How to Stop Global Warming, In 7 Steps - Vox

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How to stop global

warming, in 7 steps

Updated by Brad Plumer on November 2, 2014, 12:51 p.m. ET

@bradplumer [email protected]

AVOIDING

Global warming is here, it's man-made, and it will cause serious problemsin the years ahead. What's more, humanity has daillied so long thatavoiding the worst impacts will now require extremely sharp emissionscuts — and possibly taking carbon out of the air.

That's the upshot of a major newsynthesis report ( http://www.ipcc.ch

DRASTICWARMING MAYMEAN ZEROINGOUTFOSSIL-FUELEMISSIONS BY2100

/pdf/assessment-report/ar5/syr/SYR_AR5_LONGERREPORT.pdf)from the UN's IntergovernmentalPanel on Climate Change (IPCC). Itprovides a helpful summary of thepanel's previous three big reportson global warming

,which dealt with: 1) the physicalscience of climate change, 2) howbad it could get, and 3) how to stopit.

The new report includes a review of the evidence that carbon dioxide fromburning coal, gas, and oil is heating the planet. It notes that some amountof "irreversible" climate disruption is already locked in, but things can alsoget much, much worse. Additional global warming could wreak havocacross the globe ( http://www.vox.com/2014/4/1/5570388/the-big-question-just-how-bad-is-global-warming-going-to-get), potentiallyleading to food shortages, the flooding of major cities, and massextinctions.

Perhaps the most relevant sections are about how to avoid this fate,something the world's nations will be discussing over the next year of UNclimate talks ( http://www.vox.com/2014/8/28/6075433/global-climate-talks-paris-2015). To avoid the worst outcomes, the world would need toact immediately and drastically, reducing emissions 41 to 72 percentbelow 2010 levels by mid-century. We'd then need to keep cutting andpossibly be taking carbon-dioxide back out of the atmosphere by 2100.

That won't be easy. And the task gets all the harder if countries delayaction or if they rule out certain controversial technologies, like nuclearpower or carbon capture for coal plants. Here are seven key points fromthe report:

1) Right now, the world is failing badly at its climate

goals

(http://www.vox.com/cards/global-warming/what-is-global-warming)

How to stop global warming, in 7 steps - Vox http://www.vox.com/2014/11/2/7146215/ipcc-climate-change-s...

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EVEN IFNATIONSFOLLOWTHROUGH ONTHEIR CLIMATEPLEDGES, WE'RESTILL ON PACEFOR 3°C OFGLOBAL

Total anthropogenic greenhouse gas emissions. (IPCC)

The world's nations have pledged to prevent global average temperaturesfrom rising more than 2° Celsius

(or 3.6° Fahrenheit)above pre-industrial levels. If we go too far above that, the worry goes, wedramatically increase the risks ( http://www.vox.com/2014/4/1/5570388/the-big-question-just-how-bad-is-global-warming-going-to-get) of thingslike rapid sea-level rise or mass extinctions or severe damage to our farmsand crops.

Trouble is, on our current course, it'sunlikely that we'll meet that goal.Global average temperatures havealready risen 0.85°C since the 19thcentury, as humans have burnedfossil fuels and cleared forests andput more heat-trapping greenhousegases in the atmosphere. And, theIPCC notes, yearly greenhouse-gasemissions continue to rise fast (see

chart).

If emissions keep rising, we're likelyon pace for between 3.7°C and 4.8°Crise in average temperatures by theend of the century. The World Bank,for one, thinks that would be a total

( http://www.vox.com/cards/global-warming/why-dangerous-2-degrees-global-warming)


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WARMINGdisaster

— because "there is nocertainty that adaptation to a 4°Cworld is possible.".

Now, countries like Europe and the United States, have made variouspledges ( http://www.washingtonpost.com/blogs/wonkblog/wp/2013/11/05/how-the-world-is-failing-at-its-climate-goals-in-one-giant-chart/)to cut their emissions in recent years. But even if those pledges pan out,the IPCC estimates, the world would still be on pace for roughly 3°C ofglobal warming by the end of the century. (There's a range of possibleoutcomes, but that's the central estimate.)

2) Hitting those goals will require sharp emissions

cuts — and soon

So how can we stay below 2°C of global warming?

The IPCC calculates that annual greenhouse-gas emissions would have tostart dropping each year — until they were 41 percent to 72 percentbelow 2010 levels by mid-century. Then emissions would have to keepfalling until humans were hardly putting any extra greenhouse gases by theend of the century. We'd also likely have to pull some carbon-dioxide outof the atmosphere.

See the first row below, labeled "RCP2.6":

(IPCC)

( http://www.vox.com/cards/global-warming/4-degrees-global-warming)


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IF WE RULE OUT

This task sounds extraordinarily difficult — and it is. But the IPCC notesthat it becomes even more difficult the longer we put off cuttingemissions, because carbon-dioxide and other greenhouse gases will keeppiling up in the atmosphere in the meantime, and the cuts needed to staybelow the limit become more severe.

