NASA Study Finds World Warmth Edging Ancient Levels

NASA GISS ^ | September 26, 2006 | NASA GISS

[cogitator]

A new study by NASA scientists finds that the world's temperature is reaching a level that has not been seen in thousands of years.

The study, led by James Hansen of NASA's Goddard Institute for Space Studies, N.Y., along with scientists from other organizations concludes that, because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels in the current interglacial period, which has lasted nearly 12,000 years. An "interglacial period" is a time in the Earth's history when the area of Earth covered by glaciers was similar or smaller than at the present time. Recent warming is forcing species of plants and animals to move toward the north and south poles.

The study used temperatures around the world taken during the last century. Scientists concluded that these data showed the Earth has been warming at the remarkably rapid rate of approximately 0.36° Fahrenheit (0.2° Celsius) per decade for the past 30 years.

"This evidence implies that we are getting close to dangerous levels of human-made pollution," said Hansen. In recent decades, human-made greenhouse gases have become the largest climate change factor. Greenhouse gases trap heat in the Earth's atmosphere and warm the surface. Some greenhouse gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities.

The study notes that the world's warming is greatest at high latitudes of the Northern Hemisphere, and it is larger over land than over ocean areas. The enhanced warming at high latitudes is attributed to effects of ice and snow. As the Earth warms, snow and ice melt, uncovering darker surfaces that absorb more sunlight and increase warming, a process called a positive feedback. Warming is less over ocean than over land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there.

Hansen and his colleagues in New York collaborated with David Lea and Martin Medina-Elizade of UCSB to obtain comparisons of recent temperatures with the history of the Earth over the past million years. The California researchers obtained a record of tropical ocean surface temperatures from the magnesium content in the shells of microscopic sea surface animals, as recorded in ocean sediments.

One of the findings from this collaboration is that the Western Equatorial Pacific and Indian Oceans are now as warm as, or warmer than, at any prior time in the Holocene. The Holocene is the relatively warm period that has existed for almost 12,000 years, since the end of the last major ice age. The Western Pacific and Indian Oceans are important because, as these researchers show, temperature change there is indicative of global temperature change. Therefore, by inference, the world as a whole is now as warm as, or warmer than, at any time in the Holocene.

According to Lea, "The Western Pacific is important for another reason, too: it is a major source of heat for the world's oceans and for the global atmosphere."

In contrast to the Western Pacific, the researchers find that the Eastern Pacific Ocean has not shown an equal magnitude of warming. They explain the lesser warming in the East Pacific Ocean, near South America, as being due to the fact this region is kept cool by upwelling, rising of deeper colder water to shallower depths. The deep ocean layers have not yet been affected much by human-made warming.

Hansen and his colleagues suggest that the increased temperature difference between the Western and Eastern Pacific may boost the likelihood of strong El Ninos, such as those of 1983 and 1998. An El Nino is an event that typically occurs every several years when the warm surface waters in the West Pacific slosh eastward toward South America, in the process altering weather patterns around the world.

The most important result found by these researchers is that the warming in recent decades has brought global temperature to a level within about one degree Celsius (1.8°F) of the maximum temperature of the past million years. According to Hansen, "That means that further global warming of 1 degree Celsius defines a critical level. If warming is kept less than that, effects of global warming may be relatively manageable. During the warmest interglacial periods the Earth was reasonably similar to today. But if further global warming reaches 2 or 3 degrees Celsius, we will likely see changes that make Earth a different planet than the one we know. The last time it was that warm was in the middle Pliocene, about three million years ago, when sea level was estimated to have been about 25 meters (80 feet) higher than today."

Global warming is already beginning to have noticeable effects in nature. Plants and animals can survive only within certain climatic zones, so with the warming of recent decades many of them are beginning to migrate poleward. A study that appeared in Nature Magazine in 2003 found that 1700 plant, animal and insect species moved poleward at an average rate of 6 kilometers (about 4 miles) per decade in the last half of the 20th century.

That migration rate is not fast enough to keep up with the current rate of movement of a given temperature zone, which has reached about 40 kilometers (about 25 miles) per decade in the period 1975 to 2005. "Rapid movement of climatic zones is going to be another stress on wildlife," according to Hansen. "It adds to the stress of habitat loss due to human developments. If we do not slow down the rate of global warming, many species are likely to become extinct. In effect we are pushing them off the planet."

[RightWhale]

His tone of voice is exactly what grandfathers develop from explaining to grandkids why grass is green and the sky is blue and where the world came from even though the kids world extends to the street in front of their house and the bus ride to school. It is the 'I am being sincere' tone. All the senior Art Bell guests have that tone.

[Old Professer]

Between 1960 and 1963, if you looked up the temperature at Tyndall AFB on a given day, there is a high probability that I was the guy reading the thermometer; our temperature shelter was located on a hangar roof which housed the observation tower directly across from the ATC tower between the runways.

