Quotes from David Grinspoon

Earth would stand out as strange and perturbed, with something in the air that geology and chemistry alone could not explain, with some huge ongoing, active chemical disturbance.

Around six thousand to seven thousand years ago, sea level stabilized after a multithousand-year period of rapid rise. The first large coastal settlements on several continents all date to this period. The high-protein fish diets made possible by stable sea level and consequent coastal settlement contributed to the rise of complex societies around the world. In

Now, when you hear some people advocating or warning against "geoengineering" Earth by spraying sun-blocking aerosols into the upper atmosphere, they are proposing to induce a process that is constantly at work on Titan. I'll return to the physics, and the wisdom, of such an anti-greenhouse project in chapter 4. Climate

As a young planet, Venus was losing hydrogen rapidly to space. The oceans boiled off, and after some period of time, perhaps 600 million years, there was no surface water.

In environments that are energy-rich but liquid-poor, like near the surface of Titan, natural selection may favor organisms that use their metabolic heat to melt their own watering holes.

Even cynical, selfish people will realize, one way or the other, that it's not in their self-interest to act in self-destructive ways.

What I wonder most about the Anthropocene is not when did it start - but when, and how, will it end? Will it end? Or is it possible that our own growing awareness of our role on Earth can itself play a pivotal role in shaping the outcome toward one that we would desire?

I'm an astrobiologist, and I come from a planetary science background, so in a very broad sense, I study the evolution of planetary environments.

Ever since the environmental movement was sparked by photos of the whole Earth taken by astronauts onboard Apollo Lunar Modules, I've seen planetary exploration as an extension of a reverence and care for Earth.

Earth's biosphere gave birth to humans and our thoughts, which are now reshaping its planetary cycles. A planet with brains? Fancy that.

I don't see it as coincidence that the great acceleration of the Anthropocene influences on Earth came during the same decades as our first exploration of the other planets.

I'd like to jump a couple hundred years into the future and work with the scientists who are getting back the first information from our probes to planets orbiting nearby stars.

There's something cool about being involved in new missions to other planets.

We have all this very clever technology and all these abilities to manipulate the world in all these ways, yet we are faced with the very real question of whether we can be sustainable on this planet - whether or not, in fact, we can endure.

Titan has rivers and lakes of liquid methane and ethane, methane weather systems of clouds and storms that mirror Earth's hydrologic cycle, and seasonal cycles that rival Earth's in complexity.

The more we look at the kinds of soils and the nature of the atmosphere and the polar caps, it all adds up to tell us that some liquid, which we very much believe was water, did flow in abundance on Mars in the past.

I'd been politically active ever since my parents wheeled me in a stroller in a 'ban the bomb' march in Boston in 1963.

Humans are possessed, to some degree, with the power of foresight. Yet we so often learn things the hard way, through disaster.

Part of the point of SETI has always been a search for answers about our own cosmic potential and destiny. If 'they' are out there, it means that there may be hope for us.

When you think about alien intelligences making art, you then have to think about what art is and how bound up it is in the nature of consciousness. Why do we make art? And what can we expect to have in common with other creatures in universe?

Through space-based climate studies, my colleagues and I have learned that a stable and comfortable climate is not something to take for granted.

One of the weird things about modern physics is that we do find there are apparently these other dimensions that we don't directly experience that explain some aspects of the overall geometry and reality of our universe.

It is said that Mahatma Gandhi, when asked about Western civilization, remarked, 'I think it would be a good idea.' That's how I feel about intelligent life on Earth, especially when I think about the question of what truly intelligent life might look like elsewhere in the universe.

Humanity has at least a dim, and growing, cognisance of the effects of its presence on this planet. The possibility that we might integrate that awareness into how we interface with the Earth system is one that should give us hope.