Sentences with phrase «using paleoclimate»

Hansen and Sato (2012), using paleoclimate data rather than models of recent and expected climate change, warn that «goals of limiting human made warming to 2 °C and CO2 to 450 ppm are prescriptions for disaster» because significant tipping points — where significant elements of the climate system move from one discrete state to another — will be crossed.

Using paleoclimate as a grab bag of random, misunderstood factoids to back up wacky ideas about modern climate change is not a good policy.

This aspect shall be covered under the section entitled «Global temperature reconstructions using paleoclimate proxies - fit for purpose?»

In this manner, Hansen and Sato use climate models to help them estimate past radiative forcings and surface temperature changes using paleoclimate data without influencing their climate sensitivity estimates.

Hansen and Sato argue that the probable range of climate sensitivity values is not as large as currently believed (unlikely to fall outside the range of 2 to 4 °C for doubled CO2)- both very high and very low values can effectively be ruled out using paleoclimate data.

Best we currently have for a comparable time using paleoclimate data is not the Eemian but much further back — to the Pliocene.

This heat forcing, using paleoclimate proxies from 5 to 30 million years ago, implies approximately 2 degrees Celsius of warming this Century and about 4 degrees Celsisus of warming long term.

This means that approaches that use the first order approximation to estimate climate sensitivity from the instrumental period (such as Lewis) will underestimate climate sensitivity and approaches that use the first order to estimate climate sensitivity using paleoclimate data (Hansen and others) will overestimate climate sensitivity.

As where Marcott et al went wrong as climate scientists, when they used paleoclimate data of long millenia time scales in natural variability, with the short decadal time scale (weather) in natural variability and claim to predict the future of where the pendulum of climatology will be in the future, when actually showing that they are confused, what they are representing as evidence of the future climate is in fact their total misunderstanding of climatology and the complex chaotic circumstances that influence the real world.

is to try to use the paleoclimate record.

E. g. following volcanic CO2 release periods, you get warming, but somehow these same skeptics who use paleoclimate as an example don't seem to know this part.

In fact, climate scientists have used paleoclimate data such as that for the ice ages to show that climate sensitivity is likely to be close to the range the IPCC favors.

Authors of a recent study published in Science Advances used paleoclimate data to examine how rainfall patterns have responded to past climate shifts.

But a recent study published in Nature uses paleoclimate records from the 1500s to show that industrial - era warming first became apparent in the Northern Hemisphere in the mid-1800s.

Not exact matches

The NRC asked the committee to summarize current scientific information on the temperature record for the past two millennia, describe the main areas of uncertainty and how significant they are, describe the principal methodologies used and any problems with these approaches, and explain how central is the debate over the paleoclimate temperature record to the state of scientific knowledge on global climate change.

However, values this low are inconsistent with numerous studies using a wide variety of methods, including (i) paleoclimate data, (ii) recent empirical data, and (iii) generally accepted climate models.

As the lakes appear to be a proxy for local climate pulses, we use the lake index to explicitly test the pulsed climate variability hypothesis [15] by evaluating the relationship between paleoclimate and hominin evolution.

The endeavor becomes more scientifically challenging in light of the large variety of information sources about past climate, including tree rings, coral, glacier ice, and marine and lake sediments, not to mention the complicated array of data that are used to establish the timelines that underlie the paleoclimate records.

To identify best fit models relating paleoclimate to both the lake index and hominin evolution, we used a the stepAIC function in R package MASS to select the best fit model [38], see Figure 2.

Here we use a comprehensive set of paleoclimate indicators: East African Rift lake presence, regional Aeolian flux records from the Arabian Sea, the Mediterranean and the East Atlantic together global benthic foraminifera δ18O with to develop models predicting hominin brain size.

Mike Wallace's talk was about the «National Research Council Report on the «Hockey Stick Controversy»... The charge to the committee, was «to summarize current information on the temperature records for the past millennium, describe the main areas of uncertainty and how significant they are, describe the principal methodologies used and any problems with these approaches, and explain how central is the debate over the paleoclimate record within the overall state of knowledge on global climate change.»

We use Earth's measured energy imbalance, paleoclimate data, and simple representations of the global carbon cycle and temperature to define emission reductions needed to stabilize climate and avoid potentially disastrous impacts on today's young people, future generations, and nature.

We assess climate impacts of global warming using ongoing observations and paleoclimate data.

One can temper that with studies of paleoclimate sensitivity, but the ensemble results still should be borne in mind, since doubling CO2 takes us into a climate that has no real precendent in the part of the climate record which has been used for exploring model sensitivity, and in many regards may not have any real precedent in the entire history of the planet (in terms of initial condition and rapidity of GHG increase).

Although some earlier work along similar lines had been done by other paleoclimate researchers (Ed Cook, Phil Jones, Keith Briffa, Ray Bradley, Malcolm Hughes, and Henry Diaz being just a few examples), before Mike, no one had seriously attempted to use all the available paleoclimate data together, to try to reconstruct the global patterns of climate back in time before the start of direct instrumental observations of climate, or to estimate the underlying statistical uncertainties in reconstructing past temperature changes.

