Sentences with phrase «of past temperatures»

The case for anthropogenic global warming originally came from studies of climate mechanics, not from reconstructions of past temperatures seeking a cause.

If they don't work now, why should they be trusted to give us an accurate picture of past temperatures?

It had always struck me as a little weird to expect tree rings to be a good indicator of past temperature.

That's because, they say, other studies of past temperatures also indicate that the late 20th century was unusually warm.

If solar is increased by feedbacks (like cloud cover), that will give the same fit of past temperature data at the cost of combined GHG + aerosol.

However if «unknown feedbacks» and other forcings can explain an even greater proportion of past temperature changes, then researchers would be forced to suggest climate sensitivity to CO2 is much lower.

The researchers examined various reconstructions of past temperatures and CO2 levels to determine how the climate system has responded to previous changes in its energy balance.

NW and Ken, a short answer is that the investigators need to combine evidence of tree - line fluctuations with estimate of past temperature changes to model the spatial extent of the upper treeline zone in order to avoid this problem (by ensuring that only material that was within this zone at any given time is used).

Reconstructions of past temperatures show that even before the PETM the Earth was about 10 degrees warmer than today and then warmed an additional 5 degrees during the PETM.

Tree cores are though to be good measures of past temperature (or, are a «proxy» for temperature) through the widths of tree rings contained in the core; tree rings generally occur once a year and have a width that is correlated to temperature.

It should be noted that records of past temperature for the Southwest are still limited, and this assessment would be strengthened with additional paleoclimatic data for this region.

One of the leaked emails refers the «trick» of adding the real temperatures, as recorded by thermometers, to reconstructions of past temperatures based on looking at things such as growth rings in trees.

Rather, as demonstrated in IPCC (2001)[see this comparison here] and numerous additional studies since, it is what is perhaps more aptly termed the «Hockey Team» — that is, the multiple independent reconstructions and model simulations that now indicate essentially the same pattern of hemispheric mean temperature variation in past centuries, that support a «Hockey Stick» description of past temperature changes.

I only stated that evidence of past temperature indicates that now is warmer than most of the holocene in SH.

However, estimates of past temperatures using proxy data near B will always yield the same temperature, namely TB, rather than a corresponding scatter of temperatures.

These backcast made considerable use of current past data to reproduce some approximation of the past temperature time series.

It is true that there are big uncertainties about the accuracy of all past temperature reconstructions, and that these uncertainties have sometimes been ignored or glossed over by those who have presented the hockey stick as evidence for global warming.

Subscribers to trees as temperature proxies believe that they provide a picture of past temperatures at times when thermometers were not present.

There will always be uncertainty, as there will be greater relative uncertainty in our knowledge of past temperatures from» proxy indicators» such as tree - rings.

About models and solar forcing GCM's give some rather good simulation of past temperatures.

The «hockey stick» describes a reconstruction of past temperature over the past 1000 to 2000 years using tree - rings, ice cores, coral and other records that act as proxies for temperature (Mann 1999).

However, after taking into account changes in the three other climate - controlling factors that we know about - orbital changes, ice caps, and dust - a comparison of past temperature changes with past changes in GHG concentrations indicates that such a doubling of CO2 would actually result in a warming of 3oC or more.

That's because, they say, other studies of past temperatures also indicate they are higher now, on average, than at any time in past 1,000 years, and perhaps far longer.

The thermometers record actual temperature; the proxies record, well, various best guesses of past temperatures.

FALSE reconstructuions of past temperatures does nothing to further the study of climate science.