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Viewpoint World Scientists’ Warning of a Emergency Downloaded from https://academic.oup.com/bioscience/advance-article-abstract/doi/10.1093/biosci/biz088/5610806 by Oregon State University user on 05 November 2019

WILLIAM J. RIPPLE, CHRISTOPHER WOLF, THOMAS M. NEWSOME, PHOEBE BARNARD, WILLIAM R. MOOMAW, AND 11,258 SCIENTIST SIGNATORIES FROM 153 COUNTRIES (LIST IN SUPPLEMENTAL FILE S1)

cientists have a moral obligation as actual climatic impacts (figure 2). forest loss in Brazil’s Amazon has now Sto clearly warn humanity of any We use only relevant data sets that are started to increase again (figure 1g). catastrophic threat and to “tell it like clear, understandable, systematically Consumption of solar and wind energy it is.” On the basis of this obligation collected for at least the last 5 years, has increased 373% per decade, but and the graphical indicators ­presented and updated at least annually. in 2018, it was still 28 times smaller below, we declare, with more than The climate crisis is closely linked to than consumption (com- 11,000 scientist signatories from excessive consumption of the wealthy bined gas, coal, oil; figure 1h). As around the world, clearly and unequiv- lifestyle. The most affluent countries of 2018, approximately 14.0% of ocally that planet Earth is facing a are mainly responsible for the his- global GHG emissions were covered climate emergency. torical GHG emissions and generally by carbon pricing (figure 1m), but Exactly 40 years ago, scientists from have the greatest per capita emissions the global emissions-weighted aver- 50 nations met at the First World (table S1). In the present article, we age price per tonne of Climate Conference (in Geneva 1979) show general patterns, mostly at the was only around US$15.25 (figure 1n). and agreed that alarming trends for global scale, because there are many A much higher carbon fee price is made it urgently neces- climate efforts that involve individ- needed (IPCC 2018, section 2.5.2.1). sary to act. Since then, similar alarms ual regions and countries. Our vital Annual fossil fuel subsidies to energy have been made through the 1992 Rio signs are designed to be useful to companies have been fluctuating, and Summit, the 1997 , and the public, policymakers, the busi- because of a recent spike, they were the 2015 , as well as ness community, and those working greater than US$400 billion in 2018 scores of other global assemblies and to implement the Paris climate agree- (figure 1o). scientists’ explicit warnings of insuf- ment, the United Nations’ Sustainable Especially disturbing are concur- ficient progress (Ripple et al. 2017). Yet Development Goals, and the Aichi rent trends in the vital signs of cli- (GHG) emissions are Biodiversity Targets. matic impacts (figure 2, supplemental still rapidly rising, with increasingly Profoundly troubling signs from file S2). Three abundant atmospheric damaging effects on the Earth’s cli- human activities include sustained GHGs (CO2, methane, and nitrous mate. An immense increase of scale in increases in both human and rumi- oxide) continue to increase (see endeavors to conserve our biosphere is nant livestock populations, per capita figure S1 for ominous 2019 spike in needed to avoid untold suffering due meat production, world gross domes- CO2), as does global surface tempera- to the climate crisis (IPCC 2018). tic product, global tree cover loss, ture (figure 2a–2d). Globally, ice has Most public discussions on climate fossil fuel consumption, the number been rapidly disappearing, evidenced change are based on global surface of air passengers carried, carbon diox- by declining trends in minimum sum- temperature only, an inadequate mea- ide (CO2) emissions, and per capita mer Arctic sea ice, Greenland and sure to capture the breadth of human CO2 emissions since 2000 (figure 1, Antarctic ice sheets, and thick- activities and the real dangers stem- ­supplemental file S2). Encouraging ness worldwide (figure 2e–2h). Ocean ming from a warming planet (Briggs signs include decreases in global fer- heat content, ocean acidity, sea level, et al. 2015). Policymakers and the tility (birth) rates (figure 1b), decel- area burned in the United States, public now urgently need access to a erated forest loss in the Brazilian and extreme weather and associated set of indicators that convey the effects Amazon (figure 1g), increases in the damage costs have all been trending of human activities on GHG emis- consumption of solar and wind power upward (figure 2i–2n). Climate change sions and the consequent impacts on (figure 1h), institutional fossil fuel is predicted to greatly affect marine, climate, our environment, and society. divestment of more than US$7 tril- freshwater, and terrestrial life, from Building on prior work (see supple- lion (figure 1j), and the proportion plankton and corals to fishes and for- mental file S2), we present a suite of of GHG emissions covered by car- ests (IPCC 2018, 2019). These issues graphical vital signs of climate change bon pricing (figure 1m). However, the highlight the urgent need for action. over the last 40 years for human activi- decline in human fertility rates has Despite 40 years of global climate ties that can affect GHG emissions and substantially slowed during the last negotiations, with few exceptions, we change the climate (figure 1), as well 20 years (figure 1b), and the pace of have generally conducted business

