Klaus Hasselmann: Nobel Prize lecture in physics 2021

Transcript

the second lecture on the theme of climate is given by professor hasselman who was also born in 1931 and spent his early years in the united kingdom after returning to germany after the second world war he studied at the universities of hamburg and gertingen his career progressed via appointments at renowned institutions in europe and the united st... Read More

Summary

Professor Hasselman, a renowned climate scientist, delivers a lecture on climate change and his groundbreaking research. He expresses gratitude for receiving the Nobel Prize and discusses his early work on developing an equation for the energy balance in ocean wave spectra. He explains the significance of his research in understanding weather and climate variability and how it led to insights on climate change. He goes on to discuss his involvement in establishing a new Max Planck Institute to study the climate problem and the importance of understanding the impact of greenhouse gas emissions. Professor Hasselman also talks about his research on stochastic climate models and the concept of internal climate variability. He highlights the detection and attribution of climate change as a central focus in his work. He concludes by emphasizing the need for urgent action to address global warming and the critical role of scientists and engineers in finding solutions.

Questions & Answers

Q: How did Professor Hasselman's research on ocean wave spectra contribute to his interest in climate change?

Professor Hasselman's early work involved developing an equation for the energy balance in ocean wave spectra. He discovered that there was an important term missing in the previous equations - the transfer of energy from the peak of the wave spectrum to lower and higher frequencies. This insight led him to further explore wave dynamics and interactions, which eventually expanded his interest to include weather and climate.

Q: How did Professor Hasselman's career progress after returning to Germany?

After returning to Germany, Professor Hasselman studied at the universities of Hamburg and Göttingen. His career advanced through appointments at renowned institutions in Europe and the United States until he became the director of the Max Planck Institute for Meteorology in Hamburg, where he is currently active. His work at the institute provided crucial insights into the relationship between weather and climate and led to the development of fingerprinting methods used to assess human impact on Earth's climate.

Q: What does Professor Hasselman mean by the term "stochastic climate system"?

The term "stochastic climate system" refers to the understanding that climate variability is driven by both deterministic and random processes. In this context, stochasticity refers to the random fluctuations and variability observed in the climate system. Professor Hasselman developed stochastic climate models that showed how short-term weather fluctuations can trigger long-term climate variations. This stochastic approach helped explain the formation of long-term internal variations in climate excited by short-term random weather fluctuations.

Q: How did Professor Hasselman's research on stochastic climate models contribute to the detection and attribution of climate change?

Professor Hasselman's research on stochastic climate models allowed for the discrimination between climate variations due to external factors and those related to internal variability. By isolating the expected signal (external factors) from the noise (internal variability) in climate data, he developed the concept of fingerprints to detect and attribute climate change. This approach involves comparing observed climate signals with the expected responses to different forcing factors, such as elevated greenhouse gas concentrations, and assessing the similarity between them.

Q: How did Professor Hasselman's research on fingerprints contribute to understanding the human impact on climate change?

Professor Hasselman's research on fingerprints aimed to identify the expected climate responses associated with human activities, specifically the emission of greenhouse gases. By analyzing climate data and constructing fingerprints based on expected climate signals and internal variability, he was able to detect the human signal of climate change. This provided scientific evidence that human activities are changing the climate and emphasized the need to reduce global greenhouse gas emissions.

Q: How did Professor Hasselman's research on stochastic climate systems influence climate modeling?

Professor Hasselman's research on stochastic climate systems influenced the design of climate models by advocating for the separation of signal and noise components in modeling. Climate models represent only a smaller part of the dynamics explicitly and resolve the larger scales, while the smaller scales or variables not explicitly considered represent the noise. The effects of these unresolved scales are parametrized to capture their influence on the resolved dynamics. This separation allows for efficient modeling and analysis of climate phenomena, facilitating predictions and assessments of climate change.

Q: What were some of the challenges Professor Hasselman faced in communicating his research to the public and policymakers?

Professor Hasselman admits that he struggled with communicating his research to the public and policymakers effectively. He preferred to concentrate on research rather than public communication, which posed a challenge in raising awareness and understanding of climate change. He highlights the importance of colleagues such as Mvhib Latif and Myron Ebell-Kölher, who successfully bridged the gap between climate research and the public. Despite the efforts to communicate research findings, he expresses frustration over the lack of adequate political reactions and the need for society and politicians to think in longer-term timescales.

Q: How did Professor Hasselman incorporate economic dimensions into climate modeling?

Professor Hasselman recognized the importance of incorporating economic dimensions into climate models to address the complexities of the climate system. He worked with his wife and later Dmitry Kovalevsky to develop coupled climate and economic models. These models aimed to capture the dynamic and multi-timescale nature of both the natural sciences and the human aspects of the climate system. He believed that considering the inherent uncertainty of all model components and integrating statistical optimization models were crucial for guiding policy-making and addressing the uncertainties associated with climate change.

Q: What urgent actions does Professor Hasselman emphasize in response to global warming?

Professor Hasselman highlights the urgent need for society and politicians to take action to address global warming. He stresses that listening to scientists and engineers who understand the necessary changes to mitigate the effects of climate change is imperative. He mentions the importance of transforming current practices, as further delay will only make the necessary transformations more expensive. He highlights the cost of climate-related damages, extreme weather conditions, pandemic diseases, and global mass migration, underscoring the urgency of taking immediate action to reduce greenhouse gas emissions.

Q: What is the significance of the young girl's school strike for climate change?

Professor Hasselman references a young girl, who at the age of 15, initiated a school strike for climate change in front of the Swedish parliament. This act sparked the worldwide movement for climate justice called Fridays for Future, led by Greta Thunberg. The significance lies in the fact that young people, like Greta Thunberg, have taken up the cause and become powerful advocates for climate action. Their activism has helped raise awareness and pressure policymakers to prioritize climate change mitigation.

Q: How do the graphs presented by Professor Hasselman demonstrate the urgency of addressing global warming?

The graphs presented by Professor Hasselman show the variations in CO2 levels and differences in temperatures over hundreds of thousands of years. The black curve represents CO2 variations, the blue lines represent temperature differences, and the colored overlays display mean temperature rise patterns. These graphs demonstrate the increasing trend of global warming, with the mean temperature rising noticeably since 1970. The standard deviations also illustrate the variability associated with climate change. Professor Hasselman uses these graphs to emphasize that global warming has been escalating and urgent action is needed to curb its effects.

Takeaways

Professor Hasselman's lecture provides insights into his pioneering research on weather, climate variability, and climate change. His work on stochastic climate models and fingerprinting methods led to valuable contributions in detecting and attributing climate change to human activities. He emphasizes the need for urgent action to address global warming and highlights the role of scientists, engineers, policymakers, and public awareness in finding solutions. He also emphasizes the importance of effective communication and the integration of economic dimensions into climate modeling. The lecture serves as a reminder of the critical need for collective action to mitigate the effects of climate change.