Climate Change November 4, 2014

Global Climate Change Global Warming – describes a rapid increase in the temperature of Earth’s surface, water, and atmosphere, which is causing changing in most natural systems (such as seasons and life cycles)

Global Temp Change since 1880

Causes of Climate Change Variations in the Earth’s orbital characteristics Atmospheric variations in greenhouse gases Volcanic eruptions Variations in solar output Landforms

Variations in the Earth’s orbital characteristics The Milankovitch theory – Cyclical variations in three of the Earth’s orbital characteristics Eccentricity Rotation Tilt – Vary the amount of solar radiation that reaches the Earth’s surface

Milankovitch Cycles

Carbon Cycle

Greenhouse Effect

Carbon Dioxide Sources

What are the Fossil Fuels?

Greenhouse Gas-Temp Correlation from Ice Cores

Volcanic Eruptions Sulfur dioxide reacts with water vapor causing haze Combined with ejected particulate matter One of the coldest years in the last two centuries was 1816, the “Year Without a Summer” Caused by eruption of Tambora in 1815 Temperatures can decrease after eruptions for up to 3 years Mount St. Helens

Variations in Solar Output Climate models predict that a change in solar output of only 1 percent per century alters the Earth’s average temperature by 0.5°C (32.9°F) ̶ 1.0°C (33.8°F)

Sea Level Rise

Arctic Sea Ice Changes 2012

GCM Predictions Crop patterns and natural plant/animal habitats will shift to maintain preferred temperatures During this century, climate regions could shift miles poleward Soil moisture projected to decrease in midlatitudes Forest cover will undergo major species disturbances Expansion of zones affected by tropical diseases Alpine glaciers

Reconstructing Climate Change Prior to recorded data, use Proxy Data: – Palynology - pollen in lake sediments shows veg type - > 15,000 year record – Dendrochronology - tree rings show growth patterns – 9000-yr record – Ice Cores – air trapped over 650K yrs shows past CO 2 concentrations

Proxy Data Measures cause and effect relationships indirectly Paleoclimatology – science that studies past climates using proxy data Proxy data – ice cores, sediments, coral reefs, ancient pollen, tree-rings Antarctic ice cores have climate reconstructed back 740,000 years Air bubble in ice allow the reconstruction of atmospheric methane levels

Tree-Ring Records

Palynology

Ocean Core Records