Brought on by climate change, toxic blue-green algae are expected to return to Ohio's Lake Erie this summer, according to recent research.

On the heels of the recently released 3rd US National Climate Assessment, nearly 200 scientists spoke at a conference at The Ohio State University on Thursday to discuss how climate change is projected to affect the state of Ohio.

"The climate is changing. The debate on that part is over," Ellen Mosley-Thompson, director of the university's Byrd Polar Research Center, said in a statement. "The impacts of climate change are already evident, and will become more widespread and pervasive over the next half-century. The public and our policy makers need the best scientific information available to help them make important decisions, but communication is often challenging."

Based on the Lake Erie 2014 Harmful Algal Bloom (HAB) forecast - which the NOAA will officially release July 10 - there will be a larger-than-average bloom of harmful blue-green algae this year.

Blue-green algae are common in most Ohio lakes, fed by phosphorus from manure, fertilizers and sewage that rain washes from farm fields into nearby streams. As many as 19 public lakes, including Erie, have been tainted in recent years by toxic algae, the Associated Press reported.

"Eliminating the blue-green algae that cause the HABs would require a 40 percent reduction in phosphorus and other nutrients draining into the lake. Even with a 75 percent reduction, we could still experience a dead zone," said Ohio Sea Grant's director Jeffrey Reutter.

A dead zone is when dying and decomposing algae settles on the bottom of the lake and sucks out all its oxygen, creating dead zones that cover thousands of square miles.

The Great Lake algae bloom was so bad in 2010 that the state warned people not to touch the water. Officials say it likely caused seven people to get sick that year.

The city of Celina spends about $450,000 annually to control algae at the Great Lake, and the state has spent more than $10 million trying to treat it. According to the Ohio Environmental Protection Agency, it could take years to reverse the situation.