Sentences with phrase «glacial maximum climate»

Not exact matches

To begin with, the climate is warming much faster today than it ever did following the Last Glacial Maximum.

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 tglacial 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 tGlacial 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.

We have discussed climate sensitivity frequently in previous posts and we have often referred to the constraints on its range that can be derived from paleo - climates, particularly the last glacial maximum (LGM).

Kim, S. - J., G.M. Flato, G.J. Boer, and N.A. McFarlane, 2002: A coupled climate model simulation of the Last Glacial Maximum, Part 1: Transient multi-decadal response.

Using Mg / Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94 — 1.06 °C (W m − 2) − 1, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing.

There is a new paper on Science Express that examines the constraints on climate sensitivity from looking at the last glacial maximum (LGM), around 21,000 years ago (Schmittner et al, 2011)(SEA).

There is a new paper on Science Express that examines the constraints on climate sensitivity from looking at the last glacial maximum (LGM), around 21,000 years ago (Schmittner et al, 2011)(SEA).

We have discussed climate sensitivity frequently in previous posts and we have often referred to the constraints on its range that can be derived from paleo - climates, particularly the last glacial maximum (LGM).

The results of these simulations show that dust − climate feedbacks, perhaps set off by orbital forcing, push the system in and out of extreme cold conditions such as glacial maxima.

At the last glacial maximum (20,000 yrs ago), forcings by ice sheets, vegetation, greenhouse gases and dust loading are estimated to be around -7 W / m2, and that sustained a climate 5 to 6 degrees cooler than present.

Without our use of fossil fuels, we should be descending into another glacial maximum — albeit slowly, over tens of thousands of years (the pace of natural global climate change in the Pleistocene).

Maybe you would find our recent manuscript interesting, in which we use an efficiently - generated ensemble of a state - of - the - art GCM, tuned to present - day climate and validated (tested against out - of - sample data) with simulations of the Last Glacial Maximum.

Using Mg / Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94 — 1.06 °C (W m − 2) − 1, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing.

It is a very interesting thought experiment to ask what the plight of climate modellers would be if industrial civilization had arisen earlier, somewhat after the Last Glacial Maximum when D - O events were common and maybe even the Younger Dryas was looming.

But it is far from obvious that the climate's sensitivity to GHG forcing must be the same today as it was at the glacial maximum, when conditions were very different.

In particular, Annan and Hargreaves (2006) used a Bayesian statistical approach that combines information from both 20th century observations and from last glacial maximum data to produce an estimate of climate sensitivity that is much better constrained than by either set of observations alone (see our post on this, here).

The Last Glacial Maximum (i.e. the most recent «ice age», abbreviated LGM) probably provides the best opportunity for using the past to constrain climate sensitivity.

There were two CLIMAP experiments to reconstruct past climates, one at the Last Glacial Maximum (LGM) 18,000 years ago when sea level was about 120 meters lower than today, and one at the Last Interglacial Maximum (LIM) 125,000 years ago when sea level was about 6 meters higher than today.

[Response: The climate of the last glacial maximum was six degrees colder than today.

«A Global Perspective on Last Glacial Maximum to Holocene Climate Change.»

This case appears to be based on recent research taking two different approaches: looking at recent climate changes, and changes during the Last Glacial Maximum (LGM) about 20,000 years ago.

In most cases, these range from about 2 to 4.5 C per doubled CO2 within the context of our current climate — with a most likely value between 2 and 3 C. On the other hand, chapter 9 describes attempts ranging far back into paleoclimatology to relate forcings to temperature change, sometimes directly (with all the attendant uncertainties), and more often by adjusting model parameters to determine the climate sensitivity ranges that allow the models to best simulate data from the past — e.g., the Last Glacial Maximum (LGM).

However, sea - level fluctuations in response to changing climate have been reconstructed for the past 22,000 years from fossil data, a period that covers the transition from the Last Glacial Maximum to the warm Holocene interglacial period.

Can the Last Glacial Maximum constrain climate sensitivity?

