The supposed impact of global warming on the Gulf of Maine over the past decade has hit a multitude of media outlets. Example: take Weather.com’s article Global Warming Is Changing the Gulf of Maine, Imperiling Its Lobster, Fish Catch. According to the article, Gulf of Maine temperatures were marching along with the global average from 1982 to 2004, but then over the past decade, starting in 2004, the Gulf of Maine began warming at a rate that was 10 times faster than the previous rate.
So let’s take a look at the sea surface temperature data for the Gulf of Maine, and see what story they have to tell.
2004 to 2013 TREND MAP
For those readers who are wondering where in the world the Gulf of Maine is, I’ve highlighted its location on a trend map of ocean surface temperatures for the period of 2004 to 2013. See Figure 1. For the past 10 years, yes, the surface of the Gulf of Maine warmed at a high rate…along with the Kuroshio-Oyashio extension east of Japan and the coastal waters of western Australia. Other than those regions and a few others, global sea surface temperatures have cooled (not warmed) over the past decade. Note the negative number also highlighted on the trend map.
We’re using the coordinates of 41N-45N, 71W-66W for the Gulf of Maine sea surface temperature data in this post. That’s less than one 5-degree latitude by 5-degree longitude grid. So consider the size of the region.
The NOAA annual ERSST.v3b-based sea surface temperatures for the Gulf of Maine (1854-2013) are shown in Figure 2. Sea surfaces there were relatively cool from the 1870s until the 1920s, when there was an upward shift in the late 1920s. Sea surfaces were quite warm in the Gulf of Maine from the early-1940s to the mid-1950s. There was a dip and rebound in the 1960s. There appears to have been another upward shift in the late 1990s, followed a few decades later by a spike in surface temperatures in 2012.
I’ve highlighted the period of 2004 to 2013 in Figure 3 to give you an idea of the period they’re concerned about.
NO LONG-TERM WARMING SINCE 1930
The long-term data show the sea surface temperatures for the Gulf of Maine shifted upwards in the late 1920s. So let’s look at the sea surface temperatures there since 1930, Figure 4. While there was a recent uptick in the sea surface temperatures for the Gulf of Maine, the linear trend of the data show the warming rate there was basically flat, at only 0.004 deg C/decade, since 1930. Human-induced global warming appears to have eluded the surface temperatures of the Gulf of Maine.
In fact, without that spike in 2012, the sea surface temperatures of the Gulf of Maine would have cooled since 1930. See Figure 5, which presents the data and trend from 1930 to 2011.
NOTHING UNUSUAL ABOUT THE MOST RECENT 10-YEAR AVERAGE OR 10-YEAR TREND
The articles focused on the last decade, so maybe there something unusual about the recent decadal temperature or decadal warming rate for the Gulf of Maine. Nope.
Figure 6 shows the 10-year-average sea surface temperatures (trailing) for the Gulf of Maine. About “trailing”: the last data point at 2013 indicates the average surface temperature for the period of 2004-2013, and the data point before it presents the average for the period of 2003-2012, etc., working back in time to the first data point at 1863 for the period of 1854-1863. The 10-year-average sea surface temperatures for the periods ending in the early 1950s were noticeably higher than today.
And Figure 7 presents the 10-year trends in the surface temperatures of the Gulf of Maine. There were 10-year periods ending in the early 1930s and early 1970s when the surface of the Gulf of Maine warmed faster than they have recently.
Somehow, I don’t think any of this would come as a surprise to the fishermen and lobstermen of the Gulf of Maine. They understand the effects on their businesses of natural variations in ocean temperatures.
It’s really tough to claim that human-induced global warming has caused a warming of the Gulf of Maine, when, if you lop off the last two years of data, the surfaces there have cooled for more than 80 years. Refer back to Figure 5.
Just another example of unfounded alarmism.
The data presented are available through the KNMI Climate Explorer.
Thanks to blogger Alec, aka Daffy Duck for advising me of this nonsense.