You may have heard there’s a climate science report out.
It will generate a thousand stories and messages, in every language on the planet.
Most will center on interpretations and agendas because the findings are not new. This U.N.-chartered Intergovernmental Panel on Climate Change, in its sixth comprehensive assessment of global warming science since it was created in 1988, is charged only with reviewing published research.
The core conclusions are plenty stark enough and need no embellishment. Go to the I.P.C.C.’s list of headline statements for key takeaways but here are three distilled points:
- From “fire weather” to hurricane strength, heat waves to deluges, melting ice to searing drought, much of what has been unfolding around the planet is already, to a growing extent, intensified by the climate-altering power of hundreds of billions of tons of heat-trapping carbon dioxide and other pollutants emitted so far as a consequence of humanity’s “great acceleration” of industrial development.
- Because of the long life of CO₂ and heat already banked in the oceans and other factors, centuries lie ahead with rising temperatures, rising seas and a dangerous melange of extreme events, but the pace and the odds of deeply disruptive worst-case outcomes are still a function of humanity’s decisions, or continuing indecision, around stopping the growth of our heat-trapping carbon footprint in the atmosphere.
- In theory, there’s still time to stop dangerous warming altogether, and to forestall the worst impacts on people and the world’s ecosystems if emissions can be brought down from today’s 40-billion-tons-plus a year (and rising) to a net of zero.
That last point remains key. Every step toward emissions reduction is a step toward a safer relationship with climate in the decades ahead, including holding at bay potential deeply destabilizing abrupt or compounded changes – the “monsters behind the door,” to use an apt old phrase from Princeton scientist Steve Pacala.
But that’s where this report, “Climate Change 2021 – The Physical Science Basis,” leaves off. Unfortunately, the antiquated architecture of the panel, established decades ago, means two crucial additional parts of this assessment – on warming impacts, vulnerabilities and adaptation options and ways to mitigate warming – won’t be out until next February and March, and a final synthesis report comes in September 2022…
And that’s what’s most urgently needed.
Click back to two other periodic United Nations products – the latest reports on the glaring global “Emissions Gap” and “Adaptation Gap” – and you’ll see the deep hollowness behind many of the pledges by the nations that have spent the last century thriving on a fossil fueled energy diet. (Keep in mind there are no teeth in the 2015 Paris Agreement and the foundational 1992 Framework Convention on Climate Change that it builds on.)
Read these posts for more on adaptation capacity and vulnerability reduction as prime imperatives with quick payoffs:
- Behind Global “Climate Emergency” Rhetoric, Solvable Vulnerability Emergencies Abound – Rich-world climate impacts – explosive wildfires, deadly urban floods and heat domes – are terrible. But this phrase obscures a profound vulnerability divide among and within countries.
- Study Finds Global Surge of Flood Exposure is from Population Shifts Far More than Climate Change – Too often, rising climate risk is conflated with rising CO2. That takes the heat off national and local leaders who can cut drivers of risk on the ground now.
Here’s a deeper look at what this newest “physical-science basis” summary offers.
Like a photograph coming into focus, causes and consequences of climate change that were only hinted at a decade or two ago have sharpened markedly. The emerging clarity comes from a mix of steadily improving computer power and model sophistication and increases in the amount of evidence revealing past climate dynamics. See here how more time and analysis has only reinforced and a 1999 finding by the climate scientist Michael E. Mann and others showing the unique nature of Earth’s current hot spike:
Read a fresh commentary by Mann in Time Magazine on the new report and his old finding.
But the emerging clarity has come mostly, and sadly in a way, from all the additional observations of change in these wasted decades of indecision. The “large-scale geophysical experiment” that the scientist Roger Revelle described in the 1950s has had so much time to play out that more signals have emerged.