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Hawaii Hurricanes, El Niño, and Climate Change

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A rare event occurred this past weekend when two tropical systems approached the state of Hawaii. Hurricanes happen only occasionally in this part of the world because a fairly constant high pressure system deflects most of the storms. Also, the waters around Hawaii are typically cooler than tropical systems need in order to maintain their strength.

Hurricanes Iselle and Julio as seen by the Suomi NPP satellite. Photo: NASA

Hurricanes Iselle and Julio as seen by the Suomi NPP satellite. Photo: NASA

Hurricane Iselle made landfall Thursday night over the Big Island as a strong tropical storm (sustained winds of 60 mph), while Hurricane Julio passed safely to the north of the islands. It has been 22 years since the last direct hit. Last time, it was Hurricane Iniki, which hit the island of Kaua’i as a Category 4 storm.

The role of natural variability

In August 1992, Hurricane Andrew struck south Florida as a Category 5 hurricane. I was only a child then, but I convinced my family to drive away from our New Orleans home when Andrew turned towards Louisiana. A few weeks later I heard of another storm: Hurricane Iniki. It was a Category 4 storm and headed for the coast. I thought we might need to leave again until I saw where the storm was. It wasn’t in the Atlantic. It was in the Central Pacific and would hit Hawaii.

Iniki occurred during a fairly strong El Niño, which warmed the waters of the central Pacific and contributed to its formation. The same is the case this year. An El Niño had been forming (although it is currently shifting to neutral conditions) and the waters near Hawaii are warmer as a result. The high pressure center that usually protects Hawaii is also further north.

The role of El Niño on Hawaii hurricanes requires some basic knowledge about the location of sea surface temperature anomalies related to the phenomenon. The Niño 3 Region is bounded by 90°W-150°W and 5°S- 5°N. The Niño 3.4 Region is bounded by 120°W-170°W and 5°S- 5°N.

El Nino Regions definitions. Image: NOAA

El Nino regions definitions. Image: NOAA

The role of climate change

We know El Niño is one of the main drivers for hurricane formation in the central Pacific (Niño Region 3.4), but the proximity of the two storms near Hawaii is highly anomalous. Did climate change have a role in the Hawaii hurricanes? According to experts the answer is no. This was a natural, albeit rare phenomenon. However, new research does suggest that more hurricanes will occur in the vicinity of Hawaii, including a recent study that shows a 3-4 fold increase in storms.

There is another way that climate change might be influencing weather systems in the Pacific. Usually, during an El Niño, the west Pacific (Niño 4) cools as warm waters move to the east Pacific (Niño 3, Niño 1+2). This year this has not been the case. The rains have not let up over the islands of the west Pacific and waters have continued to be warm.

In fact, the ocean heat content of the west Pacific has remained high, hinting at a deeper pool of warm waters that has been continuously building due to strong easterly winds. These easterly winds are the same winds that have kept the tropical east Pacific cool and have contributed to a temporary speed bump in the rise of global surface temperatures.

New research suggests that the anomalous easterly winds, likely the reason for a cool east Pacific, might be due to the warming of the Atlantic Ocean. The faster warming of the Atlantic causes a difference in pressure with the Pacific, increasing the easterly winds. This is just one theory among many that describes the reason why the tropical east Pacific has been continuously cool even though the rest of the planet has warmed.

Image: NOAA/NESDIS/NODC

Image: NOAA/NESDIS/NODC

The research behind the cooling of the Pacific and the associated slowdown of the rise in global temperatures is an active area of climate science. However, the unabated rise in ocean heat content has shown us where global warming has gone: the oceans. Recent observations, such as the continuously warm west Pacific, are further proof how much heat can be trapped in the waters of our planet. And as the east Pacific warms again in the near future, global surface temperatures will likely see a sharp rise as well.

