Just for starters.
Spirit of Christmas Present wrote:
On Earth. I think it's more than enough that we ruined one planet. We ought to tidy up out own home before we visit the neighbourhood.
"ruined one planet"?
Talk about an unsupported hyperbole. Do you have anything to base it on? If so, let's see it.
Here we go again. Super alarming 'what if' scenarios based on ultra pessimistic theorising.
Alarm about accelerating and human caused extinctions is a popular meme in the media. There are constant references to the large and accelerating numbers of species that are being driven to extinction by human activity. The only problem is that it's not true. Here are the known facts about extinction.
The vast bulk of extinctions are of species that live in relatively small numbers in very restricted areas on islands. Almost all those extinctions were the result of the introduction of alien exotic species by early explorers and thus the rate of extinction has been declining since a peak period associated with the period of global exploration and empire building after 1500.
Since 1500 only 61 species of mammals have gone extinct. Of those 61 species 58 were island species. Even including the peak period during the age of global expansion the rates of extinction of mammals on the large continental land masses has been remarkable low. Of the 4,428 known mammal species (Red List 2004) living in Asia, Europe, Africa, North America, South America, and Antarctica, only three mammals have gone extinct in the last 500 years. These were the Bluebuck antelope, South Africa; the Algerian gazelle, Algeria; and the Omilteme cottontail rabbit, Mexico.
Since 1500 only 129 species of birds have gone extinct. Of the 128 extinct bird species, 123 of them were island extinctions. Of the 8,971 known continental bird species (Red List 2004), only 6 have gone extinct in the last 500 years.
It is worth bearing in mind that there are an estimated total of 8.7 million species on earth.
What can we conclude from this record of extinctions?
1) When European species met isolated local species, a number of the local species died. The Australian and island species were extremely vulnerable to pressure from imported humans, mammals, birds, plants, and diseases. 95% of all recorded bird and mammal extinctions are island or Australian species.
2) When the European species arrived, Australia and most islands had been separated from the continents for forty million years or so. The initial introduction of European species into island habitats was a one-time event. While alien species will always a problem for islands, this massive onslaught of the first coming of the European species will never be repeated — there are no places left with forty million years of isolation.
3) Total habitat destruction drove one bird to extinction.
4) While habitat reduction has been claimed as contributing (in an unknown degree) to three continental bird extinctions, to date no continental mammal or bird has been seen to go extinct due to habitat reduction alone.
So what you have is a picture of very, very low levels of actual extinctions.
Even if the rate of extinctions were to quadruple in the next 500 years, and even if we assume that the rate of extinctions for continental species accelerates massively to match the rate of island extinctions then we get an absolutely worst case nightmare scenario of a total of 760 bird and mammal species going extinct in the next 500 years out of a total of 8.7 million species.
Frankly that doesn't seem worth worrying about. It certainly is not something that should be used as a convincing case for slowing or restricting economic development (or more accurately prolonging human poverty, suffering and premature death), nor should it be an issue which is used to whip up alarm about the impact of human activity on the environment.
This is what you call "ruined one planet"?
As said, talk about an unsupported hyperbole.