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The new convention is to refer to “global warming” (something many have told us to worry about) as “climate change” (meaning pretty much the same thing since it’s supposed to be bad and caused by us anyway). The main difference appears to be that climate change is even worse, since global warming also causes global cooling along with a seemingly endless variety of other carbon dioxide-induced upheavals that we are responsible for.
So whenever someone asks whether I believe in global warming, (aka climate change) the simple answer is YES. In fact, I don’t really know anyone who doesn’t. If so they clearly aren’t very old or observant! On the other hand, I don’t buy into the causes, consequences or remedies that alarmists project.
Cyclical, abrupt and dramatic global and regional temperature fluctuations have occurred over millions of years, long before humans invented agriculture, industries, internal combustion engines or carbon-trading schemes. Many natural factors are known to contribute to these changes, although even the most sophisticated climate models and theories cannot even begin to predict the timing, scale (either up or down) or future impacts — much less the marginal contributions of various human influences.
And while global warming has been trumpeted as an epic climate change crisis with human-produced CO2, a trace atmospheric “greenhouse gas” branded as a primary culprit and endangering “pollutant”, don’t be too sure about the veracity of those pitches. Throughout earlier periods of Earth’s history those levels have been many times higher than today, with temperature changes preceding — not following — atmospheric CO2 changes. It doesn’t require a degree in a climate science, or rocket science either for that matter, to understand these basic facts.
Fossil records reveal that atmospheric CO2 levels around 600 million years ago were about 7,000 parts per million, compared with 379 ppm in 2005. Then approximately 480 million years ago those levels gradually dropped to 4,000 ppm over about 100 million years, while average temperatures remained at a steady 72 degrees. They then jumped rapidly to 4,500 ppm and guess what! Temperatures dove to an estimated average similar to today, even though the CO2 level was around twelve times higher than now. Yes, as CO2 went up, temperatures plummeted.
About 438 million years ago, atmospheric CO2 dropped from 4,500 ppm to 3,000 ppm, yet according to fossil records, world temperatures shot rapidly back up to an average 72 degrees. So regardless of whether CO2 levels were 7,000 ppm or 3,000 ppm, temperatures rose and fell independently.
Over those past 600 million years there have been only three periods, including now, when Earth’s average temperature has been as low as 54 degrees. One occurred about 315 million years ago, during a 45-million-year-long cool spell called the Late Carboniferous period, which established the beginning of most of our planet’s (gasp) coalfields. Both CO2 and temperatures shot back up at the end of it just when the main Mesozoic dinosaur era was commencing. CO2 levels rose to between 1,200 ppm and 1,800 ppm, and temperatures again returned to the average 72 degrees that Earth seemed to prefer.
Around 180 million years ago, CO2 rocketed up from about 1,200 ppm to 2,500 ppm. And would you believe it? This coincided again with another big temperature dive from 72 degrees to about 61 degrees. Then at the border between the Jurassic period when T. Rex ruled and the Cretaceous period that followed, CO2 levels dropped again, while temperatures soared back to 72 degrees and remained at that level (about 20 degrees higher than now) until long after prodigious populations of dinosaurs became extinct. And flatulent as those creatures may possibly have been, at least there is no evidence that they burned coal or drove SUVs.
Based upon a variety of proxy indicators, such as ice core and ocean sediment samples, our planet has endured large climate swings on a number of occasions over the past 1.5 million years due to a number of natural causes. Included are seasonal warming and cooling effects of plant growth cycles, greenhouse gases and aerosols emitted from volcanic eruptions, Earth orbit and solar changes, and other contributors with combined influences. Yet atmospheric CO2 levels have remained relatively low over the past 650,000 years, even during the six previous interglacial periods when global temperatures were as much as 9 degrees warmer than temperatures we currently enjoy.
Over the past 400,000 years, much of the Northern Hemisphere has been covered by ice up to miles thick at regular intervals lasting about 100,000 years each. Much shorter interglacial cycles like our current one lasting 12,000 to 18,000 years have offered reprieves from bitter cold. Yes, from this perspective current temperatures are abnormally warm. By about 12,000 to 15,000 years ago Earth had warmed enough to halt the advance of glaciers and cause sea levels to rise, and the average temperature has gradually increased on a fairly constant basis ever since, with brief intermissions.
During a period from about 750 BC to 200 BC, before the founding of Rome, temperatures dropped and European glaciers advanced. Then the climate warmed again, and by 150 BC grapes and olives were first recorded to be cultivated in northern Italy. As recently as 1,000 years ago (during the “Medieval Warm Period”), Icelandic Vikings were raising cattle, sheep and goats in grasslands on Greenland’s southwestern coast. Then, around 1200, temperatures began to drop, and Norse settlements were abandoned by about 1350. Atlantic pack ice began to grow around 1250, and shortened growing seasons and unreliable weather patterns, including torrential rains in Northern Europe led to the “Great Famine” of 1315-1317.
