Climate Change: A 21st Century Issue

Earth Is a Greenhouse Planet

• Earth's temperature allows water to exist in liquid form, which is essential for life.

• The Earth's temperature is influenced by:

  • Distance from the sun.
  • Energy output of the sun.
  • Presence of carbon dioxide.

• Greenhouse gases are transparent to UV and visible light but absorb infrared radiation, trapping heat and warming the Earth (Greenhouse Effect).

• Carbon dioxide is a significant greenhouse gas, and without it, Earth's temperature would be about $-18^{\circ}C$ ($0^{\circ}F$) instead of $15^{\circ}C$ ($60^{\circ}F$).

Geologic Evidence of Climate Change

• Global warming is the average increase in Earth's temperature, while climate change refers to the broader changes resulting from global warming.

• Geologic studies reveal significant climate changes throughout Earth's history, including hotter and colder periods.

• Evidence of past climate change includes continental glaciers in North America, Europe, and Asia.

Growth in Knowledge of Global Warming and Climate Change

• Scientists have been investigating whether the increasing average temperature of the Earth is a natural phenomenon or a result of human activity.

• There's a close correlation between greenhouse gas concentrations and global temperatures, dating back 160,000 years.

• Computer models predict that increasing greenhouse gases will lead to a warmer Earth and various climate changes.

• Other evidence of climate change includes:

  • Steady increase in atmospheric carbon dioxide.
  • Gas bubbles trapped in glaciers show lower carbon dioxide levels before the industrial revolution (mid-1700s).
  • Changes in snow and ice conditions observed via satellite photos.
  • Alterations in migration behavior of animals.
  • Ocean CO2 content, pH changes (lower pH).
  • Longer growing seasons.
  • Glacier retreat and ice sheet thinning.
  • Effects of increased CO2 on photosynthesis.
  • Changes in wind patterns and ocean currents.
  • Impacts of particulates on climate.
  • Sea level rise.
  • Frequency and strength of tropical storms.

Sources and Impacts of Principal Greenhouse Gases

• Key greenhouse gases include:

  • Carbon dioxide (CO2).
  • Methane (CH4).
  • Chlorofluorocarbons (CFCs, e.g., CCl3F and CCl2F2).
  • Nitrous oxide (N2O).

• Carbon dioxide is the most abundant greenhouse gas, contributing about 65% to global warming.

  • It's a natural product of respiration and fermentation.
  • It's released through burning fossil fuels and deforestation.

• Carbon dioxide levels at Mauna Loa Observatory increased from 317 ppm in 1960 to over 411 ppm in 2019, a nearly 30% increase.

  • Pre-industrial levels were around 280 ppm, indicating a 47% increase.

• Methane is the second most abundant greenhouse gas, responsible for about 17% of global warming.

  • It originates from biological sources (wetlands, rice paddies), fossil-fuel use, and animal digestion (ruminants, termites).

  • Preindustrial concentrations were about 700 ppb; current levels are about 1,870 ppb.

• Nitrous oxide is a minor greenhouse gas.

  • It enters the atmosphere through fertilizers and fossil fuels.

  • Soil bacteria convert nitrogen compounds to nitrous oxide.

  • It's produced during fossil fuel combustion.

• Chlorofluorocarbons are synthetic compounds with no natural sources.

  • They were used as refrigerants, cleaning solvents, propellants, and expanders.

  • CFCs are highly efficient greenhouse gases, about 15,000 times more effective than carbon dioxide at retarding heat loss.

  • Due to their ozone-depleting effects, their production has been reduced and was scheduled to be eliminated by 2020, leading to decreasing atmospheric levels.

