Speaking recently in Delhi, Rajendra Pachauri, the head of the UN's Intergovernmental Panel on Climate Change (IPCC) said that the world was running out of time to tackle the threat of uncontrolled climate change, saying "we have five minutes before midnight."
Dr Pachauri said that humans were pushing the world's climate system to the brink, leaving us with us with little time to address the growing risk of climate change. The imminent release of the first part of the IPCC's next Assessment Report (its fifth, and therefore known as AR5 in the jargon) will push climate change firmly back up the political and media agendas - and pose the question as to why this risk isn't being addressed.
IPCC Assessment Reports are huge pieces of work, running to thousands of pages and involving thousands of scientists from around the world. The reports are so big they are broken into four sections, or working group reports, looking respectively at the physical science basis for climate change, impacts and adaption, and mitigation, with the final 'synthesis' report drawing all these together.
Together these are, simply, the most authoritative reports on climate change available. And although the report's findings are couched in nuanced, complex language - as one might expect of scientific reports where definites and absolutes are rare - we can expect the basic messages to be clear.
Climate change is still happening. There is more certainty than ever that human greenhouse emissions are the main driver of this change. Climate change is a huge threat to people, species, habitats and the places we care about. In a nutshell, that the risks posed by a changing climate are deeply concerning.
At WWF we're also extremely concerned that, as Dr Pachauri highlighted, the window of opportunity to deal with climate change effectively is rapidly closing and that Governments are not currently doing enough to mitigate these risks. In other words, the 'gap' between what the science is telling us needs to be done and the policy response - at national and international levels - is starkly apparent.
Increasingly, people are coming to see climate change as a risk-management problem. If we choose to do nothing, or relatively little, to address climate change, we would need to be confident that the risks posed by climate change were very small - but science is telling us the opposite.
The IPCC Assessment Reports, and reports like it, are saying that the risks posed by uncontrolled climate change are enormous - and that Governments, businesses and investors must do much more to reduce the risks that we are exposing ourselves to.
There needs to be action on multiple levels. On policy in the UK, we need a strong Energy Bill that provides the conditions for us to cut energy-related carbon emissions to near-zero by 2030; helping people to save energy and control their bills, tackling fuel poverty and positioning the UK as a modern, efficient economy that attracts investment and creates jobs.
We also need politicians to continue to support the Climate Change Act, passed with near-unanimous agreement from all main political parties back in 2008. The fourth carbon budget - which gives confidence to businesses and their investors about the scale of change we need to make in the next 20 years - will soon be reviewed. We're looking to politicians of all parties to maintain that cross-party consensus that recognised the need for the Climate Change Act, and for them to defend it from any attempts to water down the UK's commitment to cut greenhouse gas emissions.
On a European level, we want the EU to be more ambitious on climate. The EU has started the process of reviewing its climate and energy policies and we're calling on EU member states to back ambitious targets for carbon emissions, renewable energy and energy efficiency. The EU has led the way in the response to climate science and needs to maintain that leadership and go further as the science is saying we have to.
And internationally, we want countries of the world to agree a global deal on climate change by 2015. The UN process of reaching a global agreement on tackling climate change, that reflects the science we will be hearing about from the IPCC this week, needs to strike a new deal for all countries - and the UN climate conference in Paris in 2015 will be crucial.
Investors too need to play their part, recognising that continuing to invest in high-carbon assets stores up huge economic and social risks. The successful businesses of the future will be the ones who value, manage and restore natural assets and limit their exposure to risks such as those presented by a changing climate.
Shifting investments is a key part of the jigsaw, which is why WWF's global Seize Your Power campaign is calling on governments and financial institutions worldwide to phase out investment in fossil fuels, particularly the dirtiest fossil fuels like coal, and increase investment in renewable energy by at least US$40 billion over the next 12 months. The growing trend of divestments from fossil fuel companies by investors and public institutions suggests a growing acceptance of the need to leave fossil fuels in the ground.
No doubt the IPCC fifth Assessment Report will spark heated debate around to world about the scale of the threat posed by climate change and what our response should be. In many ways, it is understandable that climate change can appear to be a frighteningly complex, intractable problem - and that the ways to tackle the issue are likewise complicated and multifaceted.
But simple facts shine through. Climate change is still happening. We are predominantly responsible, but we aren't doing enough. And, as the clock ticks toward midnight, time is running out.