On The Recent Record-High Global Sea Surface Temperatures – The Wheres and Whys

NOAA’s State of the Climate Report for June 2014 included the bullet point under global highlights (my boldface):

For the ocean, the June global sea surface temperature was 0.64°C (1.15°F) above the 20^th century average of 16.4°C (61.5°F), the highest for June on record and the highest departure from average for any month.

Yikes, it sounds as though it’s a manmade global warming problem.  But we know that’s not true because climate models doubled the warming rate of global sea surface temperatures for the past 3+ decades. So even record highs are much better than the temperatures anticipated by the latest and greatest climate models.  As an advanced warning, NOAA will be making a similar statement for July 2014.  See the graphs to the right. (Click for full size.) The red horizontal lines are the July 2014 values. NOAA bases their discussions on the ERSST.v3b-based data (bottom graph).  The satellite-enhanced Reynolds OI.v2 dataset (top graph) serves as a reference. Yup, it’s true. July 2014 global sea surface temperatures are the warmest on record, too.

In this post, we’ll present which ocean basin is showing the elevated sea surface temperature anomalies, and where they’re showing it, and provide what will likely be eventually reported as the reasons for those warm temperatures: strong trade winds and persistent high sea level pressures over eastern Siberia and Alaska.

A QUICK LOOK AT THE TWO NOAA GLOBAL SEA SURFACE TEMPERATURE ANOMALY DATASETS DURING THE SATELLITE ERA

Figure 2 presents the monthly global sea surface temperature anomalies for the period of November 1981 to July 2014. The top graph shows the NOAA Reynolds OI.v2 data, which, as noted above, is a satellite-enhanced dataset.  The bottom graph is the NOAA ERSST.v3b data, which NOAA uses in its global land+ocean temperature dataset. ERSST.v3b is a statistically infilled sea surface temperature dataset.  Anomalies are referenced to the WMO-preferred period of 1981-2010.  The Reynolds OI.v2 and ERSST.v3b data are showing close to all-time-high values recently.

Figure 2

Before we move on to illustrating where and why the sea surface temperatures are elevated, there are a few things to discuss.

CLIMATE MODELS CANNOT SIMULATE SEA SURFACE TEMPERATURES

It must be kept in mind throughout this post that the climate models used by the IPCC for their 5^th Assessment Report basically doubled the observed warming rate of the surfaces of the global oceans.  Doubled.

Figure 3

In other words, the model mean represents the central tendency of how the climate science community thinks the oceans should have warmed if they were warmed by manmade greenhouse gases, and, in the real world, the oceans only warmed at half that rate for the past 32+ years. Or to phrase it a little differently, in the models, the warming of the surface of the oceans is forced by manmade greenhouse gases, but in the real world, the ocean surfaces are obviously not as sensitive to manmade greenhouse gases as the climate science community assumes.

Now consider that the data existed before the climate simulations were run.  So modelers knew in advance the warming rate of the ocean surfaces for the most of that period.  That is, most of simulations from 1981 to present are hindcasts, not forecasts.  The modelers knew the answers they were looking for, and somehow doubling the observed warming rate of the surfaces of the global oceans (70% of Earth’s surface) over the past 32 years was the best the modelers could do.  That’s climate science in a nutshell.

THE NORTH PACIFIC IS CREATING RESPONSIBLE FOR THE HIGH GLOBAL SEA SURFACE TEMPERATURES

If you were to scroll through all the ocean basins presented in the July sea surface temperature update, you’d find that only the North Pacific has shown exceptional warming over the past year or so. But that one ocean basin has had a major impact on sea surface temperatures for the entire Pacific basin and the Northern Hemisphere, both of which are showing record highs recently.  In turn, global sea surface temperatures are at record highs.

The North Pacific sea surface temperature anomalies during the satellite era, along with the July 2014 value, are shown in Figure 4.

Figure 4

According to the NOAA webpage here, the North Pacific covers about 21% of the surface of the global oceans, or about 77 million sq. km.   To put that into perspective, the North Pacific covers almost as much of the globe as Asia, Europe and North America combined (78.5 million sq. km.), so the North Pacific is a chunk of real estate.

Notice in Figure 4 how unusual that warming in 2013 and 2014 appears.

BEFORE 2013, THE SURFACE OF THE NORTH PACIFIC HAD NOT WARMED FOR 24 YEARS

To illustrate how unusual that recent warming is, I determine how far back in time from December 2012 we could go without showing any appreciable warming in the sea surface temperature data of the North Pacific. See Figure 5.  The sea surface temperature anomalies of the North Pacific showed basically no warming from January 1989 to December 2012. That 2 ½ decade lack of warming is quite remarkable in a world where greenhouse gases are supposed to be warming the surfaces of the oceans.

