1. How does the Earth on which we live function as a whole?
Earth System Science
How does the Earth on which we live function as a whole?
This lecture is about our environment and us: you, me, and people all around the world.
Humans have always built their nests and family groups to protect their young - making houses to keep out the rain and cold, growing crops to provide food, exploiting animals for meat, clothing and transport. We have learned to make tools to help these activities, and, more recently, to mine coal and oil to provide power. We have drawn upon the rich diversity of nature which we have found around us to further our own interests. Compared to other species we have some great advantages - through language and social learning we can share experiences and knowledge, and we have established a dominant position on this planet.
Yet during our lifetime, there have emerged signs that we are fouling the nest, not just for ourselves but for our children and grandchildren on a global scale. For the first time, we are not just spectators on the natural scene, but we are actively changing it in fundamental and irreversible ways. And we have little idea of what we are doing. We need to understand how things work. Otherwise our future will be ruled by the law of unintended consequences
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2. Key Points
Human activities are affecting the environment on global scale
The impacts on human societies are potentially substantial but largely unknown
We need a basic scientific understanding of how the Earth functions as an interacting system
These Key Points will be repeated throughout the lecture to delineate the structure of ideas and to reinforce the message. They are the fundamental motivations for Earth System Science.

3. Human activities are affecting the environment on a global scale
Burning fossil fuel is causing global warming and rising sea-level
Emission of CFCs has caused the depletion of stratospheric ozone
Soil erosion is reducing agricultural productivity
Deforestation and habitat destruction threaten species diversity
Pesticides, fertilizers are polluting water resources
Sulfate and nitrogen oxide emissions cause acid rain
Global environmental issues have become increasingly apparent in the past few decades. We tend to think of them in separate compartments, each the domain of its own group of specialists. However, scientists have become aware that they are interconnected, and how managing one may make another worse.

4. The Probable Cause of Global Warming
This graph shows the concentration of carbon dioxide in the atmosphere. It started rising near the beginning of the industrial revolution and accelerated during the last half century, due primarily to the burning of coal and oil worldwide, which is injecting carbon dioxide into the atmosphere far faster than natural processes in the ocean and in the soil can assimilate it.
Most knowledgeable scientists believe this is the reason that the world is getting warmer, by about 1 degree Fahrenheit, or 0.6 degrees Centigrade over the past 100 years, globally averaged. This may not seem very much, but the rate of increase has accelerated greatly in the past three decades, and projections indicate several degrees over this coming century. By contrast, during the last ice age the world as a whole was about 5 degrees Fahrenheit cooler than at present, though much more so here in Wisconsin. Overall, it much drier and dustier, the forests, lakes and grasslands were in different places, and it was a very different environment in which to live. Our future is not an ice age, but the reverse. However, with global warming we should expect changes of comparable magnitude. Much about our climate and environment that we take for granted should thus be called in question.
IPPC 1990 page xvi

5. The Antarctic Ozone Hole
The ozone hole is often confused with global warming, but is a quite different phenomenon, due to the escape into the atmosphere of man-made chlorofluorocarbons from refrigerators, air conditioners, and spray cans. These inert molecules, a great invention of the 1930’s accumulate and work their way up to the stratosphere above where the jet aircraft fly. There they are broken apart by ultra violet radiation from the sun, and under certain circumstances the chlorine so released destroys the layer of ozone which protects us down here from that same ultra violet radiation. Ultra violet radiation causes skin cancer and cell damage to anything in direct sunlight, both humans and in plants and animals.
The blue and purple in this satellite picture show a greatly reduced ozone shield over Antarctica, surrounded by green and orange that indicate normal values over the southern ocean. This hole has appeared each spring (October-November) for the past 20 years, associated with the return of the sun after the polar night and the extreme cold temperatures special to that part of the world. A much weaker hole occurs some years in the Northern hemisphere, including Wisconsin.
Spurred on by this dramatic evidence of unexpected human impact on the environment, the industrialized nations agreed in late 1980’s and early 1990’s first to limit the growth, then to eliminate entirely the productions of CFC’s by the year The good news is that the chlorine loading of the atmosphere is beginning to decline. The bad news is that the ozone hole may be expected to be with us for another 50 years, and meanwhile increasing atmospheric carbon dioxide is likely to make the Northern hemisphere problem worse.

