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Why we need the next-to-impossible 1.5°C temperature target

Posted on 30 December 2015 by Guest Author

Simon Donner is an Associate Professor of Climatology at the University of British Columbia. For the past decade, he has researched climate change impacts and the adaptation challenges facing the Pacific island countries.

The agreement signed at the United Nations climate summit in Paris has been hailed as historic, ground-breaking, and unprecedented.

At the same time, the targets are so ambitious that many climate analysts are rolling their eyes. The agreement aims to limit warming to “well below” 2°C above pre-industrial levels, and recognizes that avoiding 1.5°C of warming “would significantly reduce the risks and impacts of climate change.”

The emissions reduction commitments made by the participating countries are not close to sufficient to achieve these targets. Carbon budget analyses show it will be next to impossible to avoid the 1.5°C limit without “negative emissions” – sucking carbon dioxide out of the air, using technologies that are unproven or not yet in existence. 

It is therefore understandable that Oliver Geden of the German Institute for International and Security Affairs would argue in his article, “Paris climate deal: the trouble with targetism,” that the temperature targets in the agreement are the height of hypocrisy. 

Yet Mr. Gedden and other critics of the Paris Agreement are missing the point of the climate negotiations. The issue facing international negotiators is not the statistical odds of staying within stated temperature limits. The issue is what happens if we do not.

After all, this is a global climate agreement. And to many countries, passing those temperature limits could be a disaster.

The temperature targets were included in the agreement out of respect for developing countries and small island states like the Republic of Kiribati, where I have conducted climate research over the past decade. In particular, the lower 1.5°C target is a signal to these countries that the world recognizes the existential threat that comes with more warming.

There is no scientifically definable “safe” amount of climate change. Science can provide us with a guide to the impacts of different levels of warming. The amount of warming we deem as “safe,” however, depends on our values and our perception of risk.

The 2°C target was informed by science, but it was chosen by developed countries – the same countries that are historically most responsible for climate change.

If you live in a small island nation in the tropics, more than 1.5°C of global warming certainly seems dangerous. With more than 1 meter of sea-level rise, around 90% of countries like Tuvalu, the Marshall Islands, and Kiribati could become so prone to flooding as to be uninhabitable. While there’s large uncertainty about the rate of future sea-level rise, evidence from the distant past suggests that every 1°C of warming will eventually cause 2.3 meters of sea-level rise.

There’s even greater concern among larger countries like Fiji about coral reefs, a key source of food, income, and coastal protection in tropical countries. The world’s coral reefs are already in trouble due to warming and acidifying ocean waters. Research led by my colleague Dr. Katja Frieler shows that if warming can be kept to less than 1.5°C, two-thirds of the world’s coral reefs could be spared from serious degradation this century. With 2°C or more of warming, reefs covered with living corals could become an artifact of history.

The critics are correct in arguing that the world is unlikely to avoid 1.5°C of warming, or even 2°C of warming. Yet to dismiss the targets entirely is to dismiss the needs of countries that are full members of the international climate negotiations.

By agreeing on the temperature limits, we are officially recognizing the scientific evidence that harm will come with more warming. This helps ensure that countries like Kiribati which are most at risk will receive the needed international assistance, a key tenet of international climate policy since the creation of the U.N. Framework Convention on Climate Change in 1992. Though they have not received much attention in the international media, the adaptation, capacity-building, and finance sections are as central to the Paris climate agreement as the sections on emissions and temperature targets.

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Comments 1 to 11:

  1. I'm all for being positive about Paris despite the warts,  but there is no sense of urgency and no appreciation by the public of the scale of the task at hand. Here in the UK we're currently experiencing record breaking weather with widespread flooding yet there's little mention in the press about the connection with climate change. it's all down to the El Nino apparently. Lots of people are finding out first hand that the 1C or so of warming we've had to date isn't safe - you don't need to live on a low lying island to be flooded. Meanwhile the government talks about flood defences and passes laws to frack under national parks. We desperately need credential carrying climate scientists on the news explaining the reality. All the congratulations post Paris lead the public to believe the job's done. 

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  2. It is terrible what is happening in England. Ancient bridges washed away. Villagtes flooded. I wonder what is happening to the wildlife. Here in Vancouver, we are are luckily having great weather. But I agree that there is no sense of urgency from the public on global warming. There seems to be more concern about what mitigation will cost them right now than what climate change will cost ( in more ways than money) in the long run.

