The global scientific consensus, most prominently supported by the work of the United Nations Intergovernmental Panel on Climate Change (IPCC), assesses with high confidence a global warming increase of 1 °C as measured against preindustrial levels. Currently experienced effects from the 1 °C global warming which has already occurred include: loss of sea ice and glacial shrinking, accelerated sea level rises, shifting atmospheric and oceanic currents, longer and more intense heat waves and hurricane seasons. Impacts on the biosphere include the shifting of plant and animal ranges, earlier plant and tree flowering, and rapid declines in bio- diversity. All of these changes threaten the equilibrium of the planet and, more fundamentally, the continued viability of human adaptation to the planet.

The most recent comprehensive report issued by the United Nation’s Intergovernmental Panel on Climate Change (IPCC) in 2018 compares the difference in impacts on human societies (the ‘delta’) if global warming is allowed to reach 2 °C as opposed to being stabilized at 1.5 °C above preindustrial levels. These delta effects2 include: an additional 10 million people endangered by sea level rise; several hundred million more people made susceptible to poverty; 50% more people exposed to water stress; loss of 1.5 million additional tons of global annual catch for marine fisheries; the number of plant and animal species on which human life depends losing half their habitat.

Clearly, the challenge is epochal. Even assuming that all countries in the world fulfill their Nationally Determined Contributions (NDC) pledged in the Paris Agreement, the world is currently on track to exceed 1.5° C by 2050 and to remain well above that threshold into the next century.

At a national level, the challenge is no less urgent or less central to societal well-being. Even for an administration notably skeptical of climate change science and aggressively committed to deregulating and redefining environmental standards so as to lessen the severity of threat assessments, the outlook remains dire. According to the Trump Administration’s most recent Climate Assessment3, which synthesizes the data and projections from thirteen federal agencies, key risks facing the nation as a direct result of climate change include risks to communities, the economy, water quality, citizen health, ecosystems, agricultural and food supply; the nation’s infrastructure; and the nation’s defense. To quote directly several specific examples:

  • “Climate change creates new risks and exacerbates existing vulnerabilities in communities across the United States, presenting growing challenges to human health and safety, quality of life, and the rate of economic growth;”
  • “Without substantial and sustained global mitigation and regional adaptation efforts, climate change is expected to cause growing losses to American infrastructure and property and impede the rate of economic growth over this century;”
  • “The quality and quantity of water available for use by people and ecosystems across the country are being affected by climate change, increasing risks and costs to agriculture, energy production, industry, recreation and the environment;”
  • “Impacts from climate change on extreme weather and climate-related events, air quality, and the transmission of disease through insects and pests, food and water increasingly threaten the health and well-being of the American people, particularly populations that are already vulnerable;”
  • “Ecosystems and the benefits they provide to society are being altered by climate change and these impacts are projected to continue. Without substantial and sustained reductions in global greenhouse gas emissions, transformative impacts on some ecosystems will occur; some coral reef and sea ice ecosystems are already experiencing such transformational changes;”
  • “Rising temperatures, extreme heat, drought, wildfire on rangelands, and heavy downpours are expected to increasingly disrupt agricultural productivity in the United States. Expected increases in challenges to livestock health, declines in crop yields and quality, and changes in extreme events in the United States and abroad threaten rural livelihoods, sustainable food security, and price stability;”
  • “Our Nation’s aging and deteriorating infrastructure is further stressed by increases in heavy precipitation events, coastal flooding, heat, wildfire, and other extreme events, as well as changes to average precipitation and temperature. Without adaptation, climate change will continue to degrade infrastructure performance over the rest of the century, with the potential for cascading impacts that threaten our economy, national security, essential services and health and well-being.”These effects are felt most directly at the local level. This is because the costs which climate change inflicts globally and nationally – costs of community disruption, slowing economic growth, deteriorating water quality, ecosystem disequilibrium, and infrastructural decay – are mostly borne at the local level. To address this challenge, the City of Philadelphia, like most major cities in the country and many counties and townships as well, has its own Climate Action Plan. Generally, these local plans have three major components: (1) at the grassroots level, the plan serves to connect with various stakeholder groups such as businesses, educational institutions, residential associations, and engaged constituencies to raise awareness and help coordinate common effort; (2) at the local governmental level, the plan articulates the limited number of focal areas where local government has determined its scarce dollars canhave greatest, proactive impact; and (3) at the supra-local governmental level, these plans serve as the blueprints for collaboration with other cities and regions, as the justification for federal budget requests, and as the channel for consolidating and reporting local ‘carbon emissions savings’ into the Paris Agreement NDC process.

As we have learned with the COVID-19 pandemic, a straightforward scientific fact can be politically complicated.  Acknowledging and addressing human-caused climate change is politically complex in the U.S. at this moment.  So is cooperating with China on anything.  Recognizing those complexities does not, however, absolve us of the responsibility to find a way forward on both the science and the international relations.

1.5° is where the U.S. and China must meet.