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We must manage global warming risks by cutting carbon pollution, top scientists conclude

Posted on 10 November 2014 by dana1981

Last week, the Intergovernmental Panel on Climate Change (IPCC) published its latest Synthesis Report, summarizing the scientific research on the causes and impacts of global warming, and how we can mitigate its consequences. The report included various graphs showing how we’re changing the Earth’s climate, and concluded that humans are causing rapid and dangerous global warming.

Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.

Much of the report focused on the risks associated with these rapid climate changes. Fundamentally, climate change is a risk management problem. Even if you’re sceptical of the vast body of scientific research pointing to dangerous and potentially catastrophic climate change, there’s a very good chance the experts and their supporting evidence are correct and your scepticism is misplaced. The IPCC report put those risks into perspective,

Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.

Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped. The risks of abrupt or irreversible changes increase as the magnitude of the warming increases.

The key word here is “irreversible,” and it’s used 14 times in the IPCC’s latest Summary for Policymakers. For example, if ice sheets in Greenland and Antarctica collapse into the ocean, as they’ve already begun to, we can’t take the ice out of the ocean and put it back on land. That lost ice and the sea level rise it causes are irreversible impacts.

Conversely, policies to slow global warming are reversible. A new study by scientists at Duke University found that the widespread rejection of climate science by American political conservatives is in large part due to their distaste for the proposed solutions. Climate contrarians are afraid that climate policies will slow economic growth, despite evidence to the contrary.

However, if it turns out that the sceptics are right in their optimism that the best case climate scenario will occur, and if we go too far in our efforts to reduce carbon pollution, we can easily scale those efforts back. We can’t reanimate extinct species, but we can adjust climate policies as needed.

Speaking of species extinctions, the IPCC discussed that serious threat as well,

A large fraction of species face increased extinction risk due to climate change during and beyond the 21st century, especially as climate change interacts with other stressors (high confidence). Most plant species cannot naturally shift their geographical ranges sufficiently fast to keep up with current and high projected rates of climate change in most landscapes; most small mammals and freshwater molluscs will not be able to keep up at the rates projected under RCP4.5 and above in flat landscapes in this century (high confidence).

Marine species are also at risk due to the dual threats of warming oceans and ocean acidification, both of which are caused by carbon pollution from burning fossil fuels.

Since the beginning of the industrial era, oceanic uptake of CO2 has resulted in acidification of the ocean; the pH of ocean surface water has decreased by 0.1 (high confidence), corresponding to a 26% increase in acidity

The IPCC concluded that if we take serious action to reduce fossil fuel consumption and greenhouse gas emissions, we can limit the future increase in ocean acidity to about 16%. If we continue on a business-as-usual fossil fuel dependent path, ocean acidity will increase by around 100%, with dire consequences for marine ecosystems. This will also hurt our fisheries and contribute to food insecurity.

Climate change is projected to undermine food security (Figure SPM.9). Due to projected climate change by the mid-21st century and beyond, global marine species redistribution and marine biodiversity reduction in sensitive regions will challenge the sustained provision of fisheries productivity and other ecosystem services (high confidence) ... Global temperature increases of ~4°C or more14 above late-20th century levels, combined with increasing food demand, would pose large risks to food security globally (high confidence).

As these figure below from the report also illustrates, about 70% of studies indicate that crop yields will decline as the Earth continues to warm after 2030, with a high chance that yields could decline by 25% or more by the end of the century if we continue on our current path.

Summary of projected changes in crop yields, due to climate change over the 21st century. Yellow indicates studies that project crop yield decreases, blue indicates studies projecting increases. Summary of projected changes in crop yields, due to climate change over the 21st century. Yellow indicates studies that project crop yield decreases, blue indicates studies projecting increases. Illustration: IPCC AR5

Climate contrarians often argue that we should continue with business as usual and try to adapt to the consequences of global warming. We will have to adapt to some inevitable climate change, but as the IPCC concluded, we must also prevent as much global warming as possible to minimize the associated impacts enough that we will be able to adapt to them.

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Comments 1 to 12:

  1. So it looks like the proverbial stuff hits the fan starting about 2030 for crop yields? I'm surprised there isn't more of a negative effect till then.

    I had heard something about a ten percent loss in global yield for every degree C of GW, and that made it sound like a rather steady, lock-step relation. But as with much else, there seems to be a lag between the basic change and the full negative consequences of the change.

