• by Dr. Sarah D. Oktay, Managing Director UMass Boston Nantucket Field Station •
I am writing this article on an unseasonably warm Sunday in November. According to Weather Underground (http://www.wunderground.com ) which is usually my go-to source for weather data the maximum temperature was 57 degrees Fahrenheit on Nantucket on the 10th of November. On November 7th of this year it was over 70 degrees on the island and hit 68 degrees in Boston, missing the record high of 77 degrees recorded in 1938 (http://www.nws.noaa.gov/climate/index.php?wfo=BOX) and much higher than the 54 degree average for that date in Boston. Today (the 10th) the ocean temperature surrounding the island is 50 degrees. Our comfortably warm fall days are a result of the ocean surrounding the island that provides a buffering envelope of water that keeps us warmer in the winter and cooler in the summer. The layer of insulating water provides about a ten degree difference in temperature for Nantucket versus mainland Massachusetts. The Wampanoag took advantage of the cool breezes that swept the island each summer, abandoning their encampments in the summer to come to the island and bask in temperatures that are on average about ten degrees cooler than the mainland. This cooling effect is due to the ocean and our distance from a large land mass. The Gulf Stream’s warm waters reach close enough to provide warm breezes and strange creatures, while the surrounding water prevents Nantucket from becoming too hot when the mainland bakes each summer.
When I check out Wikipedia to learn more about our climate I learned that: “According to the Köppen climate classification system, Nantucket features a climate that borders between a humid continental climate (Dfb) and an oceanic climate (Cfb), the latter a climate type rarely found on the east coast of North America. Nantucket’s climate is heavily influenced by the Atlantic Ocean, which helps moderate temperatures in the town throughout the course of the year. As a result, the island’s winter climate is warmer than that on the mainland of New England, and summers are cooler than on the mainland. Average temperatures during the town’s coldest month (January) are just below 32 °F (0 °C), while average temperatures during the town’s warmest months (July and August) hover around 69 °F (21 °C). Nantucket receives on average 38 inches (970 mm) of precipitation annually, spread relatively evenly throughout the year. Similar to many other cities with an oceanic climate, Nantucket features a large number of cloudy or overcast days, particularly outside the summer months.” (from http://en.wikipedia.org/wiki/Nantucket accessed November 10th, 2013.) Our snowfall is also much less than the mainland which was very evident last winter with four feet plus on the mainland and less than a foot here.
One of the reasons for this differential heating between water and land is that water is a transparent medium and land is opaque. Water allows light to penetrate to depth, leaving the surface layers cooler than they would be if the surface was opaque. A cooler water surface results in cooler air temperatures above. When solar radiation strikes land, the energy is absorbed in a thin layer that heats relatively rapidly. Likewise, it readily gives up its heat to the atmosphere. In the center of the continents the largest temperature swings occur. The ocean is our planet’s largest heat sink. By absorbing, storing and then slowly releasing large quantities of heat, the ocean buffers the climate of the nearby land and, over time, the entire planet. The very slow heat release of the ocean allows it to transport this heat all over the world. The heat carried by the Gulf Stream water travels over to Europe and keeps England and the Mediterranean parts of Europe much warmer than they would typically be at that latitude. This heat balance and the effect that climate change and warming sea temperatures are having means that more heat is being transported, and that the ocean’s metabolism effectively is speeding up. One of the biggest concerns is that hurricanes and storms will have more energy to draw from.
Of course the fact that we are sitting out in the middle of the Nantucket Sound with the Atlantic Ocean battering us on the east and the south shores also contributes to our high winds. Winds have plenty of time to build up steam with no mountains or hills or topography to slow them down.
