GThe GESLA (Global Extreme Sea Level Analysis) project grew out of the interests of several people in learning more about the changes in the frequency and magnitude of extreme sea levels. The original aim of the project was to assemble as many higher-frequency (i.e. hourly or more frequent) sea-level records as were readily available into a common format with consistent quality control flags to make it easier for researchers to maximize geographic density of data capturing tides, storm surges, extreme sea levels and other related processes on a global scale.


EThe first formal GESLA data set, denoted GESLA-1, was assembled by Philip Woodworth (National Oceanography Centre Liverpool), Melisa Menéndez (University of Cantabria) and John Hunter (University of Tasmania) around 2009. It contained 21,197 years of higher-frequency measurements from 675 records from tide gauges around the world. GESLA-1 was used first in a study of sea level extremes by Woodworth and Menendez (2010). It has since been used in a number of other published studies of extremes including the Intergovernmental Panel on Climate Change’s Fifth Assessment Report. 


SAfter some years it became apparent that GESLA-1 needed updating to include additional data and to extend its coverage in under-represented areas. Thus GESLA-2 was assembled in 2015 and 2016. When compiling GESLA-2, the three people above where helped by Marta Marcos (University of the Balearic Islands) and Ivan Haigh (University of Southampton). This second version contained almost double the amount of data compared to the first. GESLA-2 contained 39,151 years of higher-frequency measurements of sea level from 1,355 records. The compilation of GESLA-2 is described in detail in Woodworth et al. (2017). GESLA-2 has been used in many (>50) published studies, including the Intergovernmental Panel on Climate Change’s Special Report on the Ocean and Cryosphere in a Changing Climate and the Sixth Assessment Report.


LGESLA-3 was compiled in 2020 and 2021, to extend the dataset further in time and space. The assembly was led by Ivan Haigh and Marta Marcos, with help from Stefan Talke (California Polytechnic State University), Arne Arns (University of Rostock), Ben Hague (Bureau of Meteorology), Elizabeth Bradshaw (British Oceanographic Data Centre) and Phil Thompson (University of Hawaii Sea Level Center). Philip Woodworth and John Hunter have remained strongly involved at every stage of construction. GESLA-3 contains 90,713 years of data from 5,119 records. The compilation of GESLA-2 is described in detail in Haigh et al. (2021).


AA list of all of the published papers we are aware of that have made use of GESLA is given here. It can be seen that, while the study of extreme sea levels has been the main interest, the availability of as large a quasi-global sea-level dataset as possible enables many other types of study, such as changes in the ocean tides. We believe that the oceanographic community needs a global dataset such as GESLA, that is regularly updated and extended to include new historical data as it becomes available. We will continue to enhance the dataset.