Many have already written about what the latest report of Group 1 of the IPCC – the Intergovernmental Panel on Climate Change – tells us yet again and which is already well-known about the state of the climate and its likely trajectory. But there is also a lot that this report does not say. Here are four eloquent examples.

  1. This report does not tell us how to reduce anthropogenic GHG emissions.

This document, nearing a lengthy 4,000 pages, is the contribution of Group 1 of the IPCC to the latter’s sixth summary report, which will be published in a year. Group 1 is concentrating its efforts on studying the climate in order to model future behaviour as precisely as possible according to different greenhouse gas (GHG) emissions scenarios. Group 2 is responsible for providing a summary of current knowledge on the impacts of climate change on human societies, agricultural systems and ecosystems. As for Group 3, it has the cumbersome task of presenting potential decisions to reduce GHG emissions and the impacts of climate change.

That being said, the absence of a comprehensive solution in this first report does not detract from the urgency, upon reading it, of reducing emissions using all the methods that have been established for many years now. We don't need an umpteenth IPCC report to know that burning any form of fossil fuel contributes directly to climate change, whether it's in a car engine, the boiler room of a building or the furnace of a steel mill. It is also a known fact that methane emissions from livestock are one of the largest sources – at 14.5%1 – of GHG emissions. There is only one step from there to calling for more ambitious measures in order to align our public policies and our personal behaviour with these observations. Unfortunately, it’s a difficult one to take. But these difficulties stem less from uncertainty regarding the measures to be taken, and much more from collective inertia and the short-term incentives to which public action is limited in many countries.

  1. When it comes down to it, this report doesn’t really tell us anything new.

IPCC reports are based on current science at the time they are drafted. As scientists' understanding of the behaviour of glaciers, oceans and the atmosphere grows, IPCC predictions become more accurate. IPCC reports provide forecasts that are always associated with a probability range known as a confidence interval. We therefore learn in this report that scientists are now able to model the atmosphere with horizontal grid spacing of 100 km (25-50 km at the regional level). As a comparison, the size of the "grid spacing" of the model used in the first report in 1990 was 500 km. This higher resolution for climate models, like camera sensors, allows scientists to provide more accurate forecasts, and now on a regional scale instead of merely a global scale.

However, it would be wrong to conclude from this ongoing improvement that it is preferable to wait for the next report, and then the next one, in an attempt to base any decision on the most precise scientific data possible, or even to hope for conclusions that negate those drawn thus far. What has changed since 1990 is not the direction of climate change, nor its anthropogenic origin, but the fact that scientists are now able to back up these beliefs with a much larger quantity of data.

  1. This report may be the last IPCC report.

As mentioned, the first IPCC report dates back to 1990. Thirty-one years and nearly six reports later, what has been accomplished in terms of reducing GHGs on a global scale? Since 1990, emissions have increased 40% while climate diplomacy has gone from conference to conference, without the Kyoto Protocol or the Paris Agreement leading to reduced GHG emissions. And between each IPCC report, politics and economics are left hanging while awaiting the next report, which is supposed to provide decisive data likely to finally generate the electric shock needed to make the critical decisions required to really reduce emissions.

It is a question of clearly seeing that the IPCC is not the primary source of scientific knowledge on the climate, but rather a UN body aiming to propose a periodic summary on the subject written by a group of renowned scientists. As such, one might wonder if the absence of the IPCC would reduce the amount of knowledge available, or in any case make it more scattered and difficult to access. This is undoubtedly the great merit of the IPCC: to use these reports to offer a comprehensive view, accessible to decision-makers and to everyone, of the sum of knowledge on climate change at the time the reports are drafted.

  1. This report does not announce "a" disaster scenario in which the water rises 50 meters or the temperature in Paris exceeds 50°C.

For a long time, rising sea levels crystallised much of the collective imagination surrounding climate change. Although this rise is real and measured to the nearest millimetre, a misunderstanding of the figures has tended to reduce its reach. Between 1901 and 2018 the average sea level rose by 20cm. The IPCC predicts that in the worst-case scenario, this average level will rise one meter by 2100. It would be wrong, however, to conclude that it would “suffice” to raise all the dikes by one meter to solve the problem. As previously stated, this is an average level. Just as having a bank account with an “average” balance of €2,000 can hide large fluctuations from -€ 10,000 to +€ 12,000 for example, an average level also says nothing about local and more or less temporary fluctuations such as floods caused by tsunamis and storms.

What this new report says more precisely and with greater certainty than in previous reports is that behind a global average temperature which has already risen by around 1°C, and which is likely to continue to rise, hides a much more significant increase in the frequency and intensity of extreme weather events in certain regions of the world, including Europe. For example, a heat wave such as the one experienced in France in 2003 would have a good chance of occurring every 3-4 years on average with a global average temperature increase of “only” two degrees. With the same increase, precipitation along the Mediterranean rim would decrease by at least 20%, making some regions too arid to cultivate any crops.

In short and above all, the frequency and intensity of phenomena previously considered to be extremely rare “freak events” and the unstoppable increase in average temperature put the stability of our societies at risk.

 

This IPCC report represents a body of knowledge distilled into 4,000 pages that very few people will read. Like the previous ones, it represents an intellectual, scientific and human feat, with the collaboration of people from very diverse disciplines and backgrounds that were required for its production. And yet, it tells us nothing that we do not already know, nor what is essential: how to convince the many recalcitrant stakeholders to take action when the main concepts of climate change and the main solutions have been known for decades. It doesn't say anything about that because that's not its purpose, of course. And yet the urgency is in the action, not in reading reports, however substantiated they may be.

 


1 Climate Change 2014: Mitigation of Climate ChangeContribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change