6. Acid Rain http://odin.dep.no/md/publ/acid/Erodes.html
Coal fired electric generating plants and other industrial activities emit sulfur dioxide and nitrogen oxides. These give rise to acid rain, which corrodes stonework and automobile finishes, kills the fish in lakes which are not protected by alkaline soils, and contributes to forest dieback and loss of productivity. This picture shows the same statue in Germany, 40 years apart.

7. Water Resources http://www.oroville-city.com/lakeview.html
In many parts of the world clean, fresh water is the most precious natural resource. I will be addressing the hydrologic cycle in another lecture in this series.

8. Soil Degradation National Geographic Society
This is degraded land around a water hole in African savanna. Cattle like that in the foreground have eaten all the vegetation nearby. Soils and soil erosion will be the subject of a later lecture in this series.
National Geographic Society

9. Habitat Destruction
From large mammals to tiny insects, species are becoming extinct at a rate unprecedented since the demise of the dinosaurs 64 million years ago. The cause is not a meteorite but the heavy footprint of a new dominant species on the planet, cutting down forests, fracturing habitats into ever smaller pieces, and deliberately or unwittingly transporting alien species to every corner of the globe. Ecosystems will be discussed in a later lecture.

10. A Mountain Gorilla Corel Professional Photos CD-ROM Sampler #200051
An endangered species
Corel Professional Photos CD-ROM Sampler #200051

11. Key Points
Human activities are affecting the environment on global scale
The impacts on human societies are potentially substantial but largely unknown
We need a basic scientific understanding of how the Earth functions as an interacting system

12. Impacts on human societies potentially substantial but largely unknown
Fundamental values and lifestyles may be questioned
It may be decades before the effects become apparent
Remedial actions have indirect consequences
Scientists see warning signs of profound changes in the natural environment society tends to take for granted, but we have little understanding of their implications. Some may turn out to be inconsequential, others of major importance. One thing is certain: Whatever we do or do not do will have unintended consequences!
ESS p 8

13. Key Points
Human activities are affecting the environment on global scale
The impacts on human societies are potentially substantial but largely unknown
We need a basic scientific understanding of how the Earth functions as an interacting system
Faced with such uncertainty, prudence requires we teach ourselves and our children to stop, look, and listen to what nature is telling us, and weigh carefully how we could reduce our impact on climate and on the other creatures that inhabit this planet. We depend on them for our life support, and we would be wise to treat them with respect.

14. We need a basic scientific understanding of how the Earth functions as an interacting system
Understand and distinguish natural variability in climate and ecosystems
Include the interactions between the atmosphere, oceans, land surface, ice, and biosphere
Examine the evidence from the past
Document the effects of human activities
Simulate future changes and assess their probable consequences
Fluctuations in weather and climate have occurred since the formation of the earth. Do not mistake them all for human induced global warming.

15. Last Glacial Maximum xxx
The last ice age was at its peak 18,000 years ago, when most of Wisconsin was covered with a layer of ice several thousand feet thick. Due to recurring slow changes in the orbit of the Earth around the sun, the ice melted about 12,000 years ago, and since then the world has been unusually warm compared to most of the past million years. During the ice age the atmosphere everywhere was much dustier, and the forests, grasslands, and deserts in quite different places. The global average temperature was some 2 to 4 oC cooler than at present. Note that this is comparable to the additional warming expected by scientists during the coming century. This suggests that the impact on the environment of such a warming is likely to be substantial.
xxx

16. Signs of Past Glaciation
Click on the image to enlarge it.
If we look at the landscape around us, we can see tell tale signs left by the glaciers. They carried moved enormous quantities of dirt and rocks, dumping them in end moraines such as the City of Madison is built upon. Kettle holes show where huge chunks of ice were buried along with the dirt. When the ice melted, it left a big hollow in the soil with no outlet.
xxx

17. We need a basic scientific understanding of how the Earth functions as an interacting system
Understand and distinguish natural variability in climate and ecosystems
Include the interactions between the atmosphere, oceans, land surface, ice, and biosphere
Examine the evidence from the past
Document the effects of human activities
Simulate future changes and assess their probable consequences

