Climate Change

Weather and Climate

Weather - Short-term variations in the atmosphere

Climate - long-term patterns in the atmosphere based on average weather (>30 years)

Both can be measured using variable such as temperature, precipitation and wind speed

Long and Short Wave Radiation

Longwave

• Emitted by Earth in the longwave infrared spectrum

• Also known as thermal emissions because they are released as a result of solar radiation heating up the surface and atmosphere

Shortwave (Solar Radiation)

• Radiates energy in three spectra:

  • UV

  • Visible light

  • Infrared

Earth’s Energy Budget

• 30% of incoming solar radiation is reflected back to space

• 70% is absorbed by the surface and atmosphere, gaining thermal energy

• The absorbed energy will be re-emitted by Earth in the form of longwave radiation back to space

Greenhouse effect

Context: If Earth’s thermal emissions are all transmitted to space instantly, then the planet would be very cold. greenhouse gases will absorb the longwave radiation from earth and radiate it in all directions (15ºC avg)

Greenhouse Gases

Natural

Carbon Dioxide (CO2)

• Causes 1/4 of the natural greenhouse effect

• Forests and oceans are important carbon sinks that remove carbon dioxide from the atmosphere

Water Vapour (H2O(g))

• causes 2/3 of the natural greenhouse effect

• creates a positive feedback loop as CO2 concentration increases in the atmosphere

Methane (CH4)

• Much less contribution to natural greenhouse effect, but 23x more effective than one molecule of CO2 as a greenhouse gas

• produced naturally during plant decomposition in swamps and animal digestion

Ozone (O3)

• exists naturally high up in the atmosphere to protect us from UV rays

• ground-level ozone acts as a pollutant and a greenhouse gas

Nitrous Oxide (N2O)

• 300x more effective as a greenhouse gas than CO2

• Produced naturally by bacteria in soil and water

Anthropogenic

increase in the amount of infrared radiation trapped by the atmosphere due to higher levels of greenhouse gases generated by humans

Carbon dioxide

• burning fossil fuels for transportation, heating, electricity and industrial processes

• deforestation means less trees to remove CO2 from the atmosphere

Methane (CH4)

• Rice farming

• cattle ranching

• decay of organic matter in landfills and sewage treatment plants

• coal mining and natural gas extraction

• deforestation

Nitrous Oxide (N2O)

• Agriculture and livestock (mainly)

• fossil fuel combustion for transportation and industries

Chlorofluorocarbons (CFCs)

• refrigeration agents

• air conditioners

• aerosols

• leads to the depletion of the ozone layer

Proxy Records

Stores of information in the natural environment that can be measured to give clues to what the climate was like in the past

Ice cores

• can provide climate information for the past 800,000 years

• bubbles in ice contain gases that provide climate information (i.e., 16O more than 18O during ice ages)

• Obtain information regarding precipitation and volcanic eruptions

Tree rings and coral reefs

• growing trees and coral produce rings

• rings thicker during good growing conditions

• good record for more recent climate conditions (i.e., within 10,000 years)

Rocks and Sediments

• each layer of rock or soil may contain fossils, pollen, or climate information

• core can be taken from terrestrial and marine sediments

Long term and short term changes in climate

Long term changes

plate tectonics

• Continents have moved over time

• Change to LOWERN

  • Latitude changes

  • Mountain ranges form

  • ocean currents change

  • and more

Milankovitch cycles

• cyclical changes in earth’s orbit around the sun

  • shape or orbit (eccentricity) - every 100,000 years

  • Tilt of axis - every 41,000 years

  • Precession (axis wobble) every 26,000 years

Short term changes

Volcanic Eruptions

• Rocks, dust and ash spewed into the atmosphere reflect solar radiation back into space, and earth cools down for a short period of time

• volcanic eruptions in siberia is thought to be responsible for the wort mass extinction in earth’s history 250 million years ago

Air and ocean currents

• changes to air and ocean currents can impact climate since they act as energy transfers

• el niño and la niña are short term changes in wind patterns near the equator that have implications for global climate

Feedback Loop

The Albedo Effect

Albedo - measures the reflectivity of a surface

• Positive feedback loop

  • rising temperatures lead to more ice melt, which lead to lower albedo (more absorption) and higher temperatures

  • cooling temperatures lead to more ice, which leads to higher albedo (more reflection) and lower temperatures

Carbon Dioxide and Global Temperatures

• Positive feedback loop

  • increases co2, leading to warmer temperatures

  • warmer temperatures means warmer oceans

  • oceans less effective as carbon sinks (i.e., dissolving less CO2)