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  3. There is so much confusion over what weather phenomenon to "blame" on global warming. So, these types of weather happened before global warming: rain, snow, wind, hurricanes, tornados, droughts, floods, sleet, freezing rain, el ninos, cold winters, warm winters, cold summers, hot summers... All bau on planet Earth! What AGW does is to cause shifts in weather patterns. It makes the probability of more extreme weather higher. With a bias towards higher temperature extremes. So when people say, for instance, "el nino is a natural phenomenon", that is, of course, completely correct! However, we are currently experiencing the strongest el nino in recorded history. Very likely the result of AGW. As is most of the extreme weather that is happening with increasing frequency all over the planet.   That's the whole point of the concern over AGW.

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  4. Elizabeth Kolbert has a piece in the New Yorker "The Siege of Miami".  An exerpt:

    "Scientists who study climate change (and the reporters who cover them) often speculate about when the partisan debate on the issue will end. If Florida is a guide, the answer seems to be never. During September’s series of king tides, former Vice-President Al Gore spent a morning sloshing through the flooded streets of Miami Beach with Mayor Levine, a Democrat. I met up with Gore the following day, and he told me that the boots he’d worn had turned out to be too low; the water had poured in over the top.

    “When the governor of the state is a full-out climate denier, the irony is just excruciatingly painful,” Gore observed. He said that he thought Florida ought to “join with the Maldives and some of the small island states that are urging the world to adopt stronger restrictions on global-warming pollution.”

    Instead, the state is doing the opposite. In October, Florida filed suit against the Environmental Protection Agency, seeking to block new rules aimed at limiting warming by reducing power-plant emissions. (Two dozen states are participating in the lawsuit.)

    “The level of disconnect from reality is pretty profound,” Jeff Goodell, a journalist who’s working on a book on the impacts of sea-level rise, told me. “We’re sort of used to that in the climate world. But in Florida there are real consequences. The water is rising right now."

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  5. We should be careful attributing any weather incident or pattern to climate warming, it just plays into the hands of the denial industry.

    I accept the evidence on warming, which seems to have legitimate science on its side. But it appears that the effect on weather is not as well understood and forecasts can come back to bite.

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  6. I would say 1.5C is not next to impossible but actually impossible. According to Michael Mann, 1.7C is already built in, so 1.5C would take some kind of negative emissions technology, and very quickly. Indeed, that linked article also suggests 405 ppm CO2 is the limit for 2C, so that must also be regarded as impossible (though Mann, bizarrely, thinks it's still achievable).

    So these targets have been included out of respect for small low island nations? Surely that is not respectful if there is no chance of achieving the targets. What would be respectful is to actually take actions, starting now (not waiting until 2020), to reduce and, soon, eliminate GHG emissions.

    So what matters is action, not words about unachievable targets.

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  7. I would also say 1.5 C is impossible without negative emissions technology as Dr David Mills was on youtube years ago saying 440ppm was locked in.

    In that video he said it was unsure whether it was possible to go over 440ppm and then come back under it but the fact that 440ppm would be passed was deemed inevitable... and that was years ago!

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  8. I support setting the 1.5 C target. Setting a 'stretch target' is a common business practice (also applicable to sport performance and just about any other pursuit worth pursuing).

    Such 'targets' may appear to be, be able to be claimed to be, or actually be unachievable. However, the focus on aspiring to achieve them will result in a better outcome than setting 'lower standards' that can continually be lowered as you aspire to 'succeed?'.

    Many people have attempted to delay any action that would lead to the advancement of humanity to a better future for all of humanity. Many people 'like' the promotion of perceptions of 'opportunities' for some of humanity (them personally) to enjoy a better life from understood to be damaging and unsustainable developed and developing activity for as long as they can get away with.

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  9. Reducing the rate of greenhouse gas emissions means closing down many of the current high emitters and providing sound alternatives.  This can only be a slow process for practical reasons regardless of the policies adopted by governments. And carbon capture and storage systems can, at best, only slow down the global rate of emissions slightly.

    There should be more focus on measures to cope with the irreversible rapid climate change and ocean acidification and warming that is under way. Proposed amelioration measures can only slow down the unintended deleterious consequences of using fossil fuels to provide energy to power technolgical systesm.

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  10. Too late. Already passed 400 ppm. 3 C is locked in.

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  11. Actually, back in the Pliocene CO2 reached 415 ppm and caused 3 to 4 C higher temperature.

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