Clark's Spot

I’ve been reading Hot, Flat, and Crowded by Tom Friedman. He argues that demographics and globalization risk making climate change more dramatic than earlier projected. He also expands climate change to be more than Global Warming. He terms it “Global Weirding” and writes that the impact varies from place to place. Some areas have higher temperatures while others have colder weather. Certain months are impacted more than others. Sometimes the result is more rain – other places report dryer conditions.

But global warming is how everyone thinks of climate change so Friedman writes about a series of interviews where his subjects talk about noticing warmer weather. Western ranchers talk about less snow remaining on mountain tops. Another person speaks about the number of record highs and lows set across the country each week. That left me wondering whether I could find any change in weather in my area simply by looking at record highs and lows and when they were set.

I checked the National Weather Service’s repository of record highs and lows for the Scranton/Wilkes-Barre area – my current home. I used the tables from 1955 to present because they’re pulled from a consistent place (the airport) rather than the general area. I typed the date, record high (“maximum high”) and corresponding year, and record low (“minimum low”) and corresponding year into an Excel spreadsheet. It’s unfortunate that the records only cover 54 years, but they’re taken from a consistent area, which was more important to me than whether they covered 100 years worth of temperatures.

Because I wasn’t counting leap day, I had 365 days. The time period covered 54 years. Simple math says that if there are 365 record highs and 365 record lows, I should be able to expect about 7 record highs and 7 record lows each year.

If this covered two years – 1955 and 1956 – I’d expect half of the highs to be from 1955 and the other half to be from 1956. If it covered five years – 1955 to 1959, I’d expect 20 percent of the highs (73) to come from each year. Because I have 54 years, I expected 1.85 percent of the highs to have occurred in any one year. In a 365-day year, that’s 6.75 days. There were 365 lows as well – one for each day of the year. Odds say that another 6.75 lows – rounded to 7 – would set records each year.

I realize that some years just happen to be warmer or cooler than others, and so I wanted a way to lump years together. I decided to do it by decade. There were five years in the 1950s, nine years in the 2000s (the chart doesn’t cover 2009 temperatures), and 10 years for the 1960s, 1970s, 1980s, and 1990s. So odds say that I should have 33 or 34 records from the 1950s, 60 or 61 records from the 200s and 67 or 68 records for the other decades. If my numbers were around there, we’d be setting roughly equal numbers of record highs and record lows each year – and you wouldn’t be able to track the weather getting warmer or colder.

I didn’t get those results.

As you can see, there were a lot more record high temperatures set more recently than record lows. In the 1990s and the 2000s, there were 77.8 percent more record highs set than record lows set. We were still setting record low temperatures, but we were setting new high temperatures much more often. While the 1990s represented 18.5 percent of the years in the study, 26 percent of the high temperatures occurred in that decade. The 2000s represented 16.7 percent of the years, and 21.9 percent of the high temperatures. The 1950s are 9.3 percent of the years in the study, and 5.5 percent of the high temperatures. That same decade has 15.3 percent of the record lows for the period.

We’re setting both new highs and new lows in each decade. But there highs are coming more frequently most recently. But how drastic is the change? It’s difficult to see because the 1950s and 2000s don’t have the same number of years included as the other decades. To have a better view of the trend, I divided the 54 years into nine groups of six years each: 1955-1960, 1961-1966, 1967-1972, 1973-1978, 1979-1984, 1985-1990, 1991-1996, 1997-2002, 2003-2008.

Odds should say that you should have roughly equal number of record highs and record lows set in each time period – just more than 40.5 each. (1.85 percent of the highs in each of the six years is 11.1 percent of the records, and 11.1 percent of the 365 days in a year is 40.5.) The final numbers didn’t match the odds. Remember, the number of records for both highs and lows should be right around 40.

I’ve been really surprised to see this result. I’ll take some time to look into individual months to see if any part of the year is more affected than another. But it turns out to have been pretty easy to chart the fact that’s it’s getting warmer in Northeastern Pennsylvania. We’re setting many more record highs than record lows.