Understanding the leaked IPCC draft and bleaker climate warnings

Understanding the leaked IPCC draft and bleaker climate warnings
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In the last few days, a great deal of attention has been given to a leaked draft of a report by the UN’s Intergovernmental Panel on Climate Change (IPCC), which reportedly warns that climate change and the anticipated impacts will probably be on the dire side of the range of anticipated possibilities.

I am not an author on the confidential report myself, so I do not have direct knowledge of its content, but it certainly would come as no surprise that the reported outlook would be more bleak than those of past assessments. The climate of the past few decades has revealed that, within the range of potential changes predicted by scientists, reality tends to be closer to the more severe than the more benign. While science is very good at providing critical insights into the nature of change and at capturing a spectrum of potential changes and the factors that influence them, our recent experience has shown that the actual changes have frequently been in line with the more severe predictions.  

This occurs because some of the factors and processes that are difficult to quantify are often not weighted heavily in climate projections, despite their very real potential. These factors are what may lead to “tipping points,” climate conditions that, once reached, are difficult to recover from and may accelerate. The geologic record reveals such tipping points throughout our planet’s history, times of major, rapid and highly impactful climate change. Even though past tipping points are quite real, it is very difficult to quantify their near-term likelihood. Consequently, while tipping points could be reached in the foreseeable future, with very adverse consequences, declaring them with a high degree of certainty requires a level of scientific knowledge that has not yet been attained.  


However, given the fact that observed changes have frequently exceeded predictions, it stands to reason that as we improve our predictive capabilities and better represent the more unstable processes, these predictions will point to a more dramatically changing future than they may have in the past — one that is more in line with some of the surprisingly rapid and substantial changes we have seen recently. Among these are: the abrupt losses of ice in Antarctica, where ice shelves are collapsing, the more rapid than expected loss of Arctic sea ice cover, severe drought, significant escalation in fire events and increasingly intense heat waves, such as those currently occurring in the Western United States. 

For many decades, science has told us that industrialization and the excessive production and release of greenhouse gases would create such conditions. Today, we are seeing those predictions borne out. The great challenge for the future is tied to the fact that effective action is dependent not just on sound science, but on policy choices, which are influenced by many factors besides science; these include economic, political, humanitarian and other considerations. Today’s changes reflect the outcomes associated with our past choices, and what much of the scientific literature (on which the IPCC assessment is based) reports is that if those choices don’t change, the environmental outcomes will be very detrimental. 

Society has been racing toward a new normal. We live in a present that looks an awful lot like the more pessimistic predictions that were made in the past. As we look to the future, it is reasonable to assume that within the range of climate predictions for the coming years and decades, the odds favor the more severe. 

So based on what our recent history of science and observations tells us, it would not be at all surprising for the next IPCC Assessment Report — the most comprehensive, scientifically robust and definitive statement on climate conditions and outlook — to paint a more dire picture of our likely future than has previously been the case.

It is important to keep in mind, however, that what we are hearing in the news are stories based on leaked drafts of the report — drafts that have not yet gone through their full reviews and revisions. The care given to the preparation of these reports, the countless hours that hundreds of scientists spend critically examining publications, writing, editing, reviewing and revising the report are what make it so strong and credible. I am very much looking forward to reading the final report expected in February 2022, after it has been through the complete process of authorship, review and revision.  


The science does clearly point to a challenging future, one in which climate change places significant stresses on every aspect of our lives. Science, by its nature, avoids hyperbole and those who have spoken out most aggressively about the climate crisis have been derogatorily labeled as alarmists. But sometimes, when the outcomes and risks are so severe, alarm is warranted.

Alarm, however, should not necessarily equate to hopelessness. On the contrary, alarm can and should be a motivator for action, action that brings out — and takes advantage of — the best in our scientific, technological, policy, industrial and humanitarian capabilities to rise to the climate challenge and successfully overcome it. 

The content of the upcoming IPCC Assessment Report will, like those before it, present us with an opportunity to take an honest and sober look at the future we may be in for and help us determine the trajectory of humanity in the face of that future. Just as science shines a light on the challenges, science can light the path to success.

Waleed Abdalati is the director of the Cooperative Institute for Research in Environmental Sciences, a partnership of the National Oceanic and Atmospheric Administration and University of Colorado Boulder, where he is also professor in the Department of Geography.