Global Change Seminar
"It's Your Move!"

Segment #2:   Is our Planet In Trouble?

Part I: Historical Perspective

          Reflect for a moment. We want stability in our lives, yet we get bored with the same old, same old. We tend to assume that the things we like should remain unchanged for ever, and the things we don't like should get fixed ASAP. We know with our intellect that we will die, yet we spend most of our time living as if we're immortal. We think of our life span as a long time and, for the most part, base our behavior on the assumption that things won't change for the worse during it. And, now, it seems clear that the future of every species on earth is dependent on and affected by the actions of each individual member of the human species.

          Time and scale are concepts people have difficulty with. Scientists have discovered that time and space are simply different dimensions of the same thing, spacetime.  It is hard for most of us to wrap our minds around very large or very small numbers, not to mention the concept of spacetime.  These ideas are at the very edge of the human ability to grasp in a meaningful way (it rarely occurs to us that our cognitive capacity has limitations) but are basic for an understanding of our place and our situation.

          Please do (click on the link) the Doubling exercise next before proceeding with the rest of this page.

          Now, to further put one's self into a larger context, consider some facts about human origins as shown below. To the best of our knowledge, these are as well established as science has so far made them.

Scale of Time in Which We Exist
Years Ago
10 - 20,000,000,000
Our universe is born
4 - 4,500,000,000
Our solar system is formed
3 - 3,500,000,000
First life (reproducing organism) forms on planet Earth
2 - 2,500,000,000
Photosynthesis occurs and oxygen starts to build up on the atmosphere
450 - 500,000,000
Primitive fish develop in the sea
400 - 450,000,000
Early trees develop on the land
250 - 200,000,000
First dinosaurs occur
150 - 100,000,000
Earliest birds and mammals emerge
65 - 140,000,000
First flowering plants show up
58 - 66,000,000
Dinosaurs become extinct
Earliest primates occur
Earliest humans (sp. homo) emerge
Homo sapiens begins to cultivate plants
Domestication of animals begins
Printing invented in China
First mechanical calculator invented
First oil well is drilled
First automobile is produced
First public television broadcast
First commercial computer
Internet becomes available for commercial and public use
Cellphones become commercially available
2.5 - 3,000,000,000
Estimated years remaining before Earth becomes uninhabitable
Scale of Space in Which We Exist
Estimated # of galaxies in our universe
Estimated # of stars in the Milky Way (our galaxy)
Distance in miles that light travels in one second (Speed of light)
Approximate diameter of our galaxy in light years
Distance in miles from the Sun to Pluto, the farthest known planet
Average # miles from Earth to the Sun
Diameter of the Sun in miles
Distance in miles between the Earth and the Moon
Average diameter of the Earth in miles
Diameter of the Moon in miles
Thickness in miles of the troposphere (90% of the Earth's atmosphere lies within it)
Population of Tokyo (2000)
20 microns
Diameter of a red blood cell
(1 micron = 1meter ÷ 1,000,000)
Approx 30,000
Number of genes in human DNA
Number of cold viruses that can sit on a pinhead
Number of neurons in the human brain
Estimated number of currently living species
Number of known (catalogued) living species
Estimated known number of species currently becoming extinct every year
317,000 cubic miles

Amount of water on the earth

          People tend to see things in relation to their own life span and their own size scale. It is hard to realize how myopic and limited human perception is. Perhaps by reflecting on the vastness of time and space, and the minuteness of its components, one can improve one's perspective about one's own individual, and all of humanity's, place in the grand scheme of things.

Think About

    1. How many of these facts do you know?   
    2. How often do you think about them?
    3. Do you know many people who think about their life in the context of all life on the planet?
    4. What strikes you most about what you just read?


Next: Urgent Global Problems


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Page last modified on July 9, 2008