Emissions reduction efforts in the next decade pledged by governments under the Paris climate agreement are by far not sufficient to attain the explicit aim of the agreement — they will not keep warming below the 2-degrees-limit.
Emissions in 2030 would need to be at least 20 percent below what countries have pledged under the Paris climate agreement to keep costs and CO2 removal in check.
Rapid short-term emissions reductions are the most robust way of preventing climate damages and large-scale deployment of carbon removal technologies can only be avoided when reliable CO2 prices are introduced as soon as possible.
Rapid greenhouse-gas emissions reductions are needed if governments want to keep in check both the costs of the transition towards climate stabilization and the amount of removing already emitted CO2 from the atmosphere. To this end, emissions in 2030 would need to be at least 20 percent below what countries have pledged under the Paris climate agreement, a new study finds….
Removing CO2 from the atmosphere through technical methods including carbon capture and underground storage (CCS) or increased use of plants to suck up CO2 comes with a number of risks and uncertainties, and hence the interest of limiting them.
….”Emissions reduction efforts in the next decade pledged by governments under the Paris climate agreement are by far not sufficient to attain the explicit aim of the agreement — they will not keep warming below the 2-degrees-limit,”…”To stabilize the climate before warming crosses the Paris threshold, we either have to undertake the huge effort of halving emissions until 2030 and achieving emission neutrality by 2050 — or the emissions reductions would have to be complemented by CO2 removal technologies. In our study, we for the first time try to identify the minimum CO2 removal requirements — and how these requirements can be reduced with increased short-term climate action.”
…It turns out that, according to the computer simulations done by the scientists, challenges for likely keeping warming below the threshold agreed in Paris would increase sharply if CO2 removal from the atmosphere is restricted to less than 5 billion tons of CO2 per year throughout the second half of the century. This is substantial. It would mean for instance building up an industry for carbon capture and storage that moves masses comparable to today’s global petroleum industry. Still, 5 billion tons of CO2 removal is modest compared to the tens of billion tons that some scenarios used in climate policy debates assume. Current CO2 emissions worldwide are more than 35 billion tons per year…
…first, rapid short-term emissions reductions are the most robust way of preventing climate damages, and second, large-scale deployment of CDR technologies can only be avoided when reliable CO2 prices are introduced as soon as possible….”Ramping up climate policy ambition for 2030 to reduce emissions by 20 percent is economically feasible. It is all about short-term entry points: rapidly phasing out coal in developed countries such as Germany and introducing minimum prices for CO2 in pioneer coalitions in Europe and China makes sense almost irrespective of the climate target you aim for. In contrast, our research shows that delaying action makes costs and risks skyrocket. People as well as businesses want stability, and this is what policy-makers can provide — if they act rapidly.”
Jessica Strefler, Nico Bauer, Elmar Kriegler, Alexander Popp, Anastasis Giannousakis, Ottmar Edenhofer. Between Scylla and Charybdis: Delayed mitigation narrows the passage between large-scale CDR and high costs. Environmental Research Letters, 2018; 13 (4): 044015 DOI: 10.1088/1748-9326/aab2ba
20 percent of Americans account for nearly half of U.S. diet-related greenhouse gas emissions, and high levels of beef consumption are largely responsible
The researchers did not look specifically at how the beef was produced, which can influence its carbon footprint. “That information is not available on the dietary side,” Heller said [in a related Inside Climate News article]. “People aren’t saying where their beef is coming from or how it was raised. It was just beef.”
[Ellie’s note: this likely reflects CAFO cattle (cattle in concentrated agriculture feeding operations) in this national study as opposed to specific grass fed, grass finished beef which also provides other ecological benefits; note that leaks from natural gas and oil production are a more significant contributor of atmospheric methane than cattle; see more on methane, cows and rotational grazing here,here, here, and here]
the highest-impact quintile consumed more than twice as many calories on a given day — 2,984 versus 1,323 — than those in the bottom 20 percent
On any given day, 20 percent of Americans account for nearly half of U.S. diet-related greenhouse gas emissions, and high levels of beef consumption are largely responsible, according to a new study from researchers at the University of Michigan and Tulane University.
