ECOL1000: Ecological Basis of Environmental Issues - Lecture 16: Global Climate Change

ECOL1000: Ecological Basis of Environmental Issues

University of Georgia

Fall 2025
Lecture 16: Global Climate Change - Introduction

  • Goals for Climate Change Lectures:

    • Define "Climate Change."

    • Present evidence supporting its reality and human causation.

    • Discuss expected consequences for Georgia and globally.

    • Explore actions needed to address climate change.

Understanding Climate

  • Definition of Climate:

    • Climate refers to the aspect of the physical environment that most influences a particular system by placing the greatest constraints on organisms.

  • Climate vs. Weather:

    • Synonyms? No, they are not synonyms.

    • Weather: Refers to current atmospheric conditions over a short time frame (days or years).

    • Climate: Describes the atmospheric behavior over longer periods, such as two or three decades.

Current Events & Trends Related to Climate Change

  • Media coverage on climate change includes alarming headlines highlighting severe weather incidents.

    • Example presentations indicate record-breaking temperatures and severe weather events affecting large populations.

    • Illustrative media clippings emphasize experiences and consequences related to heatwaves, droughts, hurricanes, and floods affecting various regions worldwide.

Scientific Consensus on Climate Change

  • Peer Review Process Overview:

    • The scientific peer review process is designed to evaluate research manuscripts by independent experts to ensure quality, validity, and originality before publication.

    • Components of Peer Review:

    • Evaluation: Experts review research for accuracy, potential biases, and soundness to ensure high-quality outputs.

    • Quality Control: Filters out scientifically unsound research.

    • Improvement: Provides constructive feedback, enhancing clarity and quality of manuscripts.

    • Integrity: Maintains the integrity of the scientific record by enforcing quality standards for publication.

  • No longer any doubt among the scientific community regarding the reality of global climate change.

Current Evidence and Opinions on Climate Change

  • Public Opinion on U.S. Climate Measures (April 2024 Poll):

    • 76% of age group 18-29 favors action against climate change.

    • 79% of age group 30-44 favors similar actions.

    • 68% of age group 45-64 favors action.

    • 58% of age group 65+ supports taking steps to reduce climate change.

  • A report from over 11,000 scientists warned about potential "untold suffering" due to climate change unless significant governmental action is taken, emphasizing the moral obligation of scientists to relay these critical findings.

Temperature Trends and Climate Extremes

  • Annual Global Average Temperature Trends:

    • Overview: Includes historical data from 1880-2020 showing temperature deviations from the average of 1901-2000.

    • Notable temperature increases since the 1980s beyond the 20th-century average.

    • Data Visualization: Infographics provided demonstrate temperature changes annually, with error bars indicating the degree of certainty.

  • Extreme Weather Changes:

    • Discussion of how an increase in average temperature affects the frequency and severity of hot and cold weather events.

    • Mapping of past climate events illustrates a shift towards more extreme weather, emphasizing how former average conditions may now approach extremes.

Greenhouse Gases and Their Effects

  • Greenhouse Effect Process Explained:

    • Incoming solar radiation (approximately 343 W/m²) passes through the atmosphere.

    • A portion of this radiation is reflected back into space (103 W/m²).

    • Net incoming radiation after reflection totals 240 W/m².

    • Some infrared radiation escapes into space, while some is absorbed and re-emitted by greenhouse gas molecules, leading to warming of the Earth’s surface and lower atmosphere.

  • Current Concentrations of Greenhouse Gases as of 2024:

    • Carbon Dioxide (CO2): 427 parts per million (ppm)

    • Methane (CH4): 1.92 ppm

    • Nitrous Oxide (N2O): 337 parts per billion (ppb)

    • This information indicates the significant heat-trapping abilities of these gases, with different effectiveness levels of CO2 (1x), CH4 (35x), and N2O (~300x).

The Global Carbon Cycle

  • Components of the Global Carbon Cycle: Overview:

    • Details how carbon moves through different systems, indicating sources and sinks of carbon.

    • Differentiates processes such as:

    • Photosynthesis in terrestrial and marine plants (e.g., phytoplankton converting CO2 into organic matter).

    • Respiratory release of CO2 by decomposers such as microbes acting on organic matter.

    • Fossil fuel emissions influencing atmospheric carbon levels.

  • Carbon Fluxes and Storage:

    • Dynamics of carbon exchange between the atmosphere, oceans, and living organisms detailed with numerical data regarding pools of carbon (in gigatons) present in various forms (e.g., carbon in soil and oceans) and processes such as photosynthesis and respiration contributing to annual carbon increase.

Implications of Climate Change

  • Recognizes the dire consequences of unchecked climate change, highlighting moral and ethical responsibilities held by scientists and policymakers.

  • Calls for structured actions catering to climate change mitigation and adaptation strategies, emphasizing global cooperation and awareness.