BIOL 2200 Lecture 35: Staying Alive - The Challenge of Global Climate Change

Climate Change Overview

• Definition: Global climate change refers to a long-term change in average weather patterns that define the Earth's climates.

Learning Objectives

• Define climate change.
• Examine evidence supporting human-mediated climate change.
• Consider the abiotic impacts of a changing climate.
• Explore how climate is affecting biotic processes.

Climate and Greenhouse Gases

• Greenhouse Gases: These gases trap heat leaving the Earth’s surface, regulating global temperatures.
  • If absent, the Earth's surface would be approximately 33°C cooler.
  • Examples of Greenhouse Gases:
  • Carbon Dioxide (CO₂)
  • Methane (CH₄)
  • Nitrous oxide (N₂O)
  • Fluorinated gases

Long-term and Recent CO2 Trends

• Current levels of CO₂ are unprecedented in millions of years.
• CO₂ Trends: Data is collected at Mauna Loa Observatory to track daily CO₂ levels.
• Increased levels of CO₂ correlate with higher global temperatures.

Global Temperature Trends

• By 2024, mean global temperatures had risen by 1.28°C on average; some areas exceed 4°C rise.
• The ten most recent summers have been the hottest recorded.
• There is a correlation between rising temperatures and human activities rather than natural factors.

Ocean Changes

• Rising Ocean Temperatures: Annual ocean heat content is increasing, with the surface temperatures rising significantly.
• Arctic Sea Ice Decline: Arctic sea ice extent has decreased from 2.7 million square miles in 1979 to 1.7 million square miles in 2023.
• Sea Level Rise: Melting sea ice and rising ocean temperatures contribute to rising sea levels.
• Ocean Acidification: Increased CO₂ levels lead to decreased ocean pH, impacting marine ecosystems.

Climate Change and Extreme Weather

• Climate change is linked to an increase in extreme weather events (e.g., droughts, floods, and storms). Here are statistics:
  • Billion-dollar disaster events in the U.S. have risen dramatically from 1980 to 2024.

Biological Impacts of Climate Change

• Altered Biological Timing: Changes in temperature influence biological processes such as:
  • Flower blooming times.
  • Animal hibernation periods.
  • Migration patterns.
  • Reproductive cycles.
• Range Shifts: Species may shift their ranges due to climate changes (e.g., North American species moving northward).
• Altered Species Interactions: Declines in insect populations impact:
  • Pollination processes.
  • Herbivory and plant health.

Impacts on Human Health

• Health Risks Associated with Climate Change:
  • Exposure to extreme weather events (increased injuries and mortality).
  • Rise in respiratory and waterborne diseases.
  • Other challenges include malnutrition, zoonoses, and mental health issues.
• Vulnerable Populations: Health outcomes are influenced by demographic, geographical, biological factors, and the capacity of health systems.