….If Americans in the highest-impact group shifted their diets to align with the U.S. average — by consuming fewer overall calories and relying less on meat — the one-day greenhouse-gas emissions reduction would be equivalent to eliminating 661 million passenger-vehicle miles, according to the researchers— nearly 10 percent of the emissions reductions needed for the United States to meet its targets under the Paris climate accord, the authors wrote…
The highest-impact group was responsible for about eight times more emissions than the lowest quintile of diets. And beef consumption accounted for 72 percent of the emissions difference between the highest and lowest groups, according to the study.
…Emissions related to the processing, packaging, distribution, refrigeration and cooking of those foods were not part of the study but would likely increase total emissions by 30 percent or more, Heller said….
…. cows don’t efficiently convert plant-based feed into muscle or milk, so they must eat lots of feed. Growing that feed often involves the use of fertilizers and other substances manufactured through energy-intensive processes. And then there’s the fuel used by farm equipment.
In addition, cows burp lots of methane, and their manure also releases this potent greenhouse gas.
…They found that Americans in the highest-impact quintile consumed more than twice as many calories on a given day — 2,984 versus 1,323 — than those in the bottom 20 percent. But even when the findings were adjusted for caloric intake, the highest-impact quintile was still responsible for five times more emissions than the lowest-impact group.,,,
Martin C Heller, Amelia Willits-Smith, Robert Meyer, Gregory A Keoleian, Donald Rose. Greenhouse gas emissions and energy use associated with production of individual self-selected US diets. Environmental Research Letters, 2018; 13 (4): 044004 DOI: 10.1088/1748-9326/aab0ac
Up to half of plant and animal species in the world’s most naturally rich areas, such as the Amazon and the Galapagos, could face local extinction by the turn of the century due to climate change if carbon emissions continue to rise unchecked. Even if the Paris Climate Agreement 2°C target is met, these places could lose 25% of their species according to a landmark new study by the University of East Anglia, the James Cook University, and WWF.
Published today in the journal Climatic Change and just ahead of Earth Hour, the world’s largest environmental event, researchers examined the impact of climate change on nearly 80,000 plant and animal species in 35 of the world’s most diverse and naturally wildlife-rich areas….
….If there was a 4.5°C global mean temperature rise, the climates in these areas are projected to become unsuitable for many the plants and animals that currently live there meaning:
Up to 90% of amphibians, 86% of birds and 80% of mammals could potentially become locally extinct in the Miombo Woodlands, Southern Africa
The Amazon could lose 69% of its plant species
In south-west Australia 89% of amphibians could become locally extinct
60% of all species are at risk of localised extinction in Madagascar
The Fynbos in the Western Cape Region of South Africa, which is experiencing a drought that has led to water shortages in Cape Town, could face localised extinctions of a third of its species, many of which are unique to that region…..
….Dr Jeff Price, coordinator of the Wallace Initiative and also from UEA, said: “This research provides a view on the differing spatial impacts of climate change on biodiversity. It shows the benefits of combining citizen science with the research and resources of highly-ranked Universities to assist an NGO with their conservation activities.”
R. Warren, J. Price, J. VanDerWal, S. Cornelius, H. Sohl. The implications of the United Nations Paris Agreement on climate change for globally significant biodiversity areas. Climatic Change, 2018; DOI: 10.1007/s10584-018-2158-6
New research published today in Nature Ecology & Evolution demonstrates the extraordinary value of Earth’s remaining intact forests for addressing climate change and protecting wildlife, critical watersheds, indigenous cultures, and human health.
Yet the global policy and science communities do not differentiate among the relative values of different types of forest landscapes — which range from highly intact ones to those which are heavily logged, fragmented, burnt, drained and/or over-hunted — due in part to the lack of a uniform way of measuring their quality….
….Retaining the integrity of intact forests must be a central component of global and national environmental strategies, alongside current efforts to stabilize deforestation frontiers and stimulate restoration. The researchers recommend several policy interventions to fill this gap, including:
Creating new standard metrics of intactness that can be used to raise awareness of the importance of forest quality and to help target action towards the most intact places.
Embedding the intact forests concept in the UN Framework Convention on Climate and the Intergovernmental Panel on Climate Change’s Special Reports, to help ensure the Paris Agreement’s climate commitments include intact forest protections.
