With the promotion of renewable energy production and a planned phaseout of fossil fuels until 2040, the offshore wind energy sector has expanded and will continue to increase its capacity in the upcoming decades. This study presents a novel approach to deriving the installed capacity of offshore wind turbines on a global scale from spaceborne radar imagery provided by the Sentinel-1 mission. This new method contributes significantly to the information depth of freely available data sets, which provide the spatiotemporal patterns of offshore wind turbines. Furthermore, by combining freely available Earth observation and GIS data, commonly reported attributes of the offshore wind energy sector are compiled to provide a first impression of how this data can be used. All attributes are investigated to provide an in-depth overview of the developments in the offshore wind energy sector over the last five years. Between July 2016 and June 2021, the installed capacity worldwide grew from 13.5 GW to 40.6 GW. This corresponds to an increase of 27.1 GW or 200%. In total 8885 OWTs were installed until June 2021 with an additional 852 under construction. The European Union (15.2 GW), China (14.1 GW) and the United Kingdom (10.7 GW) are the three major contributors to the offshore wind energy sector. China has seen the largest growth in the last five years of 13 GW, followed by the EU with 8 GW and the UK with 5.8 GW. The provided analysis at the end of this study describes the offshore wind energy sector in a transition phase between decades of maturity and massive growth at a time when carbon-neutral energy production is massively supported. Overall the proposed approaches for independent offshore wind turbine capacity estimation and spatiotemporal investigation of the offshore wind energy sector can be used by all stakeholders involved in the upcoming challenge of integrated planning and implementation of offshore wind energy projects.