Figure 5

LET’S DIVIDE THE NORTH PACIFIC INTO FOUR REGIONS

To help present where the North Pacific has warmed, we’ll divide its data into four subsets, separating the tropics from the extratropics and dividing the data east and west at the dateline.  See the map in Figure 6.

Figure 6

The map also presents the sea surface temperature anomalies for the year of August 2013 to July 2014, referenced to the period of 1981 to 2010. Of the four regions, the eastern extratropical Pacific had the highest anomalies, while the eastern tropical Pacific had the lowest.  The two western regions both show elevated sea surface temperatures over the past year, but a region of cooler-than-normal sea surfaces offsets some of the warmth in the western extratropics of the North Pacific.

Let’s look at the sea surface temperature data for the four subsets

, starting with the region with cooling over the past 3+ decades, the…

EASTERN TROPICAL NORTH PACIFIC

Figure 7 presents the sea surface temperature anomalies during the satellite era for the eastern tropical North Pacific (0-20N, 180-80W).  Also shown is the cooling rate. The cooling of course was caused by a shift from El Niño dominance to La Niña dominance.

Figure 7

The warming in recent months is higher than we’d expect from the weak off-season El Niño conditions we’ve recently experienced.

WESTERN EXTRATROPICAL NORTH PACIFIC

We’re discussing the northwest subset of the North Pacific under this heading. As shown in Figure 8, the sea surfaces of the western extratropical North Pacific (20N-65N, 120E-180) were above average in July 2014, but not exceptionally warm.  There was also a spike a year ago, peaking in August 2013.  Will that spike repeat itself this year?

Figure 8

There are very obvious upward shifts in the sea surface temperature anomalies of the western extratropical North Pacific.  In Figure 9, I’ve highlighted in red the periods before and after the step-like responses to the 1986/87/88 and 1997/98 El Niño events. Leftover warm water from strong El Niño events (ENSO residuals) make their way into the western extratropical North Pacific during the La Niñas that trail the strong El Niños.

Figure 9

For more than 5 years, we’ve discussed the processes through which strong El Niño events cause upward shifts in surface temperatures of portions of the global oceans.  My illustrated essay The “Manmade Global Warming Challenge” (42mb) provides a detailed overview, if that topic is new to you.

Also notice that the surfaces of the western extratropical North Pacific have been cooling since the upward shift in response to the 1997/98 El Niño…even with the spike 2013.  Figure 10 confirms that the sea surfaces in the western extratropical North Pacific have cooled since 1998.

Figure 10

WESTERN TROPICAL NORTH PACIFIC

Now we’ve moved to the western tropical North Pacific (0-20N, 120E-180), Figure 11.  Sea surfaces there were much warmer than normal in July 2014 (the red horizontal line), and that’s even after cooling significantly since their peak a month ago in June.

Figure 11

There is also an obvious upward shift in the sea surface temperature anomalies of the western tropical North Pacific. That shift occurred in response to the 1995/96 La Niña. See Figure 12.  That’s the same La Niña that caused the upward shift in the ocean heat content of the entire tropical Pacific.

Figure 12

Was there another upward shift in the surface temperatures of the western tropical Pacific in 2013?

EASTERN EXTRATROPICAL NORTH PACIFIC

The last of the regions of the North Pacific, the northeastern one, is where that hotspot resides.  The sea surface temperature anomalies of the eastern extratropical North Pacific are shown in Figure 13, with the horizontal red line showing the magnitude of the July 2014 value. It is slightly higher than the June 2014 and August 2004 values.

Figure 13

But notice that the surfaces of the eastern extratropical North Pacific cooled from the late 1980s until 2012…and then appear to shift upwards. See Figure 14.

Figure 14

Figure 15 confirms that the sea surfaces of the eastern extratropical North Pacific cooled from the January 1989 until December 2012, and Figure 16 shows that the sea surfaces there show no long-term warming since January 1989, even with apparent upward shift in 2013.

Figure 15

# # #

Figure 16

The apparent late 1980s upward shift in the sea surface temperatures of the extratropical North Pacific was discussed in Trenberth and Hurrell (1995) Decadal coupled atmosphere-ocean variations in the North Pacific Ocean.  They identified two culprits:  a shift in sea level pressure (which alters wind patterns) and the 1986/87/88 El Niño.

SUSPECTED REASONS FOR THE ELEVATED SEA SURFACE TEMPERATURES IN THE NORTH PACIFIC

When the climate science community finally delves into the causes for the elevated sea surface temperatures of the North Pacific, I suspect they’ll present at least two natural causes that have interacted and compounded one another. The shift in surface temperatures in the western tropical Pacific is possibly a response to the sudden strengthening of the trade winds in the eastern tropical Pacific in 2012.  See Figure 17.  The stronger trade winds, under clearer skies, pushed additional sunlight-warmed water into the western tropical Pacific.