Supporting global and local forest policies that limit road expansion; regulate hunting, extraction, and development; invest in restoration and protected areas; and help secure indigenous communities’ land tenure rights.
Supporting efforts that both restore and make degraded forests more productive while also conserving at-risk intact systems — rather than opening intact forests to activity.
James E. M. Watson, Tom Evans, Oscar Venter, Brooke Williams, Ayesha Tulloch, Claire Stewart, Ian Thompson, Justina C. Ray, Kris Murray, Alvaro Salazar, Clive McAlpine, Peter Potapov, Joe Walston, John G. Robinson, Michael Painter, David Wilkie, Christopher Filardi, William F. Laurance, Richard A. Houghton, Sean Maxwell, Hedley Grantham, Cristián Samper, Stephanie Wang, Lars Laestadius, Rebecca K. Runting, Gustavo A. Silva-Chávez, Jamison Ervin, David Lindenmayer. The exceptional value of intact forest ecosystems. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0490-x
European national science academies report warns tepid emission cuts not enough.
A new European Academies Science Advisory Council (EASAC) report looks at a number of options, including reforestation, soil management, plankton fertilization, industrial CO2 capture plants, biofuels with emissions injected underground for storage, and even the boosting of bedrock weathering reactions.
The report’s conclusions: we have to develop carbon dioxide removal schemes more aggressively, but we also have to cut our emissions enough that we don’t rely on those schemes to save us.
….Those scenarios involved a substantial deployment of technologies to actively remove CO2 from the atmosphere. Without those technologies, we’re even further from sufficient emissions cuts.
That leaves us with a crucial question: can carbon dioxide removal techniques be scaled up to the necessary level in time? A new European Academies Science Advisory Council (EASAC) report—reviewed and endorsed by the national academies of more than two dozen countries—evaluates the outlook for carbon dioxide removal. And it’s not optimistic.…
….The EASAC report finds that few options look like they could scale up to three or four billion tons. And more importantly, none is on track to do so at this point. Reforestation and accumulating carbon in agricultural soils are probably the easiest options to make progress on, for example, but we’re currently still doing the opposite of these things: deforestation and soil degradation are adding to our greenhouse gas emissions, not counteracting them….
….The EASAC report’s conclusions are basically twofold: we have to develop carbon dioxide removal schemes more aggressively, but we also have to cut our emissions enough that we don’t rely on those schemes to save us….
Decades of diplomatic efforts to stem global warming have proven ineffectual because too many strategies have been taken off the table.
But what definitely won’t suffice is a climate strategy built out of wishful thinking: the proposition that countries can be cajoled and prodded into increasing their ambition to cut emissions further, and that laggards can be named and shamed into falling into line.
There is no momentum for investing in carbon capture and storage, since it could be seen as condoning the continued use of fossil fuels. Nuclear energy, the only source of low-carbon power ever deployed at the needed scale, is also anathema. Geoengineering, like pumping aerosols into the atmosphere to reflect the sun’s heat back into space, is another taboo. But eventually, these options will most likely be on the table, as the consequences of climate change come more sharply into focus…
Global emissions of greenhouse gases amounted to the equivalent of some 30 billion tons of carbon dioxide a year — excluding those from deforestation and land use. Worried about its accumulation, the gathered scientists and policymakers called on the world to cut CO2 emissions by a fifth.
That didn’t happen, of course. By 1997, when climate diplomats from the world’s leading nations gathered to negotiate a round of emissions cuts in Kyoto, Japan, emissions had risen to some 35 billion tons and the global surface temperature was roughly 0.7 degrees Celsius above the average of the late 19th century.
It took almost two decades for the next breakthrough. When diplomats from virtually every country gathered in Paris just over two years ago to hash out another agreement to combat climate change, the world’s surface temperature was already about 1.1 degrees Celsius above its average at the end of the 1800s. And greenhouse gas emissions totaled just under 50 billion tons….
…Climate diplomats in Paris didn’t merely reassert prior commitments to keep the world’s temperature less than 2 degrees above that of the “preindustrial” era — a somewhat fuzzy term that could be taken to mean the second half of the 19th century. Hoping to appease island nations like the Maldives, which are likely to be swallowed by a rising ocean in a few decades, they set a new “aspirational” ceiling of 1.5 degrees.