Most stations were located at approximately 6 feet above ground level for convenience and standardization.

We switched to electronic devices in 1962 and no longer made the trip down the steps to read the old mercury thermometers.

Since then most of the gauges have been automated and the majority worldwide now are largely unmanned.

There are a host of variables also subject to modernization that are largely smoothed by the sheer numbers of observation points all using instruments that are rarely calibrated.

Thirty years is but a blink in the eye of time.

[DBrow]

Lots of scienists know about the M cycles. I read lots of papers about "paleoclimate" and the longer-range papers all discuss Milankovitch. There are many papers about how well the fit is and why the 100 ky resonance is there.

Global Warming enthusiasts generally only use data for a few hundred years if that. The current flap about it being warmer in the past is supposed to strike fear in us, I think, but logically, if it was warmer in the past than now, does that not indicate cooling, and we may be getting back to normal?

The goal imo is global agrarian socialism and climate is just a way to get there. Once we have global agrarian socialism we'll stay there for at least the thousand years Marx wanted.

[cogitator]

If you read "State of Fear", you also need to read the scientific view of Crichton's book:

Michael Crichton's State of Confusion

Michael Crichton’s State of Confusion II: Return of the Science

[cogitator]

Thousands of years ago there were no SUVs to blame.

And it's been a relatively stable interglacial climate up until now, too.

[cogitator]

Oh my God, that's a little over 1 degree in 30 years.

0.2 C in 30 years is 1/3 of the total global temperature increase (approximately) from 1900-2000.

[cogitator]

There are plenty of leftists, and supporters of big and Bigger government, and doogooders who are willing to tell us how to mitigate it today. Oddly, nor maybe not so oddly, all their plans have a common thread: reduced liberty, increased costs and increased central control over the lives of the average person.

And that approach won't work. What is needed is increased efficiency with existing energy technology and new energy sources (as well as upgrades to existing and proven technologies, like nuclear power).

[cogitator]

Will they get warmer yet as the Milankovitch cycle continues?

Well, the problem is that this particular interglacial didn't seem particularly influenced by Milankovitch forcing, and therefore has exhibited very stable temperatures. So the only real forcing that might cause (and appears to be causing) increasing temperatures is increasing greenhouse gas concentrations in the atmosphere.

[cogitator]

First, the major premise contains an unproven assumption that the current postulated warming is not part of a natural statistical variation.

There are many indications that the current warming trend is not due to natural variation (primarily).

Conclusion: Changing human activity will stop global warming.

Hansen is actually a believer in alternate energy and new technology as the best way to address the situation.

Conclusion: Prudence demands implementing this change immediately.

Hansen has expressed the viewpoint that humanity, collectively, has a decade or so to start doing something substantial about global warming or irreversible changes with the potential to induce significant-to-severe climate alteration in the future will become much more probable.

In fact, ice core drillings have indicated that the earth has been warmer as well as cooler than it is now a number of times in the past without catastrophe.

Define "catastrophe" in this context. For the glacial-interglacial era, there have only been a few short periods during prior interglacials that were slightly warmer than now -- without the higher CO2 concentrations in the atmosphere that will contribute to even higher temperatures. So the Earth may be on the verge of entering an unprecedented climate state.

[cogitator]

According to the three cycles the northern Hemisphere currently should be due to return to glacial levels, ice core sediments also show that a warming spike was reached just before previous glacial epochs took hold.

A paper published in Science indicated that the expected next entry into a glacial epoch, based on Milankovitch forcing, is 50,000 years or so off.

Milankovitch cycles

"More recent work by Berger and Loutre suggests that the current warm climate may last another 50,000 years." Citation: Berger A, Loutre MF (2002). "Climate: An exceptionally long interglacial ahead?". Science 297 (5585): 1287-1288.DOI:10.1126/science.1076120.

[cogitator]

Also the most misleading result.

I agree and I think that this was done to attract attention. The more immediate concern is the 0.2 C rise in the past 30 years. If you are going to compare to temperatures over the whole past million years, you have to address the time-scale of various forms of variability.

[Wuli]

This report is a study in contradictions and assumptions; assumptions made on information that is, by all scientific acknowledgement, less that all that needs to be known. The "scientific" models are built on data that the scientists know has gaps and complete holes in places, in some areas that they know as major factors in earth heat generation and cycles.

"This evidence implies that we are getting close to dangerous levels of human-made pollution," said Hansen. In recent decades, human-made greenhouse gases have become the largest climate change factor. Greenhouse gases trap heat in the Earth's atmosphere and warm the surface. Some greenhouse gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities."

