Carl Sagan Quotes

Earth might one day soon resemble the planet Venus.

Radioactive poisoning of the atmosphere and hence annihilation of any life on earth has been brought within the range of technical possibility.

We may well blow each other up with atomic weapons before we wipe out all species of life including our own with more gradual means.

The human and environmental devastation caused by nuclear weapons - whether by testing, mistake or malice - is the very reason we need to eliminate them altogether.

There are two problems for our species' survival - nuclear war and environmental catastrophe - and we're hurtling towards them. Knowingly.

I felt proud that the baby's first real adventure should be as a protest against the insanity of world annihilation. Already a certain percentage of unborn children are doomed by fallout, and no one knows the cumulative effects of what is already poisoning the air and sea.

Burning all the fossil fuels will destroy the planet we know, Creation, the planet of stable climate in which civilization developed.

If we do nothing, the ensuing climate catastrophe will wreck our economy - including wreaking havoc on our food production systems. All credible scientists agree on this point.

With the nuclear threat we know that if sufficient weapons are used, human civilization - all of humankind - could be extinguished literally by "nuclear winter." So we have to see ourselves as part of the ultimate human group, just as we have to do with global warming.

If Earth ever suffers a runaway greenhouse effect (like what has happened on Venus), then our atmosphere would trap excess amounts of solar energy, the air temperature would rise, and the oceans would swiftly evaporate into the atmosphere as they sustained a rolling boil. This would be bad.

For my generation, coming of age at the height of the Cold War, fear of nuclear winter seemed the leading existential threat on the horizon. But the danger posed by war to all humanity-and to our planet-is at least matched by climate change.

According to a new UN report, the global warming outlook is much worse than originally predicted. Which is pretty bad, when they originally predicted it would destroy the planet.

We're looking at catastrophic impacts in our lifetime, not only that every month now we're setting a new World Almanac record.

We're putting 70 million tonnes of pollution into the atmosphere every day, trapping an enormous amount of extra heat from the sun inside the earth's atmosphere. It's threatening to push the planet past a tipping point beyond which climate change would be difficult to stop

The facts are there that we have created, man has, a self-inflicted wound that man has created through global warming.

Except for fools and madmen, everyone knows that nuclear war would he an unprecedented human catastrophe.

Remember that in any major nuclear war, the first strike destroys the country that attacks; it's been known for years. The first strike of a major power is very likely to cause what's called nuclear winter, leads to global famine for years and everything's basically gone. Some survivors straggling around. Could [Donald Trump] do it? Who knows.

Humanity is sitting on a time bomb. If the vast majority of the world's scientists are right, we have just ten years to avert a major catastrophe that could send our entire planet's climate system into a tail-spin of epic destruction involving extreme weather, floods, droughts, epidemics and killer heat waves beyond anything we have ever experienced - a catastrophe of our own making.

The environmental crisis is a signal of this approaching catastrophe.

North Korea and China have proposed what sounds like a pretty sensible option that North Korea should end its development of nuclear weapons, the US should stop carrying out hostile military maneuvers on the North Korean border. The US immediately rejected it. Modernization program is a very clear example of how security doesn't matter. There is no gain in security but massive overkill of the adversary's deterrent capacity. The only consequence of it is to elicit the likelihood of a preemptive attack. And a preemptive attack leads to a nuclear winter world.

The prediction of nuclear winter is drawn not, of course, from any direct experience with the consequences of global nuclear war, but rather from an investigation of the governing physics.

The planet will continue to cook.

I will not sleep fine if Donald Trump wins and I will not sleep fine is Hillary Clinton wins. Whether you are looking at nuclear weapons, whether you are looking at expanding wars and their blowback, which will not stop as long as those wars continue to expand, or whether you're looking at the climate, in my view, we have no choice. This is an existential moment. We are deciding not only what kind of world we will have, but whether we will have a world or not. I think it's very important to get outside this box that tells us we are powerless, when in fact, we are powerful.

We will pay for this [climate change] one way or another. We will pay to reduce greenhouse-gas emissions today and we'll have to take an enormous hit of some kind. Or we will pay the price later in military terms. And that will involve human lives. There will be a human toll. There is no way out of this that does not have real costs attached to it.

When you think of how much violence, how much blood... how much has been destroyed to create the great nations, America, Australia, Britain, Germany, France, Belgium - even India, Pakistan. Having destroyed so much to make them, we must have nuclear weapons to protect them - and climate change to hold up their way of life... a two-pronged annihilation project.