ASHEVILLE — Nobody had seen a winter quite like this; in fact, the Reverend Thomas Smith called it, "the sharpest cold."
He even described how three rivers froze over. Rev. Smith was so amazed, he recorded it all in his journal: the day was January 26, 1726, in Falmouth, Maine.
“This is a touchstone of history,” says Greg Hammer, a meteorologist at the National Centers for Environmental Information, which is a branch of the National Oceanic and Atmospheric Administration. Following down the page in the reverend's journal, Hammer adds, “and you’re seeing the work done by men and women over hundreds of years."
Hammer is familiar with all of that work. There are dozens of rows of metal shelves behind him in the National Centers archives that stretch from floor to ceiling. Each shelf is piled high with boxes.
Thomas Jefferson’s weather journals from Monticello are here. So are weather reports from Civil War battlefields and of the high temperatures from Kansas wheat fields during the dust bowl of the 1930s.
Say you want to know what the weather was like in Raleigh on New Year’s Eve 1904. The chart is here. Want to know the weather at the Admundsen Scott Antarctic Science Station in 1957? The diaries are in another box.
“To go and touch a piece of paper that someone recorded more than 100 years ago, and the love and devotion they put into their job, makes it really special to me,” adds Hammer.
The files are all located in NCEI’s archives in Asheville. It is the world’s largest repository of climatological data. This treasure trove of weather data from the mid 1700s through 1990 is all on paper. It’s been digitized and digitally received since then. In all, more than 25 million gigabytes of climate data is stored on various forms of technology at the center.
“I still can’t get over all of the information here,” says Karin Gleason, a meteorologist at the Center for Weather and Climate, another branch of the NOAA. “We’re like the nation’s scorekeeper because we collect the data, archive it and make sure it is plausible and valid by sending it through a lot of processes for quality control and quality assurance.”
But that’s the thing about history. If you look closely at the past, you can also glimpse the future. So another part of the center’s mission is to make sense of all of that data and try to put it in context. Scientists also look for trends.
And there’s a lot of science in all that data.
“We string the numbers together to see, is this year warmer than last? Is this year cooler?” Gleason says, as she traces an imaginary timeline through the air. “We basically thread the story line; the numbers are the story, we just put words to it.”
The center collects almost four petabytes, or one million gigabytes, of weather data per year. It is collected from weather stations, airports, weather observers and satellites. That’s enough information to fill 20 million four-drawer filing cabinets per year.
And Gleason says that data is showing very definite trends that can be woven into a storyline.
“We are seeing that the nation as well as the globe are showing an upward trend in temperatures,” says Gleason. “It doesn’t mean that from this year to the next you’re going to see an upward climb, there’s going to be year to year to year variability. However the overall trend over multiple decades shows that from the 1970s to the present we’ve seen a noticeable, upward, appreciable, significant swing in temperatures.”
In short, it’s more evidence the world is getting warmer. But there’s more.
The center receives two observations from weather stations each day. The first is what is known as the high maximum temperature, which is essentially the high temperature in the afternoon. The center also obtains the low temperature of the day, which usually occurs right before sunrise.
The data also shows those overall warmer temperatures are sticking around. The trend is for it not to cool off in the mornings and evenings like it used to.
“We’re seeing one thing that manifests itself in many ways,” says Jake Crouch, a meteorologist NCEI. “We see the cold parts of the day and the cold parts of the world, warming faster than other places, so that means the nighttime temperatures are warming faster than daytime temperatures. Essentially, it is not cooling down as much at night.”
The warmer temperatures also tend to make the atmosphere more active. It can also hold more moisture. So the takeaway from the clearest trend of all the data is a warning: prepare for weather that is more extreme, which means rain events that are more intense and droughts that last longer.
“Some of the climate models actually show that, when we get a heavy rain, we get more of it but we have longer spells in between,” says Kenneth Kunkel, Ph.D., with the Cooperative Institute for Climate and Satellites at North Carolina State University. “So ironically we may have more droughts but also more heavy rain because the periods when we don’t get rains may be extended.”
Kunkel adds that it makes sense for governments to begin to think about building with resilience in future projects.
“As we project ahead, we are quite confident in the direction that heavy rain is going to go and that is up; we are going to get more heavy rain, and the rainfall will be more intense,” says Kunkel. “So what that means for planning infrastructure that has a long lifetime is that it will experience a climate in the future that has much more heavy rain. We are very confident that we can say that.”