Contradictions that produce false claims: (a)"human-made greenhouse gases have become the largest climate change factor"; (b)"greenhouse gases which include water vapor, carbon dioxide, methane, nitrous oxide and ozone, while others are due to human activities"; however (c)water vapor is the largest component of "greenhouse gases" responsible for climate change and (d)most atmospheric water vapor is not "human made" and humans have almost zero ability to control it. See: http://www.geocraft.com/WVFossils/greenhouse_data.html

"The study notes that the world's warming is greatest at high latitudes of the Northern Hemisphere, and it is larger over land than over ocean areas. The enhanced warming at high latitudes is attributed to effects of ice and snow. As the Earth warms, snow and ice melt, uncovering darker surfaces that absorb more sunlight and increase warming, a process called a positive feedback. Warming is less over ocean than over land because of the great heat capacity of the deep-mixing ocean, which causes warming to occur more slowly there."

The above statement is not science or it is terribly bad communication. The atmosphere and the oceans circulate any and all earth warming or cooling. Yes, there are temperature differences, due to the specifics of a particular location such as latitude (closer to the poles or closer to the equator), altitude (elevation above sea level), path of prevailing jet-stream and trade wind patterns and other factors. But, the description in the preceding paragraph is a description of affects, not causes. The northern latitudes are not "warming" because the snow and ice are melting, exposing more land. The snow and ice are melting because it is warming there. The heat that is absorbed does contribute to warming ground temperatures, but it does not contribute immensely to warmer atmospheric temperatures and would cease to be a factor if (and when) atmospheric temperatures drop.

What has actually been observed in the northernmost latitudes is areas of snow and ice melt nearest the oceans (like Greenland and Antarctica) which has (a)reduced glaciers at the waters edge and melted snow nearest the oceans, and (b)produced greater local water vapor which when meeting the atmosphere has produced greater snow fall, which has produced much deeper and denser snow packs inland, which in affect is (c)building the makings of the next phase of glacial expansion when the warming cycle recedes again.

"The California researchers obtained a record of tropical ocean surface temperatures from the magnesium content in the shells of microscopic sea surface animals, as recorded in ocean sediments......One of the findings .........is that the Western Equatorial Pacific and Indian Oceans are now as warm as, or warmer than, at any prior time in the Holocene" - the Holocene is our current "relatively warm period that has existed for almost 12,000 years, since the end of the last major ice age. The Western Pacific and Indian Oceans are important because, as these researchers show, temperature change there is indicative of global temperature change."

Here where the science is slipping up. The oceans cover 2/3 of the earth. What happens in and under the oceans and between the oceans and the atmosphere is 2/3 of the climate story but probably less than 10% of the known data. Why? The earth, through its molten core, its magnetic field, its tectonic activity (shifting plates of land sliding around the earth) is a huge heat generator and dispenser. Most of that heat, from earthquakes, to volcanoes and millions of fissures, from tiny to immense, is dispensed under the oceans, absorbed by ocean water and transported to the atmosphere (and back) in the form of water vapor. Which, the link above has already told you is more dense lately, and the largest contributor to "global warming". And yet, that activity is not constant in its severity or its distribution. And, this part of the science is the weakest part in terms of data to represent this activity.

http://www.sciencedaily.com/releases/2006/07/060727180622.htm

http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2003/pressRelease20030718/index.html

"According to Lea, 'The Western Pacific is important for another reason, too: it is a major source of heat for the world's oceans and for the global atmosphere." In contrast to the Western Pacific, the researchers find that the Eastern Pacific Ocean has not shown an equal magnitude of warming. They explain the lesser warming in the East Pacific Ocean, near South America, as being due to the fact this region is kept cool by upwelling, rising of deeper colder water to shallower depths. The deep ocean layers have not yet been affected much by human-made warming.

And yet that explanation should also hold true for the northeastern Pacific, but it does not, because it is warmer than the eastern Pacific in the south and warmer than the western Pacific. Since the water and atmospheric flows are generally west to east (caused by the earth's rotation), what is under the middle of the northern Pacific that makes it warmer, and thus increases the northern Pacific's contribution of water vapor - the largest green house gas?

[Lucky Dog]

Hansen is actually a believer in alternate energy and new technology as the best way to address the situation.

One believes in a theological proposition. Scientific judgments are properly based upon facts and logic not belief.

My point is, very simply, that there is insufficient evidence that so-called, global warming is anything other than a naturally occurring phenomenon. Consequently, it is both premature and unfounded to assume that humankind can do much, if anything, to either mitigate, or exacerbate it.

Hansen has expressed the viewpoint…

As it is based upon unproven supposition as to the causes of so-called global warming (if such even exists), Hansen’s viewpoint is scientifically extraneous and irrelevant.

