Hurricane-force Winds and Heavy precipitation in Hurricane Beryl mostly strengthened by human driven climate change

Press Summary (First Published 2024/07/05; updated 2024/07/07)

• Cyclones near Jamaica similar to Hurricane Beryl are up to  30 mm/day (up to 30%)  wetter and up to 9 km/h (up to 10%)  windier in the present than they have been in the past.

• Hurricane Beryl was a largely unique event.

• Natural climate variability likely played a role in driving the pressure pattern and the associated increase in precipitation and wind-speed linked to Hurricane Beryl.

Event Description

Hurricane Beryl, the first hurricane of the 2024 Atlantic season, rapidly intensified to a Category 5 storm unusually early in the year. This rapid intensification was fueled by exceptionally warm ocean temperatures. Beryl formed as a tropical depression on June 28, 2024, and within 24 hours, it had intensified into a hurricane with winds of 75 mph. On July 2, 2024, Beryl became the earliest recorded Category 5 hurricane in the Atlantic, surpassing Hurricane Emily's record from 2005. This early development is remarkable, as it occurred in a region typically not conducive to such early-season hurricanes.  Hurricane Beryl is the strongest hurricane in the Caribbean for this time of year in the historical records, which start in 1850. In addition, is it only the 4th strong hurricane known to have affected the Lesser Antilles and Jamaica since the beginning of the historical records. These statistics must be taken with care as there are likely underestimates in storm intensities prior to the satellite era (pre-1966).   

Hurricane Beryl made landfall on Carriacou Island on July 02 as a strong Category 4 hurricane, bringing catastrophic winds and life-threatening storm surges to the southern Windward Islands. On July 03, hurricane Beryl's eyewall skirted Jamaica's southern coast, causing severe damage and prompting emergency evacuations from flood-prone areas. A woman in Hanover parish died after a tree fell on her home, and nearly a thousand Jamaicans were in shelters by 02 July evening, according to Richard Thompson, acting director general at Jamaica's disaster agency. The hurricane left scattered debris along the waterfront of Carriacou, Grenada, and led to the closure of Jamaica's main airports. Streets remained mostly empty after Prime Minister Andrew Holness issued a curfew for July 03, which was extended into July 04 as storm conditions persisted. 

The Surface Pressure Anomalies reveal large depression areas up to -8 hPa mainly centered on the Cayman Islands. Temperature Anomalies display up to +2°C warmer temperatures in the region covered by the study. Precipitation data show larger precipitations up to 150 mm/day offshore Jamaica. Windspeed Data indicate moderate-to-high winds (50-70 km/h) over the same region.

We remind that our analysis is based on MSWX data. This product does integrate some station observations, notably for rainfall data, but the values it provides and that we report here can nonetheless be different from those observed at single weather stations. 

Climate and Data Background for the Analysis

According to the IPCC report (IPCC AR6 WGI FR - Page 205), anthropogenic climate change has increased observed precipitation, winds, and storm surge associated with some tropical cyclones, and there is evidence for an increase in the annual global proportion of Category 4 or 5 tropical cyclones in recent decades. However, the confidence level for these findings varies from medium to low. Regarding the economic damages caused by individual extreme events, the report (IPCC AR6 WGII FR - Page 1990) states that formal attribution to anthropogenic climate change has been limited, but climate change could account for a substantial fraction of the damages.  In summary, the IPCC report suggests that climate change has had an impact on hurricane intensity and associated hazards, but the confidence level for these findings varies. The IPCC report also highlights the potential economic damages caused by individual extreme events, and recent studies have used a variety of approaches for attributing these damages to climate change.

Our analysis approach rests on looking for weather situations similar to those of the event of interest having been observed in the past. For this event, we have low confidence in the robustness of our approach given the available climate data, as the event is largely unique in the data record. Moreover, the analogues approach does not guarantee that the identified past events do actually correspond to tropical cyclones.

ClimaMeter Analysis

We analyse here (see Methodology for more details) how events similar to the low pressure system leading to Hurricane Beryl have changed in the present (2001–2023) compared to what they would have looked like if they had occurred in the past (1979–2001) in the region [-88°E -78°E 20°N 30°N]. 

The Surface Pressure Changes show a modest (<1 hPa) deepening offshore Jamaica. Temperature Changes see an increase up to +1°C in the northern part of the region analyzed. Precipitation Changes show a large increase up to 30 mm/day (+30% increase) offshore Jamaica. Windspeed Changes also display up to 9 km/h (+10% increase) windier offshore Jamaica. 

We find no significant variations in the period of occurrence of Similar Past Events, as there are no notable shifts in occurrence between months. We note that there are no analogues for this event in the months of July for both past and present periods. This is consistent with the rarity of such intense cyclones so early in the season. Considering the affected urban areas,  Kingston, Portmore and May Pen are up to 10 mm/day wetter than in the past. 

Finally, we find that sources of natural climate variability, notably the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation, may have influenced the event. This suggests that the changes we see in the event compared to the past may be partly due to human driven climate change, with a contribution from natural variability.

Conclusion

Based on the above, we conclude that cyclones near Jamaica similar to Hurricane Beryl, have become up to 30 mm/day (up to 30%) and up to 9 km/h (up to 10%) windier  in the present compared to  the past. We interpret Hurricane Beryl as a largely unique event for which natural climate variability played a role.

Quotes & Contact Authors

-Davide Faranda, IPSL-CNRS, France  📨davide.faranda@lsce.ipsl.fr   🗣️French, Italian, English

-Tommaso Alberti, INGV, Italy  📨tommaso.alberti@ingv.it   🗣️Italian, English

-Suzana J. Camargo, LDEO, Columbia University, USA;   suzana@ldeo.columbia.edu🗣 English, Portuguese