Are we in an Extinction level event right now?

Conditions which existed at the end of the Cretaceous, and especially at the end of the Permian would be killing humans as well as other creatures. Humans could probably survive a "Cretaceous extinction," but only by storing food and by having an energy source which could protect humans from the cold. It would be good if some oil, gas and coal in the ground so that we would not have to undergo a crash program to build fast breeder reactors.

In the Permian extinction, conditions were so lethal that 99% of all species did not have one surviving breeding pair. The atmosphere was probably loaded with carbon monoxide and hydrogen cyanide, products of partial combustion of forests.

"the glaciers are melting... temperatures rising... are we in the midst of an extinction level event without realizing it???"

No, you are in the midst of an extinction event without realizing it.

"Holocene Extinction event"

(10,000 BC - Present Day)

Entirely caused by people. Oh, and let's not stop there; let's go back another 40,000 years, to the dawn of organized society; guess what? At the exact same time Homo Sapiens began developing weapons, a massive number of species around the globe began to go extinct, including the awesome oversized mammals (birds with 25 foot wingspans which could support your weight and still fly, komodo dragons the size of an 18 wheel semi, giant cows, etc.)

"The Earth is great at taking care of its self. It may take a few years longer than you'd like but the cyclical nature of Earth will take care of those problem."

HA- More like a few HUNDRED MILLION YEARS!!! You think it's possible to recover from an extinction event in 'a few years'???

Yes we have caused an extinction event. I think your suggestion that we have lost 90% of forests is inaccurate, I'm sure it is much lower than that; but there are definitely some serious problems we must address.

Alec described the Holocene extinction (occurring in the past 10k years) and the Pleistocene extinction (occurring between 60k and 10k years ago). How we determine an extinction event is by looking at the fossil record to determine what the average number of extinctions are over evolutionary time (called the background extinction rate). This is very uncertain because not every species can be fossilised and we haven't discovered every fossil. But by using mathematical methods, we can estimate what the number of extinctions should be over a given time frame based on the background extinction rate.

There have been several changes in human behaviour which are linked to increased extinctions. The Pleistocene extinction was not only the result of humans, but also climate change. However the climate change also drove changes in human behaviour, and there may have been technological advances at the time (not an area of interest for me so I don't know).

Other glaring examples include the rise of intercontinental shipping during the renaissance. Cats were kept on board ships to eat the rats and mice which ate the ship's food stores. They were all accidentally introduced to islands throughout the pacific as a result and rats and cats in particular caused a vast number of extinctions in these regions (including birds, amphibians, small mammals and small reptiles). These kinds of introductions whih impact negatively on the endemic wildlife are referred to as invasive species and also include pigs, goats, dogs and other domestic animals which were sometimes left on islands as food resources for passing ships.

The invention of firearms also contributed to extinctions through "sport" hunting, where unsustainable numbers of species were killed just because they could be (eg passenger pigeon). Some of the extinctions thought to be caused directly by humans were actually not from hunting, but indirect results of invasive species and land use change (eg dodo). Land use change is the major killer right now as more areas of habitat (not just forest but also grasslands, coastal regions like mangroves etc) are altered to suit human purposes. This is going to get much worse before it gets better as the main drive for land use change is agriculture, and our species is increasing exponentially (currently 7 billion and projected to reach 9 billion by 2050). How we are going to feed all these extra people without using up more land is a big problem. If we don't use more land, food will double in cost due to increased demand so there will be more starvation. If we do use more land, there will be loss of biodiversity which may also impact on human health. So it is important we find a solution by encouraging people to breed less in the coming decades and waste fewer resources by switching to more sustainable products for those currently alive.

Anyway, as a result there is some discussion as to whether to consider the current situation a separate extinction from the Holocene as it relates directly to the incredible boom in our population occurring since the industrial revolution. The idea that we are now in a new age called the Anthropocene has been put forward but is still under discussion.

Stork (2010). Re-assessing current extinction rates. Biodiversity and Conservation Volume 19, Issue 2, pp 357-371. http://www.griffith.edu.au/__data/assets/pdf_file/...

Millennium Ecosystem Assessment Report (2004): http://www.maweb.org/en/index.aspx

UNFAO Livestock's Long Shadow (2006): http://www.fao.org/docrep/010/a0701e/a0701e00.HTM

UNEP Assessing the environmental impacts of consumption and production (2010): http://www.rona.unep.org/documents/partnerships/SC...

Water footprint- how much water is required to produce the foods you eat? http://www.waterfootprint.org/?page=files/productg...

Keesing et al. (2010). Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature Volume 468, Pages: 647–652: http://www.nature.com/nature/journal/v468/n7324/fu...

Nathan Pelletier and Peter Tyedmers. Forecasting potential global environmental costs of livestock production 2000–2050. PNAS October 26, 2010 vol. 107 no. 43 18371-18374. http://www.pnas.org/content/early/2010/09/27/10046...

I consider you would have a pair days warning, at minimal, and maybe a pair hundred years warning, at high-quality. Any extinction-stage comet can be a colossal, brilliant naked-eye object a pair days earlier than it hit.

No but we have done enough damage to the environment for climate change to be with us likely 100 years or more. The more depends on our efforts to conserve now and switch to a green energy future as soon as possible.

Yes. Sadly though the world's population is increasing which masks how badly we are doing, much like how the missing heat is hiding how badly temperatures are truly rising.

NOT for humans, but for many wildlife .. yes. Polar bears, BIg cats, sand cats, Rhinos, Gorillas, Ferrets, pygmy elephants, panda bears, etc. are all going away.

The mosquitoes are sucking blood without minding the hand that could smash them :)

The Earth is great at taking care of its self. It may take a few years longer than you'd like but the cyclical nature of Earth will take care of those problem.

And Extinction Level Event is much like an Orgasm.

If you have to ask if your having one, you aren't.