Download the Climate Action Centre primer "4 degrees hotter"
"Can, and how would, we live in a world 4 degrees Celsius warmer?" is no longer an abstract question, but one that has become the subject of debate in scientific circles, and now in the community.
Global political failure to reach agreement on greenhouse gas reduction measures in accord with the scientific imperatives will result in 4 degrees Celsius of global warming by 2100, if only the present levels of commitments by nations are achieved.
But is talk of, and planning for, adaptation to a 4-degree warmer world realistic, or delusional?
4 degrees became a sensitive issue in 2008 when an influential and controversial paper by Kevin Anderson and Alice Bows of the UK Tyndall Centre for Climate Change Research concluded that:
…it is increasingly unlikely any global agreement will deliver the radical reversal in emission trends required for stabilization at 450 parts per million carbon dioxide equivalent (ppm CO2e). Similarly, the current framing of climate change cannot be reconciled with the rates of mitigation necessary to stabilize at 550 ppm CO2e and even an optimistic interpretation suggests stabilization much below 650 ppm CO2e is improbable.In other words, adaptation would be much better guided by stabilization at 650 ppm, which is around a 4C warming. Professor Bob Watson, the chief scientific adviser to the UK Department for the Environment, Food and Rural Affairs, warned that the UK should take active steps to prepare for dangerous climate change. Whilst a much lower outcome was necessary, Watson argued that “we should be prepared to adapt to 4C” warmer.
As The Guardian reported, Watson’s plea to prepare for the worst was backed up by the government’s former chief scientific adviser, Sir David King. He said that even with a comprehensive global deal to keep carbon dioxide levels in the atmosphere at below 450 ppm there is a 50% probability that temperatures would exceed 2C and a 20% probability they would exceed 3.5C:
So even if we get the best possible global agreement to reduce greenhouse gasses on any rational basis you should be preparing for a 20% risk so I think Bob Watson is quite right to put up the figure of 4C.But Professor Neil Adger, a Tyndall Centre climate change adaptation expert thought:
…that is a dangerous mindset to be in. Thinking through the implications of 4C of warming shows that the impacts are so significant that the only real adaptation strategy is to avoid that at all cost because of the pain and suffering that is going to cost... There is no science on how we are going to adapt to 4C warming. It is actually pretty alarming.So what does 4 degrees feel and look like? In a new primer, the Climate Action Centre has surveyed some of the literature. In a nutshell, it is one in which:
- The world would be warmer than during any part of the period in which modern humans evolved, and the rate of climate change would be faster than any previously experienced by humans. The world's sixth mass extinction would be in full swing. In the oceans, acidification would have rendered many calcium-shelled organisms such as coral and many at the base of the ocean food chain artefacts of history. Ocean ecosystems and food chains would collapse.
- Half of the world would be uninhabitable. Likely population capacity: under one billion people. Whilst the loss will be exponential and bunch towards the end of the century, on average that is a million human global warming deaths every week, every year for the next 90 years. The security implications need no discussion
- Paleoclimatology tells us that the last time temperatures were 4C above pre-industrial (during the Oligocene 30 million years ago), there were no large ice-sheets on the planet and sea levels were 65–70 metres higher than today. Whilst ice sheets take time to lose mass, and the rise to 2100 may be only 1–2 metres (or possibly a couple more according to James Hansen), the world would be on the way to 65–70 metres.
- 3C may be the “tipping point” where global warming could be driven by positive feedbacks, leaving us powerless to intervene as planetary temperatures soared. James Hansen says warming has brought us to the "precipice of a great tipping point”. If we go over the edge, it will be a transition to “a different planet”, an environment far outside the range that has been experienced by humanity. There will be "no return within the lifetime of any generation that can be imagined, and the trip will exterminate a large fraction of species on the planet".
In part, there is ignorance, real or feigned. Former prime minister John Howard told Tony Jones on ABC’s “Lateline” in 2007 that an increase of 4–6 degrees would be “less comfortable for some than it is now”. But there is also a pervasive assumption that our species can adapt to whatever is thrown at us by climate change. After all, we are the masters of the planet whose industrial revolution gave us the tools to conquer distance, hold back the elements and tame nature.
In his 2010 book, “Requiem for a Species”, Clive Hamilton lays bare the trap of the “adaptation myth”:
The new understanding of the climate system and the likely influences of tipping points induced by human intervention also forces us to reconsider one of the other foundations of international negotiations and national climate strategies, the belief in the ability to adapt. From the outset of the global warming debate some have argued that as much emphasis should be placed on adapting to climate change as on mitigating it. As the setting and meeting of targets appears more difficult, more people began talking about the need to adapt.
Underlying the discussion is an unspoken belief that one way or another we (in rich countries) will be able to adapt in a way that broadly preserves our way of life because global warming will change things slowly, predictably and manageably. Wealthy countries can easily afford to build flood defences to shield roads and shopping centres from storm surges, and we can ‘climate proof’ homes against the effects of frequent heatwaves. Yet if our belief in our ability to stabilise the Earth’s climate is misconceived then so is our belief in our ability to adapt easily to climate change. If instead of a smooth transition to a new, albeit less pleasant, climate warming sets off a runaway process, adaptation will be a never-ending labour.The adaptation trap finds voice in those sceptics and delayers such as Roger Pielke Jr and Bjorn Lomborg, who insist that it is cheaper and more effective to adapt to global warming than to fight it. Pielke calls for “rejecting bad policy arguments when offered in the way of substitutes for adaptation, like the tired old view that today’s disaster losses are somehow a justification for changes to energy policies”.
Events such as New Orleans after cyclone Katrina should disavow the notion that adaptation (rebuilding the city) is more economical that mitigation (strengthening the storm defences before the event). And it won’t take too long to figure out that building a new energy system is cheaper than constantly rebuilding lives and buildings and infrastructure and agriculture when “1-in-a-100 year” extreme heatwaves, droughts, fires, floods and cyclones become regular events on the hotter planet calendar.
It is clear that our collective survival depends on the most radical mitigation effort we can imagine. Climate change is already dangerous, it is no longer a future-tense proposition. The hour is late. James Hansen, in a new paper, says that “...goals of limiting human-made warming to 2C and CO2 to 450 ppm are prescriptions for disaster.” At just 0.8C warming so far, he says we have little or no “cushion” left to avoid dangerous climate change.
Restoring a safe climate means the world very quickly building a zero-emissions economy without fossil fuels, and reducing the current level of greenhouse gases. It is a vast undertaking akin to a post-war reconstruction, but we have the technologies and the economic capacity. What we presently lack is an honest conversation about where we are headed, and the political will to build the solutions that are already available to us.
Our time is better spent working out how to make the impossible happen, rather than living the delusion that reasonable adaptation is possible to a 4-degree warmer world.