18: Global Climate Change
- Page ID
- 32283
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Describe the role of greenhouse gases in climate change.
- Describe the sources of greenhouse gases.
- Explain Earth’s energy budget and global temperature changes.
- Explain how we know about climates in the geologic past.
- Explain how positive and negative feedback mechanisms can influence climate.
- Accurately describe which aspects of the environment are changing due to anthropogenic climate change.
- Describe the causes of recent climate change, particularly the role of humans in the overall climate balance.
This chapter describes the Earth systems involved in climate change, the geologic evidence of past climate changes, and the human role in today’s climate change. In science, a system is a group of interacting objects and processes. Earth System Science is the study of these systems: geosphere—rocks; atmosphere—gases; hydrosphere—water; cryosphere—ice; and biosphere—living things. Earth science studies these systems and how they interact and change in response to natural cycles and human-driven, or anthropogenic forces. Changes in one Earth system affect other systems.
It is critically important for us to be aware of the geologic context of climate change processes and how these Earth systems interact, first, for us to understand how and why human activities cause present-day climate change and, secondly, to distinguish between natural processes and human processes in the geologic past’s climate record.
A significant part of this chapter introduces and discusses various processes from these Earth systems, how they influence each other, and how they impact global climate. For example, Earth’s temperature and climate largely change based on atmospheric gas composition (atmosphere), ocean circulation (hydrosphere), and the land-surface characteristics of rocks (geosphere), glaciers (cryosphere), and plants (biosphere).
Also necessary to understanding climate change is to distinguish between climate and weather. Weather is the short-term temperature and precipitation patterns that occur in days and weeks. Climate is the variable range of temperature and precipitation patterns averaged over the long-term for a particular region. Thus, a single cold winter does not mean that the entire globe is cooling—indeed, the United States’ cold winters of 2013 and 2014 occurred while the rest of the Earth was experiencing record warm-winter temperatures. To avoid these generalizations, many scientists use a 30-year average as a good baseline [1]. Therefore, climate change refers to slow temperature and precipitation changes and trends over the long term for a particular area or the Earth as a whole.
- 18.1: Earth’s Temperature
- Because the Moon doesn’t have much of an atmosphere, daytime temperatures on the moon are around 224℉ and nighttime temperatures are around -298℉. That is an astonishing 522 degrees of change between the light-side and dark-side of the Moon. This section describes how Earth’s atmosphere is involved in regulating the Earth’s temperature.
- 18.2: Evidence of Recent Climate Change
- While climate has changed many times in the past, the scientific consensus is that human activity is causing the climate to change today more rapidly. While this seems like a new idea, it has been suggested for more than 75 years. This section describes the evidence that scientists agree is most likely a result of anthropogenic climate change, or, human-caused climate change.
- 18.3: Prehistoric Climate Change
- Over Earth history, the climate has changed a lot. For example, during the Mesozoic Era, the Age of Dinosaurs, the climate was much warmer and carbon dioxide was abundant in the atmosphere. However, throughout the Cenozoic Era (65 Million years ago to today), the climate has been gradually cooling. This section summarizes some of these major past climate changes.
- 18.4: Anthropogenic Causes of Climate Change
- As shown in the previous section, prehistoric changes in climate have been very slow. Climate changes typically occur slowly over many millions of years. The climate changes observed today are rapid and largely human-caused. Evidence shows that climate is changing, but what is causing that change? Scientists have suspected since the late 1800s that human-produced (anthropogenic) changes in atmospheric greenhouse gases would likely cause climate change.
Thumbnail: Air pollution from smokestacks from a wartime production plant. Located at: https://commons.wikimedia.org/wiki/File:Alfred_Palmer_Smokestacks.jpg. License: Public Domain.