Sean Birkel, an assistant professor at UMaine and the state climatologist, created a website called the Climate Reanalyzer that provides weather and climate datasets and software and analysis tools for weather forecasts, climate models etc. He and his climate model were widely referred to last month when the Earth experienced its hottest week ever recorded. Derek Davis/Staff Photographer

ORONO — The average temperature in Maine last month was 70.1 degrees, almost five degrees hotter than usual and enough to make it Maine’s hottest July. But the local weather was overshadowed by a record-breaking planetary heat wave.

Still, Maine played a prominent role in telling the story of the Earth’s hottest July. Much of the data cited in recent heat wave news stories from Los Angeles to Nigeria to New Zealand came from an online climate visualization tool developed in Orono by Sean Birkel, an assistant professor at the University of Maine and the state climatologist.

The data generated by Birkel’s tool was considered preliminary at the time, although it and subsequent reports led United Nations Secretary-General António Guterres to say the “era of global boiling has arrived.” The findings were confirmed this month by the top two international authorities, the National Oceanic and Atmospheric Administration in the U.S. and the European Union’s Copernicus Climate Change Service, which made the assessment “official.”

For Birkel, a Bangor native who fell in love with science when he got his first telescope as a boy, it’s all about following the data, whether he is probing the volcanic underpinnings of sea surface temps in the North Atlantic or the reason why Maine got so much rain last month.

“Climate is the long-term weather pattern of a region,” Birkel said. “There are so many variables at play, like temperature, precipitation, wind speed. If you want to tell the story of our changing planet, you have to find a way to explore all that data and clearly illustrate the patterns.”

Birkel’s tool, called the Climate Reanalyzer, isn’t actually a climate model. It’s a website that uses charts, animated maps, and interactive timelines to bring to life the climate and weather datasets, forecasts and models sourced from other places, like NOAA.


Want to see how much Arctic sea ice remains at the end of the melt season (September) in recent years compared to the past? A dataset and map on the reanalyzer allows users to see the 50% decline from just a few decades ago.

Reanalysis is a weather forecast model that uses real-world observations from weather stations, weather balloons and satellite data going as far back as 1940 to create six- to 12-hour forecasts across the world and throughout the atmosphere.


Scientists can use reanalysis to examine the state of the atmosphere at any given hour in any part of the globe going back decades, identify historical climate trends and use the trends to fill in missing data or predict future weather patterns. Reanalysis is modeling grounded in historical real-world observations.

July Heat Climate Change

A person walks along a trail as the sun sets on July 16, in Death Valley National Park, Calif. Human-caused global warming made July hotter for four out of five people on Earth, according to a new report issued Wednesday, Aug. 2, 2023, by Climate Central. John Locher/Associated Press

While the reanalyzer has proved its value, it is no substitute for the “official” monthly or yearly weather reports from NOAA and the European Union. Those reports of actual recorded temperatures and records are considered the gold standard of weather information.

The global temperature average last month was 62.5 degrees, surpassing the previous record set in 2019 by a little more than half a degree, according to NOAA and Copernicus. July was 2.7 degrees above what is estimated to be the 1850-1900 average and 1.3 degrees above the 1991-2020 average.


Birkel began developing the reanalyzer about a dozen years ago when he was a postdoctoral associate at the University of Maine’s Climate Change Institute. Birkel is now an assistant UMaine professor jointly appointed to the institute and the UMaine Cooperative Extension.

The institute’s director, Paul Mayewski, asked Birkel if he could code a website to visualize a new climate reanalysis dataset. Birkel, a lifelong science nerd who started building computers in middle school, has since used his programming skills to write thousands of lines of code to bring the reanalyzer to life.

The website,, has been expanded to include weather forecasts and research tools that can help Maine’s fishermen, farmers and foresters, as well as weather buffs and climate scientists. With help from colleagues, Birkel hopes to add climate and weather learning modules for educators to use.

On a typical day, 6,000 people will visit the page. But in early July, on one of the record-breaking heat days, more than 80,000 people visited the reanalyzer’s page, undoubtedly drawn to it after its inclusion in headline-making news stories read all over the world.

The reanalyzer was the first website that Birkel knows of that showed that those estimated average daily global temperatures in July were hotter than any recorded since the satellite weather data record began in 1979. And it did so through color-coded maps the day after it happened, not a month later.

“It’s a difficult thing to do,” Birkel said. “You have to do a lot of coding. You need the data from all your official sources, you need scripts to visualize it and it has to be put on the web page in such a way that a layperson can easily understand it.”



Andrew Pershing, the vice president for science at Climate Central and the former chief scientific officer at the Gulf of Maine Research Institute, said Birkel’s Climate Reanalyzer has become an incredible tool for looking at weather and climate data.

