Human and the Earth

ASTR 1420

Lecture 26

Section 10.5

Dr. Martin Luther King, Jr.

"Unlike the plagues of the dark ages or contemporary diseases we do not yet understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we possess. What is lacking is not sufficient knowledge of the solution, but universal consciousness of the gravity of the problem and the education of the billions who are its victims."

Acceptance Speech: Margaret Sanger Award in Human Rights, 1966

A.D.2000

A.D.1000

A.D.1

1000B.C.

2000B.C.

3000B.C.

4000B.C.

5000B.C.

6000B.C.

7000B.C.

1+ million years

8

7

6

5

2

1

4

3

OldStoneAge New Stone Age

BronzeAge

IronAge

MiddleAges

ModernAge

Black Death — The Plague

9

10

11

12

A.D.3000

A.D.4000

A.D.5000

18001900

1950

1975

2000

2100Prediction

Billi

ons

Source: Population Reference Bureau; and United Nations, World Population Projections to 2100 (1998).

World Population Growth Through History

Expo

nenti

al G

row

th

Common misconception (or absurdity):

• All the people of the world could fit into the state of Texas, with room left over to spare (therefore, there is no overpopulation issue).

• In the same spirit, one might say all the world’s people could easily fit into Antarctica or the Sahara desert or into a large crater on the Moon.

Overpopulation is when the number of people can not be permanently maintained without depleting resources and without degrading the environment and the people's standard of living.

Any country that cannot support its people in a sustainable fashion within its own land area at its given per capita level of consumption is “overpopulated”

By this standard, every country on Earth is overpopulated

Just how many of us are there?

Paul MacCready, designer of the first solar-powered aircraft, has estimated the total weight of all terrestrial and avian vertebrates.

•When agriculture began (~10,000BC), we humans and our pets and livestock together accounted for less than 0.1% of the total.

• Today, we and our domesticated animals account for 98% of the total

Tokyo Water Park Slogan

“Welcome to breathtaking Tokyo Water Park where you can wash away the pressure and stress of the overcrowded city and relax with your friends in the smoothing enjoyment of sun, fun and splashing."

With its huge and still growing population and rapidly growing per capita use of resources, China is a great threat not only to China’s own environment, but to the world as a

whole.

• Endless construction of coal burning power plants• Destruction of the world’s rainforests to supply China with food and other

resources• Massacre of 100 million sharks a year for shark’s fin soup• Funding of numerous environmentally and socially destructive dams world-

wide

Just a few specific examples:

birthdearth???

Korea: 1.15 in 2009

Did something change here?

Logarithmic plot straight line in thisplot is exponential behavior

slope indicates growth rate

0.035% per year

1%/yr

A closer look at recent trends…

0.4%/yr

0.8%/yr

1.9%/yr

1865

1950

industrial revolution

green (oil) revolution(pesticides, irrigation, fertilizers…)

1.9%/yr x2 population in every 37 years!

Physical implications of constant growth

• 2% growth per year in energy use, for example, doubles scale every 35 years

• But plenty of sunlight hits the land, so we’re good for a whileo With 15% efficient photovoltaic panels, we would cover all the land on earth

in 320 years at a 2% per year growth rate• But what if we had 100% efficiency, and covered all the earth?o We would reach the physical limit at 2% growth in 450 years

• Let’s put our solar panels in space!o We would demand all the power the sun puts out in 1600 years (with a

manmade Dyson sphere!)• But there are more stars in the galaxyo We have to use all 100 billion stars in the Milky Way galaxy in 2800 years

• Lessons: o exponentials are physically unrealistic over timeo the last 200 year period is anomalous, and may not be the best model for

anticipating our future trajectory

Global Warming

Consequences of Global Warming

• Extreme weather pattern : o hot/dry weather wildfireo more freqeuent & severe stormso decreasing bio-diversityo increasing sealevelo …

Energy: Past, Present, and FutureA Physicist’s View

Tom MurphyUCSD

Key Points

• The past few hundred years have seen an unprecedented availability of energy resources

• Our economic framework and way of life has been built on this energy foundation

• The future of conventional energy resources is jeopardized

• What are our options for adapting to a different future?

Global Solar Potential

Assumes 8% conversion efficiency; Black dots represent area needed tocover ALL energy usage by humans (including all fossil fuels)

Oil: A Story of a Finite Resource

• Discovery must lead production: can’t pump what’s not found• Global discovery peaked in ~1960o still discovering oil, but < 10 billion barrels (bbls) per year, typically

• Production exceeded discovery in 1983• Production must peak and then diminish—but when?

Why worry about peak oil?• After all, oil is not the only fossil fuelo and there are other abundant resources besides conventional oil

• Oil is the pivot for transportationo and a global economy relies on global transportationo from what far reaches did the parts in your cell phone originate?

• Once conventional oil is in decline, demand will likely send the price shooting upo and new efforts to stem the decline (with non-conventional oil) will be unlikely to

keep up with the relentless decrease of this massive-scale resource a 3% per year decline in oil supply would require almost one new nuclear power

plant per week of equivalent power replacement• If a commodity as important to our economy as oil is in permanent decline,

can we expect continued growth?o if not, what do interest rates, loans, banks even mean?

253/12/09

Recent global production and price

broad, flat peak?

production did not budgedespite rocketing price maxed out?

tiny drop in demand(from financial crisis)resulted in huge dropin price® further evidencethat we were upagainst the wall?

So what do we do?

• DON’T PANIC, but Let your voice be heard!

• But we must take this seriouslyo our assumptions about “business as usual” are fragile, and should be

examinedo complacency presents too great a risk

• Examples of complacency:o we always solve our big problems: our scientists will save the dayo fusion/geothermal/tidal/solar/etc. will save us in timeo we find more oil all the time: no worrieso growth is what we do: look at the past few hundred yearso we’ll be moving to Mars anywayo an event like the Great Depression can’t happen in modern times: we’re

financially smarter now (imagine this statement a couple of years ago)

Dr. Martin Luther King, Jr.

"Unlike the plagues of the dark ages or contemporary diseases we do not yet understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we possess. What is lacking is not sufficient knowledge of the solution, but universal consciousness of the gravity of the problem and the education of the billions who are its victims.”

Acceptance Speech: Margaret Sanger Award in Human Rights, 1966

As learned men and women, we have responsibilities to remind the public.

In summary…

Important Concepts• Overpopulation• Exponential growth• Global Warming• Consequences of Global Warming

Important Terms• Global Warming

Chapter/sections covered in this lecture : 10.5Exam3 : the next class!!