Long Island and the Fact of Global Warming

With all of the snow we've been getting here on Long Island since late December, as well as the big snow storm that barrelled across the United States last week, the last thing on anyone's mind is global warming, except maybe as a punchline. But the big picture gets lost when people focus on the weather while ignoring the long-term climatic data.

When the subject of global warming and climate change does get coverage, it is often dominated by the receding and thinning of Arctic sea ice and how it will affect the polar bears. Out of curiosity, I decided to find out if my native Long Island is experiencing warming.

The source of my data is the NOAA's National Climatic Data Center. I was able to obtain for free temperature records collected at the NOAA's climate monitoring station in Mineola*. It was rather time consuming though, because I could only obtain one month at a time. I also damn near used up all the black ink in my toner cartridge! What I decided to do was to focus on two months as a representative sample, July and November. And to make sure I collected data for a sufficient span of time, I felt a good year to start was the year of my birth, 1969.

The data appears on what is, even up to the present day, a form with the information written in by hand. It contains the high and low temperature for each day of the month. What I did was to analyze the data in two ways. In one spreadsheet I put in columns for the first, 15th and last day for both July and November and then entered the highest temperature for those days from 1969 up to 2010. In a second spreadsheet, I created columns with temperature ranges, with columns for July for 50-59, 60-69, 70-79, 80-89, 90-99 and 100+ degrees, and columns for November for 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 degrees. For each year I counted the number of days in which the highest temperature fell**. For instance, in July of 1969, there were 15 days in which the highest temperature was between 70 and 79 degrees.

After I plugged in the numbers, I created bar graphs to see if trends in temperature change could be discerned. Unfortunately, I don't know how to insert bar graph charts into a blog post, so I can't include them in this post. However, I can describe what they show. And what they do clearly show is that for both July and November, there is a noticeable increase in temperature in the last two decades.

For July, the frequency of days with the temperature highs between 60 to 69 degrees and 70 to 79 degrees shows a decrease. The number of days with temperature highs between 80 to 89 degrees increases only slightly, but this is because the number of days in which the high temperature falls between 90-99 and 100 and over is higher. According to the temperature records for Mineola, there were no days in July that reached 100 degrees between 1969 and 1987. The first year to reach 100 degrees is 1988. While the temperature does not consistently reach 100 or more on a year to year basis, in 2002 and 2010 the number of days in July in which the temperature reached 100 or more degrees was five.

I selected November because I wanted to see if an autumn month would show a similar trend, and I can report that it does. As with July, there is a decline in the number of days with temperatures in the lower temperature ranges, in this case between 30 to 39 degrees and 40 to 49 degrees. Likewise, there is an increase in the number of days in which the high temperature falls between 50 to 59 degrees and 60 to 69 degrees. The one range where November breaks the trend is in the number of days in which the temperature reached 70 or more degrees. The record occurred in 1975, when the temperature exceeded 70 or more degrees on 7 days. The number of 70+ days is slightly higher in the first two decades than the latter two. However, 70 degree days for November were infrequent for the entire 41 year span of temperature data I collected.

Using the temperature data for July and November, the evidence shows that in the last two decades temperatures on Long Island (or at least Mineola in Nassau County!) have increased. Readers of this post who might be of a right wing or libertarian bent, before you engage in a Tourette's outburst, please note that this post does not address whether human activity is causing this warming or whether there is anything we should be doing on a policy level to address the rise in temperature. I am merely reporting the findings from the data I have analyzed. You can look at the data yourself to confirm my findings.

Climate change on Long Island being a fact, the next issue to consider is what impact it might have on those of us who live here. One thing that springs to mind is the potential to affect the Long Island wine industry. The East End of Long Island, particularly on the North Fork, has a microclimate that has been compared to Bordeaux in France. It is possible that a continued rise in temperature could adversely impact the industry. I don't know to what extent, if any, that Long Island's winegrowers have noticed any change in their growing seasons or an increase in pests that favor warmer weather. I intend to contact the Long Island Wine Council to see if they have any information on this and will report what they say in a future post.

A greater potential threat to all Long Islanders are the effects of a rise in sea levels to our underground drinking supply. Long Island gets its drinking water from underground aquifers. This web page from the New York State Department of Environmental Conservation contains a brief, useful description of our aquifers. A rise in sea level from the melting of ice in Greenland and Antarctica in combination with a decrease in our water table could increase salt water intrusion into our aquifers. This paper provides a good overview of the impact of rising temperatures and sea level on the Long Island Sound, estuaries and coast lines and the marine life that inhabit them.

In conclusion, the last two decades have seen a trend in rising temperatures for Long Island that could have potentially adverse consequences for those of use who live here if that trend continues in the coming decades.

* The data was either incomplete or missing for Mineola for November of 1982, 1984, 1988 and 1996. To the extent that it was available, I substituted data collected at the Wantagh station. Wantagh, for those of you not familiar with Long Island, is on the south shore of Nassau County, whereas Mineola is more towards the center of Nassau County.

** For November of 1977, there was no temperature data for the 8th and the 9th. For July of 1982, there was no temperature date for the 21st. For November of 1982, there was no temperature data for the 22nd and 23rd. For July of 1986, there was no temperature data for the 31st. For November of 1988, there is no temperature data for the 21st and 22nd.