For the glacial-interglacial era, there have only been a few short periods during prior interglacials that were slightly warmer than now --

This statement, alone, logically destroys the argument that so-called global warming is, conclusively and exclusively, the result of human activity. If the global temperatures at any time prior to the industrial revolution were ever equal to, or warmer than the present, then there are obviously natural mechanisms which were responsible for that increase and could be so, again, in the present.

So the Earth may be on the verge of entering an unprecedented climate state.

Then, again, it may not…

[DBrow]

"this particular interglacial didn't seem particularly influenced by Milankovitch forcing,"

Previous interglacials have been measured using sediment strata which average results considerably.

The data for this interglacial is much more recent and for hundreds of years has had direct measurement. We also are blessed with measurements of solar output, which is sparse for other cycles.

It could be that the "stability" we enjoy is the change of slope from positive to negative at the top of the curve.

I've read nothing to suggest that this interglacial is any different from the others in terms of Milankovitch forcing.

What have you seen to support lack of orbital forcing?

[cogitator]

however (c)water vapor is the largest component of "greenhouse gases" responsible for climate change and (d)most atmospheric water vapor is not "human made"

Water vapour: feedback or forcing?

What happens in and under the oceans and between the oceans and the atmosphere is 2/3 of the climate story but probably less than 10% of the known data. Why? The earth, through its molten core, its magnetic field, its tectonic activity (shifting plates of land sliding around the earth) is a huge heat generator and dispenser. Most of that heat, from earthquakes, to volcanoes and millions of fissures, from tiny to immense, is dispensed under the oceans, absorbed by ocean water and transported to the atmosphere (and back) in the form of water vapor.

The temperature of the global water column (from 0-3,000 meters) has been measured at numerous points around the world. A compilation of this data (by Levitus) indicated a clear warming of the water column, with most of the warming at the surface and just a little penetrating to depth, as would be expected. Heat from volcanic sources is negligible as a contribution to warming or the water vapor "budget".

And yet that explanation should also hold true for the northeastern Pacific, but it does not, because it is warmer than the eastern Pacific in the south and warmer than the western Pacific. Since the water and atmospheric flows are generally west to east (caused by the earth's rotation), what is under the middle of the northern Pacific that makes it warmer, and thus increases the northern Pacific's contribution of water vapor - the largest green house gas?

There isn't a lot of upwelling in the northeastern Pacific. There's a little on the PacNW and California coast, but not nearly as much as the Peru Upwelling.

[Justa]

"0.2 C in 30 years is 1/3 of the total global temperature increase (approximately) from 1900-2000."

And 30 years is about 1/3 of the time between 1900 and 2000. Your point?

Temperatures are simply returning to the norm they were at 1000 years ago before the Little Ice Age. One study of the Milankovitch cycles by Berger and Loutre predicts the current warm climate may last another 50,000 years.

[cogitator]

My point is, very simply, that there is insufficient evidence that so-called, global warming is anything other than a naturally occurring phenomenon.

Your point is incorrect.

Attribution of recent climate change

A quote from one of the many cited articles: "A recent paper (Estimation of natural and anthropogenic contributions to twentieth century temperature change, Tett SFB et al., JGR 2002), says that "Our analysis suggests that the early twentieth century warming can best be explained by a combination of warming due to increases in greenhouse gases and natural forcing, some cooling due to other anthropogenic forcings, and a substantial, but not implausible, contribution from internal variability. In the second half of the century we find that the warming is largely caused by changes in greenhouse gases, with changes in sulphates and, perhaps, volcanic aerosol offsetting approximately one third of the warming."

If the global temperatures at any time prior to the industrial revolution were ever equal to, or warmer than the present, then there are obviously natural mechanisms which were responsible for that increase and could be so, again, in the present.

"Could be responsible" does not mean that they are responsible. Please read the link that I provided. The scientists have assessed the contributions of natural factors and the assessment indicates that natural factors are insufficient to produce the major part of the observed warming trend.

[ohioman]

The climate has been stable my Arse. Climate has always had its fluctuations. Did you forget about the Little Ice Age? Also, Greenland was much warmer back when the Viking settled there than it is now.

[cogitator]

First this chart (based on Vostok ice core data):

The current interglacial is the blue zone starting about 10,000 years BP. It's fairly obvious from this chart that the interglacial temperature pattern was "spikier" in the previous interglacials than the current one. (And if this data is believed, then it appears that the peak temperatures of previous interglacials were somewhat higher than present, so I don't know if Hansen is taking a more global view. This is, after all, ultimately representative primarily of Antarctic temperatures with an overlying global pattern).

Anyway, go to this article:

Milankovitch cycles

and read the "Present Conditions" section. If you're really intrigued, you may want to try and get the Berger and Loutre paper, reference 8. This was an important paper and I wish it was available for free online, but I can't find it anywhere.

[cogitator]

Did you forget about the Little Ice Age?

No. The Holocene climate is very stable compared to other interglacials. See the chart in the post above this one.