Give me that!
This really isn't about polar bears any more.
At this very moment, the fate of civilization itself hangs in the balance.
The way we have been calculating the future impacts of climate change up to now
has been missing a really important piece of the picture.
We are now dangerously close to the tipping point in the world's climate system
this is the point of no return
after which truly catastrophic changes become inevitable.
Think of it like this:
For the past three million years,
our planet's climate has always been in one or the other of two stable states,
small changes in solar incidence pushed us from one to the other.
When we are in this cooler dip, the planet has an ice age.
When we are in the warmer one, the planet's climate is very much as it is now,
and has been throughout the whole of human history.
The problem is that our use of fossil fuels
is pushing us further and further out of our little stable dip
and up the far slope of this hill.
The tipping point is the point at which we cross the peak of the hill,
and we no longer need to keep pushing
to keep the planet moving towards a much hotter place.
It will just keep rolling onwards, all on its own.
This tipping point exists because of a set of positive feedbacks in the climate systems
mechanisms that can amplify the effects of man-made warming and lead to runaway change.
One of them is the Albedo Effect.
White surfaces reflect more solar radiation than dark surfaces,
so as global warming from greenhouse gases melts ice and snow,
it leaves behind dark ocean or land.
these surfaces now absorb more solar radiation than before - so adding to warming
which melts more ice and snow, and so on.
Uncondensed water vapour is actually a more important greenhouse gas than CO2.
Although we aren't actually emitting much water vapour directly,
as the planet warms, evaporation rates increase,
raising humidity and thickening the Earth's thermal blanket
which in turn raises temperatures, which further increases evaporation rates,and so on.
Normally, about half the CO2 emitted each year from human activities
is re-absorbed by a combination of forests, plankton, and the ocean itself.
But the ocean surface is becoming more and more acidic
as concentrations of CO2 dissolved in it rise.
At the same time the water temperature at the surface is also going up,
forming a layer of warm, acidic water that is spreading across the ocean surface,
killing off the plankton that locks CO2 out of the atmosphere.
Worse, warm water holds less CO2 than cold water
so as it heats up, it starts releasing some of the CO2 it had previously absorbed.
Just like marine ecosystems, land-based ecosystems normally act as carbon sinks,
taking carbon from the atmosphere and using it for growth.
But as these eco-systems heat up, they become unbalanced
plants become less and less effective
while micro-organisms in the soil become more and more effective at putting it out,
causing the ecosystem as a whole to go from being a carbon sink to being a carbon source.
As temperatures rise and rains fail, forests dry out, and fires don't get put out.
All of the forest's stored carbon goes up in smoke,
adding to the greenhouse gases in the atmosphere, further increasing warming,
which further degrades the carbon sinks.
In Siberia, a vast area of frozen peat bog the size of France and Germany combined
that we call the permafrost is melting,
and as it melts, it releases huge quantities of methane.
Methane is a greenhouse gas with a short lifespan in the atmosphere
but while there it has a warming effect more than 20 times as powerful as carbon dioxide.
The more methane is released, the more it adds to warming,
the more the permafrost melts, and the more methane is released.
The arctic tundra is not the only place with large stores of frozen methane.
Lurking under the sea bed there may be as much as 10 trillion tons of methane
stored as frozen crystals at sites around the world.
If we raise ocean temperatures by enough - and nobody knows how much is enough,
we could trigger the sudden release of this stored methane into the atmosphere.
The last time this happened, global temperatures rose abruptly by 10 degrees.
So, these are some of the feedback mechanisms
that explain why our global climate system has a tipping point.
Each feedback in the system has its own internal tipping point,
and it is the relationships within this complex, mutually reinforcing system,
that have been missing from our climate prediction models.
So far we have only pushed up global temperatures by around 0.8°C
but because of the 40 or 50 year time lag between emissions and temperature rise,
the emissions already in the atmosphere
commit us to raising temperatures by around another 0.6°C over the coming decades.
which could easily be enough to place us right at the peak of the hill
or even over it.
If we do pass this critical threshold, global temperatures could soar by as much as 6°C.
If this happens, the natural world will suffer a mass extinction event
which will wipe out the majority of the plants and animals with which we share the planet.
although there will be a lot more rats, flies, cockroaches and mosquitoes
as the world's ecosystems go into meltdown.
The first human impacts will come in the form of steeply declining access to fresh water,
as rainfall patterns change, glacier-fed rivers dry up,
and rising sea levels contaminate reservoirs.
As crops fail, forests burn, deserts spread and coastal regions flood permanently,
people will start to pack up their things in their billions
and move on in search of a better life elsewhere.
But where?
Humanity might survive this.
But what will 'humanity' mean in a world where countries which will remain habitable
like Britain, spend most of our resources fighting to keep out the starving millions
who can no longer live in their own countries because of what we have done?
The world is awash with weapons.
Enough firearms to arm one in every seven human beings on the planet.
As the world's ability to support the huge numbers of people alive today dwindles,
we will not die peacefully in our sleep.
OK, here's the good news:
None of this is inevitable – yet.
This is not the time to panic or to despair.
This is the time to act, while we still can.
We need to recognize that there is a huge question mark
over whether governments and corporations are capable of responding
to this threat in the time we have left.
They have had 20 years already and still have less than nothing to show for it.
This is because they remain committed to a doctrine that prioritises
short term profits and endless economic growth over the survival of life on earth.
There is no great mystery about what we need to do
to reduce emissions in line with the science.
we simply need to consume less.
But that is out of the question in a society
which is founded on the ever-increasing consumption of material resources and energy.
Nobody has all of the answers
but we do know that this is not the only way to live,
and given that it is almost certainly going to kill us all,
we'd better start looking urgently at some of the alternatives.
It's now very clear that in order to actually win the fight against climate change,
making big changes to the way we each live our own lives is not going to be enough.
we're also going to have to actively confront powerful vested interests
who will stop at nothing to prevent the changes we need from taking place.
We have to be more than just consumers.
These are extraordinary times.
Preventing runaway global warming is the most important task in all of human history.
and it has fallen to us to do it.
If we don't, then everything else we work to achieve in our lives
will be destroyed, or become meaningless.
Those who came before us didn't know about this problem,
and those who come after will be powerless to do anything about it.
But for us, there's still time!
We'd better get a move on though.
xxx translation by: yyyy