Climate Change & Humans

Climate Change &

HumansChapter 12

Are Climates Changing?Many observed climate records only go back 150 years so we have to rely on indirect evidence such as:

Ice coresSize of tree ringsComposition of coralLake sediments

What’s the concern for?The rate of climate change in the last 50 years and the amount of greenhouse gases.Remember: some areas may be cooling while others, the warming may be much greater. It’s important that we look at the average.

Avg. temperature has increased by 0.6 °C in the last century BUT this rate of increase has not occurred in the last 10 000 years!

Enhanced Greenhouse Effect

Results from GHG’s that are added to the atmosphere mostly by human activity.Water vapour takes up about 65% of the natural GHE and it can have positive and negative feedback

Positive: warming causes water vapor which loops back and temp.Negative: vapor causes clouds which reflects sunlight which has a cooling effect.Makes it hard to predict what will happen…

Warming Potential of GHGs

GHGs differ in several ways including:their global warming potential (how well they absorb infrared compared to CO2)the time they remain in the atmospherethe rate of increase since 1850

Global warming potential of GHGs

Depends on:amount of gas entering the atmosphere each yearlifetime in the atmosphereeffects on the atmospheric chemistryeffect on other gases

Carbon Dioxide and Carbon

CO2 is the most abundant GHG that contributes to enhanced GH effectproduced by burning fossil fuels, burning forests and when soil is cultivatedhas increased by 31% and concentrations have not been as high as it is now in the last 420 000 years.

Carbon CycleCarbon naturally cycles through the biosphere

Next to the hydrologic cycle, it has the largest annual exchange of matter.

Carbon Sinksa major source or reservoir of carbon compounds, can be both.

MethaneAlso known as Natural gas, produced by bacterial decay of organic matter. Also released from rice paddies, wetlands, landfill sites and cows.

Used to heat homes and generate electricity.

Has a warming potential 21X that of carbon dioxide and contributes to 20% of the enhanced GH effect.

Concentrations have increased by 146% since the 1800s.

Methane hydrateUnique structure of methane combined with water.Forms under specific temp and pressure and these deposits are primarily in deep oceans.Discovered only a few decades ago!Scientists believe that deposits contain twice the amount of conventional natural gas

Nitrous OxideHas a warming potential 300X that of carbon dioxidecontributes to 6% of the enhanced GH effectreleased when fossil fuels and wood are burned at very high temperatures and when nitrogen-containing fertilizers are used.

Halocarbons or HCFCsCarbon compounds that contain halogens, like chlorineCFC’s were developed in the 1930s as coolants and propellants in aerosols.causes thinning of the ozone layer!Has been banned in most countries

OZONE- ground level only

creates photochemical smog by oxides of nitrogen and vapours of gasoline, solvents, and oil-based paints react in heat and sunlight.Causes increased cases of asthma and other lung conditions

Changes to Canadian Biomes

Most of Canada is currently tundra and taiga but with rising CO2 levels and other factors (changes in precipitation), scientists are expecting to see deciduous, and grasslands to increase and even some desert!

Some specific effects of climate change...

changes to amounts and patterns of precipitationchanges in salinity and ocean currentsrising sea levels could put costal towns at riskhuman health could be affected by pollution and clean drinking waterchanges in composition and dominance of species

Intergovernmental Panel on Climate Change (IPCC)

Formed in 1988 by the United Nationals Environmental Program and the World Meterological OrganizationLargest gathering of scientists to work on the issueThe Third Assessment Report in 2001 projects a global temp rise of 1.4 to 5.8°C by 2100

Kyoto ProtocolAgreement created in 1997 in Kyoto, Japan to reduce GHG emissionsOver 160 countries signed (USA opted out in 2001)If targets not meet by 2012, it must make up the difference plus a 30% penaltyCriticism: Businesses will suffer, a reduction of 50% in GHG is needed to advert climate change

Human ResponseIn a group of 2, quickly prepare a “Cole’s notes” of each of the following topics to present to the class today:

Adapting to Climate Change p.459Long-term Adaptation p.459Reducing the amount of climate change p.460Storing carbon dioxide p.460Reducing GHG emissions p.461-462Renewable energy sources p.462Relating Climate Change to scientific Inquiry p.463Societal Decision Making and Climate Change p.463What are the Choices? p.465The Precautionary Principle p.465

The Gaia HypothesisDr. James Lovelock, a NASA scientist, developed the Gaia hypothesis in the 60’s

“The entire range of living matter on Earth from whales to viruses and from oaks to algae could be regarded as constituting a single living entity caple of maintaining Earth’s atmosphere to suit its overall needs and endowed with faculties and powers far beyond those of its constituent parts.”

The Earth as a single organism