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Lecture 6
ENVIRSC 2EI3 Lecture Notes - Lecture 6: World Meteorological Organization, Malaria, Coastal Erosion
5 pages26 viewsFall 2016
School
McMaster UniversityDepartment
Environmental ScienceCourse Code
ENVIRSC 2EI3Professor
Luc BernierLecture
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Module #6: Climate Change
Unit #1: What is climate?
Weather and Climate
• Weather: atmospheric conditions over a short time period (day or week)
• Climate: Composite of the variety of day-to-day weather
Climate Change
• Long-term shift or alteration in the climate of a specific location, region, or
the planet
• Global Warming
o Changes in the average surface temperature
What Causes Climate?
• Surface of the Earth is: unequally heated by the sun
• Incoming solar energy: directly from the sun hitting the earth’s surface
• Outgoing IR energy: emitted from the earth’s surface
• Greenhouse gases: absorb or trap short wave radiation and re-radiate as long
radiation resulting in heat
• Long term temperature changes are associated with shifts in the amount of
energy we receive by earth from the sun
o Axial wobble
o Variation of the tilt
Climate Indicators
• Impact of earth’s climate can be traced in glacial ice or in marine sediments
• Cycles of glaciation can be traced
• Natural disruptions may influence climate
o Ex: El Nino
▪ Represents the marked warming lf the waters of eastern and
central portions of the Pacific
▪ Impacts can cause droughts in some parts of the world and
flooding in others
Unit #2: Evidence and Explanations
What is the evidence of Climate Change?
• Since 19th century, average global temperature has increased by: 0.6 +/- 0.2
degrees Celsius
Temperature
• Increase in temperature in the Northern Hemisphere during 20th century
was the largest than any century in the past 1000 years
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• Paleoclimate Indicators: past climate indicators based on ice cores, tree rings
and coral reef data
Greenhouse Gases
• Continued to rise over the past decades
• Carbon dioxide and Methane concentrations are higher now than ever before
Reduction in permafrost and snow cover
• Since 1996, permafrost = warming
Glaciers
• Lost more mass than have gained
o Due to increases in global temperature
• Movement of glaciers due to warm temperatures
Climate Models
• Consider some or all five components in order to predict future climates
o Radiation
o Dynamics
o Surface processes
o Chemistry
o Time step and resolution
• General Circulation Models (GCM’s): most common and take the 3D nature of
Earth into account
o Combined land, atmospheric and ocean models
The intergovernmental Panel on Climate Change (IPCC)
• Established in 1988 by the World Meteorological Organization and United
Nations Environmental Program
o Created to assess the scientific, technical and socioeconomic
information related to the understanding of the risks from human
induced change of climate
Scientific Explanations of Climate Change
• Strong consensus that increase in greenhouse gases (GHG) is from human
activities
o Impacts from forestry and agriculture (methane emissions)
Changes in Radiative Forcing
• Having more greenhouse gases = more energy trapped within the Earth’s
atmosphere
Results from Climate Models
• Can only replicate current climate conditions when past human increases of
greenhouse emissions are included
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