    Kind of unfortunate, since we will not get a clear signal from this vital sector of the economy till we have already commited ourselves to truly catastrophic levels of GW. And we seem to need many very stron signals to even begin to get our attention.

    So is CO2 fertilization really that strong of an effect in the short run? If not, what exactly accounts for this lag till 2030 for something like the full negative effects of GW to start hitting the ag sector?

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  2. wili,

    I'm not sure that CO2 fertilization is expected to be a big booster of food production.

    I can't quickly find a specific online reference, you can check the references listed in the IPCC report, but I recall reading several articles on the issue that implied that the expected near-term climate changes may marginally improve growing conditions in already established farming regions. However, the continued changes after those near term changes would make many of those regions less reliable for food production.

    An unfortunate twist could be that areas not currently cleared and  usable for growing food with appropriate infrastructure will rapidly shift to having more favorable conditions then shift to not being so favourable. The changes to regional climate could be too quick and difficult for those trying to adapt to predict and effectively adapt to. The result could be a fruitless chase after regions with better growing conditions that are hoped to last.

    The 'good news' is that such a wild-goose-chase would only be for as long as the rapid changes occur. Eventually the ones who make it through the tough decades (or centuries) would have a decent chance to figure out the better places to grow food and live using the hopefully dramatically improved ability to understand what is going on and the ability to keep the less concerned people, those who only care about a better present day existence for themselves, from creating more future problems.

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  3. So if not CO2 fertilization, is it just the added heat and moisture that helps increase  yeilds?

    It all reminds me again of the (apocryphal?) anecdote about the frog in slowly warming water--at first it just seems like its just getting nicer and nicer as it warms, so why jumpt out? But by the time it starts to boil, all ability to react adequately (jump out) has been lost.

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  4. wili,

    Unfortunately what is going on is likely far more sinister than the simple frog in warming water scenario. The regions expected to momentarily improve the ability to grow food are mainly in the already well developed and wealthy nations that must make the biggest reduction of their per-capita impacts.

    So what is going on is that the leaders who try to appease popular opinion in those wealthy powerful developed nations are essentially putting the less developed regions of the planet into a pot and keeping the burner going, while the people in the pot understand exactly what is going on but are unable to stop it. And caring and considerate bystanders outside the pot are equally unable to stop it because of the power of popular opinion driven by profitable damaging ultimately unsustainable pursuits.

    It will be interesting to see what the future generations think of leaders who did not vigorously fight to improve the better understanding of what is going on. Made-up unsustainable appearances of success and affluence eventually fall apart.

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  5. wili@3

    Remember too that yields have been increasing due to modern agricultural practices. In other words, there are negative and positive forces and trends at work when it comes to crop yields.

    Re. the old frog story:

    There's nothing apocyrphal about it. I used to rescue frogs from a hot tub at my old apartment complex in Florida during rainstorms--at least those I reached in time. They would hop in and quite peacefully hang out as they heated up to the point of no return, which in a 40 degree C hot tub wasn't more than about ten minutes. On several occasions, particularly on warm rainy nights in the spring, if the tub wasn't running, I had to clear an assortment of dead and living frogs from it. The living ones were always acting like climate change deniers--they were oblivious to the threat.

    If a frog jumped in when the tub was running (and of course thus rather foamy), anyone who wasn't squeamish joined in the rescue efforts. Those who were squeamish usually exited the tub quite rapidly.

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  6. So is CO2 fertilization really that strong of an effect in the short run?

    I read this in the Australia "Land" today (online edition, agricultrual Newspaper owned by Fairfax)

    CO2 a nutrient, not pollutant: Moore

    of particular interest where the comments... sigh


    Finally this paper writes something that is truthful about CO2 and the climate change fiasco

    There is "little" hope (99% wide agreement) of structural change at a national level and virtually "none" at an international level (99.9% confidence, wide agreement) to ensure efficacy of emissions reductions with any chance of keeping under the 2 C target... over to you Professor Anderson

    • At current (2014) emission levels, the 1000Gt will be consumed in less than 23 years.
    • But with CO2 certain to rise over the coming few years, then, at the likely 2020 emission level, there will be ~13.5 years until the full 2°C carbon budget will have been consumed; i.e. full decarbonisation of energy before 2034.

