Water, Weather And Climate Water, Weather And Climate SystemsSystems

Climate Systems and Climate Change

The Water, Weather, and Climate Systems

ClimateClimate

Climate is weather over time

Climatic regions are areas with similar weather statistics

Climatology is the study of climate

Earth’s Climate System

Figure 10.1

Internal Processes Are Energized By Insolation

Figure 10.1

External Processes Affect Climatic Balance And Force Climatic Change

Figure 10.1

Climatic Relationships

Figure 10.3

World Climate Classification

Figure 10.4

Fig. 7.2

Tropical ClimatesTropical ClimatesRain forest:– Climate is constantly moist and warm– Rainy all year– Convectional thunderstorms triggered by local heating and

trade wind convergenceMonsoon:– Principally along coastal areas– Rainfall from 6-12 months of the year brought by the ITCZ– Dry season lasts one or more months

Savanna:– ITCZ dominates during summers with wetter conditions– Dry conditions when ITCZ shifts away and high pressure

dominates

Fig. 7.3

Tropical Rain Forest

Tropical Monsoon

Fig. 7.4

Tropical Savanna Climate

Intense dry periods; plants adapted to seasonally dry water budgets

Fig. 7.5MesothermalMesothermal ClimatesClimates

Humid subtropical:– Hot summers, mild winters– Maritime tropical air masses produce

convectional showers over land during summer– Frontal activity with polar air masses in winter

Marine west coast:– Warm to cool summers, mild winters– Affected throughout the year by weather

systems formed along polar frontMediterranean:– Dry summers, mild winters– Large-scale agriculture requires irrigation

Humid subtropical hot-summer climate, rainy all year

Fig. 7.6

Humid subtropical winter-dry climate

Fig. 7.7

Marine west coast climate

Affected by cyclonic storms all year

Fig. 7.9

Mediterranean climatesDry summers dominated by subtropical high;Wetter winters affected by cyclonic storm tracts Fig. 7.10

MicrothermalMicrothermal ClimatesClimatesHumid continental:– Hot to warm summers, cold winters– Maritime tropical air masses influence both

humid continental moist-all-year and winter-dry climates

– In North America, conflict between maritime tropical and continental polar in winter

Subarctic:– Cool summers to very cold winters– Boreal forests (fir, spruce, etc.) thin out to the

north to the more open woodlands and tundra– Soils thin in areas once scoured by glaciers

Humid-continental hot-summer climates

Fig. 7.11

Humid-continental hot-summer climates

Fig. 7.11Humid-continental mild-summer climate

Fig. 7.12

Subarctic cool summer, cold winter climate

High pressure dominates Churchill during cold winter

Fig. 7.13

Extreme subarctic cold winter climate

Fig. 7.14

Polar ClimatesTundra:– High latitude or high elevation– Land under continuous snow cover 8-10 months– Never warms above 10 oC– Small plants appear in spring

Ice caps and ice sheets:– Perpetually frozen– All months below freezing

Polar marine:– More moderate than polar continental– No month averages below -7 oC

Polar Tundra

Earth’s Ice Sheets

Antarctic Sound West Greenland

Fig. 7.16

Polar Marine Climate, South Georgia Island, Antarctica

Fig. 7.17

Desert Climates

Arid deserts:– Tropical, subtropical hot– Midlatitude cold

Semiarid steppes (flat grassland) – Tropical, subtropical hot– Midlatitude cold occurs poleward of 30o

latitude

Fig. 7.18

Fig. 7.19Tropical, Subtropical Hot Desert Climates Midlatitude Cold Desert Climate

Fig. 7.20

Tropical, Subtropical Hot Steppe Climate

Fig. 7.21

Midlatitude Cold Steppe Climate

Fig. 7.22

Climate ChangeClimate Change

Global warmingPaleoclimatologyClimate models Future temperatures

Global WarmingGlobal Warming

Causes of recent global warming?– Release of greenhouse gases into the

atmosphere due to burning of fossils fuels?– Recent temperature rise is just part of the

natural cycle?Intergovernmental Panel on Climate Change (IPCC) was created in 1988 to coordinate global climate-change research, climate forecasts, and formulation of policies

Greenhouse GasesGreenhouse Gases

Carbon dioxide (CO2), methane (CH4) and water vapor are essential warmers of the planet:– Without them the Earth would be an ice

ball, 35o C colderBut can our burning of fossil fuels upset the balance and cause the Earth to warm too much?

