Some of the bigger concerns that we have are species extinctions which are ramping up and getting larger and larger. Already we're in a very very large extinction period just from human beings competing with plants and animals for space on the planet. But now as climate is changing, we're seeing an acceleration in that.
James Hansen: A given temperature line is now moving poleward at a rate of about 50 to 60 kilometers per decade, about 35 miles per decade. And it's been doing that now for 30 years. Species can live within certain climatic zones. So those at the high latitudes in effect we're pushing them off the planet. We're removing the conditions in which they can survive.
Several scientists:
It's going to have an impact on biodiversity, which in my opinion is even bigger than sea level rise, right? The decay of species.
A lot of species, plants, animals, microbes are unknown to science. They live on Earth, but we don't know that they exist and they don't have even a scientific name. Every time we destroy a tropical forest, we pollute a river, we destroy a temporary forest, some mangroves or some coral reef, most likely we're losing a species. But because we don't know them, obviously it is impossible to say which ones are becoming extinct.
1.20
Every time a species goes extinct, you have lost whatever it learned throughout its becoming a species in terms of how to adapt, how to live, the medicines.
75% of the active compounds of the methods that we use right now come from plants and animals in the wild.
There's knowledge encoded in the DNA of every species out there because every species managed to survive. and every time we lose one of those, we lose valuable information.
The rate at which we're losing species today is much much higher than the rate at which species naturally originate. And so that means that global diversity is is going down.
2.00
One of the points I think it's really important for people to understand. We're sort of inured to news of extinctions. You know, the pandas are going extinct. You know, we hear it all the time. So we're just like, oh, that must be natural. But in fact, extinction should take place extremely rarely. You should really not know of any animals going extinct in the course of a human lifetime for all intents and purposes. So if you know of creatures that have gone extinct, it is a very unusual moment in Earth history.
So every time that we're losing one species, we're losing, we're eroding the capabilities of Earth to maintain life in general and to maintain human life in particular.
No matter what the cause of extinction, we see that the recovery time scale is millions of years. If you have several million years to wait around, the planet should be fine. If you are planning for your lifetime or your grandchildren's lifetime or their grandchildren's lifetime, if you're planning for the continuation of the nation that you live in or the society that you feel like you belong to, those won't be here when recovery happens from the kinds of changes that we're causing today.
3.08
Do you have a favorite global catastrophe that you like to study?
Oh, I mean there are lots of good ones.
The fifth extinction, if you will, was the extinction of the dinosaurs about 66 million years ago, which there's a pretty broad scientific consensus was caused by an asteroid impact.
Some of the other mass extinctions have volcanic activity associated with them. And so, a more common thread seems to be climate change and volcanism. When we look back in Earth history, we find events where the drivers for those environmental changes and biotic changes were tied to releases of carbon dioxide to the atmosphere just like the modern climate change is being driven by releasing of fossil fuel to the atmosphere.
3.54
So, the Permian mass extinction is the largest one in Earth history to the best of our knowledge. It's estimated upwards of 95% of all species on the planet went extinct.
This happened about 250 million years ago.
At the end of the Permian era, the planet entered one of the most extreme periods of volcanism in its history. As a region of Siberia the size of Europe erupted for thousands of years, greenhouse gas emissions were comparable to human industrial emissions today.
The magnitude the the total amount of carbon released and the buildup of carbon dioxide in the atmosphere in these major geological events is comparable to but probably somewhat larger than than our capacity to increase atmospheric CO2 through fossil fuel burning.
However, the rate of change today is about 10 times faster than in these massive events in Earth history. The rate of carbon addition, the rate of climate change and environmental change that is occurring today is unprecedented in Earth history.
One of the things about what's happening now is it's happening on a a speed that is um quite a bit faster than anything else that's been seen in the past.
And now you will hear scientists say, I have heard scientists say that that we are the asteroid because of these very radical ways that we're changing the planet.
END OF TRANSCRIPT
No comments:
Post a Comment