By Ruby Pap
Whoa, this certainly has been a nail-biting few months climate-wise, hasn’t it?
With Hurricane Olaf (hopefully) veering to the northeast of us (at least at press time), that’s a record breaking 15 named storms in the Central Pacific this season! This year’s El Niño conditions may be well on their way to being the strongest on record, promising to bring more storms as well as giant North Shore surf this winter.
Why is this happening? Let’s examine the El Niño Southern Oscillation.
The ENSO influences global atmospheric circulation, which in turn affects temperature and precipitation worldwide. It actually has three phases: El Niño (ENSO positive), ENSO neutral, and La Nina (ENSO negative). During El Niño, the central and eastern tropical Pacific experience above average sea surface temperatures. Rainfall reduces over Indonesia and increases in the tropical Pacific. The easterly winds weaken and even switch direction, from west to east. In Hawai‘i, these conditions are great for hurricanes and large winter North Shore surf.
Based on the NOAA multi-variate ENSO index (MEI), this winter is expected to be the second strongest El Niño on record (the strongest was in 1997-1998). But as oceanographer Patrick Caldwell points out, “It’s still early in the game.”
According to Caldwell, the man behind the collaborative surf forecast of the NOAA National Weather Service/National Centers for Environmental Information, the El Niño is still building and is expected to hold into spring. Historically, during El Niño, we’ve had late season hurricanes. Hurricane Iwa came to Kaua‘i in late November 1982, so remain vigilant! While our hurricane season typically runs through November, this one could extend into December.
The risk to our coastlines does not stop with the hurricane season. Caldwell’s research on O‘ahu shows El Niño winters produce giant surf on Hawai‘i’s north shores. Based on daily surf observations made primarily by lifeguards from 1968 to 2009, the number of days producing giant surf (greater than 20 feet, Hawaiian scale) is higher during El Niño winters or ENSO neutral years, with the most number of days of giant surf occurring in 1985/1986, 1986/1987, and 2002-2003. This has to do with a more persistent extended Pacific jet stream and low pressure system generating north Pacific storms closer to Hawai‘i.
Time to start waxing your gun? You probably want to consult with veteran big wave surfers on that one, myself being a notorious small-wave surfer. What I think I can say is there’s no guarantee the swells will be surfable. And, I should point out we are probably in for heavy coastal erosion on the North Shore if these predictions come true.
Erosion hot spots to watch out for are Ha‘ena, Moloa‘a and ‘Anini, all areas that have significant amounts of coastal development that could be threatened.
What about climate change? Is it affecting the ENSO? This is a really good question, and the subject of much research. Indeed, I found an aptly named blog on NOAA climate.gov website, titled “ENSO + Climate Change = Headache.” In short, there are so many variables to the ENSO cycle it is difficult to say in black and white terms how climate change is messing with those variables.
That aside, the conditions we have been experiencing, increased temperatures, more frequent storms, increased erosion, all of these are predicted impacts of climate change. They serve as a harbinger of more to come, so now is the time to watch closely and take your observations as important community indicators for not only adapting, but as motivation for reducing our own carbon footprint.
- Ruby Pap is a Coastal Land Use Extension Agent at University of Hawai‘i Sea Grant College Program. She can be reached at firstname.lastname@example.org.