Earth’s Memory, Part One Abstract Every rock carries a fragment of Earth’s memory. Collectively, these fragments preserve an extraordinary geological record spanning more than 4.5 billion years of planetary evolution. This article traces that record through the deep-time history of our planet—from the formation of Earth’s earliest crust and the Great Oxidation Event, when microbial life transformed the planet’s atmosphere, to the five great mass extinctions that repeatedly reset the trajectory of life, and the Snowball Earth episodes, when our planet experienced its most extreme glaciation. Drawing on more than two decades of fieldwork across Himalaya and Peninsular India, among ancient rocks, minerals, and fossils that bear direct witness to these planetary transformations, it explores how geologists reconstruct Earth’s early history from evidence preserved in the geological archives. Taken together, these geological events reveal a recurring pattern: Earth is a dynamic system in which every major crisis has also created the conditions for new and often more complex forms of life to evolve. That pattern, written into rocks billions of years old, continues to shape the planet today.    I first learned to listen to rocks long before I had the words to describe what that meant.  It began in the Himalaya, the youngest mountain range on Earth, still rising, still deforming, and still recording the ongoing collision between continents. During my early fieldwork, I spent long days mapping folded strata, tracing fault scarps, and trying to understand how landscapes preserve evidence of processes operating across vastly different geological timescales. At that time, I often felt that the mountains were trying to say something in a language I had not yet learned. Over time, through fieldwork, mapping, and countless hours spent among rocks and sediments, I began to decipher that silent language.  The lesson deepened across many other landscapes of India....

Jaishri Sanwal Bhatt is an Indian geologist and paleoclimatologist based at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, where she combines scientific research with a strong commitment to public outreach, advocacy, and science communication. For more than twenty years, Sanwal’s work has centered on reconstructing past climate change and active tectonic processes through the study of cave records and other geological proxies, especially paleolakes and speleothems. Her research has spanned the Indian and Nepalese Himalayas, the Andaman Islands, and both the eastern and western coasts of India, engaging major questions related to earth systems, water security, and natural hazards. In this wide-ranging and engaging InterDialogue, we discuss deep geological time, the proposed nuclear energy transition in India, the value of interdisciplinarity and clearer scientific communication, Sanwal’s efforts to organize science outreach initiatives in rural India, and much more. Timestamps 2:22 – Sanwal’s background and introduction to geology 8:43 – Big History and the evolution of the Earth through geology 14:25 – Sanwal’s research 16:45 – Tracking historical precipitation patterns through sediment 21:10 – Connecting paleoclimatology to contemporary climate science 25:53 – Tracking and analyzing extreme events through rocks 29:07 – Comparing chronological dating systems 32:52 – Sanwal’s work with lake cores 37:34 – Tracking tsunami episodes in the Andamans 44:09 – Evidence of tsunamis in mangrove forests 49:00 – Local knowledge and community collaborations 52:32 – Nuclear energy transition in India and waste disposal 57:18 – Risks of geological repositories for nuclear waste 1:00:16 – Sanwal’s rural science outreach and education initiatives

In the context of risk management and in the face of environmental and economic challenges such as climate change, coastal erosion, water insecurity, and the accelerated loss of biodiversity, among others, the concept of Nature-based Solutions (NbS) has emerged. Over the past decade, this appealing concept has been consolidated as an integrative approach that seeks to address socio-environmental challenges through the sustainable management of socio-ecological systems.  The United Nations Environment Assembly defines NbS as “actions that protect, sustainably manage, and restore natural or modified ecosystems to effectively and adaptively address societal challenges, simultaneously providing benefits for human well-being and biodiversity.” In this way, NbS represents a paradigm shift from traditional solutions based exclusively on grey infrastructure, which are now insufficient in facing many large and complex contemporary challenges. The relevance of NbS resides in their capacity to generate multiple, synergistic benefits through ecosystem services and the strengthening of socio-ecological resilience. This approach recognizes the interdependence of nature and culture, and much of its success depends on how communities perceive and acknowledge the multiple benefits socio-ecological systems provide for human well-being. Therefore, NbS must emphasize the need for participatory, equitable, and inclusive processes to ensure their legitimacy and long-term sustainability. NbS encompass actions for the protection, restoration, and sustainable management of ecosystems. Although they offer multifunctional and cost-effective benefits, their implementation faces diverse challenges. Several international frameworks acknowledge NbS as priority strategies to confront climate change and biodiversity loss, promoting guidelines for their adoption at different scales. Among these frameworks are the United Nations Framework Convention on Climate Change (1992), the Convention on Biological Diversity (1992), the Sendai Framework (2015–30), and the Paris Agreement (2015). However, it is not enough to only secure financing or display technical feasibility. It is also necessary to establish a coherent legal framework, generate open and...

Earth Observation technologies are becoming increasingly valuable for understanding our changing world. They are also critical for formulating policies to protect ecosystems and support local communities. The availability of imagery taken from satellites, airplanes, and drones offers opportunities to detect deforestation, glacier melting, crop productivity, hurricane alerts, ocean temperatures, and much more. These applications have become wide-spread and are commonly featured in the news and on social media; an informed public can now be acutely aware of the significant effects that humans have on the landscape. However, other processes of land use change are too complex to be detected and understood solely from space. For example, detecting rich minerals, tracking illicit land activities (e.g., coca farming), and monitoring water salinity. For these and other complex land changes, the imagery itself might not be enough to understand the processes shaping these changes in the landscape. New ways of addressing these are needed. About 26 years ago, Jacqueline Geoghegan and her co authors wrote a chapter in the book People and Pixels: Linking Remote Sensing and Social Science, titled “Socializing the Pixel and Pixelizing the Social in Land-Use and Land-Cover Change.” This chapter was a pioneering step forward in extracting more information from images and linking them with the social processes behind them. It helped me during my PhD studies and subsequent research to develop a strategy for connecting quantitative data from pixels with social mechanisms that impact land change. But how do these two approaches work together? The full Interdialogue with Paulo Murillo. The role of classification in traditional land use science relies on how effectively we can classify elements on the land surface. Classification is the most relevant task in remote sensing. We want to classify or differentiate between forests and agricultural fields or among diverse types of crops using...