Posted in: Global Warming Tags: , ,

About the author: Roberto Mera is a climate scientist and Kendall Science Fellow in climate attribution. His work entails analyzing specific carbon emissions to determine how they are affecting global temperatures and extreme heat events. He holds a Ph.D. in marine, earth and atmospheric science from North Carolina State. See Roberto’s full bio.

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  • Jack Roesler

    The oceans are absorbing an amount of heat being trapped by mankind’s GHGs, equivalent to that released by exploding 400,000 Hiroshima-sized bombs every day.

    • SayWhat

      You’re quick to blame it on Man, but I think you missed a key part; ” Did climate change have a role in the Hawaii hurricanes? According to experts the answer is no. This was a natural, albeit rare phenomenon.”

      We might be seeing a phase change in the PDO:
      “Major changes in northeast Pacific marine ecosystems have been correlated with phase changes in the PDO; warm eras have seen
      enhanced coastal ocean biological productivity in Alaska and inhibited
      productivity off the west coast of the contiguous United States, while
      cold PDO eras have seen the opposite north-south pattern of marine ecosystem
      productivity.”

      http://jisao.washington.edu/pdo/

      Or it could be the AMO changing phases.
      Seems we’re near a peak of a warm phase, and could be why the Arctic is warm?
      http://www.cgd.ucar.edu/cas/catalog/climind/AMO.html

      And the increase in storms for Hawaii came from a computer prediction. Can you name ONE climate prediction that has come true int he past 50 years? Just one, that’s it.

      BTW, I know it sounds really scarey, but have you actually looked the amount of energy released by exploding 400,000 Hiroshima-sized bombs every day?

      “400,000 Hiroshima bombs per day works out to 0.6 watts per square metre … in other words, Hansen wants us to be very afraid because of a claimed imbalance of six tenths of a watt per square metre
      in a system where the downwelling radiation is half a kilowatt per
      square metre … we cannot even measure the radiation to that kind of
      accuracy.”

      http://wattsupwiththat.com/2013/06/23/getting-cooked-by-hiroshima-atomic-bomb-global-warming/

      • rjmera

        Thank you for the information you provided. It is very helpful to keep the perspective. As you note, my take on this subject is that the answer to whether these hurricanes are related to climate change is indeed “no.” The “role of climate change” portion of this post is more about how the ocean heat content is rising and this provides further fuel for hurricanes on all ocean basins in which they occur. Thus, hurricanes will be stronger, research suggests. I also refer to a specific study on Hawaii hurricanes in a climate change scenario to put some perspective on the future, not attributing Hurricanes Iselle and Julio to climate change.

      • SayWhat

        “The “role of climate change” portion of this post is more about how the ocean heat content is rising and this provides further fuel for hurricanes on all ocean basins in which they occur.”

        But is it actually rising? The Argo floats have been in operation since the mid-2000s, is that enough data to make any determination of heat content? And they are limited to the top 2,000 meters.

        “I also refer to a specific study on Hawaii hurricanes in a climate change scenario to put some perspective on the future”

        But if the models don’t match reality, how can thaey add perspective on the future?

        Maybe you’re seen this already, but I think this is a decent insight into how our climate might be controlled. (paywalled)
        http://multi-science.metapress.com/content/h145188416068010/?p=93a5024742a544f4a1007484a4eac129&pi=3

        This is the free copy:
        http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/

      • rjmera

        Great comments! It is true that Argo floats are only recent additions, but there is good data from the World Ocean Database that goes back further in time. I appreciate your assertion that natural variability is a major factor. It always is. New advancements on attribution, however, can tease out the influence of different factors on the environment. Here’s one such study: http://journals.ametsoc.org/doi/full/10.1175/JCLI3329.1
        About modelling… Models have strengths and weaknesses. Hurricane landfall locations, for example, are now highly accurate. El Nino predictions are also very good. For the study I referenced (Hawaii hurricanes), these are long term trends and the uncertainty is a major factor. The key word is “suggests,” it is not a forecast.

    • rjmera

      Thanks for sharing that with us!

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