Human Activity and Climate Change Climate change is the change in long-term weather patterns in certain regions.  These changes can affect the flow of thermal energy over the entire Earth.  Several ice ages have occurred in the past 10 6 years.  Global warming refers to a global increase in the global average temperature.

The Enhanced Greenhouse Effect… …is the increased capacity of the atmosphere to absorb & emit thermal energy due to an increase in greenhouse gases. more greenhouse gases in the atmosphere = increase of natural greenhouse effect Greenhouse gases include: water vapour, CO 2, CH 4 (methane), nitrous oxide (N 2 O), CFCs and perfluoromethane (CF 4 ).

The Enhanced Greenhouse Effect… Global Warming Potential (GWP) refers to the ability of a substance to absorb and emit thermal energy.  CO 2 is given a GWP of 1  perfluoromethane has a GWP of

Greenhouse Gases & GWP

The Enhanced Greenhouse Effect: CO 2 and Methane CO 2 levels have increased greatly in the past 200 years. 1.Industrial Revolution  increased use of fossil fuels  combustion of fossil fuels releases CO 2 2.Deforestation has changed carbon sinks (forests) into carbon sources  adds to CO 2 in atmosphere Many people are attempting to reduce CO 2 emissions by… using / purchasing energy from alternative energy sources, reducing their energy consumption, planting more trees to remove CO 2 from atmosphere.

The Enhanced Greenhouse Effect: CO 2 and Methane Methane is very efficient at trapping & emitting thermal energy – 25 times more efficient than CO 2 ! CH 4 is produced by:  bacteria breaking down wastes in oxygen-free environments,  garbage decomposing in landfills,  animal digestion,  plant matter, rice paddies (and other natural wetlands),  extracting, producing & burning fossil fuels. Moo!

The Enhanced Greenhouse Effect: Nitrous Oxide Nitrous oxide is the 3 rd -largest contributor to the enhanced greenhouse effect. N 2 O comes from: bacteria (in soil, ocean water, manure), N-rich chemical fertilizers, improper disposal of human & animal waste, car exhaust.

The Enhanced Greenhouse Effect: Ozone Ozone (O 3 ) is… an important UV radiation blocker in the stratosphere, a very powerful greenhouse gas at lower altitudes, close to Earth’s surface, where it naturally occurs in trace amounts. Ozone results from chem. rxns. between solar radiation & pollution from the burning of fossil fuels (ie. hydrocarbons, N-oxides).

The Enhanced Greenhouse Effect: Chlorofluorocarbons CFCs are powerful greenhouse gases  Montreal Protocol – a treaty designed to protect the ozone layer by phasing out substances considered to be responsible for depleting the ozone layer (ie. CFCs)  Cl atoms break apart O 3 molecules CFCs are found in:  coolants (ie. for air conditioners, refrigerators)  aerosols (as propellants)  fire extinguishers

Albedo and Climate: Making Predictions About Climate Change The Earth’s surface affects the amount of solar radiation that a region receives.  If changes occur in a region’s albedo, climate changes could follow.  Forests provide a low albedo  deforestation increases albedo  region reflects more solar radiation  Arctic ice has a high albedo  melting of large areas of ice decreases albedo  region absorbs more solar radiation

Albedo for Different Materials Albedo

The Role of Science in Understanding Climate Change Measurements must be taken from around the world, over a period of time in order to identify trends in climate change. Scientists use computers to model what Earth’s climate might be like. General Circulation Models (GCMs) are computer models used to study climate.  GCMs can be used to predict future climatic conditions & have also reproduced the climates of the past  GCMs take into account changes in [greenhouse gases], albedo, ocean currents, winds & surface temperatures  GCMs are also used for weather forecasting, climate analysis and climate change predictions  GCMs consider properties of fluids, chem. rxns., how organisms affect their environment

Predicted “worst case scenarios” of projected global temperatures

The Role of International Cooperation in Dealing with Climate Change It is believed that human-induced climate change is a relatively recent phenomenon.  The United Nations Environmental Program (UNEP) and the World Meteorological Organization (WMO) created the Intergovernmental Panel on Climate Change (IPCC) to address global concerns about climate change and global warming.  The IPCC assesses:  human impact on climate change & suggests possible solutions  environmental, social & economic issues related to climate change  The United Nations Framework Convention on Climate Change (UNFCCC) created a voluntary treaty to encourage countries to reduce greenhouse gas emissions.

Per capita Emissions of Greenhouse Gases for Various Countries

Global Impacts of Climate Change Current models predict that temps. will increase more… in arctic regions (vs. equatorial regions) on land (vs. in oceans)

Global Impacts of Climate Change

Impacts of Climate Change on Canada Being in the northern hemisphere, Canada should expect to feel the effects of global warming quite severely. Parts of southern Canada have had average temperature increases of 0.5 – 1.5 ºC. greatest warming has occurred in the west Arctic regions are losing permafrost (ground that remains frozen year-round) & Arctic ocean ice cover

Impacts of Climate Change on Canada Growing seasons are getting longer & more precipitation is falling.  there could be heavier spring rains & longer heat waves in the future  fisheries could be negatively affected by changes to temp., water quality & currents in bodies of water  high summer temps. worsen effects of air pollution  worsen health issues  warmer winter temps. will allow insect pests to survive farther North than before (ie. mountain pine beetle)

Projected climate change for summer (A) and winter (B) in 2050.

Projected changes to Canada’s biomes if [CO 2 ] doubles from what it was before the Industrial Revolution.

Impacts of Climate Change on BC sea level could rise up to 30 cm along northern coast of BC over next 100 years change in weather patterns could bring more rain to some areas, drought to others fresh water glaciers are an important source of drinking water in BC; drinking water may be harder to find as glaciers shrink (See Table 11.2 on p. 493 for other impacts)

Uncertainty and Decision, An Action Plan for the Global Community The UN suggests that countries use the precautionary principle  lack of complete scientific certainty should not be used as a reason to postpone cost-effective measures to prevent serious environmental damage.  ie. “it’s better to be safe than sorry”

Uncertainty and Decision, An Action Plan for the Global Community Relatively small changes could have large positive impact on the climate in Canada.  reduce GG emissions from vehicles  require industries to reduce GG emissions  increase availability & use of energy- efficient products  set guidelines for improving indoor air quality  “carbon capture & storage”…? Recall: transportation & industry are responsible for 75% of Canada’s GG emissions! See Table 11.4 on p. 496 for strategies for addressing climate change.