Tropical Cyclones and Climate Change

28 09 2017

Dale C. S. Destin |

With the current Atlantic hurricane season being hyperactive, thus far, and several countries being severely impacted by hurricanes, tropical cyclones (tropical depressions, tropical storms and hurricanes) continue to be made the “poster child” for the potential dangerous impacts of climate change.

Hurricane Irma - Sep 5-6, 2017. Travelling Across Barbuda and Anguilla.

Cat. 5 Hurricane Irma With Winds of 185 mph – Sep 5-6, 2017. The Eye travelled Across Barbuda and the Northern Leeward Islands.

This notion was crystallized by Former U.S. Vice President Al Gore on the cover of his book – “an inconvenient truth”, when he depicted a tropical cyclone (TC) spinning out of smoke stacks. Since then, several world leaders have supported this view, including former U.S. President Barak Obama, who said that “storms [are] growing stronger with each passing hurricane season”.

Over the years, many Caribbean leaders, have also joined in asserting that TCs have become stronger and more frequent due to manmade, greenhouse gas caused climate change. According to Prime Minister Gaston Browne of Antigua and Barbuda, “hurricanes are stronger and bigger because they are absorbing moisture from increasingly warmer seas, caused by global warming.” Browne’s colleague, Prime Minister Roosevelt Skerrit of Dominica supports this view and is convinced that Hurricane Maria is the product of climate change. He told the recent United Nations General Assembly that Maria was a climate change “truth we have just lived”.

Cat. 5 Hurricane Maria - 10:30, Sep 18, 2017- Eye Over Dominica.

Cat. 5 Hurricane Maria With Winds of 160 mph – 10:30 pm, Sep 18, 2017 – Eye Over Dominica.

There is no doubt that climate change is real and is happening. There is much evidence to point to. Contrary to the current U.S. President’s assertion, it is NOT a hoax created by the Chinese. However, do TCs deserve this poster-child position? How have TCs responded to manmade climate change? How will TCs respond to future climate change? Are there any doubts as to cause of Hurricanes Irma and Maria?

How have TCs responded, and how will they respond to human-induce climate change are topics of intense interest and public and scientific debates. Over the next few blogs, I will use the latest peer-reviewed scientific papers to answer these and related questions.

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A Hyperactive 2017 Atlantic Hurricane Season Thus Far

1 09 2017

Dale C. S. Destin |

We are at the halfway mark of the 2017 Atlantic hurricane season and it has been a hyperactive one with respect to named storms. On average, the first half of the season produces four named storms; however, this year it produced nine – more than doubled the amount. The last time there were 9 named storms by the end of August was 2012. Also this has only happened 5 times in the last 82 years.


Ensemble forecast

Most of the forecasts for the season are on track. The ensemble (mean) forecast, based on predictions from yours truly, the Integrated Forecast System of the ECMWF, the National Oceanic and Atmospheric Administration (NOAA), Klotzbach of Colorado State University and Saunders and Lea of Tropical Storm (TSR) is for 17 named storms, 7 becoming hurricanes and 4 becoming major hurricanes.

Hurricane Season Forecast 2017

A better indicator of the activity for the season is the accumulated cyclone energy (ACE) index which is a measurement of the strength and duration of each tropical cyclone. Summing together the ACE of each cyclone, provides a more complete picture of how active the season is or likely to be outside of just the number of storms.

Thus far, the ACE is 29. This is relatively low and is indicative of the weak and short-live nature of the storms so far. The forecast is for a further 108 ACE over second half of the season. For the whole season, the ensemble forecast calls for an ACE index of 136. If this forecast pans out, the 2017 season would be around 30% more active than normal and the highest in seven years.

Tropical North Atlantic

The tropical North Atlantic is almost catching fire. It is the warmest June to August since 2010 and the third warmest on record dating back to 1948. The very warm sea surface temperatures are the main reason for the more than doubling of the number of named storms normal for up to this time of the year.

Probability of Antigua being hit by a hurricane

According to Klotzbach, the likely best similar years to the upcoming 2017 AHS are 1953, 1969, 1979, 2001 and 2004. Over these year, we were affected by four named storms with one being a major hurricane. Thus, based ONLY on similar years, the probability of Antigua being affected by one or more named storms is around 54%, up 5% fro the average. However, the probability for one or more hurricanes is around 2%, down by 20% from the average. Notwithstanding, as I write, there is Category 3 Hurricane Irma tracking towards the island, causing a great scare.

We are in the peak of the hurricane season – keep monitoring and complete your hurricane plan, just in case you need to use it.

Follow us and stay updated on the 2017 AHS via our social media platform, which includes twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.

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