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Figure 1. Change in global human activities from 1979 to the present. These indicators are linked at least in part to climate change. In panel (f), annual tree cover loss may be for any reason (e.g., wildfire, harvest within tree plantations, or conversion of forests to agricultural land). Forest gain is not involved in the calculation of tree cover loss. In panel (h), hydroelectricity and nuclear energy are shown in figure S2. The rates shown in panels are the percentage changes per decade across the entire range of the time series. The annual data are shown using gray points. The black lines are local regression smooth trend lines. Abbreviation: Gt oe per year, gigatonnes of oil equivalent per year. Sources and additional details about each variable are provided in supplemental file S2, including table S2. as usual and have largely failed to more severe than anticipated, threat- reinforcing feedbacks (atmospheric, address this predicament (figure 1). ening natural ecosystems and the fate marine, and terrestrial) that could lead The climate crisis has arrived and is of humanity (IPCC 2019). Especially to a catastrophic “hothouse Earth,” accelerating faster than most scientists worrisome are potential irreversible well beyond the control of humans expected (figure 2, IPCC 2018). It is climate tipping points and nature’s (Steffen et al. 2018). These climate

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Figure 2. Climatic response time series from 1979 to the present. The rates shown in the panels are the decadal change rates for the entire ranges of the time series. These rates are in percentage terms, except for the interval variables (d, f, g, h, i, k), where additive changes are reported instead. For ocean acidity (pH), the percentage rate is based on the change in hydrogen ion activity, aH+ (where lower pH values represent greater acidity). The annual data are shown using gray points. The black lines are local regression smooth trend lines. Sources and additional details about each variable are provided in supplemental file S2, including table S3. chain reactions could cause significant improve the vital signs summarized O’Neill 2018); therefore, we need bold disruptions to ecosystems, society, and by our graphs. Economic and popu- and drastic transformations regarding economies, potentially making large lation growth are among the most economic and population policies. We areas of Earth uninhabitable. important drivers of increases in CO2 suggest six critical and interrelated To secure a sustainable future, we emissions from fossil fuel combustion steps (in no particular order) that gov- must change how we live, in ways that (Pachauri et al. 2014, Bongaarts and ernments, businesses, and the rest of https://academic.oup.com/bioscience XXXX XXXX / Vol. XX No. X • BioScience 3 Viewpoint humanity can take to lessen the worst We need to quickly curtail habitat population must be stabilized—and, effects of climate change. These are and biodiversity loss (figure 1f–1g), ideally, gradually reduced—within a important steps but are not the only protecting the remaining primary and framework that ensures social integrity. Downloaded from https://academic.oup.com/bioscience/advance-article-abstract/doi/10.1093/biosci/biz088/5610806 by Oregon State University user on 05 November 2019 actions needed or possible (Pachauri intact forests, especially those with There are proven and effective policies et al. 2014, IPCC 2018, 2019). high carbon stores and other forests that strengthen human rights while with the capacity to rapidly sequester lowering fertility rates and lessening Energy carbon (proforestation), while increas- the impacts of population growth on The world must quickly implement ing and afforestation GHG emissions and biodiversity loss. massive energy efficiency and conser- where appropriate at enormous scales. These policies make family-planning vation practices and must replace fos- Although available land may be limit- services available to all people, remove sil fuels with low-carbon renewables ing in places, up to a third of emissions barriers to their access and achieve (figure 1h) and other cleaner sources reductions needed by 2030 for the full gender equity, including primary of energy if safe for people and the Paris agreement (less than 2°C) could and secondary education as a global environment (figure S2). We should be obtained with these natural climate norm for all, especially girls and young leave remaining stocks of fossil fuels solutions (Griscom et al. 2017). women (Bongaarts and O’Neill 2018). in the ground (see the timelines in IPCC 2018) and should carefully pur- Food Conclusions sue effective negative emissions using Eating mostly plant-based foods while Mitigating and adapting to climate technology such as carbon extraction reducing the global consumption of ani- change while honoring the diversity from the source and capture from mal products (figure 1c–d), especially of humans entails major transforma- the air and especially by enhancing ruminant livestock (Ripple et al. 2014), tions in the ways our global society natural systems (see “Nature” section). can improve human health and signifi- functions and interacts with natural Wealthier countries need to support cantly lower GHG emissions (including ecosystems. We are encouraged by a poorer nations in transitioning away methane in the “Short-lived pollutants” recent surge of concern. Governmental from fossil fuels. We must swiftly elim- step). Moreover, this will free up crop- bodies are making climate emergency inate subsidies for fossil fuels (figure lands for growing much-needed human declarations. Schoolchildren are strik- 1o) and use effective and fair policies plant food instead of livestock feed, ing. lawsuits are proceeding for steadily escalating carbon prices to while releasing some grazing land to in the courts. Grassroots citizen move- restrain their use. support natural climate solutions (see ments are demanding change, and “Nature” section). Cropping practices many countries, states and provinces, Short-lived pollutants such as minimum tillage that increase cities, and businesses are responding. We need to promptly reduce the emis- soil carbon are vitally important. We As the Alliance of World Scientists, sions of short-lived climate pollutants, need to drastically reduce the enormous we stand ready to assist decision-mak- including methane (figure 2b), black amount of food waste around the world. ers in a just transition to a sustainable carbon (soot), and hydrofluorocar- and equitable future. We urge wide- bons (HFCs). Doing this could slow Economy spread use of vital signs, which will climate feedback loops and poten- Excessive extraction of materials and better allow policymakers, the pri- tially reduce the short-term warming overexploitation of ecosystems, driven vate sector, and the public to under- trend by more than 50% over the next by economic growth, must be quickly stand the magnitude of this crisis, few decades while saving millions of curtailed to maintain long-term sus- track progress, and realign priorities lives and increasing crop yields due to tainability of the biosphere. We need for alleviating climate change. The reduced air pollution (Shindell et al. a carbon-free economy that explic- good news is that such transforma- 2017). The 2016 Kigali amendment to itly addresses human dependence on tive change, with social and economic phase down HFCs is welcomed. the biosphere and policies that guide justice for all, promises far greater economic decisions accordingly. Our human well-being than does business Nature goals need to shift from GDP growth as usual. We believe that the prospects We must protect and restore Earth’s and the pursuit of affluence toward will be greatest if decision-makers and ecosystems. Phytoplankton, coral reefs, sustaining ecosystems and improving all of humanity promptly respond to forests, savannas, grasslands, wetlands, human well-being by prioritizing basic this warning and declaration of a cli- peatlands, soils, mangroves, and sea needs and reducing inequality. mate emergency and act to sustain life grasses contribute greatly to sequestra- on planet Earth, our only home. tion of atmospheric CO2. Marine and Population terrestrial plants, animals, and micro- Still increasing by roughly 80 million Contributing reviewers organisms play significant roles in car- people per year, or more than 200,000 Franz Baumann, Ferdinando Boero, bon and nutrient cycling and storage. per day (figure 1a–b), the world Doug Boucher, Stephen Briggs, Peter

