Sentences with phrase «levels over millennia»

Data from ice cores show little change in the atmospheric CO2 levels over millennia despite changes in land use and small emissions from humans.

The rise and fall of sea level over the millennia, coupled with natural karst topography and clear waters, results in a diverse submarine seascape of patch reefs, fringing reefs, faros, pinnacle reefs, barrier reefs as well as off - shelf atolls, rare deep water coral reefs and other unique geological features such as the Blue Hole and Rocky Point where the barrier reef touches the shore.

Not exact matches

Jody has over 25 years of experience in the water sector where she has been responsible for driving a range of initiatives including state water reforms under the National Water initiative, driving the momentum and integration of The Living Murray, delivery of environmental water with and on behalf of Basin states, development and implementation of a plan to avoid widespread acidification to the lower lakes of the Murray system during the Millennium drought and identification of the sustainable level of take to be embodied in the Murray - Darling Basin Plan.

However, Professor Stewart believes that over a few millennia those sea level rises could have caused the fault system beneath and around Mount Etna to completely change in behaviour, sealing up old lava flows and ultimately forcing them to emerge elsewhere on the island.

This is distinctly alarmist... It is common ground that if indeed Greenland melted, it would release this amount of water, but only after, and over, millennia, so that the Armageddon scenario he predicts, insofar as it suggests that sea level rises of 7 metres might occur in the immediate future, is not in line with the scientific consensus.

Although we will not see immediate effects by tomorrow — some of the slow processes will only respond over centuries to millennia — the consequences for long - term ice melt and sea level rise could be substantial.

This would still lead to substantial climate change, with the temperature rising by 2 °C to 5 °C and the sea level rising by 0.3 to 0.8 metres by 2100, and by 7 to 13 metres over the next millennium.

Some of the world's most recognisable and important landmarks could be lost to rising sea - levels if current global warming trends are maintained over the next two millennia.

The IPCC's assessment of the literature, prior to our study, was that global sea - level fluctuations over the last 5 millennia were < ± 25 cm, and that there was no clear evidence of whether specific fluctuations seen in some regional sea level records reflected global changes.

That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].

These global projections are consistent with an independent set of global projections based upon the relationship between temperature and rate of sea - level change over the last two millennia.

============================= Says Steve McIntyre, commenting on the new sea level reconstruction paper by Kemp et al at PNAS, «Climate Related sea - level variations over the past two millennia»:

In one projected event, large parts of the ice sheet melt and drain into the ocean over the next millennia, raising global sea levels by several tens of meters.

Over many centuries or millennia, sea level could rise by several metres (Section 10.7.4).

Rather, excess CO2 returns toward baseline at a multitude a different rates, with chemical equilibration in the ocean occurring over decades (depending on depth), ocean carbonate buffering through sediment dissolution requiring centuries to millennia, and eventual restoration of carbonate sediment levels by terrestrial weathering occurring over hundreds of thousands of years — a long «tail» that can account for as much as 20 to 40 percent of CO2 excess in the estimates described by David Archer et al in CO2 Atmospheric Lifetimes.

It is certainly possible and may be likely for the polar ice sheets to disappear, causing sea level rise (SLR) of 22 + / - 10 metres over coming millennia.

The first is climate inertia — on very many levels, from fossil lock - in emissions (decades), ocean - atmospheric temperature inertia (yet more decades), Earth system temperature inertia (centuries to millennia) to ecological climate impact inertia (impacts becoming worse over time under a constant stress)-- all this to illustrate anthropogenic climate change, although already manifesting itself, is still very much an escalating problem for the future.

Thus there is no reason the doubt the value of the ice core CO2 measurements and all observations support that dT is a limited driver of CO2 levels, from fast (3 ppmv / °C) on short term (months) to slow (8 ppmv / °C) over millennia.

The researchers studied outcrops of sediments left behind when the lake was far larger, and used those and other markers to construct a timeline of lake levels, and the fluctuation of rainfall over millennia.

At the risk of oversimplifying, the effects of groundwater storage can be differentiated between shallow - aquifer effects that modulate global sea level on year to year and decade to decade timeframes, versus deep aquifer effects that modulate sea level trends over centuries and millennia.

