Transcript Lecture A
The data show that the Earth has been a ice planet, not a hothouse planet most of the past million years. Note that occasionally, we have Warm periods, the last one about One thousand years ago, the so-called Medieval Climate Optimum. Assumed Constant Tectonic processes "James Lovelock's Daisyworld is a hypothetical Earth-like planet, orbiting the same distance from a Sun-like star. Like our Sun, this star has grown progressively brighter through time, radiating more and more heat. Yet the surface temperature on Daisyworld has remained nearly constant for most of the planet's history. This results from the biosphere on Daisyworld, which consists only of dark-, light-, and gray-colored daisies. The daisies influence the surface temperature through their reflectivity. Dark daisies absorb most of the Sun's energy; light daisies reflect most back to space. [A] Early in the history of the planet, when the young Sun Is cool, dark daisies would be the most fit species, because clusters of them create local warm spots that favor the growth of more daisies. Soon the planet would be covered by dark daisies, and their collective effect would be to increase the global temperature above what it would have been in the absence of life [B] When the dark daisies had established a comfortable temperature, gray and white daisies can begin to take advantage of the warm conditions. At first, gray daisies would do better than light ones because clusters of light daisies wouldn't keep local temperatures warm enough for survival. [C] Eventually, the Sun's output would reach the point where unmoderated surface temperatures would exceed the maximum tolerable to daisies. Then, light-colored daisies begin to become the fittest species because they create cool spots that would favor the growth of more daisies. As light-colored daisies spread, their collective effect would be to decrease the global temperature BELOW what it would have been without life, and without concern for the planet, would have controlled the global environment. [E] Finally, the temperature produced by the Sun will rise so high that neither type of daisy would be able to moderate the temperature, and all species would die out. DAISY WORLD, LIGHT/DARK DASIES EFFECT OF DASIES ON GLOBAL CLIMATE Carbon Dioxide and Global Climate FACTS: 1. Global CO2 level is rising due to hydrocarbon use as an energy resource 2. During the next 50 years, the RISE in CO2 not be checked, (unless we run out of hydrocarbons to burn) 3. Some scientists believe the RISE of CO2 will be much less than predicted because it remains in the atmosphere a much shorter time than assumed PREDICTIONS: 1. The climate will warm by 5-10 degrees 2. The climate will cool 5-10 degrees 3. Nothing will happen WHAT TO DO? KYOTO PROTOCOL CHINA AND DEVELOPING COUNTRIES ARE NOT CONSTRAINED BY THE KYOTO PROTOCOL. COUNTRIES THAT ARE SIGNATORIES HAVE NOT MET THEIR PROTOCOL MANDATES. The USA, etc. are not signatories AND HAVE NOT FOLLOWED THE PROTOCOL. RESULT OF PROTOCOL: GOOD FEELING AMONG SIGNATORIES, BUT BUSINESS AS USUAL EVERYWHERE THE GREENLAND ICE CAP MEASUREMENT THE LAST 10,000 YEARS... THE PREVIOUS 250,000 YEARS... RELATED TIME SCALE DATA AND AGREEMENTS FOUND In ground coal fires In China … These are not Controlled and may NOT be possible to control. WHAT OTHER KNOWLEDGE DO WE HAVE? 1. GREENHOUSE GASES WILL INCREASE FOR AT LEAST A TIME SCALE OF SEVERAL MORE DECADES 2. VOLCANIC AND OTHER DUST SOURCES CAN COOL THE EARTH FOR OVER A YEAR, POSSIBLY CATASTROPHICALLY IN THE CASE OF A LARGE COLLISION OR A LARGE VOLCANIC ERUPTION 3. OZONE AND OTHER STRATOSPHERIC GREENHOUSE GASES ARE CHANGING FOR THE NEXT SEVERAL DECADES AT LEAST 4. BIOLOGICAL ACTIVITY IS INCREASINGLY IMPORTANT THE UNKNOWNS 1. IS THE PRESENT CLIMATE STABILITY ILLUSORY? 2. CAN WE ACCIDENTLY SHIFT THE CLIMATE STATE? 3. HOW STABLE (HOW LONG LASTING) WILL A CLIMATE SHIFT BE? 4. GIVEN THE UNCERTAINTIES, WHAT IS A POPULATION FOR THE EARTH CONSISTENT WITH THE CLOSED SYSTEM AND CLIMATE VARIATIONS????