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Carter, Rick Cavicchioli, Milton Cole, References cited of the National Academy of Sciences 115: Eileen Crist, Dominick A. DellaSala, Briggs S, Kennel CF, Victor DG. 2015. Planetary 8252–8259. Paul Ehrlich, Iñaki Garcia-De-Cortazar, vital signs. Nature Climate Change 5: 969.

William J. Ripple ([email protected]) Downloaded from https://academic.oup.com/bioscience/advance-article-abstract/doi/10.1093/biosci/biz088/5610806 by Oregon State University user on 05 November 2019 Bongaarts J, O’Neill BC. 2018. Global warming and Christopher Wolf (christopher.wolf@ Daniel Gilfillan, Alison Green, Tom policy: Is population left out in the cold? oregonstate.edu) are affiliated with the Green, Jillian Gregg, Paul Grogan, John Science 361: 650–652. Department of Forest Ecosystems and Society Guillebaud, John Harte, Nick Houtman, Griscom BW, et al. 2017. Natural climate solu- at Oregon State University, in Corvallis and tions. Proceedings of the National Academy Charles Kennel, Christopher Martius, contributed equally to the work. Thomas M. of Sciences 114: 11645–11650. Frederico Mestre, Jennie Miller, David Newsome is affiliated with the School of Life [IPCC] Intergovernmental Panel on Climate and Environmental Sciences at The University Pengelley, Chris Rapley, Klaus Rohde, Change. 2018. Global Warming of 1.5°C: An of Sydney, in Sydney, New South Wales, Phil Sollins, Sabrina Speich, David IPCC Special Report. IPCC. Australia. Phoebe Barnard is affiliated with the Victor, Henrik Wahren, and Roger [IPCC] Intergovernmental Panel on Climate Conservation Biology Institute, in Corvallis, Change. 2019. Climate Change and Land. IPCC. Worthington. Oregon, and with the African Climate and Pachauri RK, et al. 2014. Climate Change 2014: Development Initiative, at the University of Cape Synthesis Report. Intergovernmental Panel Funding Town, in Cape Town, South Africa. William R. on Climate Change. Moomaw is affiliated with The Fletcher School The Worthy Garden Club furnished Ripple WJ, Smith P, Haberl H, Montzka SA, and the Global Development and Environment partial funding for this project. McAlpine C, Boucher DH. 2014. Ruminants, Institute, at Tufts University, in Medford, climate change, and climate policy. Nature Massachusetts. Project website Climate Change 4: 2–5. Ripple WJ, Wolf C, Newsome TM, Galetti M, To view the Alliance of World Alamgir M, Crist E, Mahmoud MI, Laurance Scientists website or to sign this arti- WF. 2017. World scientists’ warning to human- cle, go to https://scientistswarning. ity: A second notice. BioScience 67: 1026–1028. forestry.oregonstate.edu­ . Shindell D, Borgford-Parnell N, Brauer M, Haines A, Kuylenstierna J, Leonard S, Ramanathan Supplemental material V, Ravishankara A, Amann M, Srivastava L. 2017. A climate policy pathway for near- and Supplemental data are available at long-term benefits. Science 356: 493–494. BIOSCI online. A list of the signatories Steffen W, et al. 2018. Trajectories of the Earth appears in supplemental file S1. System in the Anthropocene. Proceedings doi:10.1093/biosci/biz088

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