Second, the abstract admits that, «Pleistocene climate oscillations yield a fast - feedback climate sensitivity of 3 ± 1 °C for a 4 W m − 2 CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective» and also «Ice sheet response time is poorly defined».

To better understand these discrepancies, a recent study published in Geophysical Research Letters investigates the drivers of changes in deep ocean circulation across a range of modern and Last Glacial Maximum (LGM, ~ 21000 years ago) climate simulations from the latest Paleoclimate Modelling Intercomparison Project (PMIP).

Hansen took a shortcut in the early 1980s using his early climate model results (for the last glacial maximum for example) where his climate model came up with -6.6 watts change.

I'm sure CO2 starvation - desertificaion and consequent dust are major features of the glacial maxima, but I doubt all atmosphere - based climate explanations (CO2, aerosols, acid, ozone, etc..)

Pleistocene climate oscillations yield a fast - feedback climate sensitivity of 3 ± 1 °C for a 4 W m − 2 CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective because of poorly defined LGM global temperature and possible human influences in the Holocene.

Webb, R.S., D.H. Rind, S.J. Lehman, R.J. Healy, and D. Sigman, 1997: Influence of ocean heat transport on the climate of the Last Glacial Maximum.

Climate response and radiative forcing from mineral aerosols during the last glacial maximum, pre-industrial, current and doubled - carbon dioxide climates

Results show that the coldest glacial maxima temperatures are a product of the dust − climate feedbacks considered here (Fig. 5B).

Global connections between aeolian dust, climate and ocean biogeochemistry at the present day and at the last glacial maximum

Our choices for climate sensitivity (2.5 K) and glacial maxima cooling (− 4 K) are both on the low side for such properties in other work cited above.

Here we briefly discuss the radiative forcing estimates used for understanding climate during the last millennium, the mid-Holocene and the Last Glacial Maximum (LGM)(Section 9.3) and in estimates of climate sensitivity based on palaeoclimatic records (Section 9.6.3).

Maher, B.A. et al. (2010) Global connections between Aeolian dust, climate and ocean biogeochemistry at the present day and at the last glacial maximum.

Current models are also able to reproduce the large - scale patterns of temperature during the Last Glacial Maximum (LGM), indicating an ability to simulate a climate state much different from the present.

The most that they have done [as far as I know] is to reproduce the climate of the Last Glacial Maximum.

Observations of recent global warming, short - term cooling after major volcanic eruptions, cooling at the Last Glacial Maximum and other periods in the historical record, and the seasonal variation in climate, all provide some information which helps to determine the value of climate sensitivity.

«Here, we show central China is a region that experienced a much larger temperature change since the Last Glacial Maximum than typically simulated by climate models... We find a summertime temperature change of 6 — 7 °C that is reproduced by climate model simulations presented here.»

Principally, there is paleo - climate data from previous quasi-equilibria like the Last Glacial Maximum or Eocene; evidence from the instrumental trends since the 19th Century; and climatological observations that correlate to longer term responses (either in the mean, seasonally or over interannual variations).

You say that the essentials of the climate sensitivity story can be boiled down to finding the single best - documented glacial - interglacial oscillation, at that so far that is the LGM (Last Glacial Maximum) to Holocene oscilglacial - interglacial oscillation, at that so far that is the LGM (Last Glacial Maximum) to Holocene oscilGlacial Maximum) to Holocene oscillation.

Some previous site - specific studies in the Northwest had yielded evidence of a drier climate during the Last Glacial Maximum, while similar studies in the Southwest found evidence for a wetter climate.

Some EMICs have been used to investigate both the climate of the last glacial maximum (see Section 8.5) as well as to investigate the cause of the collapse of the conveyor in global warming experiments (Stocker and Schmittner, 1997; Rahmstorf and Ganopolski, 1999) while others have been used to undertake a number of sensitivity studies including the role of sub-grid scale ocean mixing in global warming experiments (Wiebe and Weaver, 1999).

Climate model simulations of the Last Glacial Maximum show an even stronger Bodélé LLJ compared with that of the present, and dated evidence points to the conditions under which deflation would have been capable of excavating the depression which was later partly filled by paleolake Megachad (31).