What is Climate?
• Average weather experienced by a particular region
• average temperature and precipitation
Climate Controls
• Global Atmospheric Circulation
• global wind patterns
• subtropical highs and equatorial lows
• Tropic and deserts
Temperature & Precipitation
• global controls =
– atmospheric circulation
– Latitude
• Oceanic circulation
Temperature & Precipitation
• localized influences
• mountain ranges
• rain shadows
• elevation
Climate Regions
• tropical
• dry
• mesothermal
• microthermal
• polar
• highlands
Climate History / Climate Change
• Have humans changed the climate of Earth?
• Possible Human Impact on Climate
– Global Warming
• an increase in atmospheric concentrations of greenhouse gasses
• industrialization
• ~ 1 Cū rise in temp in the last 400 yrsClimate History / Climate Change
• Consequences?
• Sea Level Rise - Climate Zones Change
• Another Ice Age
• Are humans to blame?
Climate History / Climate Change
• Short Term Changes in Global Climate
• The Vikings
• Medieval Warm Period
• Little Ice Age
• Viking migration and colonization
• 1 Cū rise in temp. in the last 400 yrs
What benefit can the geologic record have for solving modern problems?
• Context
• Mechanisms for change
How do we know that climate has changed during the history of earth?
• Actual measurements - temperature and precip.
– 140 years
• Climate Proxies
Climate Proxies
• Supplement our 140 yr instrument record
• Historical
Climate Proxies
• Tree rings
• Ice Cores
Climate Proxies
• Ocean and Lake Sediment
• Corals, Foraminifera, Pollen
Isotopes of Oxygen from the skeletons of organisms
• Lighter isotope evaporates and is incorporated into ice sheets
• Enrichment of heavy isotope in skeletons = ice age