The Greenhouse The Greenhouse EffectEffectEnvironmental ScienceEnvironmental Science

Why greenhouse?Why greenhouse?

The term The term greenhouse greenhouse effecteffect comes from the comes from the idea that the idea that the atmosphere traps heat atmosphere traps heat in the troposphere like in the troposphere like the glass walls of a the glass walls of a greenhouse dogreenhouse do

Without these gases Without these gases the earth would be the earth would be frozen like Marsfrozen like Mars

What are greenhouse What are greenhouse gasses?gasses?

Small amounts of specific gasses act as Small amounts of specific gasses act as insulators in the atmosphereinsulators in the atmosphere

These are known as These are known as greenhouse gassesgreenhouse gasses and include the following:and include the following: Carbon dioxide (COCarbon dioxide (CO22))

Water vapor (HWater vapor (H22O)O)

Methane (CHMethane (CH44))

Nitrous Oxide (NNitrous Oxide (N22O)O)

What do greenhouse What do greenhouse gasses do?gasses do?

Sunlight heats up the earth’s surfaceSunlight heats up the earth’s surface The earth’s surface reflects the heatThe earth’s surface reflects the heat The greenhouse gasses absorb the heat The greenhouse gasses absorb the heat

and warm the troposphereand warm the troposphere These greenhouse gasses occur These greenhouse gasses occur

naturally in the atmosphere.naturally in the atmosphere. Without the greenhouse gasses, earth Without the greenhouse gasses, earth

would be cold and lifeless.would be cold and lifeless.

Natural Greenhouse Natural Greenhouse GassesGasses

Volcanoes are one Volcanoes are one source of natural source of natural greenhouse gassesgreenhouse gasses

Swedish chemist Swedish chemist Svante Arrhenius Svante Arrhenius first recognized the first recognized the natural warming natural warming effect of gasses in effect of gasses in the troposphere. the troposphere.

USGS

Carbon DioxideCarbon Dioxide

Next to water, carbon dioxide is the most Next to water, carbon dioxide is the most abundant greenhouse gas in the abundant greenhouse gas in the atmosphereatmosphere

Carbon dioxide is controlled by the Carbon dioxide is controlled by the carbon cyclecarbon cycle

A molecule of carbon dioxide will spend A molecule of carbon dioxide will spend 100-120 years in the atmosphere100-120 years in the atmosphere

Historical RecordHistorical Record

Bubbles in the ancient ice will contain Bubbles in the ancient ice will contain samples of the ancient atmosphere.samples of the ancient atmosphere.

By analyzing these ancient air samples By analyzing these ancient air samples scientists can discover the greenhouse scientists can discover the greenhouse gas levels in the atmosphere thousands gas levels in the atmosphere thousands of years agoof years ago

Records exist to describe the Records exist to describe the atmosphere for the past 160,000 yearsatmosphere for the past 160,000 years

More RecentlyMore Recently

Since 1958 records of atmospheric COSince 1958 records of atmospheric CO22

levels have been collectedlevels have been collected Carbon dioxide levels will fluctuate during Carbon dioxide levels will fluctuate during

the year according to the seasons – the year according to the seasons – lower in the summer and higher in the lower in the summer and higher in the winterwinter

Even with these fluctuations during the Even with these fluctuations during the year the average COyear the average CO22 levels are rising levels are rising

Human ImpactsHuman Impacts

Sometimes plants will be buried under silt and Sometimes plants will be buried under silt and compressed over millions of yearscompressed over millions of years

This organic matter is turned into coal, oil, and This organic matter is turned into coal, oil, and natural gasnatural gas

We burn this for energy and release carbon We burn this for energy and release carbon dioxide into the atmospheredioxide into the atmosphere

As a result most scientists now believe that the As a result most scientists now believe that the extra greenhouse gasses are warming the extra greenhouse gasses are warming the atmosphereatmosphere

Human Impacts cont.Human Impacts cont.

In addition to carbon In addition to carbon dioxide, we are also dioxide, we are also releasing many other releasing many other additional greenhouse additional greenhouse gassesgasses

Scientists now believe Scientists now believe that the extra that the extra greenhouse gasses greenhouse gasses are warming the are warming the atmosphere tooatmosphere too

Global WarmingGlobal Warming

Global WarmingGlobal Warming - an - an increase in the average increase in the average global temperature that global temperature that occurred in the 20occurred in the 20thth centurycentury

As the earth warms, As the earth warms, there will be several there will be several consequencesconsequences Changing weather Changing weather

patternspatterns Disruptions of agricultureDisruptions of agriculture Rising sea levelsRising sea levels

Changing Weather Changing Weather PatternsPatterns

As the earth warms up, so do the As the earth warms up, so do the oceans. oceans.

Warmer oceans may make hurricanes Warmer oceans may make hurricanes and typhoons more commonand typhoons more common

They may also lead to changes in the They may also lead to changes in the pattern of ocean currentspattern of ocean currents

Droughts could become more frequent Droughts could become more frequent and impact agricultureand impact agriculture

Melting IceMelting Ice

As the Earth warms, the ice caps and As the Earth warms, the ice caps and glaciers will start to meltglaciers will start to melt

This could lead to rising sea levels that This could lead to rising sea levels that have several consequences:have several consequences: Coastal wetlands and low-lying areas are Coastal wetlands and low-lying areas are

floodedflooded People who live near the coast loose their People who live near the coast loose their

homes and livelihoodhomes and livelihood Salt water enters coastal aquifers Salt water enters coastal aquifers