    I know you guys keep going on with the evidence but as this study in to anti vax indicates, you may actually be doing more harm than good ?

    researchers found that while they were able to teach parents that the vaccine and autism were not linked, parents who were surveyed who had initial reservations about vaccines said they were actually less likely to vaccinate their children after hearing the researchers messages.

    Which brings me to my question :)  Where the sites advocating actions that are effective, something akin to here ?  I know we have people like Naomi Klien etal flying all over the Planet, flogging product, telling us not to fly all over the Planet and flog product but there must be some sites with a little more "integrity" ? or is the reason we don't hear from these people because they just live a low emissions lifestyle themselves ? eg Joan Pick's / Ted Trainer's etal of this world 

    Perosnally I think encforced penury is the only true solution, emisisons dipped with the global economic crisis and I know when I quit my job (no welfare) and moved remotely off grid to lower my emissions, having no money enforced a low emissions lfestyle but am interested in debate on this issue .

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  7. No edit,

    I forgot to include the link to Professor Kevin Andersons comments and the typos above.. forgive me.

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  8. Dana is falling for a bad case of "single-study syndrome" when he makes the claim that a revenue-neurtral carbon tax could be beneficial for the economy. This one study seems pretty dubious to me. It also seems odd, basic economics tells you if you want people to stop using fossil fuels, you have to make them more costly. If a carbon tax is truly revenue-neutral, no one would change their behavior. They'd put up with higher energy costs because they are getting a subsidy from the gov. 

    The study seems hard to believe. 

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  9. austrartsua - Did you post on the thread you intended to? There's no mention of taxes in either the opening post or any of the comments until yours. 

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  10. Trevor_S,

    I would suggest that a start towards increased acceptance of the science and the policy requirements it irrefutably leads to would be for 'people who understand and accept the science and acknowledge that CO2 emissions need to be dramatically reduced' to stop repeating made-up claims that the people who try to deliver messages to encourage better understanding are excessively travelling in damaging ways to spread their message.

    The real problem is the people profiting from damaging unsustainable activity who abuse their wealth to fund the creation and dissemination of such made-up claims.

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  11. There is a link in the above post to a discussion of the economic benefits of a revenue neutral carbon tax.  It is one study - feel free to reference any evidence to the contary.  I don't think any exists.

    Also, a revenue neutral carbon tax does make carbon fuels more expensive.  In most households those costs are offset by the resulting rebate, but who wants to turn around and give that money right back to the oil companies?  Higher prices are still a motivator even if the funds are returned to the taxpayers.

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  12. Regardless of where austrartsua should have posted, his elimination of a vast literature which is reduced to (apparently) just one study by the parroting of a phrase (which it is questionable as to whether austrartsua understands).  Just one sample from that literature:

    "Bush-era tax cuts are scheduled to expire at the end of 2012, leading to interest in raising revenue through a carbon tax. This revenue could be used to either cut other taxes or to avoid cuts in Federal programs. There is a body of economic research suggesting that such an arrangement could be a win-win-win situation. The first win—Congress could reduce personal or corporate income tax rates, extend the payroll tax cut, maintain spending on social programs, or some combination of these options. The second win—these cuts in income taxes would spur the economy, encouraging more private spending and hence more employment and investment. The third win—carbon dioxide (CO2) pollution and oil imports would be reduced. This analysis uses the MIT U.S. Regional Energy Policy (USREP) model to evaluate the effect of a carbon tax as part of a Federal budget deal. A baseline scenario where temporary payroll cuts and the Bush tax cuts are allowed to expire is compared to several scenarios that include a carbon tax starting at $20 per ton in 2013 and rising at 4%. We find that, whether revenue is used to cut taxes or to maintain spending for social programs, the economy is better off with the carbon tax than if taxes remain high to maintain Federal revenue. We also find that, in addition to economic benefits, a carbon tax reduces carbon dioxide emissions to 14% below 2006 levels by 2020, and 20% below by 2050. Oil imports remain at about today’s level, and compared to the case with no carbon tax, are 10 million barrels per day less in 2050. The carbon tax would shift the market toward renewables and other low carbon options, and make the purchase of more fuel-efficient vehicles more economically desirable."

    (Rausch & Reilly, 2012, emphasis added)

    As the bolded sentence makes plain, there is a body of economic research on the topic (not a single study).  In fact, my search on google scholar found 22,800 results (excluding citations and patents).

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