“To put it simply, the state of the planet is broken,” as United Nations (UN) Secretary-General António Guterres said in the 2021 State of the Planet address.1 Over the course of this past year and while the COVID-19 pandemic continues to ravage the world, massive wildfires wreaked havoc in places such as Siberia, western USA, and Greece; cyclones devastated parts of Southeast Asia and the South Pacific; unprecedented and severe winter storms caused an extended power outage in the southern US state of Texas; and many parts of Europe experienced catastrophic flooding. The latest Intergovernmental Panel on Climate Change (IPCC) report should have put to rest any remaining doubts about the sources or impacts of climate change, and the 2018 IPCC Special Report covered how climate change strongly intersects with and amplifies threats to human and ecosystem health. The present study of the past year’s climate change research parses the complexity of earth’s systems in this context by highlighting 10 pertinent aspects, each of which is intrinsically linked to all others. 

As this summary report shows, achieving the Paris Agreement target of a maximum of 1.5℃ global temperature warming above pre-industrial levels is still possible. However, this will require transformations across all sectors, including deep decarbonization, and drastic coordinated global action to support lower-income countries in making climate-smart transitions as well as holding the highest emitters to account. Targeted measures that are designed and implemented to prioritize equity are needed urgently at all levels: structural, political, and individual. The greatest responsibility falls on wealthy, developed countries to rapidly transition away from fossil fuels and support a global shift to clean energy, transport, industry and housing.

This is particularly true after decades of insufficient responses to the climate crisis (as evidenced by the roughly 60% rise in fossil fuel emissions since the first IPCC report in 1990).2 The most favourable outcome is to keep global warming below 1.5°C, but at the same time is the most challenging scenario. Exceeding this threshold would degrade ecosystems irreparably, resulting in a negative feedback that further increases emissions of the greenhouse gases CO2, methane (CH4), and nitrous oxide (N2O), with deleterious consequences for the climate system and catastrophic consequences for the most vulnerable populations. Furthermore, many extremes that we already experience such as megafires are projected to intensify, and the probability for crossing thresholds of critical components of the climate system will increase strongly with devastating effects for all aspects of the Earth system.

In addition to massive cuts in CO2 emissions, we must address growing emissions of other greenhouse gases (such as CH4 and N2O), as well as other climate forcings. In fact, remaining budgets of all greenhouse gases with respect to the 1.5°C target may have to be revised to account for additional warming sources such as fires, permafrost thaw in the Arctic and accelerating degradation of ecosystems. Witnessing degradation of ocean ecosystems and the implications that this degradation has on the broader climate system, namely affecting their capabilities to store heat and buffer rising carbon dioxide (CO2) emissions, should encourage new approaches and scales of governance to recognize and protect the oceans as global commons and to begin to restore marine ecosystems. Particulate matter pollution, which in some places is compounded by worsening wildfires and which leads to millions of premature deaths and contributes to higher COVID-19 death tolls, is predominantly caused by burning of fossil fuels.3,4,5 Furthermore, deforestation is linked not only with the exacerbation of global warming effects but also with new infectious diseases.

Harnessing strategies that offer co-benefits is a crucial way to facilitate just transitions to lifestyles in alignment with the 1.5°C target of the Paris Agreement. Moreover, acting on climate change results in multiple short- and long-term benefits. In fact, the Global Commons Alliance survey from August found that the majority of citizens in G20 countries are worried about the global commons and 83% are willing to do more to protect and regenerate them.6  The implementation of nature-based solutions (NbS) and other strategies to halt deforestation contribute to climate change mitigation by protecting carbon storage, as well as contributing to the reduction in health risks. It is estimated that in many large economies, the cost savings from reduced air pollution alone will offset the costs of mitigation, even in the short term. Meeting World Health Organization guidelines for air pollution is expected to add 17 billion years to life spans globally.4

The challenge is massive, but, with willingness, humans have the capacity to overcome great challenges. We are not limited by our knowledge of the problem, by economic factors, or even technology, but by other obstacles. These are structural, social, cultural, and especially political, and inhibit the pace and scale of implementation that are needed to achieve the goals of the Paris Agreement. Embracing a sense of the planet as a set of interconnected and integral commons might guide decision-making to hear the voiceless, empower the disempowered, build greater equity through thoughtful resource distribution, and otherwise engage in justice-oriented climate action. This report summarizes clearly the most recent message from science: action to steer away from catastrophic climate change is necessary, urgent, and possible.

Definitions of a selection of terms is provided at the end of this document, preceding references.

All statements in this summary report are based on the following article, except when referring to a specific source: Martin et al. (2021): Ten New Insights in Climate Science 2021 – A Horizon Scan. In Global Sustainability. DOI: 10.1017/sus.2021.25. Online available at https://www.cambridge.org/core/product/identifier/S2059479821000259/type/journal_article.

Explore 2021's 10 Insights in Climate Science


Stabilizing at 1.5°C warming is still possible, but immediate and drastic global action is required

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Rapid growth in methane and nitrous oxide emissions put us on track for 2.7°C warming

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Megafires – climate change forces fire extremes to reach new dimensions with extreme impacts

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High-impact risks from climate tipping elements

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Global climate action must be just

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Supporting household behaviour changes is a crucial but often overlooked opportunity for climate action

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Political challenges impede effectiveness of carbon pricing

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Nature-based Solutions are critical for the pathway to Paris – but look at the fine print

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Building resilience of marine ecosystems is achievable by climate-adapted conservation and management, and global stewardship

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Costs of climate change mitigation can be justified by the multiple immediate benefits to the health of humans and nature

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