Global Warming I: The Science and Modeling of Climate Change

Go to Course: https://www.coursera.org/learn/global-warming

Introduction

**Course Review: Global Warming I: The Science and Modeling of Climate Change** As the urgency to address climate change continues to escalate, understanding the science behind global warming has never been more critical. "Global Warming I: The Science and Modeling of Climate Change," offered on Coursera, emerges as an accessible yet informative course designed specifically for individuals curious about climate science without needing to possess a deep scientific background. ### Course Overview This course provides a comprehensive overview of the science that underlies global warming and its implications for humanity. Drawing from a multidisciplinary approach, the curriculum integrates concepts from physics, chemistry, biology, earth sciences, and economics, all presented through the lens of simple algebra. This democratized, engaging teaching method ensures the content is palatable for non-scientists while retaining the rigor needed to address such a complex topic. ### Detailed Syllabus Review **1. Heat, Light, and Energy** The course begins with essential concepts regarding units of measurement related to temperature, energy, and light—foundational knowledge that sets the stage for further exploration. Understanding these units not only aids comprehension of subsequent lectures, but also equips students with analytical skills necessary for engaging with climate data. **2. First Climate Model** Learners will create a basic climate model, illustrating the greenhouse effect through energy flow analysis. This module comes with practical exercises, allowing students to construct both analytical and numerical models of planetary temperature, fostering hands-on learning. **3. Greenhouse Gases and the Atmosphere** This segment dives deeper into the mechanisms of greenhouse gases’ interactions with solar and infrared radiation. Students will learn about the selective absorption properties of different gases, like CO₂ and methane, and how such nuances affect climate predictions. **4. The Structure of the Atmosphere** Explaining the importance of atmospheric layers, this part focuses on heat distribution processes and how the upper atmosphere's characteristics contribute to climate dynamics. **5. Weather and Climate** Students explore the difference between weather variability and long-term climate trends, emphasizing the roles of winds and ocean currents that redistribute heat across the planet—an essential concept to understand global climate systems. **6. Feedbacks** Feedback mechanisms are crucial in climate science, and this module elucidates loops that either stabilize or destabilize climate systems. A hands-on exercise involving a runaway ice albedo feedback showcases the course's commitment to experiential learning. **7. The Carbon Cycle** Transitioning from climate physics to the ecological implications of carbon, this section explains the carbon cycle’s complexities and its vital role in maintaining Earth's climate. **8. The Perturbed Carbon Cycle** By modeling temperature responses to carbon emissions, learners gain insights into potential future climate scenarios, making the problems posed by fossil fuel consumption tangible. **9. Looking for Human Impact on Climate** This module examines historical temperature records, helping students identify evidence of anthropogenic effects on climate systems. **10. Potential Impacts** Focusing on the consequences of ongoing CO₂ emissions, this section prepares participants to understand both the risks and opportunities associated with climate change. **11. Mitigation** The course culminates in exploring pathways for mitigating human influence on climate. By engaging students in creative solutions, the final module inspires hope that challenges posed by climate change can be addressed through collective human effort. ### Overall Impression and Recommendation "Global Warming I: The Science and Modeling of Climate Change" is a meticulously structured course that not only educates but also empowers its participants. The use of clear, intuitive explanations combined with practical exercises ensures that even those with minimal scientific training can grasp complex concepts. As our world grapples with climate emergencies, understanding the fundamental science behind global warming is essential for everyone, from policymakers to concerned citizens. This course serves as an excellent resource for developing this understanding. **Recommendation:** If you have a curiosity about climate science and are seeking a deeper understanding of the mechanics behind climate change, I highly recommend enrolling in "Global Warming I." The course's interdisciplinary approach, facilitated by engaging teaching methods and practical modelling exercises, makes it a worthwhile investment in your knowledge base, better preparing you to navigate the challenges of climate change in today's world.

Syllabus

Overview

What you will find in this class.

A primer on how to use units to describe numbers when describing temperature, energy, and light. Even if you don't plan on doing calculations yourself, understanding how units work will help to follow the rest of the lectures in the class. If you are interested in practicing your analysis skills, using units to guide calculations, there are some exercises in the Part II of this class.

The balance of energy flow, as incoming sunlight and outgoing infrared, allow us to create our first simple climate model, including a simple greenhouse effect. There are two extended exercises in Part II of this class, one an analytical (algebraic) model of the equilibrium temperature of a planet, the other a numerical model of how that temperature might evolve through time.

The Layer Model above assumes that the pane of glass representing the atmosphere absorbs all of the infrared radiation that hits it and that it radiates at all infrared wavelengths. In other words, the layer model atmosphere is an infrared blackbody, but transparent in the visible. In reality, greenhouse gases are not "black" at all; they are very choosy about which frequencies of light they absorb and emit. This selective absorption of infrared light by greenhouse gases leads to the band saturation effect, which makes rare, trace gases like methane disproportionally powerful relative to higher-concentration gases like CO₂.

The greenhouse effect works because the air in the upper atmosphere is colder than the ground, so that absorption and re-emission of IR by greenhouse gases decreases the amount of energy leaving the planet to space. Here we explore the physics responsible for keeping the upper atmosphere cold.

Another property of the real world, missing in our model so far, is that the real world is not everywhere the same temperature, and the heat fluxes to and from space do not necessarily balance at any given time or location. This is because the winds in the atmosphere and the currents in the ocean carry heat around, in general from the hot tropics up to the cold high latitudes.

Feedbacks are loops of cause-and-effect that can either stabilize Earth's climate or amplify future climate changes. There is an exercise in Part II of this class where you solve for a planet's temperature by iteration, and in the process demonstrate a runaway ice albedo feedback that might have led to the Snowball Earth climate state 700 million years ago.

Now we shift gears in a major way — away from climate physics (you now have seen its main ingredients) to the emergent miracle that is the carbon cycle on Earth. Not only is carbon the chemical element of life, it is also the means of storing life's energy. We will look at how carbon cycles through the land, the oceans, and the deep earth, going in and out of the atmosphere -- and how that stabilizes the earth's climate.

On the carbon locked up in fossil fuels and what happens when we burn those fuels. In Part II of this class, you can create a simple but somewhat realistic model of Earth's temperature evolution in the coming decades, in response to the release of CO2 (or in the sudden stop of emissions in a scenario called "The world without us").

You have now seen the ideas behind the forecast for a human impact on Earth's climate. The next question is: Do we see it happening today? It turns out that the "smoking gun" for a human impact on climate is the global average temperature record since about the 1970's. In order to interpret that temperature change, we need to consider it within the context of natural climate changes in Earth's geologic past.

This unit we focus on the potential impacts of continued business-as-usual CO2 emissions. This is also the topic of the Working Group 2 volume of the IPCC reports (the Working Group 1 report is on the scientific basis, which is what we've been studying so far this course). You may find this material distressing, but hang on, because next week we'll go over "Mitigation", which is what it takes to avoid climate change (treated in the Working Group 3 report). Remember that most of the carbon we're worried about is still in the ground, so these impacts are inevitable only if we continue to decide to make them so. In Part II of this class, you can create a simple ice sheet model of your own.

The last unit of the class finds us considering the options for avoiding, or "mitigating," a human impact on Earth's climate. Bottom line: I think it would be a challenge that humankind could beat if we decided to. If there hypothetically were no more coal on Earth, our potential to alter the climate would be much less. Finding energy sources in that world would not be an existential threat would just be a business opportunity. The hard part, in my opinion, is making that decision.