To stick to a 2 degree limit, we would have to start reducing global emissions for real within about a decade at most — and then do more. Half a century from now, we would have to figure out how to suck vast amounts of carbon out of the air. Keeping the lid at 1.5 degrees would be much harder still.
And yet, when experts tallied the offers made in Paris by all the countries in the collective effort, they concluded that greenhouse gas emissions in 2030 would exceed the level needed to remain under 2 degrees by 12 to 14 billion tons of CO2.
Are there better approaches? The “climate club” proposed by the Yale University economist William Nordhaus has the advantage of including an enforcement device, which current arrangements lack: countries in the club, committed to reducing carbon emissions, would impose a tariff on imports from nonmembers to encourage them to join.
Martin Weitzman of Harvard University supports the idea of a uniform worldwide tax on carbon emissions, which might be easier to agree on than a panoply of national emissions cuts. One clear advantage is that countries could use their tax revenues as they saw fit.
Mr. Barrett argues that the Paris agreement could be supplemented with narrower, simpler deals to curb emissions of particular gases — such as the 2016 agreement at a 170-nation meeting in Kigali, Rwanda, to reduce hydrofluorocarbon emissions — or in particular industries, like aviation or steel.
Maybe none of this would work. The climate club could blow up if nonmembers retaliated against import tariffs by imposing trade barriers of their own. Coordinating taxes around the world looks at least as difficult as addressing climate change. And Mr. Barrett’s proposal might not deliver a breakthrough on the scale necessary to move the dial.
…But what definitely won’t suffice is a climate strategy built out of wishful thinking: the proposition that countries can be cajoled and prodded into increasing their ambition to cut emissions further, and that laggards can be named and shamed into falling into line.
Inveigled by three decades of supposed diplomatic progress — coupled with falling prices of wind turbines, solar panels and batteries — the activists, technologists and policymakers driving the strategy against climate change seem to have concluded that the job can be done without unpalatable choices. And the group is closing doors that it would do best to keep open.
There is no momentum for investing in carbon capture and storage, since it could be seen as condoning the continued use of fossil fuels. Nuclear energy, the only source of low-carbon power ever deployed at the needed scale, is also anathema. Geoengineering, like pumping aerosols into the atmosphere to reflect the sun’s heat back into space, is another taboo.
But eventually, these options will most likely be on the table, as the consequences of climate change come more sharply into focus. The rosy belief that the world can reduce its carbon dependency over a few decades by relying exclusively on the power of shame, the wind and the sun will give way to a more realistic understanding of possibilities.
The ‘likely’ range of ECS (amount of global warming if doubled CO2) as stated by the Intergovernmental Panel on Climate Change (IPCC) has remained at 1.5–4.5 degrees Celsius for more than 25 years1. The possibility of a value of ECS towards the upper end of this range reduces the feasibility of avoiding 2 degrees Celsius of global warming, as required by the Paris Agreement.
New study presents a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC ‘likely’ range) of 2.2–3.4 degrees Celsius.
If one is the loneliest number, two is the most terrifying. Humanity must not pass a rise of 2 degrees Celsius in global temperature from pre-industrial levels, so says the Paris climate agreement. Cross that line and the global effects of climate change start looking less like a grave situation and more like a catastrophe.
…today in the journal Nature, researchers claim they’ve reduced the uncertainty in a key metric of climate change by 60 percent, narrowing a range of potential warming from 3°C to 1.2°C.
…The metric is called equilibrium climate sensitivity, but don’t let the name scare you. “It’s essentially the amount of global warming we would predict if we just doubled the atmospheric carbon dioxide and let the atmosphere and climate come to equilibrium with the carbon dioxide,” says lead author Peter Cox, who studies climate system dynamics at the University of Exeter….
….the researchers say this means the probability of the ECS being less than 1.5°C—the Paris Climate Agreement’s super optimistic goal beyond the 2°C goal—is less than 3 percent. The upside, though, is they say this new estimate means the probability of the ECS passing 4.5°C is less than 1 percent.
…It’s just that global climate change is an exceedingly complex problem. There’s no way any scientist can dig down into all the granular details—changes in vegetation, small-scale hydrology, every single weather event like a hurricane or tornado. So what scientists do is find simplified descriptions of these small-scale events….
