World Scientists’ Warning of a Climate Emergency

Humanity is on a collision course with Nature.
A damaged Nature will survive. We may not.
We must change course to avert an ecological disaster.
We must take action if we are to survive.

This is the warning that our scientists have been trying to deliver since 1992. It’s short and to the point:
World Scientists’ Warning of a Climate Emergency also has a compelling message to deliver to the world.

The climate crisis is closely linked to excessive consumption of the wealthy lifestyle. The most affluent countries are mainly responsible for the historical GHG emissions and generally have the greatest per capita emissions). In the present article, we show general patterns, mostly at the global scale, because there are many climate efforts that involve individual regions and countries. Our vital signs are designed to be useful to the public, policymakers, the business community, and those working to implement the Paris climate agreement, the United Nations’ Sustainable Development Goals, and the Aichi Biodiversity Targets.

Profoundly troubling signs from human activities include sustained increases in both human and ruminant livestock populations, per capita meat production, world gross domestic product, global tree cover loss, fossil fuel consumption, the number of air passengers carried, carbon dioxide (CO2) emissions, and per capita CO2 emissions since 2000. Encouraging signs include decreases in global fertility (birth) rates, decelerated forest loss in the Brazilian Amazon, increases in the consumption of solar and wind power, institutional fossil fuel divestment of more than US$7 trillion, and the proportion of GHG emissions covered by carbon pricing. However, the decline in human fertility rates has substantially slowed during the last 20 years (figure 1b), and the pace of forest loss in Brazil’s Amazon has now started to increase again. Consumption of solar and wind energy has increased 373% per decade, but in 2018, it was still 28 times smaller than fossil fuel consumption (combined gas, coal, oil; figure 1h). As of 2018, approximately 14.0% of global GHG emissions were covered by carbon pricing, but the global emissions-weighted average price per tonne of carbon dioxide was only around US$15.25. A much higher carbon fee price is needed (IPCC 2018, section Annual fossil fuel subsidies to energy companies have been fluctuating, and because of a recent spike, they were greater than US$400 billion in 2018.

Especially disturbing are concurrent trends in the vital signs of climatic impacts. Three abundant atmospheric GHGs (CO2, methane, and nitrous oxide) continue to increase, as does global surface temperature. Globally, ice has been rapidly disappearing, evidenced by declining trends in minimum summer Arctic sea ice, Greenland and Antarctic ice sheets, and glacier thickness worldwide. Ocean heat content, ocean acidity, sea level, area burned in the United States, and extreme weather and associated damage costs have all been trending upward. Climate change is predicted to greatly affect marine, freshwater, and terrestrial life, from plankton and corals to fishes and forests (IPCC 2018, 2019). These issues highlight the urgent need for action.

Despite 40 years of global climate negotiations, with few exceptions, we have generally conducted business as usual and have largely failed to address this predicament. The climate crisis has arrived and is accelerating faster than most scientists expected (IPCC 2018). It is more severe than anticipated, threatening natural ecosystems and the fate of humanity (IPCC 2019). Especially worrisome are potential irreversible climate tipping points and nature’s reinforcing feedbacks (atmospheric, marine, and terrestrial) that could lead to a catastrophic “hothouse Earth,” well beyond the control of humans (Steffen et al. 2018). These climate chain reactions could cause significant disruptions to ecosystems, society, and economies, potentially making large areas of Earth uninhabitable.

To secure a sustainable future, we must change how we live, in ways that improve the vital signs summarized by our graphs. Economic and population growth are among the most important drivers of increases in CO2 emissions from fossil fuel combustion (Pachauri et al. 2014, Bongaarts and O’Neill 2018); therefore, we need bold and drastic transformations regarding economic and population policies. We suggest six critical and interrelated steps (in no particular order) that governments, businesses, and the rest of humanity can take to lessen the worst effects of climate change. These are important steps but are not the only actions needed or possible (Pachauri et al. 2014, IPCC 2018, 2019)

World Scientists’ Warning of a Climate Emergency