While I was going through some books recently, trying to clear some space on the shelves. Among those on the clear-out list is Bill McGuire’s climate change Q+A book Seven Years to Save the Planet. A lot has changed since it was published in 2008, so it can’t serve as a reference. And it’s not very good either. But before it goes to the charity shop, it’s worth considering that title.
The book is called Seven years to save the planet because when it was written, that was the time we had to get global CO2 levels to peak and begin their decline. Global emissions needed to peak in 2015 if we were to stay within 2 degrees of global warming.
There’s some good logic to the 2015 date. The longer we leave it to begin reducing emissions, the more dramatic the cuts need to be. If emissions peak by 2015, then we’re looking at reducing CO2 levels by a relatively manageable 2.2 degrees a year towards a sustainable level. It’s a fairly gentle slope towards a low or zero carbon world. Here’s a graph from
As the graph also shows, leaving an emissions peak until later has two main consequences. First, you need a much steeper decline. Waiting until 2030 would then require cuts of over 9% a year, a level generally considered impossible outside of recession. The second problem is that every delay puts more carbon into the air, which then needs to be removed with negative emissions technologies.
In other words, if CO2 emissions didn’t peak in 2015, then stopping climate change is much harder and much more expensive. Maybe even impossible. Here’s the IEA’s chart showing what’s happened to global emissions:
It’s possible that carbon emissions have peaked. Or perhaps we’ve reached a plateau, or it could just be a hiatus before they start growing again. A peak is only ever visible in hindsight, but this is provisionally good news.
Of course, we need to see those emissions falling, preferably in line with the model. So far the pledges from the Paris Agreement are nowhere near that. Much depends on China, India, and Trump’s America. And in the time since the initial modeling was done, we’ve realised that 1.5 degrees is a better target than 2 degrees. That’s a much bigger challenge.
Still, I’ll be passing along Bill McGuire’s book with just a little satisfaction that we didn’t completely blow his seven year deadline.