Ann Arbor and the rest of Michigan tend to see warmer winters with less snow and more rain when El Niño strengthens, according to a new study led by a University of Michigan scientist that ties the trend to human-caused climate change.

Julia Cole, chair of U-M's Department of Earth and Environmental Sciences, is the lead author of research published Aug. 27 in the journal Science showing that El Niño events over the past four decades were stronger than any in the 1,000 years before the industrial era began around 1850.

"The events of the last 40 to 50 years have no parallel in the pre-industrial record," Cole said in a U-M profile of the research published Wednesday, Sept. 9. "Not even close. And it all tracks with the warmer world."

Cole's team examined 29 coral fossils from the Galápagos Islands, the oldest dating to around the year 1100. Corals grow one to two centimeters per year by secreting layers of calcium carbonate. The chemistry of those layers records seawater temperature over time.

The team measured calcium-to-strontium ratios and oxygen isotopes in coral skeletons to derive two independent temperature readings, the Associated Press reported. Uranium-thorium measurements determined when the skeletons formed.

The results: modern El Niños are about 36% stronger than before the mid-1800s, with a 16% jump in just the last 40 years, according to the study.

The findings arrive as a powerful El Niño builds in the tropical Pacific. As of early September, the most recent weekly reading stood at 4.9 degrees Fahrenheit above normal, well above the 3.6-degree "very strong" threshold, the AP reported.

The World Meteorological Organization forecast a nearly 100% chance the current event will continue through February, according to the Los Angeles Times.

For Michigan, Cole said the main effect of El Niño is warmer winters with less snow and more rain, though she noted the signal gets "wobbly" farther from the Pacific. She added that stronger El Niños bring stronger impacts globally, including droughts, floods, wildfire, food insecurity and infrastructure damage.

The study did not find that climate change is worsening La Niña, El Niño's cooler counterpart. Cole told the Los Angeles Times on Friday, Sept. 4 that the shift is "kind of lopsided," leaning toward stronger warm events.

Cole's team coordinated fieldwork with the Galápagos National Park and the Charles Darwin Research Station. The U.S. National Science Foundation and the United Kingdom Natural Environmental Research Council funded the research.

Not all scientists agree on the conclusions. Kim Cobb, a coral and climate scientist at Brown University, called corals "the gold standard for El Niño reconstruction" and said paleoclimate data broadly points to intensification with warming. University of Pennsylvania climate scientist Michael Mann and University of North Carolina marine scientist John Bruno said the coral data conflicts with recent water temperature observations near the Galápagos, the AP reported.