Chapter 19 Global Change Global Change Global change
Chapter 19 Global Change
Global Change Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. Earth’s climate has varied naturally through time Global climate change- describes changes in the climate of the Earth (temperature, precipitation, wind, storm frequency, etc. ) Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth. Only one aspect of climate change
Four factors exert the most influence on climate The sun = without it, Earth would be dark and frozen Supplies most of Earth’s energy The atmosphere = without it, Earth’s temperature would be much colder The oceans = shape climate by storing and transporting heat and moisture How Earth spins, tilts, and moves through space influence how climate varies over long periods of time
• The atmosphere, land, ice, and water absorb 70% of incoming solar radiation
As Earth’s surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation Greenhouse gases = atmospheric gases that absorb infrared radiation Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons [chlorofluorocarbons (CFCs)] After absorbing radiation, greenhouse gases reemit infrared energy, losing some energy to space Greenhouse effect = energy that travels downward, warming the atmosphere and the planet’s surface
Greenhouse gases have always been in the atmosphere We are not worried about the natural greenhouse effect Anthropogenic intensification is of concern Global warming potential = the relative ability of one molecule of a greenhouse gas to contribute to warming Expressed in relation to carbon dioxide (potential = 1) Methane is 25 times as potent as carbon dioxide
Greenhouse Gases in order from most to least Water vapor Carbon dioxide Methane Nitrous oxide Ozone
It is not the most potent greenhouse gas, but it is extremely abundant The major contributor to the greenhouse effects CO 2 exerts six times more impact than methane, nitrous oxide, and halocarbons combined Deposition, partial decay, and compression of organic matter (mostly plants) in wetlands or marine areas led to formation of coal, oil, and natural gas These deposits remained buried for millions of years
Methane = fossil fuels, livestock, landfills, crops (rice) Levels have doubled since 1750 Nitrous oxide = feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers Ozone levels have risen 36% due to photochemical smog Halocarbon gases (CFCs) are declining due to the Montreal Protocol Water vapor = the most abundant greenhouse gas Contributes most to the natural greenhouse effect Concentrations have not changed
Natural Greenhouse Gases Volcanic eruptions- mainly carbon dioxide Methane – from decomposition Nitrous oxide- from denitrification Water vapor-from evaporation and evapotranspiration
Anthropogenic Causes of Greenhouse Gases Burning of fossil fuels Agricultural practices Deforestation Landfills Industrial production- CFC’s are an example
Increasing CO 2 Concentrations David Keeling began measuring CO 2 in 1958.
Emissions from the Developed and Developing World
Global Temperatures since 1880 Since 1880 temperatures have increased 0. 8°C (1. 4 o F)
Temperatures and Greenhouse Gas Concentrations in Past 400, 000 No one was around thousands of years ago to measure Years temperatures so we use other indirect measurements. Some of these are Changes in species compositions Chemical analyses of ice
Atmospheric CO 2 concentrations have increased from 315 ppm to 389 ppm
• Proxy indicators tell us about the Paleoclimate = climate past of the geological past • Gives a baseline to compare to today’s climate • Proxy indicators = indirect evidence that serve as substitutes for direct measurements - Shed light on past climate - Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history - Trapped bubbles in ice cores provide a timescale of: - Atmospheric composition, greenhouse gas concentrations, temperature trends - Snowfall, solar activity, and frequency of fires
Cores in sediment beds preserve pollen grains and other plant remnants Tree rings indicate age, precipitation, droughts, and fire history In arid regions, packrats carry seeds and plants to their middens (dens) Plant parts can be preserved for centuries Researchers gather data on past ocean conditions from coral reefs Scientists combine multiple records to get a global perspective
Putting It Together We know that an increase in CO 2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO 2 gas and, as a result, they release CO 2 into the atmosphere.