“This year, it has played a crucial role in helping the world see how unusual conditions are on our planet,” Pershing said. “Sean has had a unique vision for how to aggregate and visualize weather and climate data, and I’m thrilled to see his work getting the attention it deserves.”

Climate Change Atlantic Ocean

The sun rises over fishing boats in the Atlantic Ocean in Sept. 2022, off of Kennebunkport, Maine. Maine’s climate is going to change, getting both hotter and wetter, and the Gulf of Maine will rise, Sean Birkel, an assistant professor at UMaine and the state climatologist said. Robert F. Bukaty/Associated Press, file

Birkel was shocked that what had begun as a coding project had attracted so much attention. His project has gotten publicity before, but nothing like this. The 45-year-old father of two is still a bit dazed, but he is happy to draw international attention to the work being done at the institute and UMaine.

Birkel, a Maine native who grew up in Bangor, wanted to be an astronomer as a boy, but he wound up majoring in geology as an undergraduate at UMaine. A class on ice ages turned him on to the impact of climate change, leading him to study historic glaciation as a UMaine graduate student.

He started studying modern climate as a postdoctoral fellow at the Climate Change Institute, joined the research faculty in 2013 and became the state climatologist in 2015. In that role, he collects, interprets and shares climate data with policymakers and the public to inform decision-making and planning.


Sometimes that means giving a talk to a civic or school group, but it also meant serving on the scientific and technical subcommittee of the Maine Climate Council, which developed the scientific underpinning for the “Maine Won’t Wait” climate action plan.

“When we kicked off four years ago, we knew that all of our work on climate had to be driven by science data,” said Hannah Pingree, the council’s co-chair and the director of the Governor’s Office of Policy Innovation & the Future. “We have led with science and Sean has led that effort.”

For example, the state asked the council to determine how much sea level rise it should incorporate into its coastal management and planning, Pingree said. The subcommittee estimated Maine is likely to see a 1.5-foot rise by 2050 and 3.9 feet by 2100.

The state Department of Environmental Protection is factoring those projections into licensing decisions and the state Department of Transportation is factoring them into its new construction projects, such as coastal bridges and roads, Pingree said.

Field agents at the UMaine Cooperative Extension are using Birkel’s site-specific weather observations and forecasts in their work with Maine’s fruit and potato growers, running different crop development, pest and disease development models, and are excited about the potential to grow these applications.

This data has the potential to be “the backbone to farming in Maine,” said Lily Calderwood, an assistant UMaine professor of horticulture and a wild blueberry specialist who works with Maine growers out of the extension office. Crop development, pest and disease models will boost agricultural efficiency, she said.


“Farmers could know exactly when they should spend the labor and resources to do certain farm tasks,” Calderwood said. “With labor shortages, both small- and large-scale farmers are forced to be as efficient as possible.”


As the state climatologist, Birkel is often asked about where Maine’s climate is headed. How long until summers will require an air conditioner? How will climate change impact the ski season? How will planting seasons change? Will the Gulf of Maine really grow too hot for lobster?

To understand that future, Birkel believes you first have to look to the past. Maine’s climate is warmer and wetter than it was a century ago, he said. Since 1895, Maine’s climate has warmed about 3 degrees and its total annual precipitation has increased by about 6 inches.

Those two things are related, Birkel said. Warming oceans enhance evaporation, making the air itself wetter. More moisture in the atmosphere means a growing number of heavy storms that dump a lot of water in a short period of time. Such deluges are more likely to wash away crops and roads.

The rising temperatures mean the growing season is lengthening, but the variability in the weather can still produce crop-killing frosts in the late spring or early fall, or midwinter thaws that cause flowers and insects to emerge too soon and leave logging trucks stuck in the mud.


When he looks to the future, tapping the combination of datasets and models to see Maine’s projected climate through 2100, Birkel sees temperatures rising from 2 to 10 degrees and 10% to 20% more rainfall, depending on worldwide carbon dioxide emissions.

For a farmer, that represents two to four more weeks to grow your crops, if they don’t wash out. For a ski resort operator or a fisherman, that’s two to four fewer weeks to keep the mountain open or huddle around the ice-fishing hole.

In the shorter term, Birkel projects Maine’s annual temperature will warm 0.7 degrees over the next 20 years, which is comparable to what’s happened here over the last 20 years. In other words, more of the same: earlier springs, hotter summers, later fall frosts and more winter thaws.

Despite the projections included in the Climate Council’s subcommittee reports, Birkel remains hopeful.

Maine’s climate is going to change, getting both hotter and wetter, and the Gulf of Maine will rise. Maine faces significant challenges, but the state isn’t facing the potential catastrophe that looms for other parts of the world in the next 30 to 50 years.

“The challenge will be how we adapt to these changes that we know are coming,” Birkel said. “We need to prepare our infrastructure, prepare our businesses, prepare our people. I think Maine is already doing that. Maine didn’t wait. Now we have to make sure Maine doesn’t stop.”


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