Our much cooler spring temperatures and delayed start for the growing season can also be attributed to the waters surrounding the island. It takes a long time for water temperatures to change. And the water surrounding the island typically does not reach sixty degrees until the past few days of June (http://www.seatemperature.org/north-america/united-states/nantucket-june.htm). But climate change could even accelerate our spring warm up and has already affected our winter temperatures. The New England Aquarium has an excellent web site that presents data collected on our ocean and local climate and monitors how that is changing in a warmer world (http://www.neaq.org/conservation_and_research/climate_change/climate_change_in_new_england.php accessed November 11, 2013. “According to the New England Climate Coalition, these are some of the impacts of climate change in Massachusetts: Over the last century, the average temperature in Amherst, Massachusetts, has increased 2 degrees F. Precipitation has increased by up to 20 percent in many parts of the state. By 2100, temperatures could increase by about 4 degrees in winter and spring and about 5 degrees in summer and fall. Precipitation by 2100 is estimated to increase by about 10 percent in spring and summer, 15 percent in fall, and 20 to 60 percent in winter. The amount of precipitation on extremely wet or snowy days in winter is likely to increase while the frequency of extremely hot days in summer would also increase. According to a report from the Northeast Climate Impacts Assessment (NECIA) team, since 1970, the Northeast has been warming at a rate of nearly .5 degrees F per decade, with winter temperatures rising faster, at a rate of 1.3 degrees F per decade from 1970 to 2000, all changes consistent with those expected to be caused by global warming.”
Weather station and offshore data buoys will help record these changes and allow scientist to update their models and track trends. The Nantucket Field Station will be getting a new weather station for Christmas and we will go back online with our historical and current data.
Since this is the last issue of Yesterday’s Island for 2013, I just had to include a very different story in this weather article to let everyone know that I think the Tuckernuck headless millipede mystery may solved! You may have read in my August article on Tuckernuck this year (find it at http://yesterdaysisland.com/magical-island-tuckernuck/). I was stumped as many people have been about the mystery of the headless centipedes. I had no idea what was causing these weird corpses around the island. Well, fortunately when we hold a biodiversity conference, dozens of scientists including entomologists (people who study bugs) come to the island and when I mentioned this mystery, my friend and fellow geek Dr. Paul Goldstein immediately knew the culprit. Glowworms, seriously, killer ninja glowworms! You may recall that these millipedes have one heck of a defense system, poison called benzoquinones is held in glands along each leg segment. When threatened they release this poison into the unfortunate and dumb creature that attacks it. But the larva of the phengodid beetle, Phengodes laticollis, has been shown to feed on a similar millipede to the Tuckernuck species, in this case the Floridobolus penneri, or Florida scrub millipede without risking exposure to the repellent benzoquinones ordinarily ejected by the millipede from its defensive glands when attacked. This glowworm larvae latches onto the hapless millipede; quickly injects gastric (stomach) fluid into it and paralyzes it immediately (ninja stomach juice) then leisurely sucks out the innards leaving only a carcass with intact glands full of the benzoquinones toxins. One species of Glowworm from California (Zarhipis integripennis) essentially pulls a rodeo move on the millipedes it eats. Remember that these little larvae are basically just bioluminescent chubby little worms. When they sense a millipede nearby, they kick into high gear (for a larvae) and run alongside, jumping onto the back of the millipede, throwing a body coil over the heads parts and quickly chomping into the base of the “neck” area (where head meets thorax and all those poisonous legs) then they inject their stomach fluids into the millipede to paralyze it. Next the glowworm dismounts the millipede, burrows down into the soil (nap-time for cowboy larvae), and then come back a few hours later to digest the inside of the millipede. I’d rather encounter an enraged Chuck Norris frankly.
The well written paper on this topic written by Thomas Eisner et al., can be found at http://m.pnas.org/content/95/3/1108.full accessed on November 11, 2013.What is really interesting is that the author had heard about the headless millipedes in the north and had assume that a rodent was to blame for the wasteful kill and limited head consumption of the millipede. But our finding the “burnt”-like remains of the millipede implies that something like this glowworm may be to blame. So now you know what I’ll be doing next summer…….looking for glowworms on Tuckernuck!
I hope you have a wonderful warm and slightly snowy winter. Look for more science articles next year in Yesterday’s Island. Learn more about our climate, and how climate change is affecting New England at http://www.neaq.org/conservation_and_research/climate_change/climate_change_and_the_oceans.php