In fact, if annual emissions in 2030 are still above today's levels, it becomesall but impossible to stay below that 2°C limit. (And even 3°C would bedifficult to avoid.)

3) Cutting emissions will require a massive

technological push

A grass covered mock VW electronic beetle car is pictured at the Hannover Messe industrialtrade fair in Hanover, central Germany on April 7, 2014. (JOHANNES EISELE/AFP/GettyImages)

So how do we cut emissions that sharply? First, the IPCC says that theworld would have to triple or even quadruple the share of clean energythat it uses by 2050 — and keep scaling it up thereafter. Second, we'd haveto get dramatically more efficient at using energy in our homes, buildings,and cars.

Right now, about 13 percent (http://www.vox.com/2014/6/19/5821250/these-5-charts-show-why-the-world-is-still-failing-


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TECHNOLOGIESLIKE NUCLEARPOWER, THETASK BECOMESMUCH HARDER

on-climate-change) of the world'senergy is "low-carbon" — a little bit ofwind and solar power, some nuclearpower plants, a bunch ofhydroelectric dams. Thosetechnologies would need to continueto improve and expand dramatically.

That means two things. First, it'stough to rule out any particulartechnologies. For instance, someenvironmentalists are opposed to nuclear power. But the IPCC estimatesthat the task of cutting emissions becomes between 4 and 18 percentmore expensive if nations shuttered all their nuclear plants. Likewise, thetechnology to capture carbon emissions from coal plants and bury itunderground is still in its infancy ( http://www.washingtonpost.com/blogs/wonkblog/wp/2013/10/22/is-china-the-last-hope-for-carbon-capture-technology/). But if that technology proves unworkable or limited, theIPCC estimates, then the task of cutting emissions becomes twice asexpensive:

(IPCC)

(It's worth noting that there are factors pushing the other way, too: Solarpower has become much, much cheaper ( http://www.vox.com/2014/10/16/6987915/solar-power-cheaper-balance-of-systems-costs) since theIPCC drew up its assessment, which makes the overall task of cuttingemissions a bit easier.)


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AND THE TECHTO PULLCARBON OUTOF THEATMOSPHERE ISSTILLUNPROVEN

Second, the IPCC notes that investment in fossil fuels — coal, oil, andnatural gas — would have to decrease by 20 percent in the next fewdecades. After all, if renewable energy ramps up, but conventional coalexpands even faster, emissions would rise, not fall.

Is this all doable? The IPCC report suggests that it's at least technologicallyfeasible. Whether it's politically realistic is another matter. The reportnotes that countries could start taxing carbon emissions as way of pushingprivate companies to redirect their investments. So far, however, thosepolicies have been slow to catch on — in the United States, a carbon tax isa non-starter in Congress.

4) We'd also likely need to pull carbon out of the

atmosphere

Back in its 2007 report on preventing climate change, the IPCC suggested( https://www.ipcc.ch/publications_and_data/ar4/syr/en/mains5-4.html)that the world's emissions would have to peak in 2015 if we wanted toprevent 2°C or more of global warming.

That's obviously not going to happen — 2015 is next year, and emissionsare expected to keep rising. So why does the IPCC think we still have achance this time around?

The panel is putting its hopes intechnologies that allow us to pullcarbon out of the atmosphere (http://en.wikipedia.org

/wiki/Negative_carbon_dioxide_emission) toward the end of the century.What if, for instance, we grew trees that sucked carbon dioxide out of theatmosphere. Then we burned those trees for fuel. But instead of letting


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STAYING BELOW2°C WILL COST

the carbon dioxide from those trees go back into the atmosphere whenwe burned it, we captured the emissions and pumped them underground?Voilà: That whole process would, in theory, be "carbon-negative."

The problem? The IPCC concedes that the availability of these techniquesis "uncertain" and the technology is currently "limited." So the panel isputting a lot of hope in an unproven concept to help limit global warmingand stay below the 2°C target.

5) Cutting emissions will cost us — but so will

global warming

A bulldozer is used to push sand from a discharge pipe into place during a federally fundedshore protection project by Great Lakes Dredge and Dock on May 17, 2013 in Fort Pierce,Florida. (Joe Raedle/Getty Images)

The IPCC estimates that staying below the 2°C target will likely cost us.After all, we're giving up cheaper fossil fuels and replacing them withpricier electric cars and solar panels and nuclear plants.

Economic modeling suggests thatthis would shave 0.06 percentagepoints off global economic growtheach year. So instead of growing by,say, 3 percent per year we'd begrowing by 2.94 percent. The world


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US — BUT SOWILL GOINGABOVE IT

would still get richer over time, but ata somewhat slower rate. By century'send, a massive clean-energy pushwould have cost between 3 and 11percent of global income.

That sounds manageable, though it'salso assuming all the necessary technologies work out and that countriesstart cutting immediately. It also assumes that countries adopt the mostcost-effective emissions policies possible — which is far from a given.

