The release of the fifth big summary of climate change science should settle the debate on whether or not human beings are driving climate change.
On Friday September 27, the Intergovernmental Panel on Climate Change (IPCC) will release its fifth report on climate change. This assessment report – which has been leaked – will make a hugely significant step to end the debate over whether humans are driving climate change with carbon emissions.
The last report in 2007 concluded it was "very likely" that human greenhouse gas emissions had contributed to more than half of the global warming in the previous century, which means more than 90% certainty. In the intervening six years, the science that allowed for some uncertainty has been improved upon, which has allowed the UN-mandated body to change this.
The new report is expected to push this number up to 95%, or "extremely likely". This is as high a certainty as science can currently provide.
This expected pronouncement has brought sceptics out in force to attack the report and its findings, as well as scientists involved in the report who have defended the findings and methodology.
Lord Nicholas Stern, who did seminal research on the economic costs of not acting on climate change, told the Guardian: "The science is unequivocal and shows there is serious danger. What is coming from sceptics is just noise, and should be treated as noise."
From 200 years of climate science and observations, it was clear that there was a strong association between the increase of carbon dioxide and global surface temperature, he said. "It is astonishing, irrational and unscientific to suggest that the risks are small. How can they [sceptics] say the risks are small?"
Amending government policies
Given the authority of the IPCC and the involvement of so many countries, the report will provide the basis for a great deal of policy around the world. By ending the debate on whether humans are driving climate change, and focusing on what changes will happen and what can be done, the report will give a solid grounding for governments to amend their own policies.
In this instance South Africa is at the forefront, with strong environmental legislation and commitments. It agreed at the 2009 Copenhagen climate change conference to voluntarily lower carbon emissions by 42% by 2025.
It also hosted COP17 in Durban two years ago, where the roadmap for a globally binding climate change agreement was set out. This will be agreed-upon by 2015, and is set to come into action by 2020. The plan is for countries to have binding targets for lowering their carbon emissions, in an attempt to ensure that temperatures do not increase by more than two degrees in the coming century.
Need to Know:
What is the IPCC?
The Intergovernmental Panel on Climate Change was established in 1998 by the World Meteorological Organisation and United Nations Environment Programme.
What does it do?
The IPCC creates comprehensive assessments of all the available science on climate change from around the world. It has published four big reports in the past, saying what the consensus on climate change is, what the impacts will be, and what are the possible options for mitigating these effects and adapting to them. Its last report won the team the Nobel Peace prize in 2007.
Who does it?
The IPCC invites scientists from around the world to contribute to the process. This report was compiled by 600 authors from 32 countries. They pored through 9 200 peer-reviewed studies, based on two-million gigabytes of data.
What's happening in Stockholm?
The majority of the report is compiled through correspondence. This week scientists and country representatives met in Stockholm to thrash out the final content of the synthesis report. The open nature of this and the involvement of so many groups means that any final text has to be reached by consensus.
What's the point?
On Friday, the Summary for Policymakers will be released. This will form the basis of all the planning that governments will do around climate change for the coming years. By moving on from the debate around whether humans are driving climate change, to what can be done to mitigate and adapt to this, the report will give governments more impetus to deal with climate change.