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Visualizing Environmental Science

Global Atmospheric Changes

Chapter 9

Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

The Atmosphere and Climate• Weather—conditions in the

atmosphere at a given place and time– Can vary hour to hour and due to

temperature, atmospheric pressure, precipitation, humidity

• Climate—weather patterns that occur in a place over a period of years– Determined by Earth’s distance from

sun, distribution of water and land, vegetation--but moreover by temperature and precipitation

• Because climate changes over hundreds of years, organisms have adapted to them

© 2014 John Wiley & Sons, Inc. All rights reserved.

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Solar Radiation and Climate

• Sunshine warms the planet and makes life on Earth possible

• 69% of solar energy absorbed and used to run biogeochemical cycle, warm the planet, power photosynthesis


Temperature Changes With Latitude and Season

• Exposure to solar energy varies due to Earth’s shape and tilt of axis

• Sunlight hitting the equator vertically (left lamp) is concentrated on Earth’s surface

• As you move towards the poles, light hits more indirectly and covers larger area (right lamp)


Temperature Changes With Latitude and Season

• Earth’s tilt on its axis is 23.5 degrees perpendicular to the orbital plane

• This tilt determines the seasons

• Half the year the Northern Hemisphere tilts towards the sun (March –Sept), the other half it tilts away


Precipitation• Differences in precipitation

depends on three factors– Amount of water in the

atmosphere• Equatorial uplift

– Geographic location

– Topographic features• Rain shadows—dry on one

side of a mountain, away from wind, while raining on the other side


• Anthropogenic accumulation of CO2, CH4, N2O, CFCs, and O3

• Car engines release N2O and CO2

• Global climate change result

of these gases absorbing

infrared radiation, warming

the lower atmosphere

referred to as the

enhanced

greenhouse

effect

Causes of Global Climate Change


• CO2 has increased from 288ppm 200 years ago to 390ppm in 2009– Burning fossil fuels accounts for

>70% of CO2 increase

Causes of Global Climate Change


Causes of Global Climate Change• Radiative forcing is the capacity

to retain heat in the Earth’s atmosphere– Greenhouse gases cause positive

radiative forcing and can remain in atmosphere for hundreds of years

• Aerosols remain suspended in the air for days and tend to cool the atmosphere– Human-induced aerosols (sulfur

emissions from fossil fuels) and natural causes of aerosols (volcanic eruption)


Global Climate Change• Earth’s average temperature is

increasing

• This is based on many types of data

– Daily measurements taken by meteorological stations, weather balloons, tree rings, ocean sediment

• NOAA: global temperatures in 1998 and 2001–2010 hottest years on record

– Last two decades of the 20th century were its warmest

– Increase in heat waves, heat-related deaths

• Spring in Northern Hemisphere comes six days earlier than in 1959; autumn comes five days later—this affects phenology


Melting Ice and Rising Sea Levels

• Continental and polar ice is melting

• Glacial ice has diminished globally by 46ft in thickness from 1955 to 2005

• The images are the Muir Glacier in Alaska in 1903 and in 2004, a fraction of its former size

• Culprit? Anthropogenic CO2

emissions from burning fossil fuels


Effects of Global Climate Change

• Melting land ice vs. ocean ice

• Ice cap at North Pole decreased especially in past three decades

• Sea-level rise – Antarctic ice cap and continental

glaciers melting

– Water expands as it heats

• Impacts on agriculture and human water supply

• Wildlife impacts (polar bears)

• Residents of the low-lying islands of the Maldives may need to relocate


Florida with a 20 ft. rise in sea level.

If all the ice caps melted… 170 ft rise.


• Some models predict that the North Pole will be clear of ice during the summer by 2020

• This figures shows Arctic sea ice volume from 1979–2011


The Effects of Global Climate Change

• Warmer Antarctica temperatures threaten the Adelie penguin’s food supply and reduce reproductive success

• The coqui tree frog in Puerto Rico has become rarer due to climate change

• Ocean warming and acidification stresses coral, causing bleaching

• Greater hurricane intensity



• Impacts on human health– Heat-related illnesses

– Disease-carrying mosquitoes will expand their range and transmit more malaria, dengue fever, yellow fever


Global Climate Change

• United Nations has charged the Intergovernmental Panel on Climate Change (IPCC) to provide scientific assessment of climate change

– Predict a 1.8–4.0° C increase in global temperature, among others


Dealing With Global Climate Change:Mitigation and Adaptation

• Mitigation is the moderation of effects by reducing greenhouse emissions

• Adaptation is the response to changes caused by climate change

• Approach will require a combination of both mitigation and adaptation


Mitigation of Global Climate Change• Goal is to develop alternatives to fossil fuels (renewable

energy), reduce energy use and increase energy efficiency– Plant and maintain forests as carbon sinks

– Increase fuel economy of motor vehicles

– Carbon management—separate and capture CO2 produced during fossil fuel combustion


Adaptation to Global Climate Change

• Most pressing issue is rising sea level• Solution is to move coastal settlements inland or

construct sea walls on coastal areas—both expensive options

• Adapt to shifting agricultural zones– Find substitute crops to grow on warming land– Develop heat and drought resistant crops/trees


Ozone Depletion in the Stratosphere• Ozone (O3) is a natural

component of the stratosphere but a human-made pollutant in troposphere

• Ozone layer in stratosphere shields the Earth from UV radiation

• Without ozone layer, Earth would be uninhabitable

• Unnatural thinning of ozone, referred to as the ‘ozone hole’


Effects of Ozone Depletion

• Ozone depletion means more UV radiation reaches Earth’s surface– Disrupts ecosystems

– Linked to ocular issues, weakened immunity and skin cancer

• This graph shows the average yearly ozone column over New Zealand and the correlation with annual melanoma rate


Ozone Depletion in the Stratosphere

• Discovered as ozone depleting substances (ODSs) in 1970s, banned in the U.S. in 1978

• Other ODSs include halons, nitrous oxide, chloroform


Reversing Ozone Layer Thinning

• 1978—U.S. banned CFC propellants

• 1987—Montreal Protocol agreement stipulated a 50% reduction of CFC production by 1998

• Industrial companies developed CFC substitutes called HFCs and HCFCs that do not deplete the ozone but the latter are potent greenhouse gases

• Developing countries phased out CFC use in 2005

• HCFCs to be phased out in 2030© 2014 John Wiley & Sons, Inc. All rights reserved.

global atmospheric changes - palm beach state college · • melting land ice vs. ocean ice • ice...

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