It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
originally posted by: systemic.aberration
Here's a crazy thought: Maybe nobody (and i mean NOBODY) actually understands the dynamics of climate change... So all this data, and all these trends, and all these contradictory results are just more evidence that nobody knows what the hell they are talking about (yet). Just keep in mind, science is not an endpoint, it's a process.
originally posted by: Xeven
Maybe our warming of the Earth has saved us from an Ice Age. Had we not spent last 100 years warming the earth with carbon maybe we would be freezing about now or soon. You can't know for sure...Earth has regular Ice ages.
The Earth’s current warm period that began about 11,000 years ago should give way to another ice age within about 1,500 years, according to accepted astronomical models. However, current levels of carbon dioxide are trapping too much heat in the atmosphere to allow the Earth to cool as it has in its prehistoric past in response to changes in Earth’s orbital pattern.
The research team, a collaboration among University College London, University of Cambridge and UF, said their data indicate that the next ice age will likely be delayed by tens of thousands of years.
The last interglacial climate interval ended about 120 000 yr BP when new glaciation began in Canada after about 6000 yr of a warm and relatively stable climate. The present interglacial has now also lasted about 6000 yr, and the idea of an imminent renewal of ice sheet growth has occupied the attention of many workers in the climate field for almost a century. The suspected cause of the ending of the last interglacial was decreasing Northern Hemisphere summer insolation due to cyclic change of Earth’s orbital parameters. This is widely assumed to have caused a cooling that initiated ice sheet growth.
However, in an exhaustive study Rind et al. (1989) used the values of Milankovitch insolation in the general circulation model of the Goddard Institute for Space Studies and were unable to initiate glacial ice cover in Northern high-latitude regions. They concluded that: “If the model was correct . . . we really do not understand the cause of ice ages and the Milankovitch connection.”
This paper proposes a more subtle connection between ice age initiation and orbital change, and addresses the question: Why was the last ice age triggered so abruptly after about 6000 yr of quite ice-free Northern interglacial climate? And what does the proposed explanation imply for possible future climate change?
We predict that a carbon release from fossil fuels or methane hydrate deposits of 5000 Gton C could prevent glaciation for the next 500,000 years, until after not one but two 400 kyr cycle eccentricity minima. The duration and intensity of the projected interglacial period are longer than have been seen in the last 2.6 million years.
Differences in the duration of interglacials have long been apparent in palaeoclimate records of the Late and Middle Pleistocene. However, a systematic evaluation of such differences has been hampered by the lack of a metric that can be applied consistently through time and by diffculties in separating the local from the global component in various proxies. This, in turn, means that a theoretical framework with predictive power for interglacial duration has remained elusive.
This analysis suggests that the insolation minimum at 397 ka BP, which provides the best available analogue to the present insolation minimum, terminated interglacial conditions in Europe. At that time, tundra–steppe vegetation spread in Central Europe and pine forests dominated in the eastern Mediterranean region.
Because the intensities of the 397 ka BP and present insolation minima are very similar, we conclude that under natural boundary conditions the present insolation minimum holds the potential to terminate the Holocene interglacial. Our findings support the Ruddiman hypothesis (Early Anthropogenic Hypothesis), which proposes that early anthropogenic greenhouse gas emission prevented the inception of a glacial that would otherwise already have started.
The Early Anthropogenic Hypothesis considers that the natural evolution of climate consisted in a decline in greenhouse gas concentrations throughout the Holocene, leading today to conditions favourable to accumulation of ice in the Northern Hemisphere (Ruddiman et al. (2011) and references therein).
This hypothesis supposes an important premise: it is possible to predict the slow evolution of climate several millennia ahead. Indeed, suppose that climatologist lived 8,000 years ago. What the Early Anthropogenic Hypothesis says is that a forecast for the 8,000 years to come made by this early climatologists would have been a decline in greenhouse gas concentrations and ultimately, glacial inception.
Throughout this paper we will consider that this premise should not be taken for granted.
The next 20 kyr will have an abnormally high greenhouse effect which, according to the CO2 values, will lengthen the present interglacial by some 25 to 33 kyr. This is because the perturbation of the current interglacial will lead to a delay in the future advance of the ice sheet on the Antarctic shelf, causing that the relative maximum of boreal insolation found 65 kyr after present (AP) will not affect the developing glaciation. Instead, it will be the following insolation peak, about 110 kyr AP, which will find an appropriate climatic state to trigger the next deglaciation.
In the “before” picture (moving the slider all the way to the right), you can see lots of ice in the water. Note, though, the ice piled up along the coastline. You can see the muddy water pooling in fingers stretching toward the water. That ice acted as a dam, holding the water back.
In the “after” picture (slider to the left) the dam is gone, and you can see the river water infiltrating the sea—the brown swirls are sediment washing out into the sea. Sometime in the intervening weeks the warm river water melted the ice dam and broke through, flooding the sea. This sudden infiltration of warm water raised the temperature of the sea considerably, melted the ice floating beyond.
The darkest blue is cold water/ice at about -2° C, and white/lavender is +15° C. As you can see, in just a few weeks the temperature went up substantially; in some places it went up about 15° Celsius, a huge increase in thermal energy; by my rough calculations it would far, far exceed the energy released by a nuclear weapon.
No wonder that ice melted.
Scientists think this is what contributed to the huge drop in Arctic ice that year. If the water were to move into the sea more slowly (as it usually does), then there would be time for its excess heat to radiate away into the atmosphere or be dropped into deeper waters. Instead, the sudden inundation due to the ice dam breaking dumped all that warmth into the sea surface, where it could melt the ice.
That’s why 2012 saw record low ice in the Arctic. The next year, things were more normal, and the ice extent and volume were more like they had been in previous years.