Environmental Science Changes Through Time 16 Positive Values

Environmental Science Changes Through Time (16)

Positive Values Indicate Cooler Water

Shape of the path Tilt of the axis Closeness to the sun Milankovitch Cycles

Greenland Icesheet Reached Bottom Summer 2003; ice before last ice age Coral Reefs show similar trends

Ice Age Cycles • N. Am. ice sheet forms • The Gulf stream shuts down due to decrease in salinity • Poles cool • Thermohaline circulation returns • Moving warm air poleward - warming

Communities Through Time • Communities have to change as climate change. • Communities move latitudinal and altitudinal • Paleoecology – reconstruction of past ecosystems

Ambrosia

Plant Migrations

Olympic Marmot

Vancouver Marmot

Cascades

Only Wettest Areas Remained

Alternate Hypothesis

Blitzkrieg Hypothesis

Reliability of Data

Global Temperatures – New Views With Better Resolution and Periods

25% reduction in sea ice

The Last 50 Years • Mainland Europe, 22 species of butterflies extended their range northward since 1970 • Several bird species likewise – bee eater, Turkish dove • In southern England frogs lay their eggs 20 days earlier and newts return 40 days earlier • Danish Agriculture experience 10 more growing days • Birds lay their eggs 8 -10 days earlier • Marmots appear 38 days earlier in Colorado since 1976

Natural Fluctuations or Humans? • Highest temperatures in the past 650, 000 years • Rate of change is the greatest ever

CO 2 and Temperature

1015 g

Habitat Fragmentation • Species area curves • Lessons from islands

Cowbirds

Metapopulations • • Naturally Man-made Source populations Sink populations

Area of uncut forest in the 48 states

Most Preserved Forest Landscapes Are Uniform

Today’s Landscape Forest Fields Urban Fringe