18. Equatorial Pacific Sea SurfaceTemperature
El Nino
Normal
La Nina
Dec 97
We heard a lot about El Nino during This irregular oscillation is marked by warmer than usual temperature across the equatorial Pacific Ocean, coupled to a slackening of the Easterly trade winds that usually prevail in that part of the world. Since then we have been in its opposite, called La Nina, with unusually strong trade winds. These images were reconstructed from data obtained from weather satellites high above the earth, and from arrays of buoys floating in the ocean.
Dec 90
NOAA/PMEL
Dec 88

19. Measuring Ocean Winds and Temperature
National Oceanic and Atmospheric Administration

20. Vegetation Stress El Nino (top) La Nina (bottom)
Click on the image to enlarge it.
Scientists have recently discovered that El Nino and La Nina affect the weather all round the world. The red areas in these maps of Southern Africa indicate drought, detected by the absence of green vegetation reflecting sunlight back to a satellite high above. The blue areas indicate unusually dense vegetation.

21. We need a basic scientific understanding of how the Earth functions as an interacting system
Understand and distinguish natural variability in climate and ecosystems
Include the interactions between the atmosphere, oceans, land surface, ice, and biosphere
Examine the evidence from the past
Document the effects of human activities
Simulate future changes and assess their probable consequences

22. Drilling Ice Cores in Peru
Annual layers in the Quelccaya Ice Cap
Distant view of ice cap
There are a few ice caps in the tropics. This one is at 14o S high in the Andes mountains. The white dome visible on the horizon in the picture at right is indeed the ice cap. The animals in the foreground are llamas. The cliff at the left is a close-up of the icecap, in which you can see the layers formed each year by fresh snowfall. This enables to scientists to assign a precise date to date each layer of ice. Then by analyzing the chemicals and air bubbles trapped in in the ice, they can reconstruct the history of past climates. It is from records like this that we know about how climate has varied in the past, long before humans were have a significant impact on it.
Lonnie Thompson

23. We need a basic scientific understanding of how the Earth functions as an interacting system
Understand and distinguish natural variability in climate and ecosystems
Include the interactions between the atmosphere, oceans, land surface, ice, and biosphere
Examine the evidence from the past
Document the effects of human activities
Simulate future changes and assess their probable consequences

24. Pipeline in British Columbia
We depend on oil for much of modern life. Yet if not properly maintained, pipelines like this can cause devastating pollution and damage to ecosystems. Good records of the state of the ecosystem prior to a disturbance such as this are just as important to a good scientific understanding of its impact as are careful measurements after a cleanup.
© jpg

25. We need a basic scientific understanding of how the Earth functions as an interacting system
Understand and distinguish natural variability in climate and ecosystems
Include the interactions between the atmosphere, oceans, land surface, ice, and biosphere
Examine the evidence from the past
Document the effects of human activities
Simulate future changes and assess their probable consequences

26. The Intergovernmental Panel on Climate Change
Scientists from around the world contribute to regular assessments of the state of our knowledge of global warming and its possible causes and impacts. These consensus judgments were the underpinning of the commitments to reduce future emissions of greenhouse gases that were made in Kyoto in 1997 by most of the developed nations of the world.
IPPC 1995

27. Projected Future Warming
For various emission scenarios
For high or low climate feedback multiply by 1.8 or 0.6
IPPC 1995
The governments in Kyoto considered a number of different scenarios for emissions reduction, ranging from “very severe” to “business as usual”. This graph shows a simulation of the change in global average temperature through this century according to each of these scenarios. It shows how the burning of coal and oil in the past and near future has predetermined most of the expected warming, with action to reduce emissions significantly decreasing the rate of rise of temperature only late in the decade. The actual increase in temperature may be greater or less than that shown here if the physical sensitivity of the climate system to greenhouse gases proves to be different from that assumed in this simulation. Reducing the uncertainty in our estimates of this sensitivity is the goal of a major scientific research program.
In any case, it would appear prudent to plan for ongoing warming throughout the century, and focus on ways of adjusting to its effects and minimizing their impact.

28. Key Points
Human activities are affecting the environment on global scale
The impacts on human societies are potentially substantial but largely unknown
We need a basic scientific understanding of how the Earth functions as an interacting system
In summary

29. Earth System Science Sources of Information
Earth System Science - Overview, NASA, (ESS)
Climate Change 1995 , Intergovernmental Panel on Climate Change (IPPC)
Referenced web sites
The version of this lecture that is on the website contains many links, both in the summary index, and in the captions to individual images.