The world has passed a critical threshold in the struggle to keep greenhouse gas emissions at a level that humans can survive.
The level of carbon dioxide in the atmosphere – the most widespread greenhouse gas – has been at the centre of climate negotiations for the last two decades. These have focused on reducing the level of carbon pumped into the atmosphere, mainly by the burning of fossil fuels for energy.
The urgency has been driven by measurements from the Mauna Loa research station in Hawaii at the end of last week that levels had hit 400 parts of carbon per million parts of air. Founded in 1958, it is the longest direct record of carbon concentrations in the air. Every other record comes from ice core samples and other natural recordings.
When it started working, levels were 318 parts per million (ppm). Two hundred years ago, just before the modern era kicked off with the Industrial Revolution, these were 280ppm.
Highest in two-million years
Carbon levels have not been this high in all the time humans have been around – the last time this level was reached was two-million years ago.
In the decades following the 1960s, the concentration of carbon grew at 0.7ppm a year. In the last decade this has accelerated to a 2.1ppm increase every year. The institution said this is clear evidence that human activity is increasing the rate of carbon.
And at the end of last week, levels hit 400ppm – meaning humans have increased levels by 30% in two centuries, a rate of increase that normally takes centuries.
Scientists, their findings collated by the intergovernmental panel on climate change, have said this has directly led to increasing global temperatures and accelerated climate change. Their latest report will be published later this year, but a copy was leaked last year and it is virtually certain that this is true.
Sceptics will deny this. But the World Meteorological Organisation said last year was the 27th consecutive year where global land and sea temperatures were higher than the average over the three decades before 1990. Last year was half a degree warmer than the average for those years.
It was the ninth warmest year since records began 160 years ago, it said. The 11 years from 2001 to last year were also all in the top 13 warmest on record.
​And what is worrying is that the most recent warming happened in spite of la niña – the ocean phenomenon which traditionally cools the oceans. Warm oceans expand, and they are 20 centimetres higher on average than in 1880.
People becoming refugees
Lord Nicholas Stern, head of the Grantham Research Institute on Climate Change, told the Guardian that a changing climate will lead to "hundreds of millions" of people becoming refugees. This will be driven by desertification and crop failure making their current homes unsustainable, he said.
"The trouble will come when they try to migrate into new lands, however. That will bring them into armed conflict with people already living there. Nor will it be an occasional occurrence. It could become a permanent feature of life on Earth," he said.
The institute has predicted that if business-as-usual levels of pollution occur, the levels of carbon in the atmosphere could hit 600ppm by the end of this century.
Jim Hansen, a climate scientist at Nasa, said the amount of pollution in the atmosphere traps enough extra heat in a day to be the equivalent of 400 000 Hiroshima-sized bombs going off. This heat warms everything.
At a 2°C increase, the planet can just about absorb the effects. This increase is virtually guaranteed by the 400ppm. Whereas, a 4°C rise becomes problematic for the computers modelling the change. The computers that do all the modelling cannot handle the number of chain reactions that occur. The reactions expected include: rain will either fall less frequently in much heavier doses, or dry up and push the expanding deserts; warmer oceans will create more storms, and rise as they expand and ice melts into them.
Each one of these has its own string of reactions.
Help the most vulnerable adapt
For rich countries the money is already there to assist people to adapt the possible reactions. But for the poor, the effects of a changing climate are already starting to devastate – changing rainfall patterns are destroying crops and forcing people to move to cities to look for work.
The Green Climate Fund is meant to help the most vulnerable adapt. Its budget is supposed to be $100-billion a year by 2020. It's still empty.
South Africa is the 13th largest emitter of greenhouse gases per capita in the world, with a total of half-a-billion tonnes a year. Almost half of this comes from Eskom and its coal power stations. Sasol is the second largest emitter. China emits 10-billion tonnes a year, with the United States nudging six-billion tonnes.
At the 2009 Copenhagen climate summit, South Africa pledged to reduce its carbon emissions by 34% by 2020. But this was voluntary, and reliant on assistance from other countries. Since then the climate summit in Durban two years ago set up a new roadmap to lowering global emissions. This is supposed to be agreed upon by 2015, and come into action by 2020.
One of the world's biggest climate change groups, 350.org, however said that emissions have to peak very soon and drop back down to this level. Current progress therefore lacks ambition and is too slow, it said. This is because the carbon already in the atmosphere will be there and affecting change for a long time to come.
Low carbon technologies
China and the US have traditionally blocked any binding resolutions on lowering carbon emissions. But recently the country agreed to work together on the research and development of low carbon technologies. China has also started working with the European Union on a carbon trading scheme, which it said will make its economy more carbon efficient.
The year's big climate talks will be held in Poland, which has a similar reliance on coal power as South Africa. And leading up to this, talks have been held in Germany. Politicians there said that unlike in previous years there is a much greater focus on getting a global agreement in place and working by 2015. Christiana Figueres, head of the United Nations body running the process, said, "There is an increasing sense of urgency".
"With 400ppm carbon dioxide in the atmosphere, we have crossed an historic threshold and entered a new danger zone," Figueres warned.
"The world must wake up and take note of what this means for human security, human welfare and economic development. In the face of clear and present danger, we need a policy response which truly rises to the challenge," she said.