of America. During the period covered by the historical data, the south-eastern US experienced only one "maximum summer temperature" day (in which the temperature exceeded 95 °F, or 35 °C ) every 20 days. However, according to the climate model, the business as usual scenario would see the frequency of maximum summer temperature days in the southeast of the US rise to the point that they are occurring once every other day.

The southwest is not the only region to see potentially damaging alterations to the local climate, including significantly longer summers.

"The Midwest could see large unusual heat events, like the 1995 Chicago heat wave, which killed more than 800 people, become more common and perhaps even occur as many as five times per year by the end of the century," comments professor Donald Wuebbles of the University of Illinois' Department of Atmospheric Sciences. "Heat waves increase the mortality rate within the Midwest and the Northeast because people in these densely populated regions are not accustomed to coping with that kind of heat that frequently."

Alongside any potential interference to the ecosystem and loss of life from conditions such as heatstroke, the extreme heat and unusual weather could play havoc with crops and further stretch the already scarce water supply. Access to water could also become an issue in the west of the country, as the longer warm seasons limit the period in which frost can gather on higher terrain. This, in turn, lowers the amount of water provided when this frost thaws and flows downhill as meltwater.

Moving forward, the team hopes to update its results to account for regional precipitation patterns.

A paper detailing the results of the study has been published in the journal Earth's Future.