2019 will be the hundredth anniversary of a new start of international scientific collaborations after the First World War, in particular with the creation of the International Union of Geophysics and Geodesy, its associations, and national committees. It is a remarkable opportunity to celebrate the accomplishments of nonlinear geophysics during this past century, as well as to look forward to the challenges of the next century. It is also a remarkable opportunity to think about NPG's revival and testifies to its importance. NPG is therefore inviting the EGU Richardson medallists to contribute to this issue.

Please note that this special issue is only for invited contributions.

As a consequence of the pandemic situation, a series of online seminars titled Perspectives on Climate Sciences: from historical developments to research frontiers was organized in October 2020. The seminars were such a success that the series was extended twice, finally running until July 2021.

The aim of this initiative was to allow senior researchers in the field of climate sciences to share their expertise and exchange ideas with early-career scientists. The ultimate goal was to raise awareness of the chain of arguments, discoveries, and technological breakthroughs that have enabled today's most interesting and relevant lines of research in climate sciences. The speakers were asked to give their perspective on what future developments they expect in the field and, last but not least, how their personal background, the historical situation at the time of their most seminal works, and the network of interactions they established, contributed to their career.

The seminar series, hosted on online platforms, was supported by the Nonlinear Processes in Geosciences (NP) division of the European Geosciences Union (EGU) at first and later by the EGU as a whole, as an official NP Campfire event. It featured 24 contributions that were livestreamed and uploaded on a Youtube channel, with more than 300 subscribed users. Overall, almost 1000 users registered for the seminars, and the livestream featured an average of about 80 participants, with peaks of 170. The abstracts from the seminars can be found here: https://sites.google.com/view/perspectivesonclimate/materials

The development of theories and tools in nonlinear sciences contributed crucially to the understanding and prediction of the climate system. One well-known example is the development of chaos theory, which allowed us to understand the apparently erratic behavior of climate fields and their sensitivity to initial and model errors, and it pushed forward the development of probabilistic predictions. Other important examples are the successes of (i) the theory of stochastic resonance for understanding the transitions between glacial and interglacial climate states, (ii) the development of optimal fingerprinting techniques in order to separate the forced changes from internal variability, and (iii) applications of stochastic methods, such as stochastic parameterizations, which pushed breakthrough achievements in the setup of efficient and manageable Earth system models for climate prediction. Some of these advancements have been recognized for their outstanding contribution to the detection of anthropogenic climate change and their impact on human societies by awarding the 2021 Nobel Prize in Physics to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their studies on nonlinear dynamics in complex systems and their applications in climate sciences and beyond. Klaus Hasselmann was one of the speakers of this seminar series.

With this special issue, we want to build upon the outcomes of the seminar series, and we wish to highlight some of the nonlinear and interdisciplinary foundations on which modern climate sciences were built, by inviting a group of influential scientists to review their achievements and the perspectives of their work.

This special issue is associated with session NP6.2 of EGU GA 2022, entitled Turbulence and Plankton: https://meetingorganizer.copernicus.org/EGU22/session/42642. The participants of this session are invited to contribute to the special issue, which is also open to submissions from interested colleagues who did not participate in the session.

Planktonic organisms live in suspension in marine or fresh waters, where they have adapted through the slow process of natural evolution (over hundreds of thousands of generations) to the harsh turbulent currents of their environment. Therefore, contrary to what the meaning of their name marine drifter might lead one to speculate, their dynamics are often different to those of inert bodies passively transported by fluid flows. Indeed, it is known that these organisms have developed many adaptive strategies involving shape and density regulation, swimming activity, aggregation and other mechanisms in order to be sheltered from or to take advantage of turbulent flow features.

Suitable topics for this special issue involving phytoplankton and turbulence include, but are not limited to, bloom inception, thin phytoplankton layer formation, biased motility and migration, nutrient uptake, photosynthesis, and Lagrangian dynamics. Jumps, swimming activity, grazing, contact rates and vertical migration are, among others, appropriate topics concerning the behaviour of zooplankton in turbulent flows. For all planktonic species, adaptive mechanisms in response not only to mechanical but also chemical and electro-magnetic (such as luminous) cues are topics of great interest.

This special issue will welcome manuscripts from marine ecologists, oceanographers, fluid dynamicists, physicists and applied mathematicians. Contributions in the fields of observation, laboratory experiments, numerical models (such as computational fluid dynamics simulations of non-spherical or motile particles) are welcome, involving phytoplankton and/or zooplankton in marine or freshwater environments.

