🌿Intro to Environmental Science Unit 9 – Climate Change: Global Impacts

What's Climate Change Anyway?

• Climate change refers to long-term shifts in global or regional climate patterns
• Primarily attributed to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels
• Earth's average surface temperature has risen about 2.05 degrees Fahrenheit (1.14 degrees Celsius) since the late 19th century
  • Most of the warming occurred in the past 40 years
  • 2016 and 2020 are tied for the warmest year on record
• Warming is causing widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere
• Greenhouse gases trap heat and make the planet warmer
  • Carbon dioxide (CO2) is the primary greenhouse gas emitted through human activities
  • Methane (CH4), nitrous oxide (N2O), and fluorinated gases also contribute to the greenhouse effect
• Climate change encompasses not only rising average temperatures but also extreme weather events, shifting wildlife populations and habitats, rising seas, and a range of other impacts

The Science Behind the Warming

• The Earth's climate is regulated by the balance between incoming solar radiation and outgoing infrared radiation
• Greenhouse gases in the atmosphere absorb and re-emit some of the outgoing infrared radiation, causing the Earth's surface and lower atmosphere to warm
  • This process is known as the greenhouse effect
  • Without the natural greenhouse effect, Earth's average temperature would be near 0°F (-18°C) instead of the much warmer 59°F (15°C)
• Human activities, particularly burning fossil fuels (coal, oil, and natural gas), are increasing the concentration of greenhouse gases in the atmosphere
  • CO2 levels have increased by more than 50% since the Industrial Revolution began around 1750
  • Methane levels have more than doubled
• Deforestation and land-use changes also contribute to the increasing greenhouse gas concentrations
• The current warming trend is of particular significance because it is unequivocally the result of human activity since the mid-20th century and proceeding at an unprecedented rate over millennia
• Climate models project continued warming under all plausible future emission scenarios, with the rate and magnitude of warming primarily determined by the cumulative emissions of greenhouse gases

Global Impacts: It's Getting Hot in Here

• Global temperature rise is causing observable effects on the environment
• Glaciers are shrinking, ice on rivers and lakes is breaking up earlier, plant and animal ranges are shifting, and trees are flowering sooner
• Effects that scientists had predicted would result from global climate change are now occurring
  • Loss of sea ice
  • Accelerated sea level rise
  • Longer, more intense heat waves
• Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities
• The Intergovernmental Panel on Climate Change (IPCC) forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century
• Future changes are expected to include more frequent wildfires, longer periods of drought in some regions, and an increase in the number, duration, and intensity of tropical storms
• Global sea level rose about 8 inches (20 centimeters) in the last century
  • The rate in the last two decades is nearly double that of the last century and accelerating slightly every year

Ecosystems on the Edge

• Climate change is causing significant impacts on ecosystems around the world
• Many plant and animal species are shifting their geographic ranges, seasonal activities, migration patterns, and interactions in response to ongoing climate change
  • Some species will adapt to new conditions, while others will suffer population declines or go extinct
• Warming is causing spring events, such as leaf unfolding and egg laying, to happen earlier in the year
• Species' geographic ranges are shifting to higher latitudes and elevations as temperatures warm
  • In the Northern Hemisphere, species are moving northward and to higher elevations
• Coral reefs, which are highly sensitive to small changes in water temperature, are suffering mass bleaching events and die-offs
  • Half of the Great Barrier Reef has been bleached to death since 2016
• Warmer, drier conditions are contributing to more frequent and intense wildfires
  • The number of large wildfires in the western United States has increased since the early 1980s
• Pests and invasive species are expanding their ranges into new territories as conditions become more favorable for their survival

