The opinion of the world scientific community.
Underestimating the Challenges of Avoiding a Ghastly Future
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We report three major and confronting environmental issues that have received little attention and require urgent action. First, we review the evidence that future environmental conditions will be far more dangerous than currently believed. The scale of the threats to the biosphere and all its lifeforms—including humanity—is in fact so great that it is difficult to grasp for even well-informed experts. Second, we ask what political or economic system, or leadership, is prepared to handle the predicted disasters, or even capable of such action. Third, this dire situation places an extraordinary responsibility on scientists to speak out candidly and accurately when engaging with government, business, and the public. We especially draw attention to the lack of appreciation of the enormous challenges to creating a sustainable future. The added stresses to human health, wealth, and well-being will perversely diminish our political capacity to mitigate the erosion of ecosystem services on which society depends. The science underlying these issues is strong, but awareness is weak. Without fully appreciating and broadcasting the scale of the problems and the enormity of the solutions required, society will fail to achieve even modest sustainability goals.
The dangerous effects of climate change are much more evident to people than those of biodiversity loss (Legagneux et al., 2018), but society is still finding it difficult to deal with them effectively. Civilization has already exceeded a global warming of ~ 1.0°C above pre-industrial conditions, and is on track to cause at least a 1.5°C warming between 2030 and 2052 (IPCC, 2018). In fact, today’s greenhouse-gas concentration is >500 ppm CO2-e (Butler and Montzka, 2020), while according to the IPCC, 450 ppm CO2-e would give Earth a mere 66% chance of not exceeding a 2°C warming (IPCC, 2014). Greenhouse-gas concentration will continue to increase (via positive feedbacks such as melting permafrost and the release of stored methane) (Burke et al., 2018), resulting in further delay of temperature-reducing responses even if humanity stops using fossil fuels entirely well before 2030 (Steffen et al., 2018).
Human alteration of the climate has become globally detectable in any single day’s weather (Sippel et al., 2020). In fact, the world’s climate has matched or exceeded previous predictions (Brysse et al., 2013), possibly because of the IPCC’s reliance on averages from several models (Herger et al., 2018) and the language of political conservativeness inherent in policy recommendations seeking multinational consensus (Herrando-Pérez et al., 2019). However, the latest climate models (CMIP6) show greater future warming than previously predicted (Forster et al., 2020), even if society tracks the needed lower-emissions pathway over the coming decades. Nations have in general not met the goals of the 5 year-old Paris Agreement (United Nations, 2016), and while global awareness and concern have risen, and scientists have proposed major transformative change (in energy production, pollution reduction, custodianship of nature, food production, economics, population policies, etc.), an effective international response has yet to emerge (Ripple et al., 2020). Even assuming that all signatories do, in fact, manage to ratify their commitments (a doubtful prospect), expected warming would still reach 2.6–3.1°C by 2100 (Rogelj et al., 2016) unless large, additional commitments are made and fulfilled. Without such commitments, the projected rise of Earth’s temperature will be catastrophic for biodiversity (Urban, 2015; Steffen et al., 2018; Strona and Bradshaw, 2018) and humanity (Smith et al., 2016).
Regarding international climate-change accords, the Paris Agreement (United Nations, 2016) set the 1.5–2°C target unanimously. But since then, progress to propose, let alone follow, (voluntary) “intended national determined contributions” for post-2020 climate action have been utterly inadequate.
If most of the world’s population truly understood and appreciated the magnitude of the crises we summarize here, and the inevitability of worsening conditions, one could logically expect positive changes in politics and policies to match the gravity of the existential threats. But the opposite is unfolding. The rise of right-wing populist leaders is associated with anti-environment agendas as seen recently for example in Brazil (Nature, 2018), the USA (Hejny, 2018), and Australia (Burck et al., 2019). Large differences in income, wealth, and consumption among people and even among countries render it difficult to make any policy global in its execution or effect.
