The phrase
"warm interglacials" refers to periods of time in Earth's history when the climate was relatively warm and stable between ice ages.
Full definition
Many of the glaciers that jut out into the ocean are thinning, but whether the ice sheet itself has remained stable and intact, even
during warm interglacial periods, is a matter of considerable debate.
a) a glacial cycle over 100,000 years
with warm interglacial periods in red and the long glacial period in between.
They have further discovered that there is a difference in the fractal behaviour in the ice age climate and in the current
warm interglacial climate.
But an ice core collected in nearby Greenland suggests that the planet experienced continuous cold from 40,000 to about 115,000 years ago, when the
last warm interglacial period ended, Miller said.
«The time span of the last 130,000 years has seen the global climate system switch
from warm interglacial to cold glacial conditions, and back again.
Currently, the shifts between ice ages and
warm interglacial phases are thought to be influenced by three cyclical changes to Earth's motion.
The sediment cores used in this study cover a period when the planet went through many climate cycles driven by variations in Earth's orbit, from extreme glacial periods such as the Last Glacial Maximum about 20,000 years ago, when massive ice sheets covered the northern parts of Europe and North America, to
relatively warm interglacial periods with climates more like today's.
The WAIS has retreated at least once during the Pleistocene (38), but the full extent of retreat is not known, nor is whether it occurred in the Eemian or the long,
warm interglacial MIS - 11 ≈ 400 ka.
Russian astro - physicist Milankovich developed the understanding of the combinations of these cycles and how they interact to create out 30ma trend of long gradually declining ice ages interspersed with relatimely brief
global warm interglacials (like our present).
However the AND - 1B drill core indicates that it has retreated further south during
exceptionally warm interglacials, most recently probably during MIS 31 (though apparently not during MIS 5e or MIS 11 when the WAIS is often claimed to have melted).
«We have analyzed the transition from the last glacial period until our
present warm interglacial period, and the climate shifts are happening suddenly, as if someone had pushed a button,» said Dahl - Jenson.
But the calculations can only be done well when the temperature change is large, notably at glacial terminations (the gradual change from cold glacial climate to
warm interglacial climate).
The researchers particularly want to learn more about the Eemian Stage, the
last warm interglacial period before the current era.
Interestingly, assuming a ballpark figure of a 1.2 mm / year groundwater base flow, unbalanced groundwater discharge could also explain the much higher sea levels estimated for the
previous warm interglacial, the Eemian.
In the past 2m years the temperature has gone up and down like a yo - yo as ice ages have alternated
with warmer interglacial periods.
For the past million years, atmospheric CO2 has ranged from around 280 ppm
during warm interglacial periods to as low as 180 ppm during cold ice ages.
Researchers from the Niels Bohr Institute have analysed the natural climate variations over the last 12,000 years, during which we have had
a warm interglacial period and they have looked back 5 million years to see the major features of the Earth's climate.
The climate during
the warm interglacial periods is more stable than the climate of ice age climate.
Over the past 2 million years — the Quaternary period — these oscillations have increased in amplitude and global climate has lurched between periods of glaciation and
warmer interglacials.
For example, the polar bear specimen from roughly 120,000 years ago survived in Svalbard during
a warm interglacial period because that Arctic archipelago remained more frozen than other areas.
The geologic record shows that the differences in ice cover, sea level and precipitation as well as in plant and animal populations were quite dramatic between the ice ages and
the warm interglacials.
Previous estimates suggested that peak temperatures during
the warmest interglacial periods — which occurred at around 125,000, 240,000 and 340,000 years ago — were about three degrees higher than they are today.
But Sime's team says that although that relationship holds up for the cold glacial periods, it does not work so well during
the warmer interglacials.
Both dipped down during glacial ice ages and back up again during
warm interglacials.
Ice sheet models can be run through many glacial cycles (i.e. cold glacial periods and
warm interglacial periods).
Historically, methane concentrations in the world's atmosphere have ranged between 300 and 400 nmol / mol during glacial periods commonly known as ice ages, and between 600 to 700 nmol / mol during
the warm interglacial periods.
They also found that there were long periods when the speleothems didn't grow at all — certainly not during ice ages, when permafrost locked the soil across most of Siberia, but not even, in the northernmost caves, during
warmer interglacial periods, like the one we're in now when glaciers went into retreat.
Substantial and correlated changes in marine carbonate (CaCO3) content of oceanic sediments commonly accompany the transitions from cold glacial periods to
warm interglacial periods.
Over that time, the globally averaged temperature difference between the depth of an ice age and
a warm interglacial period was 4 to 6 °C — comparable to that predicted for the coming century due to anthropogenic global warming under the fossil - fuel - intensive, business - as - usual scenario.
When the orbital cycle brought increased the intensity of insolation in the northern hemisphere, ice sheets melted and we went into
a warm interglacial.
The ice ages were actually many pulses of cold glacial phases interspersed with
warmer interglacials.
Aside from
some warm interglacials, the average climate was last as warm as we expect in 2100 during the Pliocene epoch — before the emergence of the genus Homo which includes you and me.
Terminations I through V are significant paleoclimate events where the termination of the glacial state occurs, and Earth begins to change into
a warm interglacial state.