Sentences with phrase «occurred over hundreds of years»

Not exact matches

This identical wash, rinse, repeat cycle has occurred literally hundreds of times over the past 38 years, with no serious investigations or prosecutions whatsoever in that this is official, state - sponsored, for - profit corruption.

The overall retreat of several kilometers that has occurred over the past 20,000 years was interrupted by a stillstand or a re-advance of several hundred years at the beginning of the ACR, and then by increasingly minor glacial episodes at the end of the YD, at the beginning of the Holocene (around 10,000 years ago) and during the Little Ice Age (13th to 19th centuries).

In the past several decades, scientists have discovered that the North — South distributions of certain plants often result from a single jump across the tropics, not as a result of gradual movements or events that occurred over a hundred million years ago.

«Though very rarefied by Earth standards, these interstellar clouds are the sites of complex chemical reactions that occur over hundreds - of - thousands or millions of years,» said Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, Md. «Over time, more and more complex molecules can be formed in these cloover hundreds - of - thousands or millions of years,» said Jan M. Hollis of the NASA Goddard Space Flight Center in Greenbelt, Md. «Over time, more and more complex molecules can be formed in these cloOver time, more and more complex molecules can be formed in these clouds.

Evolution is typically thought of as a process that occurs over hundreds or thousands of years, but this doesn't mean that we can not observe genetic changes as they develop.

The ball dropping at the Times Square New Year's Eve celebration in New York City — along with the hundreds of count - down festivities occurring all over the world — seems to cue an onslaught of advertising for the many weight - loss programs that abound in this growing market.

MalcolmT says: «Nick @ 20 Previous climate changes occurred over a time scale of hundreds or thousands of years.

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 would require a much stronger relationship of temperature driving CO2 than occurred during the ice age — interglacial oscillations (and it is also important to remember that those changes occurred over much longer timescales too... which is the presumed reason why there is a several hundred year lag time between temperatures starting to rise or fall and CO2 starting to rise or fall).

Problem being that the huge influx of anthropogenic CO2 has pretty much overwhelmed this negative feedback process as it occurs over thousands and tens of thousands of years, and we'll have doubled CO2 in just a few hundred years.

Only one of the past «Big Five» mass extinctions (the dinosaur extinction event at the end of the Cretaceous) is thought to have occurred as rapidly as would be the case if currently observed extinctions rates were to continue at their present high rate (Alvarez et al., 1980; Barnosky et al., 2011; Robertson et al., 2004; Schulte et al., 2010), but the minimal span of time over which past mass extinctions actually took place is impossible to determine, because geological dating typically has error bars of tens of thousands to hundreds of thousands of years.

However, the Big Five occurred over periods of hundreds of thousands to millions of years, so Barnosky and colleagues also attempted to determine how long it might take us to reach mass extinction levels (75 % of species extinct).

To answer this question, the scientists examined a hypothetical scenario in which the Big Five extinctions occurred suddenly, such that all of the species went extinct over just 500 years rather than over hundreds of thousands to millions of years.

I think the solution to this conundrum is that those 10 ^ 15 - 10 ^ 16 moles of CO2 correspond to volcanoes that occur only very infrequently and that none of the ones over the last couple of hundred years has even come anywhere close to that.