Rising Waters and Extreme Weather

• Global sea level is rising due to two main factors related to global warming: the added water from melting ice sheets and glaciers, and the expansion of seawater as it warms
• Sea level rise will cause inundation of low-lying lands, more destructive storm surges, and displacement of millions of people in coastal areas and island nations
  • A 2-foot rise in global sea level would displace 14 million people in the United States alone
• Hurricanes are becoming more intense, with stronger winds and more precipitation, due to warmer ocean waters that fuel their energy
  • The proportion of Category 4 and 5 hurricanes has increased substantially in recent decades
• Extreme precipitation events, both heavy downpours and major snowstorms, are becoming more frequent and intense
  • The frequency of heavy precipitation events has increased since 1950 in most regions of the United States
• Droughts are becoming more frequent and severe in some regions as temperatures rise and precipitation patterns change
  • The Southwest United States has experienced increasing drought conditions, with more frequent and intense mega-droughts

Human Health and Social Consequences

• Climate change is affecting human health in a variety of ways
• Extreme heat events are becoming more frequent and intense, leading to increased heat-related illnesses and deaths
  • The European heat wave of 2003 resulted in over 70,000 excess deaths
• Air pollution and airborne allergens are increasing, exacerbating respiratory diseases such as asthma and allergies
• The geographic range and transmission season of vector-borne diseases, such as malaria and dengue fever, are expanding as temperatures warm
• Water and food security are threatened by changing precipitation patterns, droughts, and extreme weather events
  • Crop yields are projected to decline in many regions as temperatures rise and water stress increases
• Climate change is a "threat multiplier" that exacerbates existing social and political stresses and can contribute to conflict and migration
  • The Syrian refugee crisis has been linked in part to a severe drought worsened by climate change
• Indigenous communities are particularly vulnerable to the impacts of climate change, as their livelihoods and cultural identities are often closely tied to the land and natural resources

Economic Ripple Effects

• Climate change is having significant economic consequences across sectors and regions
• Agriculture is being impacted by changing temperature and precipitation patterns, with crop yields projected to decline in many regions
  • Each degree Celsius increase in global mean temperature is estimated to reduce global yields of wheat by 6%, rice by 3.2%, and maize by 7.4%
• Tourism and outdoor recreation industries are being affected by changes in snow cover, sea level rise, and extreme weather events
  • Ski resorts at lower elevations are experiencing shorter and more variable ski seasons
• Energy demand is increasing for cooling in the summer, while heating demand is decreasing in the winter
  • This shift in energy demand is straining electric grids and increasing energy costs
• Infrastructure, including roads, bridges, and coastal properties, is being damaged or destroyed by sea level rise, storm surges, and extreme weather events
  • The cost of coastal flooding in the United States could reach $1 trillion annually by 2050
• The insurance industry is facing increasing costs from climate-related disasters, such as hurricanes, wildfires, and floods
  • Global insured losses from natural disasters have increased from an annual average of around $10 billion in the 1980s to around$50 billion in the last decade

Taking Action: Mitigation and Adaptation

• Addressing climate change requires a two-pronged approach: mitigation (reducing greenhouse gas emissions) and adaptation (preparing for and responding to the impacts)
• Mitigation strategies include transitioning to renewable energy sources, improving energy efficiency, reducing deforestation, and implementing carbon pricing mechanisms
  • The Paris Agreement, adopted in 2015, aims to limit global warming to well below 2°C above pre-industrial levels and pursue efforts to limit the increase to 1.5°C
• Adaptation strategies include building resilient infrastructure, developing early warning systems for extreme weather events, and improving water management practices
  • The Netherlands has implemented a comprehensive flood defense system, including dikes, sand dunes, and flood barriers
• Nature-based solutions, such as restoring wetlands and planting trees, can provide both mitigation and adaptation benefits
  • Mangrove forests protect coastal communities from storm surges and sequester large amounts of carbon
• Individual actions, such as reducing energy consumption, driving less, and eating a plant-based diet, can also contribute to climate change mitigation
• Education and public awareness are crucial for building support for climate action and encouraging behavior change
  • The youth-led Fridays for Future movement has organized global climate strikes and raised awareness about the urgency of the climate crisis