Temperatures dropped dramatically in the middle of the 16th century, and although there were notable year year-to-year fluctuations, the coldest regime since the last Ice Age (a period termed the “Little Ice Age”) dominated the next hundred and fifty years or more. Food shortages killed millions in Europe between 1690 and 1700, followed by more famines in 1725 and 1816. The end of this time witnessed brutal winter temperatures suffered by Washington’s troops at Valley Forge in 1777, and Napoleon’s bitterly cold retreat from Russia in 1812.
Although temperatures have been generally mild over the past 500 years, we should remember that significant fluctuations are normal. The past century has witnessed two distinct periods of warming. The first occurred between 1900 and 1945, and the second, following a slight cool-down began quite abruptly in 1975. That second period rose at quite a constant rate until 1998, and then stopped and began falling again after reaching a high of 1.16 degrees above the average global mean.
About half of all estimated warming since 1900 occurred before the mid-1940s despite continuously rising CO2 levels. Even U.K. East Anglia University Climate Research Unit (CRU) Director Phil Jones has admitted that there has been no statistically significant warming for at least a decade. He has also admitted that temperatures during the Middle Ages may have been higher than today.
So perhaps you’ll wish to ponder this question; Given that over most of the Earth’s known climate history, the atmospheric CO2 levels have been between four and eighteen times higher than now – throughout many times when life not only survived but also flourished; times that preceded humans; times when CO2 levels and temperatures moved in different directions – how much difference will putting caps on emissions accomplish? Consider also that about 97% of all current atmospheric CO2 derives from natural sources.
And yes, change is the true nature of climate. After all, if climate didn’t change, we really wouldn’t need a word for it would we? Wouldn’t it all just be “weather”?
's Categories: Op/Ed, byline=Larry Bell
Larry you mentioned a lot of information there which may seem to infer you are beyond reproach in your argument. However not only did you start with a faulty premise (that we humans are not responsible for climate change) but you have ignored a lot on the other side of the argument too. The atmospher is a balance of elements such as nitrogen, oxygen, carbon dioxide, etc. The atmosphere at any time is like a “closed loop” where matter decays and gives off CO2, trees take in CO2 and give out oxygen as do phytoplankton; animalas and people breathe out CO2 and take in oxygen, etc. The balance of the closed loop is robust and can handle changes that occur over time. Such things as volcanic eruptions can shift that balance suddenly. But something that dramatic has not happened in this age yet CO2 has risen beyond the safe level of 350 parts per million since 1998. Burning coal and oil that has been buried deeply in the earth and took millions of atmospheres to form, goes into this atmosphere, the one you and I are breathing right now and alters the balance markedly. It’s a bit like an overdose of carbon. Coupled with that is the removal of carbon uptake vehicles such as trees, and shifts in currents due to warming causing changes to phytoplankton populations (this has huge consequences). But that’s not all! As CO2 raises temperatures (yes you said temp rises occurred before CO2 rises in the past) but regardless, as the oceans are warming and the ice melting, yes raising sea levels true, but most of all causing the permafrost to melt also. Melting permafrost releases trapped methane, a gas 20 times more potent in greenhouse characteristics than CO2. Once that happens we’ve really got no foreseable way of stopping a chain reaction leading to inhospitable planetary results. Now if that’s not a reason to sound urgent I don’t knwo what is but sounding urgent somehow is poo-pooed because no one wants to change the way they do things. We can still have progress and use energy but it’s got to be clean and renewable of which there is ample, like wave and solar and wind. How are you and those who think as you do, going to recompense the rest of us if you are wrong? You need to see this: http://www.ted.com/talks/kathryn_schulz_on_being_wrong.html
Mr. Bell
every scientists trained in climate science would say you are 100% wrong.
C02 throughout earths long history has regulated the temperature of the planet. Lets cover the last 55 million years- going back 400 million years leaves too much information out of making an objective evaluation of climate and global temperatures.
