Transcript Document
Global warming and CO2―Are we headed for global catastrophe in the coming century? Don J. Easterbrook Is global warming real? Global, N. Hemisphere temperature What is the magnitude of present global warming compared to global climate changes that have occurred in the geologic past? Were past global climate changes caused by changes in atmospheric CO2? What is the role of solar changes in global climate changes? On a recent TV documentary about global warming, a climate modeler said: “CO2 levels in the atmosphere have risen to record heights and never before in the history of the earth has climate changed as rapidly as in the past century, proving that global warming is caused by anthropogenic CO2.” “Our civilization has never experienced any environmental shift remotely similar to this. Today’s climate pattern has existed throughout the entire history of human civilization.” (Gore, 2006) Increase in atmospheric CO2 Atmospheric CO2 emissions CO2 cannot have been the cause of climatic warming episodes prior to 1945 because atmospheric CO2 didn’t increase significantly until after 1945 ▲ Multiple 25-30 year periods of alternating warm and cool temperatures have occurred since the Little Ice Age (~1600 AD). Temperatures during the Little Ice Age were about 4° C (~7° F) lower than present. ▲ ~ 80% of the CO2 from human activities was added to the air after 1940, so these warming episodes had to be natural fluctuations unrelated to anthropogenic atmospheric CO2. Global temperatures rose 0.5° C (0.9 ° F) from 1890 to 1940, well before the sharp rise in atmospheric CO2, so it couldn’t have been caused by CO2. Global temperatures dropped 0.5° C (0.9 ° F) from early 1940s to 1977 at a time when atm. CO2 was soaring. Since 1890 only about half of the global warming corresponds to elevated atm. CO2. CO2 began to rise sharply in 1945, but global temperatures declined for 30 years 10 episodes of global warming and cooling that cannot have been caused by atmospheric CO2 10 episodes of global warming and cooling that cannot have been caused by atmospheric CO2 1. ~15,000 yrs ago, sudden climatic warming (~12° C; ~21° F) caused dramatic melting of large Ice Age ice sheets 2. A few centuries later, temperatures plummeted (~11° ; ~20° F). 3. ~14,000 yrs ago, global temperatures increased (~4.5°C; ~8° F). 4. ~13,400 yrs ago, global temperatures plunged (~8°C; ~14° F) 5. ~13,200 yrs ago, global temperatures rose rapidly (~5°C; ~9° F) 6. 12,700 yrs ago global temperatures plunged sharply (~8°C; ~14°) F) at the start of the Younger Dryas. 7. 11,500 yrs ago, global temperatures rose sharply (~12° C; ~21°F) marking the end of the Younger Dryas. 8. 8,200 yrs ago, a sudden global cooling (~4° C; ~7° F) lasted a few centuries. 9. ~1000 AD, global temperatures rose several degrees to begin the Medieval Warm Period, which lasted a few centuries, then ~1230 AD dropped ~4°C (~7° F) in ~20 years. 10. ~1600 AD, global temperatures cooled several degrees at the beginning of the Little Ice Age Solar effects and climate change Global climate changes correlate well with changes in: 1. Solar irradiance. 2. Numbers of sunspots. 3. Production of 10Be and 14C in the atmosphere from radiation. Solar effects and climate change During each global climate change: 1. Changes in the rate of production of 10Be in the upper atmosphere by radiation indicate changes in radiation input. 2. Changes in the rate of production of 14C in the upper atmosphere by radiation also indicate changes in radiation input. 3. These changes correlate with changes in numbers of sunspots and solar irradiance. LITTLE ICE AGE Much colder and wetter, ~4° cooler than present ~1300 AD, temp. dropped ~4° C (7° F ) in ~20 yrs Glaciers advanced all over the world Massive crop failures in Europe; ~1.5 million people starved to death; Large population decline in Europe Wine production dropped sharply Themes Violent River in London froze over storms, early snow, flooding Few sunspots occurred during the Little Ice Age Changes in 14C production rates correlate with sunspot minimums and climate changes Sunspots and changes in production rates of 10Be in the upper atmosphere 14C production rates match sunspot variations Solar irradiance, sunspots, and glacial advances (blue) Global temperature change and sunspots Solar irradiance variations correlate with global temperature change Glaciers on Mt. Baker show a recurring pattern of advance and retreat that matches the Pacific Decadal Oscillation and variation in solar irradiance Easton Glacier, Mt. Baker (modified from Harper, 1993) 1940 to 1956 1956 to 1979 Coleman Glacier, Mt. Baker 1940 to 1947 (modified from Harper, 1993) 1947-1979 Comparison of glacial activity and N.Atlantic temp changes Warm/cool cycles with constant atmospheric CO2 Predicted global temperature changes this century Predicted global temperature changes this century Two checkpoints of the ICPP vs. Easterbrook projections: By 2010, ICPP projects ~1° F warmer, Easterbrook slightly cooler. By 2040 ICPP projects ~2° F warmer, Easterbrook ~0.4° F cooler. After 2040, temp. rises again. CONCLUSIONS During these abrupt climate changes, CO2 was not a factor. Far more severe global warming in much shorter time has occurred repeatedly in the geologic past. Global climate changes have coincided with changes in sunspot activity, solar irradiance, and production rates of 14C and 10Be 25-30 yr. global warming/cooling phases during the past 4 centuries coincide with changes in solar irradiance. A 30-yr global cooling period during accelerating CO2 levels suggests that CO2 is not be the cause of global warming. Projecting the global warming curve for the next century suggests cooling from 2006 to ~2040, warming from 2040 to ~2075, and cooling from 2075 to 2100 with a total warming of only ~0.3 degrees by 2100. Global temperatures rose 0.5° C (0.9 ° F) from 1890 to 1940, well before the sharp rise in atmospheric CO2, so it couldn’t have been caused by CO2. 80% of atmospheric CO2 accumulated after the sharp rise in CO2 ~1945, but temperatures for the next 30+ years cooled 0.5° C (0.9 ° F) in the Northern Hemisphere and 0.2 ° C (0.4 ° F) instead of global warming. 10 times in the past 15,000 years, sudden warming of ~8-12° C (~14-21° F) occurred in less than 100 years and could not have been caused by anthropogenic CO2. Glaciers have recorded multiple 25-35 year warm/ cool cycles over the past 400 years. Only the last one could possibly be attributed to atmospheric CO2. During the Little Ice Age, temperatures dropped ~4° C (~7° F) in ~20 years. The global warming that has occurred since then could not be due to atmospheric CO2.