Viewpoint World Scientists’ Warning of a Climate 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 fossil fuel 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 carbon dioxide 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 climate change 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 Kyoto Protocol, and the public, policymakers, the busi- because of a recent spike, they were the 2015 Paris Agreement, 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- greenhouse gas (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 glacier 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 https://academic.oup.com/bioscience XXXX XXXX / Vol. XX No. X • BioScience 1 Viewpoint 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 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 2 BioScience • XXXX XXXX / Vol. XX No. X https://academic.oup.com/bioscience Viewpoint 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 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