Over the last 55 million years we have had two major warming events- both caused by significant carbon forcing- the ‘PETM’ the so called Paleocene"“Eocene Thermal Maximum
Global temperatures rose by about 6°C (11°F) over a period of approximately 20,000 years
The latter observations strongly suggest that a massive input of 13C-depleted carbon entered the hydrosphere or atmosphere at the start of the PETM. Recently, geoscientists have begun to investigate the PETM in order to better understand the fate and transport of increasing greenhouse-gas emissions over millennial time scales.
verage global temperatures increased by ~6°C (11°F) within about 20,000 years. This is based on several lines of evidence. There is a prominent (>1"°) negative excursion in the ?18O of foraminifera shells, both those made in surface and deep ocean water. Because there was a paucity of continental ice in the early Paleogene, the shift in ?18O very likely signifies a rise in ocean temperature. The temperature rise is also supported by analyses of foraminifera Mg/Ca and ratios of certain organic compounds.
Due to the positive feedback effect of melting ice reducing albedo, temperature increases would have been greatest at the poles, which reached an average annual temperature of 10 to 20 °C (50 to 68 °F); the surface waters of the northernmost[8] Arctic ocean warmed, seasonally at least, enough to support tropical lifeforms requiring surface temperatures of over 22°C.
Evidence for carbon addition Clear evidence for massive addition of 13C-depleted carbon at the onset of the PETM comes from two observations. First, a prominent negative excursion in the carbon isotope composition (?13C) of carbon-bearing phases characterizes the PETM in numerous widespread locations from a range of environments. Second, carbonate dissolution marks the PETM in sections from the deep-sea.
There was a similar spike in carbon and temperatures in the Eocene- some 15 millions after.
Since then the earth has had no other similar warming events- except during interglacial’s- which are not caused so much by carbon, but by changes in the earths orbit.
When James Hansen talks climate change, people listen. The head of climate studies at NASA, Hansen first gave evidence on the issue to the US Congress in 1988, and is now an eminent scientist and a prominent public advocate.
In new research just out, Hansen concludes that at the current temperature, no "cushion" is left to avoid dangerous climate change, and that the Australian government target goals ""¦ of limiting human-made warming to 2° and CO2 to 450 ppm are prescriptions for disaster".
The question Hansen raises is direct and brutal in its implications: is the planet already entering a zone of dangerous climate change?
With Arctic sea-ice in a "death spiral", Greenland in 2010 melting at an unprecedented rate, a seemingly extraordinary number of extreme climate events in the past year from the Russian fires to the Pakistan floods, and 18 countries setting temperature records, have we already gone too far for a safe climate?
In a draft of a new research paper, Hansen and his collaborator Makiko Sato has opened a new debate about what might be the conditions for a safe climate; that is, one in which people and nations can continue to live where and as they have been, with secure food production, and in a bio-diverse environment.
The period of human settlement over the past 10,000 years is known as the Holocene, during which time temperatures and hence sea levels (the two having a close correspondence) have been remarkable stable. Temperatures over the period have not been more than 0.5C warmer or cooler than the mid-line (see chart). The warmest part of the Holocene (the "Holocene maximum") was about 8000 years ago, and according to Hansen, today's temperature is about, or slightly above, the Holocene maximum:
""¦ we conclude that, with the global surface warming of 0.7C between 1880 and 2000, global temperature in year 2000 had returned, at least, to approximately the Holocene maximum."
Note, this is to the year 2000, and temperatures have increased ~0.15C in the last decade, so:
"Global temperature increased 0.5C in the past three decades to a level comparable to the prior Holocene maximum, or a few tenths of a degree higher."
That is, we are already a little above the Holocene maximum. This matters because Hansen's and Sato's look at climate history (paleoclimatology) in this new research finds that it is around this temperature level that the large polar ice sheets start to behave differently. During the Holocene, the Greenland and Antarctic ice sheets have been relatively stable, as reflected in the stability of the sea level. But once substantial melting starts, the loss of heat-reflecting white sea-ice, which is replaced by heat-absorbing dark ocean water, produces an "albedo flip":
"Summer melting on lower reaches of the ice sheets and on ice shelves introduces the "albedo flip" mechanism. This phase change of water causes a powerful local feedback, which, together with moderate global warming, can substantially increase the length of the melt season. Such increased summer melting has an immediate local temperature effect, and it also will affect sea level."
""¦ the stability of sea level during the Holocene is a consequence of the fact that global temperature remained just below the level required to initiate the "?albedo flip' mechanism on Greenland and West Antarctica."
The implication is clear that "just above" the Holocene maximum lurks real danger. As Hansen and Sato say:
""¦ the world today is on the verge of a level of global warming for which the equilibrium surface air temperature response on the ice sheets will exceed the global mean temperature increase by much more than a factor of two."
That is, warming at the poles will become more rapid and exceed the ratio so far, of being twice then global average. This change, they say, can be found in past warming events such as the Pliocene about 3 million years ago, so that:
""¦ even small global warming above the level of the Holocene begins to generate a disproportionate warming on the Antarctic and Greenland ice sheets. "
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