Geologic evidence of recurring climate cycles and their implications for the cause of global warming and climate changes in the coming century Don J. Easterbrook

 Geologic issues about global climatic warming global climatic warming  Is global warming real?  What is the evidence for CO 2 as the cause of global warming?  What is the geologic evidence for natural cycles as the cause of global warming?

Some Geologic Facts  Global climate warmed ~0.6° C from 1910 to ~1940.  Global climate cooled ~0.5° C from ~1940 to 1977  Global climate warmed ~0.5° C from 1977 to  Global climate cooled ~0.3° C between ~1880 to ~1910 and was ~0.9° C cooler in 1890 than 2000  The global climate has been warming since the Little Ice Age (~400 years).

Evidence that CO 2 is the cause of global warming  CO2 and global temperature have both risen over the past 30 years.  Computer models can be adjusted to show temperatures parallel to global temperatures.

Composition of the atmosphere CO 2 now makes up 0.038% of air Before human input, CO 2 was 0.028% to 0.030% Human input has raised CO 2 by 0.008%

Facts: 1. Half of the warming in the past century occurred before CO2 began to rise sharply. 2. For 30 years after CO2 began to soar, global cooling occurred, rather than warming. 3. Of the many global warmings and coolings, only the last one (the past 30 years) corresponds to rising CO 2..

~80% of CO 2 emissions have occurred since 1945

Greenland warming has followed the global pattern

 “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)   “Temperature has spiked within the past few years unlike any previous temperature spike in history.” (Mote, 2007) .” (  “Current warming is 10 times greater than ever before seen in the geologic record. The chance that warming is natural is less than 10 percent..” (Newsweek, August 13, 2007) Past climate changes

10 episodes of global warming/cooling in the past 15,000 yrs

What the data shows  Global temperatures have risen 1° F in the last century.  Temperatures in Greenland changed abruptly at least 9 times in the late Pleistocene.  Temperature changes of 18-23° F/100 yrs occurred 3 times.  Temperature changes of 13-14° F/100 yrs occurred 3 times.  Temperature changes of 5-7° F/100 yrs occurred 4 times.  None of these temperature changes could have been caused by manmade CO 2 emissions.

Holocene climate changes

Rapid cooling and warming at 8200 yrs. B.P.

Medieval Warm Period   The Medieval Warm Period was a time of warm climate ~900–1300 AD.   Grain crops flourished in Europe.   The population more than doubled and many new cities arose.   The Vikings took advantage of the warm climatic to colonize Greenland.   Wine grapes were grown as far north as Britain.   Prolonged droughts affected the southwestern U.S.   Western North America warmed, glaciers receded.   An eastern Antarctic Peninsula ice core shows warmer temperatures   Sediments in Lake Nakatsuna in Japan record warmer temperatures.   Sea surface temperatures in the Sargasso Sea were approximately 1°C warmer than today.   Equatorial east Africa was drier from AD.   The Medieval Warm Period appears to have been a global event.

LITTLE ICE AGE  ~1300 AD, temp. dropped ~4° C (7° F ) in ~20 yrs  Much colder and wetter, ~4° C cooler than present  Violent storms, early snow, flooding  Glaciers advanced all over the world.  Massive crop failures in Europe--large population decline in Europe; ~1.5 million people died;  Wine production dropped sharply  Themes River in London froze over

Solar irradiance, sunspots, and glaciers

Boulder Glacier, Mt. Baker 1940 to to 1979

Easton Glacier, Mt. Baker 1940 to to 1979

Comparison of glacial activity and ocean temperatures

Facts About Global Climate Change Over the Past Century and Millennia  Evidence for recurring cycles of global climate change over the past centuries and millennia clearly show many natural climatic warming and cooling events, long before CO 2 emissions raised atmospheric CO 2 levels.  Greenland ice core isotope and temperature data show 10 periods of climatic warming far greater than recent warming (up to 20 times greater per century). Glacier fluctuations and ice core data show a repeating pattern of warm/cool episodes in the past 500 years and we are right on schedule with two cooling periods and two warming periods this century. All of the global warming in the past 500 years can be explained by these natural climatic cycles.  Past climate changes follow cyclic year patterns that can be traced for the past 400–1000 years in Greenland ice cores, glacier fluctuations, and historic observations.  The Earth is now near the end of a 30–year warm cycle, fitting the pattern of comparable cycles over the past 200 years.

 The current warm cycle coincidently corresponds to high atmospheric CO 2 levels. However, the preceding 30–year global cooling cycle ( ) occurred despite the dramatic rise in CO 2 emissions that began about 1945).  About half of the global warming of the past century occurred before 1945, so increased atmospheric CO 2 clearly did not control global climate changes then. The abrupt shift in 1977 from the cool period to the warm period was not reflected by any significant change in CO 2.  The only physical evidence for CO 2 causing global warming is that warming and CO 2 have both risen for the past 30 years. After CO 2 began to soar in 1945, global cooling occurred for 30 years, rather than warming.

CO 2 began to rise sharply in 1945, but global temperatures declined for 30 years

Global climate changes correlate well with changes in: 1.Solar irradiance. 2. Numbers of sunspots. 3. Production of 10 Be and 14C in the atmosphere from radiation.

Few sunspots during the Little Ice Age

Global temperature change and sunspots

Solar irradiance and global warming  yr. global warming/cooling phases that occurred during the past century coincided with changes in solar irradiance.  Global climate changes in the geologic past have coincided with changes in production rates of 14 C and 10 Be.

Where are we headed during the coming century?

ICPP predictions Global temperatures will increase as much as 10° F by 2100

Predicted global temperature changes this century

 The IPCC predicts that global temperature will rise 1° F (above present temp) by 2011, whereas the pattern of natural warm/cool cycles predicts slight cooling. The difference is so large, that in only 3 years we should know which direction we’re heading.  The predicted IPCC temperature increase by 2011 is 1° F greater than that predicted by extrapolation of past climatic cycles and nearly 2° F greater by These differences are greater than warming of the entire past century, so should be easily detectible. Thus, the next few years may tell us whether we're heading for the global catastrophe predicted by IPCC or minor warming predicted by climate cycles.

 Two choices:  If past climate cycles persist and climate cools in the next 30 years (rather than soaring), the IPCC will have been the greatest scientific boondoggle in the history of science.  If IPCC predictions are correct, we’re headed for the greatest global catastrophe since the Little Ice Age. What lies ahead in this century?