Tropospheric warming will transfer more water to the air But the effects are uncertain A positive feedback loop = more water vapor … more warming … more evaporation … more water vapor … A negative feedback loop = more water vapor … more clouds … shade and cool Earth OR increase evaporation Minor modifications of the atmosphere can lead to major effects on climate
Evidence that climate conditions have changed since industrialization is everywhere Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc. Scientific evidence that climate has changed is overwhelming and indisputable Intergovernmental Panel on Climate Change (IPCC) was established in 1988 Composed of hundreds of international scientists and government officials
• The IPCC reports on the synthesis of scientific information concerning climate change Global consensus of scientific climate research Summarized thousands of studies Documented observed trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc. Predicted impacts of current and future climate change on wildlife, ecosystems, and human societies Discussed strategies to pursue in response to climate change
Average surface temperatures increased 0. 74 °C since 1906 Most of the increase occurred in the last few decades Extremely hot days have increased The 16 warmest years on record have been since 1990
In the next 20 years, temperatures will rise 0. 4 °C At the end of the 21 st century, temperatures will be 1. 8– 4. 0 °C higher than today’s We will have unusually hot days and heat waves Polar areas will have the most intense warming Sea surface temperatures will rise Hurricanes and tropical storms will increase In power and duration
Projected increases in surface temperature for 2090– 2099 relative to 1980– 1999
Some regions are receiving more precipitation than usual, and others are receiving less Droughts have become more frequent and severe Harming agriculture, promoting soil erosion, reducing water supplies, and triggering fires Heavy rains contribute to flooding Killing people, destroying homes, and inflicting billions of dollars in damage
Precipitation will increase at high latitudes and decrease at low and middle latitudes
Mountaintop glaciers are disappearing Glaciers on tropical mountaintops have disappeared The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2020 or 2030 Reducing summertime water supplies Melting of Greenland’s Arctic ice sheet is accelerating Warmer water is melting Antarctic coastal ice shelves Interior snow is increasing due to more precipitation Melting ice exposes darker, less-reflective surfaces, which absorb more sunlight, causing more melting
Nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes Permafrost (permanently frozen ground) is thawing Destabilizing soil, buildings, etc. and releasing methane
Runoff from melting glaciers and ice will cause sea levels to rise As oceans warm, they expand Leading to beach erosion, coastal floods, and intrusion of salt water into aquifers
An earthquake caused the 2004 tsunami (tidal wave) that killed 100 Maldives residents and caused $470 million in damages Storm surge = temporary, localized rise in sea level Caused by the high tides and winds of storms Cities will be flooded 53% of people in the U. S. live in coastal areas
1 million acres of Louisiana’s wetlands are gone Rising sea levels eat away vegetation Dams upriver decrease siltation Pollution from the Deepwater Horizon Millions of people will be displaced from coastal areas
Coral reefs are habitat for food fish Snorkeling Warmer waters contribute to coral bleaching Which kills corals Increased CO 2 is acidifying the ocean Organisms and scuba diving sites for tourism can’t build their exoskeletons Oceans have already decreased by 0. 1 p. H unit Enough to kill most coral reefs
Organisms are adapted to their environments They are affected when those environments change Global warming modifies temperature-dependent phenomena (e. g. , timing of migration, breeding) Animals and plants will move toward the poles or upward in elevation 20– 30% of species will be threatened with extinction Rare species will be pushed out of preserves Droughts, fire, and disease will decrease plant growth Fewer plants means more CO 2 in the atmosphere
GTS- 12 adorable animals affected by climate change. Be able to describe one animal and how its affected. http: //mashable. com/2015/12/05/climate-changeanimals/#z. SNPna. UH 2 kqt
Societies are feeling the impacts of climate change Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts Increasing Forestry: increased fires, invasive species Insect hunger and disease outbreaks Health: heat waves and stress can cause death Respiratory ailments, expansion of tropical diseases Disease and sanitation problems from flooding Drowning from storms
Costs will outweigh benefits of climate change It will widen the gap between rich and poor Those External costs of damages will be $10– 350/ton of carbon It will cost 1– 5% GDP on average globally Poor with less wealth and technology will suffer most nations will lose more than rich ones The Stern Review predicts it will cost 5– 20% of GDP by 2200 Investing 1% of GDP now could avoid these costs
Where we live will determine how we experience the impacts of climate change Temperature changes have been greatest in the Arctic Melting ice sheets, thinning ice, increasing storms, etc. Harder for people and polar bears to hunt U. S. temperatures will continue rising Plant communities will shift north and upward More frequent extreme weather events The southern U. S. will get drier, the northern wetter Sea levels will rise and may be worse in the East
The Arctic has suffered the most so far U. S. temperatures will continue to rise
In 2009, scientists reported and predicted: Temperature increases Worse droughts and flooding Decreased crop yields Water shortages Health problems and diseases Higher sea levels, beach erosion, destroyed wetlands Drought, fire, and pests will change forests More grasslands and deserts, fewer forests Undermined Alaskan buildings and roads
By 2050, Illinois will have a climate like Missouri’s By 2090, it will have a climate like Louisiana’s
Scientists agree that increased greenhouse gases are causing global warming Burning In 2005, scientists from 11 nations issued a joint statement urging political leaders to take action There is a broad and clear scientific consensus that climate change is a pressing issue But fossil fuels is increasing greenhouse gases many people deny what is happening People will admit the climate is changing But doubt we are the cause
The Controversy of Climate Change The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists. What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops.
Most people accept that our planet is changing They are searching for solutions Mitigation = pursue actions that reduce greenhouse gas emissions to lessen severity of future climate change Energy efficiency, renewable energy, protecting soil, preventing deforestation Adaptation = accept that climate change is happening Pursue strategies to minimize its impacts on us Seawalls, leaving the area, coping with drought, etc. Both are necessary
Adaptation: even if we stopped all emissions, warming would continue Mitigation: if we do nothing, we will be overwhelmed by climate changes The faster we reduce our emissions, the less we will alter the climate
The Kyoto Protocol In 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warming. The agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5. 2% below their 1990 levels by 2012. Other countries resent the U. S. because it emits 20% of the world’s greenhouse gases but won’t take action U. S. cities and states have set their own guidelines to reduce emissions Developing nations did not have emission limits imposed by the protocol.
Carbon Sequestration An approach involving taking CO 2 out of the atmosphere. Some methods include storing carbon in agricultural soils or retiring agricultural land allowing it to become pasture or forest. Researchers are looking at cost-effective ways of capturing CO 2 from the air, from coal-burning power stations, and from other emission sources. This captured CO 2 would be compressed and pumped into abandoned oil wells or the deep ocean.
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