Climate Chapter 11: Global Climate Change

Chapter 11: Climate: How Does Global Climate Change?

• This chapter examines global climate change, measuring past, present, and future changes.
• It explores the role of human activities in driving recent global warming, including the impact of industrialization on greenhouse gases.
• The chapter also explores the impact of ocean currents, and climate feedback loops.
• Methods for measuring global climate, including instrumental records (using thermometers since 1860), weather satellites, and ocean measurements (since the 1850s) are discussed.
• The chapter describes how Earth's climate is warmed by a greenhouse effect, where gases in the atmosphere reradiate heat toward the surface.
• The influence of the ocean currents on global climate is detailed as saltwater covers most of Earth, affecting areas thousands of miles away.
• Ocean currents are always moving, acting as a connected mass that distributes heat around the globe.
• Countercurrents, and changes in normal ocean currents, are also examined, including the El Niño-Southern Oscillation (ENSO).
• The ongoing decrease in pH of Earth's oceans, due to absorption of CO2 from the atmosphere, is described as ocean acidification.
• The chapter provides a take-home message on how humans are impacting climate change.
• This message emphasizes the increasing amounts of GHGS such as carbon dioxide and methane are the dominant factor influencing climate change, and that the atmosphere's CO2 content is higher than ever before.
• The impact of climate change on various locations are explained, such as the threat of rising sea levels to the Maldives island nation, and the effects on extreme weather, including droughts, floods, and hurricanes.
• The chapter also details the effects on ecosystems, such as altering seasonal behaviors, the range of many species, and their migration.
• Scientists are improving global climate models to forecast future climate change effects by identifying and applying feedback loops.
• Positive feedback enhancements the original change, while negative feedback counters the original change.
• Scientists also studying tipping points in the climate system where sudden changes can rapidly influence global climate.
• The importance of modeling alternative scenarios for future human responses in climate models is highlighted, with a special focus on how these predictions are made.
• Various examples of actions individuals can take to mitigate their carbon footprints are provided, such as choosing more sustainable products.
• Information and examples of how to reduce carbon emissions through individual actions and behaviors are featured in the study guide.
• The chapter concludes by highlighting, using numerous examples, the impact of individual and global actions to mitigate climate change.

Chapter Objectives

• Describe how Earth's climate is warmed by a greenhouse effect.
• Explain how scientists estimate historical changes in Earth's climate.
• Recognize that Earth's climate has changed dramatically in its history, and that the recent temperature of air and water at Earth's surface has been warming.
• Explain how ocean currents influence Earth's climate.
• Describe how human activities are driving recent global warming.
• Summarize how global warming can alter precipitation patterns, the frequency and intensity of extreme weather, sea levels, and ocean acidity.
• Identify steps that individuals, businesses, and governments can take to address climate change.

11.1: How Do We Measure Global Climate?

• Climate describes average weather conditions, over significant periods of a certain region.
• Global climate describes average weather conditions over a region for the entire planet.

11.2: What Caused Climate Change in the Past?

• Over geologic time, global climate has changed naturally, evidenced by both geological and fossil records.
• Polar regions were forested during the Cretaceous Period, and evidence of a 700-million-year-old glacial period occurred near the Earth's equator.

11.3: How Do Oceans Influence the Climate?

• Saltwater covers most of Earth and plays a major role in global climate.
• The ocean constantly moves as a connected mass, transporting energy around the globe, influencing regions thousands of miles away from shore.

11.4: What's Happening with Our Climate Now?

• Earth's climate is currently experiencing global warming.
• This warming is primarily driven by increased industrial activity, leading to more greenhouse gases.
• Rising sea levels from glacial melting are impacting areas such as Isle De Jean Charles.

11.5: What Are Some Effects of Climate Change?

• Global warming increases the frequency and intensity of extreme weather events such as floods, droughts, and hurricanes.
• Ocean acidification, from increasing CO2 levels, is impacting marine species.
• The ranges of various species are also shifting due to changes in the seasonal timing of biological activities.

11.6: What About the Future?

• Climate models predict increased global warming based on various possible scenarios of human intervention or lack thereof.
• These changes are impacted by various feedback loops.

11.7: What Can I Do?

• Individuals can reduce their carbon footprint through various activities, such as living closer to work or using sustainable options for transportation.
• Choosing energy-efficient appliances can help to reduce energy use.