Global Change

Global Change Is the change of any physical, chemical, or biological properties of the Earth Can include climate change Change in average weather patterns Can include global warming Warming of land, water and atmosphere

Sun-Earth Heating System Solar (ultraviolet) radiation either bounces off the stratosphere or enters the troposphere Solar radiation heats the planet’s surface and that heat is re-emitted (infrared) Infrared is either absorbed by greenhouse gases or is lost to space

Greenhouse Effect Is caused by gases in the atmosphere that absorb heat and re-emit it Traps heat in the troposphere and increases the planet’s surface temperature Gases can be measured in greenhouse warming potential How much a molecule can contribute to global warming over 100 years

Major Greenhouse Gases Water Vapor Most abundant natural greenhouse gas Carbon dioxide Methane Nitrous oxide (N2O) Chlorofluorocarbons (CFCs) Solely manmade Particulates are not a gas, but they do contribute to the greenhouse effect

Natural Greenhouse Gas Sources Volcanic eruptions produce CO2 and particulates Decomposition of organic matter produces methane and/or CO2 Denitrification (part of nitrogen cycle) produces nitrous oxide (N2O) Evaporation of water into the air produces water vapor

Anthropogenic Greenhouse Gas Sources Fossil Fuels Production and burning release CO2 Can also produce methane and particulates Agriculture Fertilizers add nitrogen to make N2O Decomposition of organics releases methane Landfills Chemicals CFCs deplete ozone and retain heat Deforestation Removes trees that absorb CO2

CO2 and Temperature are Linked This can be shown by determining historical gas concentrations and temperature and charting them together Intergovernmental Panel on Climate Change (IPCC) was formed to track these changes Scientists from UN and World Meteorological Organization

CO2 Varies Seasonally Discovered when atmospheric CO2 concentration monitoring began in 1958 on Mauna Kea Drops in spring when photosynthesis increases and increases in fall when leaves die Has shown an overall increase since monitoring began

Do the Math p. 526 Projecting future increases in CO2 From 1960 to 2010 CO2 has increased from 320 to 390 ppm Average annual increase over 40 years? 390 ppm – 320 ppm = 70 ppm 70 ppm CO2/40 years = 1.75 ppm CO2/year If rate of CO2 increase is 1.4 ppm/year, what will CO2 concentration be in 2100? 1.4 ppm/year x 90 years = 126 ppm 126 ppm + 390 ppm = 516 ppm CO2

Do the Math p. 526 What will the CO2 concentration be in 2100 at a faster rate of 1.9 ppm/year? 1.9 ppm/year x 90 years = 171 ppm 171 ppm + 390 ppm = 561 ppm CO2

CO2 Emissions Around the World Vary greatly among nations Developed nations produce the most CO2 Should be examined on a nationwide and per-capita basis Are changing rapidly as populous nations like China and India develop industry and infrastructure

Global Temperatures Have been directly measured since the 1880s Have increased since these measurements began 2000-2009 were 9 of the 10 hottest years on record

Determining Ancient CO2 Concentrations and Temperature Indirect measurements include species composition and chemical analysis of ice cores Species composition of foraminifera changes as the water temperature changes When they die their skeletons become part of ocean sediments

Ice Cores Air bubbles are trapped in ice in glaciers and ice shelves These tiny samples provide information about atmospheric gases and temperature Oxygen isotopes appear more frequently in warmer temperatures A single core can show 500,000 years of data

How do we know temperature change is anthropogenic? Increased solar radiation would increase heat when the sun shines Increased greenhouse gases would increase heat when the sun isn’t shining Patterns of heating show increases that are not correlated to the sun shining

Climate Change Models Global warming is a confirmed phenomenon What remains to be seen is exactly how much the temperature will rise Models can help us predict what will happen

Feedback Loops and Climate Change Positive feedback Faster decomposition from warmer temperatures adds more CO2 Melting ice exposes darker soil which retains heat and increases melting

Feedback Loops and Climate Change Negative feedback Increase in CO2 causes more plant growth, and more plants reduce CO2 Increase in cloud cover causes more solar reflection, and temperatures drop

Consequences of Global Warming Melting polar ice caps and glaciers Adds large amounts of fresh water to the oceans Could expose new sources of fossil fuels Thawing permafrost Releases methane and CO2 Could make land usable in new ways Change in precipitation patterns More water vapor is added to the atmosphere Some areas get more, others get less

Consequences of Global Warming Rising sea levels Endanger low-lying human settlements through flooding and polluting groundwater Increase in heat waves Can cause drought and increased energy use for cooling Can increase forest fires Decrease in cold spells Increase in tropical pests Could be good for agriculture

Consequences of Global Warming Increased storm intensity Warm air holds more water Change in ocean currents Influx of fresh water could affect how heat is distributed Change in distribution and extinction of organisms Range of cold-tolerant organisms will decrease and heat-tolerant organisms will expand Reproduction could be affected

Consequences of Global Warming Increase in tropical diseases and other health problems Mosquito range and population could increase, carrying West Nile and malaria further Increased heat stroke, asthma, and allergies Change in agriculture and recreation Increased land for agriculture Change in winter tourism

The Kyoto Protocol Addresses climate change at the international level Asked nations to reduce greenhouse gas emissions to 5.2% below 1990 levels by 2012 US 7%, EU 8%, Russia 0%, developing countries 0%

Carbon Sequestration Involves taking CO2 out of the atmosphere Storing carbon in soil or deep underground Absorption by plants