This special issue is associated with session NP6.2 of EGU GA 2022, entitled Turbulence and Plankton: https://meetingorganizer.copernicus.org/EGU22/session/42642. The participants of this session are invited to contribute to the special issue, which is also open to submissions from interested colleagues who did not participate in the session.

Planktonic organisms live in suspension in marine or fresh waters, where they have adapted through the slow process of natural evolution (over hundreds of thousands of generations) to the harsh turbulent currents of their environment. Therefore, contrary to what the meaning of their name marine drifter might lead one to speculate, their dynamics are often different to those of inert bodies passively transported by fluid flows. Indeed, it is known that these organisms have developed many adaptive strategies involving shape and density regulation, swimming activity, aggregation and other mechanisms in order to be sheltered from or to take advantage of turbulent flow features.

Suitable topics for this special issue involving phytoplankton and turbulence include, but are not limited to, bloom inception, thin phytoplankton layer formation, biased motility and migration, nutrient uptake, photosynthesis, and Lagrangian dynamics. Jumps, swimming activity, grazing, contact rates and vertical migration are, among others, appropriate topics concerning the behaviour of zooplankton in turbulent flows. For all planktonic species, adaptive mechanisms in response not only to mechanical but also chemical and electro-magnetic (such as luminous) cues are topics of great interest.

This special issue will welcome manuscripts from marine ecologists, oceanographers, fluid dynamicists, physicists and applied mathematicians. Contributions in the fields of observation, laboratory experiments, numerical models (such as computational fluid dynamics simulations of non-spherical or motile particles) are welcome, involving phytoplankton and/or zooplankton in marine or freshwater environments.

As a consequence of the pandemic situation, a series of online seminars titled Perspectives on Climate Sciences: from historical developments to research frontiers was organized in October 2020. The seminars were such a success that the series was extended twice, finally running until July 2021.

The aim of this initiative was to allow senior researchers in the field of climate sciences to share their expertise and exchange ideas with early-career scientists. The ultimate goal was to raise awareness of the chain of arguments, discoveries, and technological breakthroughs that have enabled today's most interesting and relevant lines of research in climate sciences. The speakers were asked to give their perspective on what future developments they expect in the field and, last but not least, how their personal background, the historical situation at the time of their most seminal works, and the network of interactions they established, contributed to their career.

The seminar series, hosted on online platforms, was supported by the Nonlinear Processes in Geosciences (NP) division of the European Geosciences Union (EGU) at first and later by the EGU as a whole, as an official NP Campfire event. It featured 24 contributions that were livestreamed and uploaded on a Youtube channel, with more than 300 subscribed users. Overall, almost 1000 users registered for the seminars, and the livestream featured an average of about 80 participants, with peaks of 170. The abstracts from the seminars can be found here: https://sites.google.com/view/perspectivesonclimate/materials

The development of theories and tools in nonlinear sciences contributed crucially to the understanding and prediction of the climate system. One well-known example is the development of chaos theory, which allowed us to understand the apparently erratic behavior of climate fields and their sensitivity to initial and model errors, and it pushed forward the development of probabilistic predictions. Other important examples are the successes of (i) the theory of stochastic resonance for understanding the transitions between glacial and interglacial climate states, (ii) the development of optimal fingerprinting techniques in order to separate the forced changes from internal variability, and (iii) applications of stochastic methods, such as stochastic parameterizations, which pushed breakthrough achievements in the setup of efficient and manageable Earth system models for climate prediction. Some of these advancements have been recognized for their outstanding contribution to the detection of anthropogenic climate change and their impact on human societies by awarding the 2021 Nobel Prize in Physics to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their studies on nonlinear dynamics in complex systems and their applications in climate sciences and beyond. Klaus Hasselmann was one of the speakers of this seminar series.

With this special issue, we want to build upon the outcomes of the seminar series, and we wish to highlight some of the nonlinear and interdisciplinary foundations on which modern climate sciences were built, by inviting a group of influential scientists to review their achievements and the perspectives of their work.

2019 will be the hundredth anniversary of a new start of international scientific collaborations after the First World War, in particular with the creation of the International Union of Geophysics and Geodesy, its associations, and national committees. It is a remarkable opportunity to celebrate the accomplishments of nonlinear geophysics during this past century, as well as to look forward to the challenges of the next century. It is also a remarkable opportunity to think about NPG's revival and testifies to its importance. NPG is therefore inviting the EGU Richardson medallists to contribute to this issue.

Please note that this special issue is only for invited contributions.