• Table 17.1 summarizes principal greenhouse gases, their pre-1750 and 2019 concentrations, contribution to global warming, and sources:

  • Carbon Dioxide (CO2):
    • Pre-1750: 280 ppm, 2019: 411 ppm, Contribution: 65%.
    • Sources: Burning fossil fuels, deforestation.
  • Methane (CH4):
    • Pre-1750: 0.70 ppm, 2019: 1.87 ppm, Contribution: 17%.
    • Sources: Bacteria in wetlands, rice fields, livestock guts, and fossil fuel use.
  • Chlorofluorocarbons (CFCs):
    • Pre-1750: Zero, 2019: 0.00083 ppm, Contribution: 8%.
    • Sources: Foams, aerosols, refrigerants, solvents.
  • Nitrous Oxide (N2O):
    • Pre-1750: 0.270 ppm, 2019: 0.332 ppm, Contribution: 6%.
    • Sources: Fertilizer and manure in agriculture, burning fossil fuels.

The Current State of Knowledge about Climate Change

• The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the UN to study climate change.

  • The IPCC provides regular assessments of the state of knowledge about climate change.

• The IPCC has several working groups:

  • Working Group I: physical science related to climate change.
  • Working Group II: impacts of climate change.
  • Working Group III: mitigation of climate change effects.

• Working Group I's Fifth Assessment Report (2013) stated:

  • Human activity clearly influences climate.
  • Increased greenhouse gas concentrations, especially carbon dioxide, are causing temperature increases.
  • Evidence of increased temperature is clear.

• Key findings from the Fifth Assessment Report:

  • The average Earth temperature has increased by $0.65-1.06^{\circ}C$ ($1.2$ to $1.9^{\circ}F$) since 1880.

  • Spring snow and ice have decreased in the Northern Hemisphere, with earlier melting.

  • Cold days have decreased, and warm days have increased.

  • The Arctic region is warming 2 to 3 times faster than the rest of the world.

  • Permafrost temperatures have increased by $2$ to $3^{\circ}C$ ($3.6$ to $5.4^{\circ}F$), with decreased thickness and area.

  • There's a reduction in Arctic sea ice cover during summer.

  • Greenland and Antarctic ice sheets are losing mass, and glaciers are melting.

  • Spring arrives earlier in many regions.

  • Oceans are affected by increased carbon dioxide and temperature.

  • Approximately 28% of carbon dioxide emissions end up in the ocean.

  • Increased CO2 has decreased ocean pH by 0.1 unit (26% increase in hydrogen ion concentration).

  • About 90% of additional energy added to Earth is stored in the oceans, increasing the upper 75 meters' temperature by about $0.44^{\circ}C$ ($0.8^{\circ}F$) in the last 40 years.

  • Sea level has risen about 19 cm (7.5 in.) between 1901 and 2010.

  • The rate of sea level rise was about 3.2 mm/year (0.125 inches/year) from 1993 to 2010 (3.4 mm/year in 2019).

Consequences of Climate Change

• Even a small average temperature increase can trigger changes that significantly alter regional climates.

• Computer models suggest rising temperatures will affect:

  • The hydrologic cycle.
  • Sea level.
  • Human health.
  • Survival and distribution of organisms.
  • Use of natural resources.

• Some ecosystems and settlements will adapt, while others won't.

• Poorer nations are more vulnerable to global warming impacts.

  • They depend more on climate-sensitive economic activities and lack resources to adapt.

  • The IPCC identifies Africa as most vulnerable due to widespread poverty.

• Working Group II of IPCC lists 8 major risks:

  1. Coastal flooding.
  2. Inland flooding.
  3. Severe weather disrupting infrastructure and services.
  4. Extreme heat-related deaths and illnesses.
  5. Food insecurity due to warming, drought, or flooding.
  6. Reduced agricultural productivity due to water shortages.
  7. Loss of marine and coastal ecosystem services.
  8. Loss of terrestrial and freshwater ecosystem services.

• Oceans and Climate Change:

  • Oceans are intimately linked to climate.
  • Equatorial waters are warmer, causing wind patterns.
  • Oceans are the primary source of water vapor for precipitation.
  • Prevailing winds and water vapor from oceans drive weather patterns over land.

