Rising populations may be driving Earth towards a disastrous 'tipping point' where humanity starves itself out



If 50% of landscape has been altered by man, Earth may hit 'tipping point'

World is already at 43%



Warning from committee of 22 scientists

Some areas may already be so overpopulated as to be beyond hope

Effects on fish and farming could starve whole areas

Rising populations are driving Earth towards a 'tipping point' where species we depend on die out, says a committee of 22 scientists - hitting industries such as fishing, agriculture, forestry and water.

Some areas of the planet may already be so overpopulated as to be beyond hope - and once the planet is more than 50% under tarmac and agriculture, the results could be global disaster.

When smaller areas hit levels above 50%, the results are disastrous. If the entire planet hits this 'tipping point', the effects would be impossible for scientists to predict.

Rising populations are driving Earth towards a 'tipping point' where species we depend on die out, says a committee of 22 scientists - hitting industries such as fishing, agriculture, forestry and water

The committee calls for 'global leadership' to prevent such a disaster - but warns ome areas of the planet may already be so overpopulated as to be beyond hope.



If the entire planet hits a 'tipping point', the results will be impossible for scientists to predict - and the committee calls for 'global leadership' to prevent such a disaster.



Professor Anthony Barnosky, the lead author from the University of California, Berkeley, warns: ‘It really will be a new world, biologically, at that point.



‘The data suggests that there will be a reduction in biodiversity and severe impacts on much of what we depend on to sustain our quality of life, including, for example, fisheries, agriculture, forest products and clean water. This could happen within just a few generations.’

Studies of small-scale ecosystems have shown that once 50-90 percent of an area has been altered, the entire ecosystem tips irreversibly into a state far different from the original, in terms of the mix of plant and animal species and their interactions and usually resulting in species extinctions and a loss of biodiversity.



Currently with 7 billion people about 43 percent of Earth's land surface has been converted to agricultural or urban use and with a predicted rise to 9 billion by 2045 it is estimated that half will be disturbed by 2025.



‘Can it really happen? Looking into the past tells us unequivocally that, yes, it can really happen. It has happened. The last glacial/interglacial transition 11,700 years ago was an example of that,’ Professor Barnosky said.



‘I think that if we want to avoid the most unpleasant surprises, we want to stay away from that 50 percent mark.’

Population density is rising, as seen from this night view of Earth: If the entire planet hits this 'tipping point', the results will be impossible for scientists to predict - and the committee calls for 'global leadership' to prevent such a disaster.

The paper, by 22 internationally renowned scientists, calls for better predictive models based on a detailed understanding of how the biosphere reacted in the distant past to rapidly changing conditions - including climate and human population growth.



UC have begun a £2.6 million research project to develop reliable, detailed biological forecasts, to understand how plants and animals responded to major shifts.



The authors of the review - biologists, ecologists, complex-systems theoreticians, geologists and paleontologists from the United States, Canada, South America and Europe - argue that, although warning signs are emerging, no one knows how close Earth is to a global tipping point.



Professor Barnosky said: ‘We really do have to be thinking about these global scale tipping points, because even the parts of Earth we are not messing with directly could be prone to some very major changes.



‘And the root cause, ultimately, is human population growth and how many resources each one of us uses.’



Co-author Elizabeth Hadly from Stanford University said: ‘We may already be past these tipping points in particular regions of the world. I just returned from a trip to the high Himalayas in Nepal, where I witnessed families fighting each other with machetes for wood - wood that they would burn to cook their food in one evening.



‘In places where governments are lacking basic infrastructure, people fend for themselves, and biodiversity suffers. We desperately need global leadership for planet Earth.’



They urge global cooperation to reduce population growth and per-capita resource use, to replace fossil fuels with sustainable sources, develop more efficient food production and distribution, and management of land and oceans not already dominated by humans as reservoirs of biodiversity and ecosystem services.



‘Ideally, we want to be able to predict what could be detrimental biological change in time to steer the boat to where we don't get to those points,’ Professor Barnosky said.



‘My underlying philosophy is that we want to keep Earth, our life support system, at least as healthy as it is today, in terms of supporting humanity, and forecast when we are going in directions that would reduce our quality of life so that we can avoid that.’



‘My view is that humanity is at a crossroads now, where we have to make an active choice.



‘One choice is to acknowledge these issues and potential consequences and try to guide the future (in a way we want to). The other choice is just to throw up our hands and say, 'Let's just go on as usual and see what happens.' My guess is, if we take that latter choice, yes, humanity is going to survive, but we are going to see some effects that will seriously degrade the quality of life for our children and grandchildren.’



Climate change, population pressure and widespread destruction of natural ecosystems may be driving toward an irreversible change in biosphere with devastating consequences, the prestigious group of researchers say.



In just a few generations our food and water supplies could be gravely effected with some plant and animal species being wiped out completely.

But we can prepare ourselves by learning lessons from what happened in the past, it is said.



The review paper, which will be published tomorrow in the journal Nature, compares the biological impact of past incidences of global change with processes under way today and assess evidence for what the future holds.

