The urgency of taking action on climate change is a complicated matter. On the one hand, the damage of inaction is real and growing every year. On the other hand, there is no “too late”. Plug in some numbers and you can set an appropriate deadline to achieve a goal, but we’re not dealing with an all-or-nothing proposition. There is a continuum of consequences, and our choices can always take us up a notch toward “better” or “worse.”
Against this background, the latest report by the Intergovernmental Panel on Climate Change (IPCC) shows that the next few years represent a crucial window for our hopes of limiting global warming to the 1.5°C or 2°C guideline values. These numbers aren’t magic, but they make sense. First, they represent a brighter future than any larger number on the thermometer. Second, these are the goals around which international negotiations have long revolved.
(Giga)tons of work to do
the release is the third and final section of the sixth assessment report. The first two publications dealt with the physical science of a changing climate and the effects of climate change. This deals with the climate solutions called “reduction” in hazard jargon. The publication examines past and present greenhouse gas emissions and sheds light on the path to eliminating emissions and stabilizing our planet’s climate.
There are clear signs of progress. Previous reports have been forced to describe future scenarios of massive issuance as business-as-usual continuations of current trends. This report states that these scenarios no longer appear likely. The rapid decline in the cost of renewable energy has led to accelerated growth in clean energy, among other trends. This, together with national commitments, puts us on a course towards around 3°C by 2100 rather than the 4+°C world of a “burn every bit of carbon you can find” emissions scenario.
From there to get into a world that actually stops However, warming by 2°C or 1.5°C is a tall order. Emissions data over the last few years have raised the possibility that we are near the top of the emissions curve. That should be true. In scenarios where warming stops at around 1.5°C or at 2°C, the report says, “emissions are expected to peak between 2020 and before 2025 at the latest.” In other words, emissions must start falling around now.
And after the peak, the emissions must also steep Reject. For the 1.5°C limit, emissions must fall by more than 40 percent by 2030 and reach net zero in the 2050s. Reaching 2°C doesn’t get much easier – we need to cut over 25 percent by 2030 and reach net zero in the 2070s.
Another way to visualize these changes is to imagine a remaining “budget” of emissions before the world crosses a chosen limit. About 1,200 gigatonnes of CO2 would push us down to 2°C from where we are now. Just 400 gigatonnes would push us down to 1.5°C. To put some sobering context into account, the world emitted about 410 gigatonnes in the 2010s alone.
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