The Greenhouse EffectThe Greenhouse Effect

Sun’s energy enters the Earth’s atmosphere at relatively short wavelengths (mostly within visible range)Some of this energy heats Earth’s surfaceSurface heat is then reradiated outward at longer wavelengths (infrared)Greenhouse gases absorb and re-emit some of this long wavelength energy back to the surface, warming the atmosphere

The Recent Past (60 years)The Recent Past (60 years)

The concentration of carbon dioxide has increased steadily since 1958 with smaller, annual variationsThe smaller variations can be explained by seasonal changes in the biosphereThe longer trend shows increasing carbon dioxide concentrations:– Increasing CO2 from burning of fossil

fuels

Increase in Atmospheric Carbon-Dioxide since 1955

Fig. 2.18

Recent Past (Continued)Recent Past (Continued)

Temperatures have also increased over the last 50 years!– BUT is the temperature increase related

to the increase in CO2?Large temperature changes have also occurred in the geologic past, so it is not clear!– Global temperatures during the Middle

Cretaceous and Early Cenozoic were higher than today

Figure 10.30Fig. 7.25

1951-1980 global average

Temperature Anomalies For 2010 Compared To The Base Period Of 1951-1980

Figure 10.30

Fig. 7.25

PaleoclimatologyPaleoclimatology

Temperature changes over the last few thousand years must be obtained indirectly in what are known as proxy recorders:– Trapped atmospheric gases in ice cores– Oxygen isotope changes in ice cores– Oxygen isotope and other changes in

fossils in oceans and lakes

1000 YearsOf CO2 And

Temperatures

Figure 10.29

Earth today is close to equaling the highest average temperature of the past 125,000 years

Fig. 7.23

10,000 Years Of Greenhouse

Gases From Ice-Core And Modern Data

Figure 10.32

Fig. 7.27

Climatic Models And Future Climatic Models And Future TemperaturesTemperatures

Predicting The Extent And Consequences Of Global

Warming

Computer Model Comparison of Anthropogenic and Natural Forcing (red) vs. Only Natural Forcing (blue)

Figure 10.31Fig. 7.26

General Circulation ModelsGeneral Circulation Models

Scientists developed a complex computer climate model known as a General Circulation Model (GCM)A GCM contains several sub-model programs for the following:– Atmosphere– Ocean– Land surface– Cryosphere– Biosphere

General Circulation ModelsGeneral Circulation Models

Variables in GCMs include the following:– Temperature– Precipitation– Air Pressure– Relative Humidity– Wind– Sunlight intensity

GCMs calculate scenarios of future climate change based on input parameters and variables

Figure 10.33

Input parameters for an atmospheric layer

Atmospheric layers

A General Circulation Model consists of a grid of boxes, each representing a different location on Earth; Each box consists of multiple layers and interacts with adjoining boxes

Fig. 7.28

Different scenarios take into account economics, population, global cooperation and greenhouse gas emissions

Holding emissions at 2000 concentrations

Fig. 7.29

Reasons For Concern

Overall Effects Of Climate Change

Figure 10.34

Fig. 7.24

Loss of glaciers (global warming), coral reefs (ocean acidification), barrier islands and small islands (rising sea level): ecosystems migrate and species become extinct

Melt-water from melting glaciers flow into the oceans, causing sea level to rise

Figure 10.34

Fig. 7.24

Dynamic equilibrium is disrupted, tipping point is reached and the system spasms to a new equilibrium state: disruptions include melting of mountain and continental glaciers, sea-level rise, and ocean acidification

Oceans acidify due to absorption of increasing amounts of atmospheric CO2

Figure 10.34

Fig. 7.24

Climate change results in monetary damage due to crop failures and diminishing water supplies: lives are changed or lost; poorer countries might not adapt successfully

Figure 10.34

Fig. 7.24

Magnitude and frequency of extreme weather events increase: precipitation and floods intensify: hurricane and tornado intensities increase: more heat waves, droughts, and wildfires

Figure 10.34

Fig. 7.24

Impacts are greatest in low-latitude and less-developed countries due to shifts in crop patterns and spread of diseases. At high latitudes, indigenous people of the circumpolar Arctic will be affected by rapid melting of ice sheets/permafrost.