Sea Level: Delegates included new text on the timeframe indicating: a transition in the late 19th to early 20th century from relatively low mean rates of rise over the previous two millennia to higher rates («high confidence»); and that the rate of global mean sea level rise has «likely» (66 - 100 % probability) continued to increase since the early 20th cenLevel: Delegates included new text on the timeframe indicating: a transition in the late 19th to early 20th century from relatively low mean rates of rise over the previous two millennia to higher rates («high confidence»); and that the rate of global mean sea level rise has «likely» (66 - 100 % probability) continued to increase since the early 20th cenlevel rise has «likely» (66 - 100 % probability) continued to increase since the early 20th century.

A new study examining the long - term effects of sea - level rise on the 720 spots around the world that have been designated UNESCO World Heritage Sites found that roughly 20 percent of them could be ruined if temperatures rise 5.4 degrees Fahrenheit (3 degrees Celsius) above pre-industrial levels over the next two millennia, said study lead author Ben Marzeion, an assistant professor at the Institute of Meteorology and Geophysics at the University of Innsbruck in Austria.

Anyway, today we try to explain the exact opposite: how northern hemisphere ice ages can quite suddenly weaken — at least in case of the last one, which had its cold peak around 18,000 years ago, after which atmospheric CO2 levels «suddenly» (over a millennium or so) rose by 30 per cent, and temperatures started to climb closer * to our current Holocene values.

Kemp, A. C., B. P. Horton, J. P. Donnelly, M. E. Mann, M. Vermeer, and S. Rahmstorf, 2011: Climate related sea - level variations over the past two millennia.

«It is exceptionally unlikely that we would be seeing a record year, during a record warm decade, during a multi-decadal period of warmth that appears to be unrivaled over at least the past millennium — if it were not for the rising levels of planet - warming gases produced by fossil fuel burning.»

It is defined as the amount of warming expected if carbon dioxide (CO2) concentrations doubled from pre-industrial levels and then remained constant until Earth's temperature reached a new equilibrium over timescales of centuries to millennia.

Over millennia, marine life have endured and responded to CO2 levels well beyond anything projected, and temperature changes that put coral reefs and tropical plants closer to the poles or had much of our land covered by ice more than a mile thick.

If the CO2 were to stay in the atmosphere for millennia, why has its level in the atmosphere not doubled in the last 15 years, or gone up tenfold - plus over the last 100 hundred years?

That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].

There is medium confidence that at least partial deglaciation of the Greenland ice sheet, and possibly the West Antarctic ice sheet, would occur over a period of time ranging from centuries to millennia for a global average temperature increase of 1 - 4 °C (relative to 1990 - 2000), causing a contribution to sea - level rise of 4 - 6 m or more.

Except and unless you accept the premise that all observations are completely useless because someone is able to quibble over their details, follow through the math, compare with the original works, and you still come up with much too little error to account for the 22 % -25 % differences seen over the past quarter millennium and the maximum CO2 level measured in the past 60K - 85K years and extrapolated for the past 10 - 15 million years.

The reconstructed changes in sea level over the past millennium are consistent with past global temperatures, the researchers say, and can be determined using a model relating the rate of sea level rise to global temperature.

«Having a detailed picture of rates of sea level change over the past two millennia provides an important context for understanding current and potential future changes,» says Paul Cutler, program director in NSF's Division of Earth Sciences.

Proxy and instrumental sea level data indicate a transition in the late 19th to the early 20th century from relatively low mean rates of rise over the previous two millennia to higher rates of rise (high confidence).

Sustained warming greater than some threshold would lead to the near - complete loss of the Greenland ice sheet over a millennium or more, causing a global mean sea - level rise of up to 7 meters [23 feet](high confidence).

The statement, and the figure selection, emphasizes the noise in the sea level curve's first derivative, and glosses over the facts that (1) the rate always is positive in that period, and also the fact that (2) the total amount of sea level rise over the last 114 years is comparable to the total amount over the previous two millennia.

Based on the findings from wide - ranging studies of community variation (eg, why Aboriginal teen suicide and Aboriginal employment levels vary hugely from band to band; why seniors die during heat waves in some neighbourhoods and not others; why some watershed communities maintain sustainable agriculture over a millennium while others do not; why the United States biogenetic technology industry is now concentrated in only three places, compared with thirty areas a few decades ago) there is now a strong evidentiary base revealing common underlying characteristics of groups, at the nongovernmental level, that successfully address these challenges.