A central concept in ecology is density feedback (Herrando-Pérez et al., 2012)—as a population approaches its environmental carrying capacity, average individual fitness declines (Brook and Bradshaw, 2006). This tends to push populations toward an instantaneous expression of carrying capacity that slows or reverses population growth. But for most of history, human ingenuity has inflated the natural environment’s carrying capacity for us by developing new ways to increase food production (Hopfenberg, 2003), expand wildlife exploitation, and enhance the availability of other resources. This inflation has involved modifying temperature via shelter, clothing, and microclimate control, transporting goods from remote locations, and generally reducing the probability of death or injury through community infrastructure and services (Cohen, 1995). But with the availability of fossil fuels, our species has pushed its consumption of nature’s goods and services much farther beyond long-term carrying capacity (or more precisely, the planet’s biocapacity), making the readjustment from overshoot that is inevitable far more catastrophic if not managed carefully (Nyström et al., 2019). A growing human population will only exacerbate this, leading to greater competition for an ever-dwindling resource pool. The corollaries are many: continued reduction of environmental intactness (Bradshaw et al., 2010; Bradshaw and Di Minin, 2019), reduced child health (especially in low-income nations) (Bradshaw et al., 2019), increased food demand exacerbating environmental degradation via agro-intensification (Crist et al., 2017), vaster and possibly catastrophic effects of global toxification (Cribb, 2014; Swan and Colino, 2021), greater expression of social pathologies (Levy and Herzog, 1974) including violence exacerbated by climate change and environmental degradation itself (Agnew, 2013; White, 2017, 2019), more terrorism (Coccia, 2018), and an economic system even more prone to sequester the remaining wealth among fewer individuals (Kus, 2016; Piketty, 2020) much like how cropland expansion since the early 1990s has disproportionately concentrated wealth among the super-rich (Ceddia, 2020). The predominant paradigm is still one of pegging “environment” against “economy”; yet in reality, the choice is between exiting overshoot by design or disaster—because exiting overshoot is inevitable one way or another.
Given these misconceptions and entrenched interests, the continued rise of extreme ideologies is likely, which in turn limits the capacity of making prudent, long-term decisions, thus potentially accelerating a vicious cycle of global ecological deterioration and its penalties. Even the USA’s much-touted New Green Deal (U. S. House of Representatives, 2019) has in fact exacerbated the country’s political polarization (Gustafson et al., 2019), mainly because of the weaponization of ‘environmentalism’ as a political ideology rather than being viewed as a universal mode of self-preservation and planetary protection that ought to transcend political tribalism. Indeed, environmental protest groups are being labeled as “terrorists” in many countries (Hudson, 2020). Further, the severity of the commitments required for any country to achieve meaningful reductions in consumption and emissions will inevitably lead to public backlash and further ideological entrenchments, mainly because the threat of potential short-term sacrifices is seen as politically inopportune. Even though climate change alone will incur a vast economic burden (Burke et al., 2015; Carleton and Hsiang, 2016; Auffhammer, 2018) possibly leading to war (nuclear, or otherwise) at a global scale (Klare, 2020), most of the world’s economies are predicated on the political idea that meaningful counteraction now is too costly to be politically palatable. Combined with financed disinformation campaigns in a bid to protect short-term profits (Oreskes and Conway, 2010; Mayer, 2016; Bakan, 2020), it is doubtful that any needed shift in economic investments of sufficient scale will be made in time.
While uncertain and prone to fluctuate according to unpredictable social and policy trends (Boas et al., 2019; McLeman, 2019; Nature Climate Change, 2019), climate change and other environmental pressures will trigger more mass migration over the coming decades (McLeman, 2019), with an estimated 25 million to 1 billion environmental migrants expected by 2050 (Brown, 2008). Because international law does not yet legally recognize such “environmental migrants” as refugees (United Nations University, 2015) (although this is likely to change) (Lyons, 2020), we fear that a rising tide of refugees will reduce, not increase, international cooperation in ways that will further weaken our capacity to mitigate the crisis.