  • leads to further increase in atmospheric CO2

Carbon Dioxide and the Arctic

• Positive feedback loop

  • Increased CO2 leads to warmer temperatures

  • Warmer temperatures melt permafrost and increase organism activity in the soil

  • Increased organism activity generates more CO2 and CH4, leading to more greenhouse gases in the atmosphere

Evidence of Climate Change

Rising sea level

• melting ice around the world

• thermal expansion of water

• increased groundwater flowing into oceans

Changes in severe weather

• more intense heat waves, droughts, and hurricanes

• increased forest fires in canada, heat waves in europe, etc.

Changes in precipitation patterns

• more snow is falling as rain

• heavier precipitation events more common

• drier weather experienced in many parts of the world

Changing seasons

• less snow deposition during winter in Canada

• fewer cold and frost days

• lengthening growing seasons

Changes in ecosystems

• plants flower earlier

• animals are staying year-round instead of migrating

• organisms are migrating further north

Why Humans are the Cause of Climate Change

• Scientists modelled two scenarios for global temperatures: without human influence (natural factors only) and both human and natural factors

• current observations match the temperature trends in the latter scenario

Climate Projections and Uncertainties

Climate Projection

• A scientific forecast of future climate based on observations and computer models

• input different scenarios (usually a control or baseline scenario)

• predict areas of uncertainties

Uncertainties in Climate Projection

• the exact quantities of greenhouse gases being emitted and absorbed (i.e., the rate of CO2 absorption by oceans, etc.)

• How different natural systems interact with each other (i.e., atmosphere and biosphere, etc.)

• How people will behave (government policies, individual choices, etc.)

• technological advancement (i.e. how quickly technology will advance, how quickly new technologies are adopted, etc.)

Global Impacts of Climate Change

• Risks of human-caused climate change being evaluated by the intergovernmental panel on climate change (ipcc)

  • thousands of climate scientists from around the world sharing research and findings on climate change

• expected changes

  • rising sea level

  • impacts of agriculture

  • impacts on ecosystems

  • impacts on humans, plane and animal

Climate change in the Canadian Arctic

• due to the albedo effect, the arctic is warming much faster than elsewhere in the world

• problems:

  • polar bears and people will find it harder to find food

  • coastal erosion as ice metls

  • more vulnerable to storms

  • melting permafrost and ice

possible benefits of climate change in the arctic

• more reliable and faster shipping routes

• more valuable resources can be mined

• more trees will grow and absorb carbon dioxide

• more crops can be grown at higher latitudes

Impacts of Climate change in Ontario

Temperature and Precipitation

• Warmer winters with less snow

• hot, humid summers with more rain

• less ice on great lakes leads to longer shipping seasons

• less costs for heating and salting roads, more costs for air conditioning

Changing Lake levels

• less ice cover

• more evaporation

• more precipitation

• more invasive species and poorer water quality

Changing ecosystems

• vegetation regions moving further north

• animals living in colder climate will migrate further north

• plants flowering earlier and reproducing faster

• species can become endangered or extinct

Disease and Illness

• More disease-carrying organisms at temperatures increase (i.e., lyme, west nile, etc)

• more heat-related illnesses and death

• worse smog as they form faster in warmer

Agricultural

• longer growing seasons for crops and other plants

• more weeds lead to more herbicide usage

• more smog (i.e., ozone) will damage crops

• more agriculture in northern regions

Forests

• more forest fires due to hotter and drier summers

• more pests will attack native trees

• forest regions migrating further north

• less healthy plants lead to less carbon dioxide being absorbed

Electricity use

• more air conditioning used during summer

• less heating during winter

• more blackouts possible as electricity production cannot match demands

• less hydroelectricity (main source of electricity generation in ontario) as lake levels drop

Tackling Climate change

• using clean energy sources (produce little to no greenhouse gases)

  • wind

  • geothermal

  • hydroelectricity

  • biofuels

  • nuclear

• actions by government

  • kyoto protocol - plan by the UN to control greenhouse gas emissions

  • provide clean energy sources

  • provide public transportation

  • support green technologies

• actions by businesses and industries

  • use more efficient transportation methods

  • develop cleaner and more efficient technologies

  • limit pollution

  • use less resources

• actions by individuals

  • take public transportation

  • use less electricity and switch off lights

  • save water

  • join volunteer groups that help our environment

Definitions