Figure 17

And, of course, there has been a persistent high sea level pressure (north of the eastern extratropical North Pacific) in the Eastern Siberian Peninsula and Alaska, according to the NCAR sea level pressure data, Figure 18.  At the KNMI Climate Explorer the dataset is identified as “1899-now: Trenberth’s NH”.  The coordinates used for the sea level pressure were 60N-75N, 180-150W.

Figure 18

Figure 19 presents a correlation map of the Eastern Siberian Peninsula and Alaska sea level pressures (highlighted on the map) with the sea surface temperatures of the North Pacific, where the sea surface temperature data lag the sea level pressure data by 3 months.  So I suspect that hotspot in the North Pacific will be blamed on the sea level pressures in Eastern Siberia and Alaska.

Figure 19

SUBSET TREND COMPARISON

For those interested, the spaghetti graph in Figure 20 compares the warming and cooling rates of the four North Pacific sea surface temperature subsets during the satellite era.

Figure 20

I’ve isolated the individual subsets in Animation 1.

Animation 1

A NOTE ABOUT THE PDO

As you may have noticed, I discussed the warming of the sea surface temperatures of the North Pacific, and the extratropical North Pacific, without once mentioning the Pacific Decadal Oscillation.  The JISAO Pacific Decadal Oscillation Index is derived from the sea surface temperatures of the extratropical North Pacific but the PDO Index does not represent the sea surface temperatures of that region.  The PDO Index cannot be used to explain the warming of the North Pacific sea surfaces…or global surfaces for that matter.  For more on what the PDO does and does not represent, see the post here.

HAS THERE BEEN A CLIMATE SHIFT IN THE PACIFIC?

The 1976 Pacific climate shift preceded a period of strong El Niño events.  See Figure 21.  In 1976, the sea surface temperatures of the eastern Pacific ocean (about 33% of the surface of the global oceans) shifted upwards by almost 0.25 deg C, according to the NOAA ERSST.v3b dataset.  The shift is actually easiest to see with the levels the minimums reached during the La Niña events before and after 1976.

Figure 21

I’ve noted the possible recent shift in a number of graphs in this post. The recent shift also makes its presence known in the sea surface temperature data for the entire tropical Pacific (0-20N, 120E-80W), not just the western portion.  Figure 22 shows the satellite-era data for that region until December 2012.  Everything looks reasonable.  The El Niño and La Niña events are easy to pick out and there has been no long-term warming.

Figure 22

Now, when we add the 2013 and 2014 data to the graph, Figure 23, it looks like there’s a super El Niño taking place now.

Figure 23

HOW LONG WILL THE HOTSPOT EXIST IN THE EASTERN EXTRATROPICAL NORTH PACIFIC AND WHERE WILL THE WARM WATER GO?   

The greatest warming over the past year took place in the eastern extratropical North Pacific. That hotspot in the sea surface temperature anomaly map (Figure 6) stands out.  It’s hard to miss.  The question now is how long will it persist?

And will the hotspot reemerge again next year?  “Reemergence” is a process that causes sea surface temperature anomalies at mid-latitudes from one year to reemerge the next year. See the post here. In the North Pacific, reemergence is believed to occur west of the hotspot in the western extratropical North Pacific.  But that hotspot in the eastern extratropical North Pacific is a rarity.  So reemergence might be something else to consider.

Ocean currents should eventually carry part of that warm water back to the tropics, warming the California current along the way.  Will that warm water influence ENSO when it reaches the tropics?

My Figure 24 is page 26 from the NOAA weekly ENSO update for August 11, 2014. (Click on it for full-sized illustration.)  The hotspot can be seen at the top of the Aug-Sep-Oct map, but it disappears by Oct-Nov-Dec, and by next year, they’re showing cooling where the hotspot now resides.

Figure 24

CLOSING

I’ve shown throughout this post that the sea surface temperatures of the North Pacific warm in shifts, the results of naturally occurring processes:  ENSO and variations in sea level pressure.  Not too surprisingly, those are processes climate models still cannot simulate to this day. Climate models will one day be a valuable resource, but we’ll have to wait until modelers can simulate naturally occurring, sunlight-fueled, coupled ocean-atmosphere processes that can cause warming of sea surfaces and the oceans to depth.  We may be in for a long wait.

With the unusual warming events taking place recently in the North Pacific, global sea surface temperatures are at record high levels. Alarmists will attempt to use that to advance a political agenda.  Unfortunately for those trying to advance those policies, climate models serve as the only support for human-induced global warming. Their not-very-illustrious climate models cannot explain why sea surface temperatures of the North Pacific have warmed at a much lower rate than anticipated during the satellite era, and the models cannot explain why the surfaces of the North Pacific stopped warming for almost ¼ of a century. See Animation 2.

Animation 2

That, of course, will not stop alarmists from making all sorts of nonsensical claims about the recent sea surface warming, and the mainstream media will join them on the bandwagon.

SOURCE

The data, climate model outputs and the maps presented in this post are available from the KNMI Climate Explorer.