About 43 percent of Earth's land surface has been converted to agricultural or urban use. Scientists say this and other human pressures on the climate mean we could see a major species extinctions and ecosystem changes within a few generations.
UC Berkeley paleontologist Tony Barnosky says at a minimum, the change would be as great as the last glacial transition, where about half the large mammals went extinct.
He says we're putting substantial and unprecedented pressures on climate and ocean.
Barnosky: "All of those things are more intense than what happened during the last time we saw one of these major global state shifts 11,700 years ago. So the pressures we're exerting are actually stronger then the pressures exerted during last time this happened."
If the planet hits such a tipping point, he says it'd really be a new world biologically. And for California, that grows over 200 crops, that could mean major shifts in what can be grown where.
Here's more from my conversation with co-author Tony Barnosky. The research is published Wednesday in the journal Nature.
So what might a change of this magnitude look and feel like?
The kinds of changes I'm talking about are, I would expect to see some loss of biodiversity, so the extinction of species. Remaining species would be combinations of species that are not living together today would live together in future, so very different looking communities. For example, if you went to say Yosemite National Park, you might not see the same species living there that you would expect to see today.
The big issues for humans, you know we tend to depend on biological systems as we have experienced them over the past 11,000 years or so. That's been a time of pretty constant, state if you will, in earth's biological systems.
When things change rapidly, and unexpectedly, that's when we see societal disruption, economic disruption. So I think those would be the biggest impacts on people. For example, think about farming. The green revolution is based on certain strains of crops, certain kinds of rice, corn. Well it turns out those kinds of crops, those particular strains, are not well adapted to growing under the climatic conditions we're predicting. So that's an issue. Another issue is climate zones where have crops growing and rely on for food and for world economics, those areas are going to shift.
Are these changes we're facing in this century?
I think the bottom line on what we present in this paper is if we do nothing differently, we can expect some very major changes in earth's biosphere, within this century. And the reason I say that is because the kinds of pressures that we're putting on the world in terms of population growth, how we use the land and the sea and natural resources, how fast we're changing climate, how fast changing the oceans, in terms of both temperature and ocean chemistry, ocean acidification and so on, all of those things, are more intense than what happened during last time we saw one of these major global state shifts 11,700 years ago. So the pressures we're exerting are actually strong then the pressures that were exerted during last time this happened.
This paper reads pretty scary -- you're talking about huge changes to the world as we know it within this century? Should I be worried?
Yeah, I think we should be alarmed to a certain extent, but sky isn't necessarily falling. I think the important thing that a study like this brings out is that humanity is at a crossroads, we're past the point can just say 'Oh let's go along and do busines as usual and everything going to turn out all right.'
Instead we have to look into future, and say these are the ranges of problems we face, what are the solutions. And let's work towards those solutions. So it's a matter of realizing we are pretty clever, we're having a huge impact on earth, we can drive boat in a direction we want to -- but we have to realize that's necessary to do.