By the time we reach a common consensus, if we ever do, it will be too late to reverse what is happening and probably too late to mitigate the effects.
People want certainty before agreeing to make major changes. But there can only ever be ''evidence'' over what has happened in the past. It is pointless to hope for evidence over something that may or may not happen in the future.
Even if everything that is known provides strong probability rather than just possibility, it does not qualify as ''evidence''.
Partly this is because public opinion has been skewed by the role of the news media in seeing it all as political rather than scientific. That is because politics are more easily understood, more easily debated, than science and because any solution can only be arrived at in a political context - by politicians.
The general public as well as the politicians themselves are bored by all the detail in the science and the uncertainties in the argument. So the debate cannot provide unarguable certainties; so the naysayers can always produce counter-arguments.
This book has a preface by Helen Clark, a long-time advocate for action to halt global warming and climate change. But even she, as formerly an elected politician, and now as an international deal-maker, can only go on saying that consequences ''might happen''.
Virtually nowhere in this collection of scientific papers and essays do the authors state categorically that something ''will happen''. They are academics and it is not part of their academic discipline to be so dogmatic.
Being dogmatic is what lobbyists and politicians bring to the debate. So people trying to influence politicians need to be and are dogmatic too.
The horror that is foreseen by the lobbyists, the environmentalists, drives them to make extreme predictions and judgements, leading to equally extreme rejections.
There is a prediction in the book based on very powerful evidence that by 2050 - only 35 years away - that there will be no coral reefs left. Even the 3000km-long Great Barrier Reef off eastern Australia is due to die.
But when I put this to a sceptic, he sneered and said: ''What? Not a single piece of living coral?''
No-one is saying that there will not be a single piece of living coral remaining. What they are saying is that the rapid warming of the ocean, rapidly rising sea levels, and increasing acidity of the water caused by industrial pollution - the main cause of global warming itself - will kill off the billions of fish dependent on coral reefs, the human fishing industries dependent on the fish stocks, and as a by-product kill off the billion-dollar tourist industries based around them.
This is a very depressing book to read. New Zealand-based climatologist Jim Salinger has overseen a collection of powerful arguments. Yet, even his presence is used as a distraction by those who dislike what they see of him on television in their living rooms.
These papers are based on international assumptions about economic growth, technological developments and population growth.
These scenarios, in spite of major differences in emissions, show different paths for global temperature increase that do not diverge dramatically until the mid-20th century.
This has led some to declare that there is very little difference in climate change across scenarios and that therefore emissions reductions can be delayed for many decades. This is a big mistake.
It will take many decades to replace current polluting energy systems. Some of the risks are bringing irreversible dangers. In fact, this is a text book in specific effects from changing the climate - rainfall, sea levels, fresh water, glaciers, biodiversity, crops, livestock, fisheries, viticulture, public health, and many more.
Not everyone will have the stamina to read everything. But there is something here for everyone, and in an accessible form, if in some cases obscured by jargon.
The final paper, by Jonathan Boston, sees it all as a moral argument. So it is. There are so many aspects to it and they take us to the very limits of moral imagination. No wonder getting agreement over climate change and global warming is proving so difficult.
• Oliver Riddell is a retired journalist in Wellington.