ABSTRACT: Equilibrium climate sensitivity (ECS) remains one of the most important unknowns in climate change science. ECS is defined as the global mean warming that would occur if the atmospheric carbon dioxide (CO2) concentration were instantly doubled and the climate were then brought to equilibrium with that new level of CO2. Despite its rather idealized definition, ECS has continuing relevance for international climate change agreements, which are often framed in terms of stabilization of global warming relative to the pre-industrial climate. However, the ‘likely’ range of ECS as stated by the Intergovernmental Panel on Climate Change (IPCC) has remained at 1.5–4.5 degrees Celsius for more than 25 years1. The possibility of a value of ECS towards the upper end of this range reduces the feasibility of avoiding 2 degrees Celsius of global warming, as required by the Paris Agreement. Here we present a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC ‘likely’ range) of 2.2–3.4 degrees Celsius. Our approach is to focus on the variability of temperature about long-term historical warming, rather than on the warming trend itself. We use an ensemble of climate models to define an emergent relationship2 between ECS and a theoretically informed metric of global temperature variability. This metric of variability can also be calculated from observational records of global warming3, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.
A research note from Barclay’s Bank last week summed up what the boom in electric vehicles, along with gains in fuel efficiency, might mean for oil demand—a reduction, by 2025, almost as large as Iran’s total production. And if electric vehicles seize a third of the car market by 2040, the drop in demand would be nearly as much as Saudi Arabia produces.
That kind of jaw-dropping outlook has become increasingly common in recent months amid signs that a tipping point is coming for electric vehicles.
The technology breakthroughs, market forces and government policies might also augur a peak in oil demand, and that would be a big step toward wiping out emissions of greenhouse gases from the automotive tailpipe.
From Europe to Asia, and in parts of the United States, policymakers are talking about how to make it happen.
France and Britain committed in July to ban the sales of all gasoline- and diesel-powered cars by 2040, motivated largely by health concerns about air pollution. Then China, the world’s largest auto market, announced last month that it will set a deadline for automakers to stop selling internal combustion engine vehicles and set emissions targets for automakers. California officials said they want to follow suit.
..Earlier this year, Sussmas co-authored a study for Carbon Tracker titled “Expect the Unexpected” that predicted EVs would be cost-competitive with internal combustion engine vehicles by 2020 and have a 35 percent market share by 2035….Carbon Tracker predicts that oil demand will peak as soon as 2020, remain somewhat flat until 2030, then drop off. It bases that analysis in part on its growth projections for EVs, which it says would displace 2 million barrels of oil use by 2035…
…Instead, in China, toxic air pollution from coal plants and car emissions are causing human illnesses and crop failures that have sparked public protests. The government responded to the pollution problem with strong subsidies for EVs, Sussmas said…
…The Energy Information Agency (EIA), which is the data arm of the U.S. energy department, recently projected that worldwide emissions of carbon dioxide from the burning of all fossil fuels—oil, coal and gas—would grow 16 percent by 2040 from the levels of 2015, the year that the nations of the world agreed to the landmark Paris Agreement on climate change that is intended to reverse the trend.
The EIA’s current scenario shows a slowing, but no decline, in global petroleum use. …For EVs to make the most of their emissions-reducing promise, the electricity sector will also have to continue its rapid shift to renewable energy sources.
A new study evaluating models of future climate scenarios has led to the creation of the new risk categories ‘catastrophic’ and ‘unknown’ to characterize the range of threats posed by rapid global warming. Researchers propose that unknown risks imply existential threats to the survival of humanity. These categories describe two low-probability but statistically significant scenarios that could play out by century’s end, in [the] new study…
The risk assessment stems from the objective stated in the 2015 Paris Agreement regarding climate change that society keep average global temperatures “well below” a 2°C (3.6°F) increase from what they were before the Industrial Revolution.