Methods have improved of course, and no doubt will improve further (paleoclimate reconstruction using weather forecast data assimilation methods is the latest and most promising recent development).

«In the mid-1990s the use of ground boreholes as a clue to paleoclimate history was becoming well - established.

David's comments reminded me of something that Suki Manabe and I wrote more than 25 years ago in a paper that used CLIMAP data in a comparative evaluation of two versions of the 1980s - vintage GFDL model: «Until this disparity in the estimates of LGM paleoclimate is resolved, it is difficult to use data from the LGM to evaluate differences in low latitude sensitivity between climate models.»

Cochelin et al used a model of intermediate complexity to show that the orbital variations over the next 100,000 years are weak enough that even a little human CO2 remaining in the atmosphere is enough to keep the earth out of an ice age («Simulation of long - term future climate changes with the green McGill paleoclimate model: The next glacial inception»).

To come to their findings, the authors used a mixture of paleoclimate records, computer models, and observations of current rates of sea level rise, but «the real world is moving somewhat faster than the model,» Hansen says.

Now, if you want to argue that the paleoclimate community could use some new blood and some new ideas, that's one thing.

In this study, which was led by Oregan State University, funded by the US National Science Foundation's Paleoclimate Program and just published in Science, researchers used «extensive sea and land surface temperature reconstructions» of around 21,000 years ago — in stead of the (late) Holocene temperature record that is mostly used.

This approximation is basically what Nic Lewis does for his estimates and what James Hansen does for his Paleoclimate estimates (actually pretty much all Paleoclimate estimates use this approximation).

CLIMAS Paleoclimate Tool: use the map to view reconstructed data by Arizona / New Mexico State Climate Divions

They have proved that TEX86 in Lake Tanganyika is teleconnected to global temperature without realizing it and thus this single proxy can be used to reconstruct global paleoclimate, similar to, and perhaps more robust in this teleconnection, to the Graybill Bristlecones.

The study, «Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data,» was also co-authored by Julia E. Cole, David M. Meko and Jonathan T. Overpeck of University of Arizona; and Gregory T. Pederson of the U.S. Geological Survey.

On the first sentence stating that the WGI report considers evidence of past and future climate change based on many independent scientific analyses from observations of the climate system, paleoclimate archives, theoretical studies of climate processes, and simulations using climate models, Saudi Arabia proposed clarifying that evidence of future climate change is based on models and simulations only.

Mann's PC1 has been used more by third parties AFTER the problems were identified than before; it's as if the paleoclimate community is showing solidarity with Mann because he's been criticized by outsiders.

The study uses models, paleoclimate data and modern observations to analyze the impact of ice shed from Antarctic ice shelves and Greenland.

BBD writes - «Finite fossil hydrocarbon reserves (note I do not limit this definition to «fuel») plus robust physics of radiative transfer, plus paleoclimate evidence plus uncertainty are, together, more than sufficient grounds to justify the rapid reduction in fossil HC use.»

Very interesting, Mr. S. For those of us unfamiliar with the literature can you answer for us the most pressing question about this as a reply to Alson's question: are the paleoclimate runs referred to in this abstract performed by one of the models used for contemporary climate prediction and informing the global political process — i.e., one of those referred to in the IPCC reports?

Likewise, the current and / or irreducible uncertainty regarding paleoclimate reconstructions using treerings, including things like comparing individual years to previous centuries, means we can be pretty certain that it is NOT possible to say 1998 was the warmest year in a millenium, as one famous scientist is wont to do.

After discrediting the entire basis for tree - ring paleoclimate reconstruction, he says that the studies do not invalidate their qualitative use.

Finite fossil hydrocarbon reserves (note I do not limit this definition to «fuel») plus robust physics of radiative transfer, plus paleoclimate evidence plus uncertainty are, together, more than sufficient grounds to justify the rapid reduction in fossil HC use.

If IPCC and the paleoclimate Team stopped using it, we could stop discussing it.

Plotted are the period and phase (of expected peak coldness) of two extraterrestrial signals (astronomical determinations of the spiral arm pattern speed and cosmic ray flux reconstruction using Iron meteorites) and two paleoclimate reconstruction (based on sedimentation and geochemical records).

In my opinion, while the techniques used in the original Mann et al papers may have been slightly flawed, the work was the first of its kind and deserves considerable credit for moving the field of paleoclimate research forward.

In paleoclimate, if you want to know the certainty of the average trend in the blade of the stick, you wouldn't take the extremes of all the inputs to calculate uncertainty, you take the variance in the output and use some method i.e. monte carlo or a DOF estimate.

OZ, India, USA etc have experienced very extreme long periods of drought and flooding over the paleoclimate record and at present we are fortunate that we live in a modern era with better monitoring and forecasting of weather, backed up with modern technology plus the ability (if we have the brains) to quickly use more R&D.

We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland.