Why Ice Cores?

 

• Ice cores contain a long and detailed record of the past atmosphere
• They can be well resolved and dated
• They contain a proxy record of temperature
• They hold samples of the past atmosphere trapped as bubbles in the ice

Why Greenland and Antarctica?

• Far from civilization \ no local pollution \ clean atmosphere
• Inland ice cores are the best examples of the ëbackground atmosphereí
• Ice cores are very sensitive to natural/anthropogenic change
• Well marked seasonal cycle , with long polar night and extremely cold and dry
• Large positive accumulation of snow

Problems with dating

• Poor quality and missing core
• Complete year's snow missing due to blowing snow etc.
• Smoothing of signal in particular chemical
• One season's snow missing or mixed

Vostok Ice Core

• Reached 3623m depth
• Below 3310m core believed to be disturbed so studied only above this
• At 3310m age is 420,000 yr.
• This is 4 glacial/interglacial periods

Data measured

• Deuterium content (Temp. proxy)
• Dust content (desert aerosol)
• Na concentration (marine aerosol)
• CO₂
• CH4
• d18O2 of O₂ (measure of global ice volume and hydrological cycle)

Sequence of Events

1. Orbital forcing
2. Amplified by greenhouse gases
3. Deglaciation and ice-albedo feedback