There was much made in the media about a new report that claims modern day temperatures are the highest in 5,000 years. Moreover, the investigators assert that this century's temperature rise is “unprecedented,” echoing the assertions of climate change alarmists over the past 30 years. Various news outlets seized upon this report as final proof that the world is headed for a hot steamy demise because of human greenhouse gas (GHG) emissions. There are, however, a number of problems with that assertion. First among them is the methodology used to generate the global temperature history and the comparison of proxy data with instrument data from recent times. This may be science but it is being used to deceive the public into believing that anthropogenic global warming (AGW) is a crisis on an unprecedented scale.
It is well known that water, H2O, is the single most important greenhouse gas. But water also plays a central role in determining the delicate balance of energy and mass that regulates the temperature of Earth. A wide range of predictions have been made regarding water in a warming climate, ranging from catastrophic droughts to increased monsoon rains and tropical storms. Conventional wisdom states that a warmer world is a wetter world. In a newly published paper in the journal Science, two researchers examine the Eocene (∼56 to 34 million years ago), looking for clues to the tropical climate–water relationship. Annual global temperatures during the Early Eocene Climatic Optimum (EECO) around 50 million years ago were as much as 12°C higher than modern values. The new results provide compelling evidence that the tropical engine of the water cycle was more active than predicted by current climate models.
Around 19,000 years ago, oceanic conditions underwent dramatic changes that coincided with a shift in global climate, marking the onset of the Holocene warming. In the North Atlantic, major changes in the Meridional Overturning Circulation (MOC), which carries warm and highly saline surface water north to cooler regions, played a substantial role in regulating climate and levels of atmospheric carbon dioxide. Scientists are now convinced that the ocean absorbed, stored, and released vast quantities of carbon in the past, playing a major role in the end of the last Pleistocene Ice Age glacial period. Understanding the ocean's role in the past is important to understanding how it may influence climate in the future. A new report in Science shows that the MOC experienced a series of abrupt changes that lasted from decades to centuries, and may have stored and released more CO2 than previously thought.
The influence of the Sun on Earth’s climate over time scales of centuries and millennia is all but ignored by current climate change dogma, with many climate scientists dismissing solar variation as too feeble to have much of an impact. Though it was recently discovered that variation at ultraviolet wavelengths is considerably greater than at lower frequencies, the change in total solar irradiance over recent 11-year sunspot cycles amounts to <0.1%. New research on longer time scales finds the change in total irradiance sufficient to affect the dynamics of the El Niño–Southern Oscillation (ENSO). Detailed model studies of the Little Ice Age (~1400 to 1850 AD) conclude that the Sun controls an “ocean dynamical thermostat” that affects climate variability over large regions of the globe. It was also found that fully coupled general circulation models (GCMs), the kind used by the IPCC to make predictions of future global warming, lack a robust thermostat response. This means that the sensitivity of the climate system to solar forcing is underestimated by current GCMs—the climate models are proven wrong again.
Climate scientists continue to be fascinated with the Paleocene–Eocene Thermal Maximum (PETM), which took place about 55 Myr ago. This period of sudden global warming and increasing atmospheric CO2 represents a possible model our present era of warming climate and growing CO2 emissions. Studying the PETM, therefore, may provide insight into climate system sensitivity and feedbacks. Just such a study, reported in Nature Geoscience, found that CO2 forcing alone was insufficient to explain the PETM warming. Scientists speculate that other processes and/or feedbacks, hitherto unknown, must have caused a substantial portion of the warming during the Paleocene–Eocene Thermal Maximum. Simply put, CO2 did not cause the PETM climate change.
Increased insolation 20,000 years ago caused deglaciation in the Northern Hemisphere, according to a new report in the August 7, 2009, edition of Science. Further more, it was the onset of deglaciation of the West Antarctic Ice Sheet, which occurred between 14 - 15 thousand years ago, that was the source of sea-level rise at the beginning of the Holocene warming. Such events are often associated with rising CO2 levels by climate catastrophists but the evidence says otherwise.
When it comes to climate, the early Paleogene period (~65-34 mya), at the start of the Cenozoic Era, had one of the most Eden like climates of the Phanerozoic Eon. As the Cenozoic progressed a cooling trend set in leading up to the formation of permanent ice caps and the Pleistocene Ice Age we are still experiencing. But before the world started to ice up our planet underwent one of the most dramatic bouts of global warming known to science—the Paleocene Eocene Thermal Maximum or PETM. Recently, global warming activists have tried to liken human CO2 emissions to the cause of the PETM, 55 million years ago. Is it true, that our actions may trigger a sudden sharp rise in global temperature?
Around 1.2 million years ago, a shift in global climate began that caused a change in the timing of the alternating warm and cold periods—called interglacials and glacials—that have persisted during the Pleistocene Ice Age. Prior to that time, ice age glacial periods lasted about 40,000 years but since ~700,000 years ago ice-age cycles have lasted for around 100,000 years. Orbital variations, called the Croll-Milankovitch cycles, do exert some forcing on the 100,000 year time scale, but it is relatively weak. Orbital cycles seem to many too feeble an explanation for the change in glacial-interglacial timing. Some scientists have attempted to attribute the timing shift to a drop in CO2 but a new study confirms that carbon dioxide levels were not the cause of the climate shift.