• Impacts:

  • Increased ocean temperature has occurred; About 90% of additional heat is absorbed by oceans.
  • In 2019, the average surface temperature was about $0.8^{\circ}C$ ($1.4^{\circ}F$) above the long-term average.
  • Oceans are becoming more acidic, about 25% of released CO2 is absorbed into the oceans.
  • CO2 dissolved in water creates carbonic acid.
  • There has been about a 0.1 pH unit decrease in ocean pH (about a 33% increase in acidity).
  • Many marine organisms struggle to maintain skeletal structures.

• Disruption of the Hydrologic Cycle:

  • The hydrologic cycle is driven by energy from the sun and the heat-trapping effect of greenhouse gases.

  • Changes in Earth's temperature are expected to change weather and climate.

• Weather includes short-term activities while Climate is the long-term average of weather patterns.

• Higher temperatures lead to increased evaporation:

  • Some areas become drier (drought, less water in lakes and rivers).
  • Some areas have greater rainfall (floods, more severe storms, wetter soil).
  • Snowfall patterns change.

• Recent data suggest:

  • Decreased spring snow.
  • Earlier snow melting.
  • More powerful hurricanes.
  • More hot days and fewer cold days.
  • Earlier spring arrival.

• Rising Sea Level:

  • A warmer Earth leads to rising sea levels due to thermal expansion and melting glaciers.

  • Rising sea levels erode beaches and coastal wetlands, inundate low-lying areas, and increase vulnerability to flooding.

  • By 2100, the IPCC projects sea level to rise by 26 to 98 centimeters (10 to 39 inches).

  • A 50-centimeter rise will cause substantial coastal land loss, especially along the southern Atlantic and Gulf coasts.

  • About 600 million people live in low-lying coastal areas worldwide and some island nations would change considerably.

• Changes to Ecosystems

  • Geographic distribution of organisms will change.

  • Terrestrial plants and animals are shifting their range toward poles.

  • Tundra regions are converting to forests.

  • Ocean organisms (plankton, fish, mammals) are shifting their ranges.

  • Coral reefs are affected because of increase ocean temperature and acidity.

  • Mangrove forests and marshes on shorelines are being affected by sea-level rise and storm surges from more violent weather events.

• Health Effects:

  • Hotter temperatures increase mortality rates and can cause heatstroke and respiratory problems.

  • Climate change worsens air pollution by increasing ground-level ozone concentrations, leading to lung tissue damage and respiratory diseases.

  • Children and the elderly are most vulnerable to warmer temperatures and poorer air quality.

  • Tropical diseases could migrate to former temperate regions and diseases spread by mosquitoes and other insects could become more prevalent.

  • Vector-borne diseases include malaria, dengue fever, yellow fever, and encephalitis and algal blooms could occur more frequently as temperatures rise.

• Challenges to Agriculture and the Food Supply

  • Crop yields are affected by climate.
  • Yields fall in regions where drought and heat stress increase.
  • A warmer climate will alter the kinds of crops that can be grown in an area and increase irrigation demands and Expansion of the geographic ranges of insect pests could also increase vulnerability and result in greater use of pesticides.
  • Regional changes will occur—some will have reduced productivity but Total world agricultural productivity is not likely change much and Poor regions of the world will suffer decreased productivity.

Addressing Climate Change

• Energy Efficiency and Green Energy increases energy efficiency reduces carbon dioxide release and conserves energy resources.

  • Increase energy efficiency regardless of global warming concern.

  • A tax on carbon emissions would increase fuel costs and stimulate demand for efficient products and alternative fuels while also generating funds for research in fuel efficiency and alternative fuel technologies.

• Other benefits of increased energy efficiency:

  • Reduced air pollution.

  • Lower health care costs.

  • Reduced need for new power plants.

  • Switching to green energy sources (wind, solar, hydroelectric, nuclear).

