Lake Michigan is heating up due to climate change, study reveals
is spreading deeper into the Earth than previously believed. The National Oceanic and Atmospheric Administration (NOAA) revealed water hundreds of feet below the surface of Lake is warming. The agency warns this could disrupt the lake's seasonal patterns, which would ultimately alter the ecosystem that evolved to adapt to the current environment. Using a 30-year dataset of deep water temperature measurements, the study found that Lake Michigan is as much as 0.06 degrees Celsius per decade and is a reflection of rising temperatures and prolonged summers. The rise in water temperatures, according to experts, could result lead to long-term shifts, alter the food chain and force fisheries into uncharted territory. Craig Stow, a NOAA Great Lakes Environmental Research Laboratory scientist and author of the study, said: 'These changes may seem very small, a couple tenths of a degree per decade, but this has been going on for several decades now, perhaps longer than is reflected in our monitoring.' Experts have long known that Lake Michigan temperatures are rising and ice cover is dwindling as a result of human activity. The world caught a glimpse of this destruction last month, when ice covering Lake Michigan broke off and drifted away from the shoreline. Although lakes continue to change from the moment they form, Stow said this one in particular is changing much faster. 'It when they change fast it means humans have to adapt to the changes that occur. And if we don't monitor for them we run the risk of being caught by surprise,' he continued. Using a 30-year dataset of deep water temperature measurements, NOAA Great Lakes Environmental Research Laboratory scientists investigated how Lake Michigan's seasonal mixing patterns are being influenced by climate change. Researchers found that the overall warming, ice loss and shorter winters could lead to long-term shifts, alter the food chain and force fisheries into uncharted territory. Some of the surfaces of the world's largest lakes are warming faster than ocean and air temperatures. 'We've known for a while now based on surface temperaturesnot just in Lake Michigan but smaller lakes and large lakes worldwidethat the surface temperatures seem to be increasing,' Stow said. Lake Michigan surface temperatures are estimated to be warming at a rate of as much as a third to a fourth of a degree Celsius per decade. Researchers have been investigating Lake Michigan since 1990, using a string of thermometers floating vertically in southern Lake Michigan to gather measurements. NOAA Great Lakes Environmental Research Laboratory scientists pulled together 30 years of measurements, some hourly, to track seasonal patterns far below the surface. In deeper water, warming is estimated to be as much as .06 degrees Celsius per decade. 'This is a big lake,' Stow said. 'That's a lot of water. That's a lot of change. 'It could have been that we'd only see an effect down in the first 30 or 40 meters,' Stow said. 'But we saw it down really far.' Lakes can serve as 'climate change sentinels,' the study says, and deep water measurements can be particularly important because they provide a 'climate memory.' 'What we can see from this data is a reflection of larger scale and longer-term processes,' Stow said. 'They're not obscured by the noise that might occur from a couple very warm or a couple very cold years.' Records dating back to 1973 show the area has also experienced ice loss. The Great Lakes has had a five percent decline per decade and Lake Michigan's ice coverage decline is about 3.6 percent. Lake Michigan is dimictic, meaning there's a top-to-bottom mix of the water column twice a year. With warmer surface temperatures, the fall mixing cycle is starting later, leading to a shortened cooling period for deep waters and a longer summer period without mixing. 'The organisms that live there, the plankton and the fish, are used to the lake the way it was,' Stow said. 'They evolved over thousands of years to take advantage of those systems that mixed twice a year.' If the lake changes to warm monomictic, mixing once a year, Stow said it would signal fundamental change. 'And the other thing you have to remember is this is not the only thing going on,' Stow said, noting changes spurred by invasive zebra and quagga mussels. 'All of that's happening