Global Changes in Climate Atmospheric effect Global Changes in Climate

Fig 9

Redistributing Energy from the Sun

Differential heating of Earth

Insolation

Temperature at Surface

Fig. 8C.

Evaporation minus Precipitation

Circulation Effect on Energy Balance

Wind-driven surface ocean circulation

Salinity at Surface

Density of Water Ocean is stratified Density increases with increasing salt content Density increases with decreasing temperature Temperature and salinity are set at the surface and are “conserved” in the deep ocean The ocean’s deep waters are COLD and thus deep waters were last at the surface at high latitudes At high latitudes, cooling is important for increasing water density and sending it to the bottom The “great ocean conveyor” acts as a giant heat pump in the Northern Atlantic

Fig. 14.6A

Atmosphere-Ocean Organization ENSO NAO

Normal State of the Pacific Fig. 18.

El Niño State of Pacific Fig. 19.

Ocean Response to Atmospheric Circulation Fig. 7. Winds cause a general westward motion of tropical surface waters Winds also cause the warmest waters to “pile up” at the western Pacific (western Pacific warm pool)

El Niño, after Ropelewski and Halpert 1987, MWR, 1606-1626. Regions with consistent precipitation anomalies associated with El Niño, after Ropelewski and Halpert 1987, MWR, 1606-1626.

NAO+ NAO-

11

Natural Causes of Climate Change on Long Timescales

Geometry of Earth’s orbital variations and tilt

60°N summer insolation minima coincide with glaciations

The Carbon Cycle Fig. 18.15

Plate Tectonics

Modern distribution of continents Pangaea ~250 Ma Modern distribution of continents

Before uplift After uplift

Effect of uplift on climate

d18O d13C 10 20 30 Age (Ma) 40 50 60 70 Zachos et al., 2001

Inferring climate change far back in time Proxies Inferring climate change far back in time

What would we like to know? Temperature Rainfall Evaporation Seasons Winds Ocean currents Deep ocean overturning