    • These do not release carbon dioxide.

• The Role of Biomass plays a role in determining atmospheric carbon dioxide, Because forests consist of many long-lived tree species that can tie up carbon for centuries and preserving forests slows the rate of increase of atmospheric carbon dioxide.

• The burning of tropical rainforests increases carbon dioxide into the atmosphere and reduces the rainforests’ ability to remove carbon dioxide from the atmosphere.

• Planting trees has also been supported as a way to reduce atmospheric carbon dioxide however critics argue that this approach will provide only a short-term benefit because Eventually, the trees will mature and die, and their decay will release carbon dioxide into the atmosphere at some later time.

• Technological Approaches can reduce United States carbon emissions by almost 400 million metric tons therefore can stabilize emissions at 1990 levels.

• Fossil fuels currently provide nearly 90 percent of the world’s energy,

  • Converting to a greater reliance on nonfossil-fuel energy sources will require a great deal of new construction and technological improvements.
  • Prevent carbon dioxide from being released into the atmosphere by reacting carbon dioxide to produce solid carbonate minerals which could be stored in landfills and carbon dioxide can be captured and stored underground.
  • Government policies that stimulate the deployment of these technologies will be needed.

International Agreements

• The Montreal Protocol—Dealing with Chlorofluorocarbons.

  • Established to phase out chlorofluorocarbon production and CFCs in the atmosphere have begun to decline.

    • Changes made to protect the ozone layer have had the side benefit of reducing the release of a potent greenhouse gas.

• Kyoto Protocol—Dealing with Greenhouse Gases.

  • Established in 1997 and expired in 2012, an agreement was reached to extend the protocol through 2020 and Economically developed countries required to limit their greenhouse gas emissions below 1990 levels where Economically developing countries did NOT have requirements.

• The Paris Agreement—Establishing Goals to Cut Greenhouse Gas Emissions A follow-up to the Kyoto Protocol.

  • Goals of the agreement: Prevent human activity from causing a $2^{\circ}C$ increase in global temperature this century and strive to keep it below $1.5^{\circ}C$.

    • Each country publish its plans to reduce greenhouse gas emissions.

    • Each country pledged to report every 5 years on progress and revise plans and Developed countries pledged to provide funding to help developing countries (Green Climate Fund).

• International Agreements progress.

  • Meeting in Paris 2015.

  • Mechanism for achieving goals.

  • The U.S. will likely rejoin the Paris Agreement.

  • European industrialized countries are meeting their NDCs.

• Madrid Climate Change Meeting.

  • Took place in 2019.Goals: Establish how each countries NDCs will be measured and Encourage more aggressive greenhouse gas reductions.

  • Current NDCs do not meet the goal of limiting temperature increase to 2°C.

    • Further action deferred to next meeting.

    • Establish carbon credit trading mechanism— Not achieved.

    • Develop plan for compensating developing countries for the damage they incurred because of energy use in developed countries.— No agreement reached.

• The Kigali Agreement—Dealing with Chlorofluorocarbons and Hydrofluorocarbons.

  • Chlorofluorocarbons and hydrofluorocarbons destroy stratospheric ozone and are greenhouse gases.and Phases out the production of hydrofluorocarbons therefore The Kigali Agreement is an amendment to the Montreal Protocol.

• The concept of climate change is not new, Geological studies have demonstrated that climates have change greatly over the Earth’s history.

• Today’s climate change is different in that it is highly likely that it is being caused by human activities and includes warming of the Earth, particularly near the poles.

• The warming will result in melting of the permafrost, glaciers, and sea ice; changes in rain and snowfall patterns; shifts in the distribution of plants and animals; more intense heat waves and severe storms; a rise in sea level; and acidification of the oceans.

• The primary factor involved in climate change appears to be the carbon dioxide released from the burning of fossil fuels. Since fossil fuel use is closely tied to economic development, many developing countries are unwilling to accept limits to their use of fossil fuels.