Even if that objective is met, a global temperature increase of 1.5°C (2.7°F) is still categorized as “dangerous,” meaning it could create substantial damage to human and natural systems. A temperature increase greater than 3°C (5.4°F) could lead to what the researchers term “catastrophic” effects, and an increase greater than 5°C (9°F) could lead to “unknown” consequences which they describe as beyond catastrophic including potentially existential threats. The specter of existential threats is raised to reflect the grave risks to human health and species extinction from warming beyond 5° C, which has not been experienced for at least the past 20 million years…
…”When we say five percent-probability high-impact event, people may dismiss it as small but it is equivalent to a one-in-20 chance the plane you are about to board will crash,” said Ramanathan. “We would never get on that plane with a one-in-20 chance of it coming down but we are willing to send our children and grandchildren on that plane.”…
….Aggressive measures to curtail the use of fossil fuels and emissions of so-called short-lived climate pollutants such as soot, methane and HFCs would need to be accompanied by active efforts to extract CO2 from the air and sequester it before it can be emitted. It would take all three efforts to meet the Paris Agreement goal to which countries agreed at a landmark United Nations climate conference in Nov 2015.
…Xu and Ramanathan point out that the goal is attainable. Global CO2 emissions had grown at a rate of 2.9 percent per year between 2000 and 2011, but had slowed to a near-zero growth rate by 2015. They credited drops in CO2 emissions from the United States and China as the primary drivers of the trend. Increases in production of renewable energy, especially wind and solar power, have also bent the curve of emissions trends downward. Other studies have estimated that there was by 2015 enough renewable energy capacity to meet nearly 24 percent of global electricity demand.
…most of the technologies needed to drastically curb emissions of short-lived climate pollutants already exist and are in use in much of the developed world. They range from cleaner diesel engines to methane-capture infrastructure.
“While these are encouraging signs, aggressive policies will still be required to achieve carbon neutrality and climate stability,” the authors wrote.
The historic Paris Agreement calls for limiting global temperature rise to “well below 2 °C.” Because of uncertainties in emission scenarios, climate, and carbon cycle feedback, we interpret the Paris Agreement in terms of three climate risk categories and bring in considerations of low-probability (5%) high-impact (LPHI) warming in addition to the central (∼50% probability) value. The current risk category of dangerous warming is extended to more categories, which are defined by us here as follows: >1.5 °C as dangerous; >3 °C as catastrophic; and >5 °C as unknown, implying beyond catastrophic, including existential threats. With unchecked emissions, the central warming can reach the dangerous level within three decades, with the LPHI warming becoming catastrophic by 2050. We outline a three-lever strategy to limit the central warming below the dangerous level and the LPHI below the catastrophic level, both in the near term (<2050) and in the long term (2100): the carbon neutral (CN) lever to achieve zero net emissions of CO2, the super pollutant (SP) lever to mitigate short-lived climate pollutants, and the carbon extraction and sequestration (CES) lever to thin the atmospheric CO2 blanket. Pulling on both CN and SP levers and bending the emissions curve by 2020 can keep the central warming below dangerous levels. To limit the LPHI warming below dangerous levels, the CES lever must be pulled as well to extract as much as 1 trillion tons of CO2 before 2100 to both limit the preindustrial to 2100 cumulative net CO2 emissions to 2.2 trillion tons and bend the warming curve to a cooling trend.
The temperature baseline used in the Paris climate agreement may have discounted an entire century’s worth of human-caused global warming, a new study has found.
Countries in the Paris climate agreement set a target of keeping warming below 2 degrees Celsius by curbing carbon emissions compared to their preindustrial levels. But a new study shows that the preindustrial level used in the agreement, based on temperature records from the late 19th century, doesn’t account for a potential century of rising temperatures caused by carbon dioxide emissions. Accounting for those gases, released from about 1750 to 1875, would add another one-fifth of a degree to the baseline temperature, the study found.
Published yesterday in Nature Climate Change, the research suggests there’s less time than previously believed to address global warming, said Michael Mann, a climatologist at Pennsylvania State University.
The study estimates that there may have already been 0.2 degree Celsius of warming, or 0.36 degree Fahrenheit, built into Earth, he said. That means the Paris Agreement would have to be more aggressive, according to the study, which was also written by researchers from the universities of Edinburgh and Reading in the United Kingdom.
“When you take that into account, it turns out we have 40 percent less carbon to burn than we thought we had,” Mann said….
Andrew P. Schurer, Michael E. Mann, et al. Importance of the pre-industrial baseline for likelihood of exceeding Paris goals Nature Climate Change doi:10.1038/nclimate5