Why August 9 is a huge day for climate action

The key report that informs how the world responds to climate change is about to be made public.

For climate scientists – and anyone concerned about the planet – August 9 is the date they’ve been waiting for the last eight years. The IPCC (Intergovernmental Panel on Climate Change) will release a mammoth, detailed report combining the best and latest climate science from around the world, its first since 2014.

This planetary health check will set the scene for November’s pivotal United Nations climate summit in Glasgow. Here’s why this is such a big deal.

Why the big build-up?

All of us – including governments, councils and businesses – are making decisions about how to prepare for climate change. Is buying that coastal dream home a good idea? Will my crop be safe from drought? Does this apartment need airconditioning? Is that a good place to build a stadium?

But the main source of evidence for these decisions – the reports of the IPCC – are updated painfully slowly, even though climate science is being updated all the time.

There are good reasons for the slow pace. The reports require co-operation by hundreds of scientists, drawing on a globe’s worth of published research. The process works by consensus, and involves a lot of cross-checking. The writers don’t get paid, and they have to fit their reading, assessing, debating and late-night Zoom meetings around other, full-time jobs.

To help fill the void between reports, the IPCC put out some interim reports since the last full version – most notably its report on the importance of trying to stay inside global warming of 1.5 degrees Celsius. That prompted governments, including New Zealand’s, to commit to a 1.5C target.

In 2018, Christchurch hosted an authors’ meeting for another interim report, on food and land.

But the slow-cooked, full report is considered the most authoritative. The next one, due on August 9, will be the first in a set of three – and early hints suggest the news could be bleak, even by climate change standards.

The first segment in August will cover the source of the problem, or what our greenhouses gases are physically doing to the planet. The second, due in February next year, will outline the impacts on us, the people, and the species we share Earth with. The third, due March next year, will canvass what we can do about it.

How many times have we repeated this palaver? Is anyone listening?

The clue is in the title, Assessment Report 6 or AR6. This is the sixth time this process has been repeated since 1988, hence the number of the working group.

Since then, the amount of published research has exploded, and so have greenhouse gas emissions, says New Zealander Andy Reisinger, the vicechairman of an IPCC working group.

Each time, authors from around the world look at all the studies measuring global temperatures, the greenhouse effect and the impact of a hotter climate on cities, food production, diseases, sea-level rise, fisheries and other things.

Combining a huge range of peerreviewed research from different fields helps eliminate bias and errors that might occur in any one study. (A similar, albeit smaller process of synthesising individual medical trials is often done to determine whether a medicine is effective.)

There are always differences of opinion about emerging areas of research, such as: Which model best reflects the pace of melting ice sheets? Resolving those has been more difficult than ever as the scientists couldn’t meet personally, thanks to Covid. An already fractious process was made ‘‘more painful’’ on email, because disagreeing writers didn’t have to face each other over a table, says Victoria University’s Dave Frame.

As for whether anyone’s listening, well, government pledges to cut climate pollution are still well below what’s required to keep heating inside 1.5C or even 2C. New Zealand is no exception.

But signatories to the global greenhouse-cutting Paris Agreement have until November to put forward better efforts. That’s when a pivotal UN summit will be held in Glasgow, to negotiate some of the last remaining details on how to keep us all under 1.5C heating or, at worst, 2C. The conference, known as COP26, was pushed back a year because of Covid.

The United Kingdom Government has been pushing hard for countries to go all out. It’s hoped the release of this report could provide an added incentive, by highlighting the cost of failure.

Are New Zealanders involved? Do we punch above our weight?

The writing group is made up of climate scientists from academic institutions across the world, and the full list is available online.

There’s a hierarchy: South Korean energy policy specialist Hoesung Lee has been the IPCC’s chairman since 2015. Below him are three vice-chairpersons, from the United States, Brazil and Mali.

The two highest-ranking Australasians are Reisinger and Mark Howden, of the Australian National University, both of whom are climate and agriculture specialists. They are vice-chairmen of IPCC working groups, putting them on the executive committee. As well as doing his core research, Reisinger attempts to help people understand IPCC reports by boiling them down into haiku, which he posts on social media.

Each chapter of the full report has two or three co-ordinating lead authors, plus

10 to 15 lead authors. Another two to three scientists act as review editors.

It’s perhaps not surprising discussions can get a bit cranky: The second draft of the report we’re about to see received

51,000 review comments. Each one had to be individually answered in writing.

New Zealand typically contributes a handful of authors who are considered experts in their areas. For example, Victoria University’s James Renwick (one of our climate change commissioners) is a co-ordinating lead author of AR6.

So is the University of Canterbury’s Bronwyn Hayward, who is a co-ordinating lead author of a chapter about cities, settlements and infrastructure.

Other Kiwi authors include the Climate Change Commission’s Harry Clark (a lead author in the agriculture and forestry section), Victoria University’s Frame (a lead author of the part covering Earth’s energy budgets and climate feedbacks) and Lincoln University’s Anita Wreford (a lead author of the Australasia chapter).

After the scientists have compiled their draft, the report is opened up to other experts and governments to offer feedback.

Wait, what? Why do governments have a say on a scientific report?

Fair question. The answer often given by the scientists is that it is governments that need to accept and act on the findings, if we are to get a handle on climate change.

Giving them a chance to review the draft before the rest of us see it increases the chances of political buy-in, or so the argument goes.

And, technically, the IPCC is made up of governments – they just get scientists to do the work.

The finished document is a huge beast, packed full of citations, so the writers prepare a high-level summary, called the Summary for Policymakers. This is the version that is actually read by most people, including most politicians, who engage with the reports.

Over the next two weeks, government representatives will be meeting key scientists involved in the first part of AR6 to go over and agree every line of this summary. However, Reisinger says the scientists don’t let political representatives make changes that aren’t true to the science. ‘‘They can’t change black to white.’’

What will it say?

Authors are sworn to secrecy during the process. Renwick, however, suggests the findings will be ‘‘stark’’.

One area to watch for is sea-level rise, where researchers have been busily updating and comparing their ice sheet models. An interim report on ice and the oceans showed scientists had grown more confident in their models since 2014, enough to increase the upper bounds of melting from Antarctica.

A third of Antarctica’s ice sheet is below sea level, making it vulnerable to widespread collapse as the world around it warms. The interim report highlighted the need to understand this risk, given Antarctica alone could raise the sea by several metres, not including melted ice from Greenland and the world’s glaciers.

Victoria University’s Nick Golledge, who is helping write AR6’s oceans section, says the differences between ice sheet models are now understood well enough that AR6 will be able to explain more clearly what scientists don’t know about future melting, as what bits of the science are solid. ‘‘It doesn’t mean the unknowns have gone away, but we can differentiate between them better.’’