It's happened before: An asteroid colliding with the Earth could extinguish much of the planet's life.
Credit: Photolibrary
OUR DAYS ARE NUMBERED. We're not likely to go extinct any time soon, but we can be pretty certain we're not going to last forever. So the number of days we have left might end up being very large – human civilisation could even expand beyond Earth into the wider cosmos and last for billions of years – or the number might be alarmingly small.
There are countless calamities that could befall us and bring humanity, or at the very least, modern civilisation to its knees. We know it's happened before. Our remarkable lack of genetic diversity suggests Homo sapiens have already clung to the precipice of extinction at least once in our distant past, when our numbers dwindled to perhaps as few as 1,000 breeding pairs.
The last several millennia have also seen many civilisations rise, make a big splash and then fall. From small island communities to mighty empires spanning half the globe, none have been immune to calamity and ultimate collapse. So what makes us think our civilisation is any different?
Jared Diamond, a geographer at the University of California in Los Angeles and author of Collapse: How Societies Choose to Fail or Succeed, has intensively studied the decline and fall of civilisations.
He thinks our modern society is significantly more robust than any that have come before, primarily because we wield the power of information. With the accumulated knowledge of thousands of years of human history, we can better understand the causes of societal collapse in the hopes of avoiding them. Yet along with our great strength comes a crucial weakness – one that could be fatal.
"Today the world no longer faces just the circumscribed risk of another Easter Island society or Maya homeland collapsing in isolation, without affecting the rest of the world," says Diamond. "Instead, societies today are so interconnected that the risk we face is of a worldwide decline." So even a local calamity might drag the rest of the world down with it.
Some of the threats we face are of natural origin, others are of our own folly or design. But few are inevitable, and it should be with great interest that we work to prevent a preventable catastrophe.
CLIMATE CATASTROPHE
WE'VE ALL HEARD THE HORROR STORIES of future climate catastrophes: rising sea levels, rampant droughts, thousands of species under threat of extinction. And we've all heard the sceptics warning us not to get carried away by the panicked cries of climate alarmists.
Well, it might actually be time for alarm. Because recent findings by climate scientists such as Pieter Tans, from the U.S. National Oceanic and Atmospheric Administration, suggest we're pumping carbon dioxide into the atmosphere faster than we thought. "When they started measurements in the 1960s average growth was 0.7 ppm [parts per million] a year," he says. "But in the last five years it's been at 2 ppm, which is more or less proportional to the rate at which we are burning fossil fuels."
As a result, our temperature trajectory is looking even more dramatic than the worst-case scenarios posited in 2007 by the United Nations Intergovernmental Panel on Climate Change (IPCC), a scientific body made up of thousands of senior scientists who evaluate the risk of climate change caused by human activity. This makes it even more likely that we'll see warming of more than a few degrees this century.
This alone would be costly to our society, but there's an even more troubling scenario that has climate scientists like Tans sweating. And that's if a feedback mechanism kicks in that drives temperatures even higher.
One such mechanism is the prospect of widespread melting of Arctic ice, which would rapidly release vast amounts of stored carbon and methane into the atmosphere. This could increase temperatures by as much as 10°C by the end of the century – and no amount of cuts in fossil fuel use or emissions can stop the process once it starts.
The thing is, no one knows at what point this feedback mechanism might kick in. It might happen after 5°C of warming, or it might start after just 3°C … or even less.
Global Warming
It was a record 35 below in my area the other day..Global warming is funny..All the planets around us are warming too,Hmmm must be humans out there driving cars and creating climate change...lol...Keep finding ways to tax us you pigs...
Warming on other planets does not correlate with solar output.
Yes, solar output has increased during most of the last century. No, it's not a big enough increase to explain the global temperature increases we see here on Earth. Yes, half the planets in the solar system seem to be experiencing warming right now. No, they are not warming at the same rates. No, increased solar output does not explain all planetary warming.
Fluctuations up and down are perfectly normal. The problem here on Earth is that we have introduced new factors into the equation which are causing the temperature to change much more rapidly than is normal. If the industrial revolution hadn't taken place, the Earth would have warmed by less than one tenth of a degree C during the last century. That would have been a perfectly normal reaction to the increased solar output and natural volcanic activity. Ice core samples show this kind of fluctuation happens all the time, and it follows predictable trends.
What is NOT normal is the way we humans have altered the atmosphere in such a short space of time. As a result, the global temperature has risen six tenths of a degree C during the last century. All indications are that it will be twice as bad in the next century.
Small changes are normal. We are causing big changes, and that's dangerous.
<h3>Humanity is a smoker</3>
My theory is that humanity kills itself slowly! We are very smart, indeed, but we are stupid when it comes to realize we are about to die, i personally don't think humanity will survive even this century, we are way to many to survive 5-6 more viruses, what we have had resently, is to viruses with very short ti,e between, and it the second was more effective, i guess in some time, it will come a virus that can go trough air, and then we are all dead... :'(
<h3>ehm</h3>
does it work now than..