One question, meanwhile, is how this compares to the costs of not doinganything. The IPCC notes that it's difficult to assess the costs ofunchecked global warming. More extreme weather and higher sea levelsand crop failures were all likely to be quite damaging — but there wasn'tenough research to put a precise dollar figure on it. (The panel suggested (http://www.vox.com/2014/4/1/5570388/the-big-question-just-how-bad-is-global-warming-going-to-get) that just 2.5°C of warming wouldcost between 0.2 and 2 percent of annual income in 2100, though it notedthat this was likely to be a low-ball figure.)

So a lot depends on how much risk we're willing to take on. If we pay lessfor cutting emissions, we'll likely pay more in damages from highertemperatures — and vice versa. In his recent book The Climate Casino (http://yalepress.yale.edu/book.asp?isbn=9780300189773), Yaleeconomist William Nordhaus suggested that the costs and benefits werelikely to balance out at around 2.5°C of global warming. But others havecome up with higher and lower targets to aim for.

(By the way, there's a good argument that it's impossible to get precisecost-estimates for any of this. David Roberts has made that argument (http://grist.org/climate-energy/we-dont-and-cant-know-how-much-it-will-cost-to-tackle-climate-change/) at length for Grist. But the broadconceptual points — that it costs more if we delay cutting emissions, andthat higher temperatures typically mean higher costs — tend to holdregardless of exact numbers.)

6) Countries will have to start working together for

a change


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RICH AND POORCOUNTRIESSTILL CAN'TAGREE HOW TODIVVY UPEMISSIONSCUTS

Delegates attend the last day of the UN climate talks in Doha, on December 7, 2012. (KarimJaafar/AFP/Getty Images)

The IPCC notes that all the world's major nations would have to worktogether to halt global warming. That's because additional carbon-dioxidein the atmosphere helps heat up the planet no matter who emits it.

So it's not like Europe can cut all ofits emissions and the problem issolved. Everyone else — China, India,the United States, Japan — wouldhave to reduce their greenhousegases, too.

And that raises thorny questions.How do the different nations divvy upthe necessary cuts? Should wealthierregions like Europe and the UnitedStates cut more, since they'reresponsible for most of theman-made greenhouse gases thathave already been put in theatmosphere? Should they pay poorer countries to help cut emissions?These sorts of questions have often bogged down ( http://www.vox.com/2014/9/22/6805513/un-climate-talks-in-seven-charts) UN climate talksand led to stalemates.


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COUNTRIESWILL NEED TOSTARTADAPTING TO AWARMERCLIMATE UNDERANY SCENARIO

7) Even if we cut emissions, we'll still need to adapt

to a hotter world

Not exactly adapting. (Oxfam East Africa/Wikimedia Commons ( http://en.wikipedia.org/wiki/2011_East_Africa_drought#mediaviewer/File:2011_Horn_of_Africa_famine_Oxfam_01.jpg))

Even if the world cuts emissions drastically and stays below 2°C ofwarming, the IPCC notes, we've already locked in some amount of"irreversible" climate change, whose effects will "continue for centuries."That will mean changes in sea levels, rainfall patterns, extreme weather,and so on. And countries all over will have to adapt. Some examples:

-- Africa faces an increased risk ofcrop failure due to increased heat anddrought. Countries can partly offsetthese risks through things like betterirrigation practices, more loans forsmall farmers, providing access tofertilizer and better farmingpractices, and creating "early-warningsystems" against drought.

-- Asia needs to worry aboutincreased flooding from heavy stormsand tropical cyclones, among otherthings. Adaptation might involve


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early-warning systems and stricter building codes so that homes canwithstand flooding.

-- North America will face increased wildfires and deadly heat waves.Possible adaptations include providing "cooling centers" for people whodon't have air conditioning during heat waves. Governments could alsostop subsidizing people who live in wildfire-prone areas.

And the hotter it gets, the harder it gets to adapt. If we get 2°C of globalwarming, for instance, the risk of crop failures in Africa due to drought andheat rises to "very high." If Africa then invests a lot of money in adaptation,it can get that risk back down to "medium." If, however, we get 4°C ofglobal warming, then Africa's risk of crop failures becomes "very high"even with high levels of adaptation. There's only so much you can defendagainst extremely high heat levels.

Further reading

-- Two degrees: How the world failed on climate change (http://www.vox.com/2014/4/22/5551004/two-degrees)

-- 7 charts that show why UN climate talks keep breaking down (http://www.vox.com/2014/9/22/6805513/un-climate-talks-in-seven-charts)

-- Here was my rundown ( http://www.washingtonpost.com/blogs/wonkblog/wp/2013/09/26/will-the-u-n-s-massive-new-climate-report-tell-us-anything-new/) of the initial IPCC report in 2013, on the science ofglobal warming itself. Here's a summary ( http://www.vox.com/2014/4/1/5570388/the-big-question-just-how-bad-is-global-warming-going-to-get) of the second IPCC report on the impacts of global warming.

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How to Stop Global Warming, In 7 Steps - Vox

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