Earth： The Living Planet
Carnegie Institution of Washington
Dr. Sean C. Solomon
Thank you very much, Dr. Kinoshita. I'm honoured and delighted to be here today to talk to you about the Earth - the living planet - and to help celebrate the occasion of the beginning of OD21.
My talk will involve three themes, which you see on the slide on your left. (fig.1)
* The first theme is that our planet is very special. And I will explain what I mean by that.
* The second theme is that the various spheres of the Earth - the atmosphere, the hydrosphere, our oceans, lakes, the solid part of the planet and the biosphere are all complex interacting coupled systems. And those interactions are the subject of much of research in our science today.
* The third theme, with which I will end my talk, is that the oceanic crust is a critical research frontier for understanding these Earth systems.
I would like to begin with the slides.
This image (fig.2) is simply to remind us what a beautiful planet we live on. It is the only planet in the solar system with liquid oceans, and of course the land on which we sit today, and the wonderful atmosphere that we breathe, visible here in the clouds. It is a living planet in the sense of several meanings. It is the only planet we know of in the solar system that has life. But it is a living planet in many other ways because it is a very dynamic planet. And we see that dynamism in many different ways： through severe storms, like this space view of a typhoon (fig.3). Of course in Japan I don't have to explain about earthquakes. In seismology this is a very famous image (fig.4) which some of you will recognise from the 1964 Niigata earthquake. But earthquakes are common all over the world - last week there was a very damaging one in Columbia.
Volcanic eruptions - this is one of the most famous in the United States anyway - Mount Saint Helens in 1980 (fig.5). But you are also very familiar with the tremendous energy and damage involved in volcanic eruptions.
Another kind of rare dynamic event that luckily we have not seen in our lifetime is the impact from space of a very large object. This is an artist's rendition of (a famous space scientist / artist named William Hartmann) of the formation of the Chicxulub structure (fig.6) - an impact structure in the Yucatan of Mexico, thought to mark the end of the Cretaceous, and thought by many to contribute to the extinction of many species - including the dinosaurs, but also many others. And if that theory is correct, the impact event gave rise to the population of the Earth by mammals, and in no small way is responsible for our being here today, rather than at some meeting of lizards.
The Earth, of course, as I've said is populated by life, arguably intelligent life, here depicted by a space view of the city of London (fig.7). That intelligent life is capable of modifying its environment to a substantial degree. Here you see a space view, taken by the Space Shuttle, of the fires in Kuwait, during Desert Storm (fig.8) - a vivid illustration of how our species has the ability to alter our environment.
Now it is believed that all of the planets formed out of the solar nebula, here depicted by William Hartmann (fig.9), at the same time and by the same processes, and so a question that planetary scientists ask is： how did the planets turn out so different ? And different indeed they are.
Most of the mass of the planets are in the gas giants. Here you see Earth depicted. Next to the gas giant planet Jupiter (Fig.10).
