“Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change”
The response amongst many groups was of cautious optimism and certainly some of the media were pleased with the outcome whilst acknowledging some of the Agreement’s limitations.
While I, like many climate scientists, was pleased to see a more ambitious target being set, I feel that actually achieving the 1.5 °C target is nigh on impossible (in the absence of large-scale carbon capture after 1.5 °C has already been breached). I worry that there is a strong disconnect between what the public and climate scientists think is achievable.
Limiting global warming to 1.5 °C is virtually impossible
In 2015 we saw temperatures a little over 1 °C above pre-industrial levels and 2016 will very likely be even hotter. Admittedly these are individual years with a strong El Niño influence making them a bit warmer than average, but the point is we’re already well on track to reach 1.5 °C pretty soon. Using the CMIP5 ensemble of state-of-the-art climate models and under a high emissions scenario (which most closely resembles the current trajectory of greenhouse gas emissions) we project that decadal global mean warming of 1.5 °C above pre-industrial levels will likely occur in the 2020s or early 2030s. This means we probably only have about a decade before we reach the most ambitious 1.5 °C average global warming mark that the Paris agreement is aiming for.
Last week, the Australian-German Climate and Energy College at the University of Melbourne published these spiral graphs which showed just how close we’re getting to 1.5 °C warming. We have very little time left to realistically limit warming to 2 °C let alone 1.5 °C, especially when you bear in mind that even if we stopped all greenhouse gas emissions now we’d likely have about another half a degree of warming as the climate has to catch up with the effects of our recent carbon emissions.
John Cook and colleagues have previously shown that the public seriously underestimate the level of consensus amongst climate scientists that human activities have caused the majority of global warming in recent history. Similarly, I fear that there is a level of naivety amongst much of the general public that we have time to act on climate change and that we can avoid the worst impacts by slowly and steadily reducing greenhouse gas emissions over the next few decades. This is simply not the case, rapid and drastic cuts to emissions are required as soon as possible.
Is 1.5 °C even enough to avoid “dangerous” climate change?
The stated 1.5 °C and 2 °C targets are designed to avoid the worst impacts of climate change. It’s certainly true that the more we warm the planet the worse the impacts are likely to be. However, I would argue that we’re already experiencing dangerous impacts of climate change affecting society and the environment. For example, a recent study led by Dann Mitchell found that many of the excess deaths reported during the summer 2003 heatwave in Europe could be attributed to human-induced climate change. Also, work I led showed that the warm seas associated with the bleaching of the Great Barrier Reef in March 2016 would have been almost impossible without climate change.
We are already experiencing some of the detrimental effects of climate change and these are likely to get worse as we continue to warm the planet.
I don’t think it’s likely that we will achieve the targets set out in the Paris Agreement, but it is vital that we do as much as we can to limit global warming. The more we do now, the less severe the impacts will be later with potentially far fewer deaths linked to extreme weather and less environmental damage.