March 10, 2023
By Kelly Matheson, Anders Carlson and Paul Rink
All eyes will be on Strasbourg this spring when the Grand Chamber hears the first two in a trio of cases legally defining the relationship between human rights and climate change: KlimaSeniorinnen v. Switzerland, Carême v. France, and Duarte Agostinho v. Portugal and 31 Others. Courts around the world have already recognized that climate change “put[s] at risk the survival of man on Earth”, is coming dangerously close to “approaching ‘the point of no return’”, and that the “real threat of dangerous climate change” has a “direct negative effect on the daily lives of current and future generations”. As a Court mandated to confront human rights violations head on, the importance of the Grand Chamber’s judgments in these historic cases addressing the single greatest threat to human rights cannot be overstated: the impacts of judicial decisions always extend far beyond the parties but, rarely do they have the potential to influence the course of humanity for millennia to come. The judgments in these cases—for better or worse—most certainly could.
These are not the only climate change cases currently before the Court, but their prominence as the first to be heard in Strasbourg means that the Grand Chamber’s findings will be of great interest around the world and heavily analyzed by legal professionals, academics, media, and most importantly, other courts. And the stakes are high. Although the Court will be deciding each case on its individual merits, the judgments, as a whole, are likely to be viewed as an indicator of the Court’s broader approach to addressing the largest and most pervasive threat societies and the world have ever experienced at a crucial point in the trajectory of climate litigation.
Considering the weight the Court’s words will carry, this article focuses on an established truth: human rights—in the context of already dangerous climate change—can only be fully protected if States are required to act in accordance with the best available science. It is vital that the Court’s decision-making in these cases is informed by the most up-to-date and complete scientific record. This importance of placing the best available scientific evidence at the heart of these cases begins with the threshold question of what target must be achieved in order to protect human life and health within the meaning of Articles 2 and 8 of the European Convention on Human Rights (“the Convention”) and extends all the way through to the nature and extent of appropriate remedies in these first climate cases to reach the Court.
A Distinction that Matters: Risk Reduction v. Violation Prevention
The politically negotiated targets set forth in Article 2(1)(a) of the Paris Agreement are that of “[h]olding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels” (“Paris temperature targets”). While the Paris Agreement is an important framework treaty signed by the States involved in the trio of cases at hand, it is not a human rights treaty and its temperature targets are framed in terms of reduction of risk rather than in terms of adherence to human rights standards. While it is uncontroversial that achievement of the Paris temperature targets would, as Article 2 states, “significantly reduce the risks and impacts of climate change” this assertion is true only by reference to the even greater devastation that temperatures of 3.0°C or 4.0°C would wreak upon humanity and the planet. By contrast, the requirements of applicable human rights standards cannot be met simply by risk reduction. Instead, the protection of human rights requires violation prevention.
This distinction matters because a focus on meeting the Paris temperature targets alone would not only be at odds with established human rights protections set forth in the Convention but, would also risk creating the erroneous impression that there is still time to spare for States to address their obligations. Such an approach would literally be fatal.
As will be discussed next, scientific evidence shows that the Paris temperature targets are insufficient to protect human life and health in a manner that is consistent with the Court’s own jurisprudence obliging states to take all steps within its powers to protect human life. In fact, according to the best available scientific evidence, a 1.5°C warmer world condemns millions across Europe—and billions worldwide—to endure a litany of human rights violations, particularly harming children. Sanctioning 2.0°C of warming is even more reckless from a human rights perspective.
Endangering Human Rights: The Paris Temperature Target of 1.5°C
Scientists, including those who are part of the Intergovernmental Panel on Climate Change (IPCC), are clear that planetary heating of 1.5°C will have disastrous consequences for humanity. The 2018 IPCC Special Report on 1.5°C expressly stated with high confidence that allowing a temperature rise of 1.5°C “is not considered ‘safe’ for most nations, communities, ecosystems and sectors and poses significant risks to natural and human systems as compared to the current warming of 1°C.” The 600-plus page report summarizes a significant body of science projecting that warming of 1.5°C and above would be catastrophic. And, in the subsequent four years since the report’s publication, an ever-growing body of robust scientific research has continued to methodically demonstrate that the risks are even more serious than the IPCC initially concluded. The risks of 1.5°C are many. Looking solely at Europe, heatwaves will be more frequent and severe, causing more of those living in Council of Europe States to suffer heat-related illnesses and deaths. The fire season will be longer, resulting in increased threats to human health from smoke exposure and increased risk of property damage and loss. Up to 66.3 million Europeans will be exposed to drought in any given year. Tick-borne diseases as well as West Nile Fever, Dengue, Chikunga, Zika, Malaria, and Vibrio will become more common. European glaciers are poised to lose significant volumes of ice, compounding water scarcity. Agricultural yields will decline across the continent affecting food supplies. And, an estimated 3.5 million Europeans will be exposed to coastal flooding in any given year. Science often informs the law but rarely do courts have access to copious expert evidence establishing that negotiated targets set forth in an international agreement will spawn more frequent and severe disasters that threaten and take lives, jeopardize critical food and water supplies, and harm human health and livelihoods, especially for already at-risk individuals, especially for children and seniors.
Scientists also find that heating of up to 1.5°C or beyond for any length of time could drive our planet across climate tipping points that will fundamentally alter large portions of the globe. Climate tipping points—also known as points of no return—are critical thresholds that, if crossed, would lead to large and sometimes irreversible changes in components of the Earth’s climate system that contribute significantly to the well-being of humanity. These tipping points do not stand alone—if one tipping point is crossed, the likelihood that others may be crossed increases, risking a “tipping cascade” which would likely add more momentum to global warming.
In September 2022, researchers updated a comprehensive assessment of climate tipping points. At global warming of ~1.5°C, four large-scale tipping points in the global climate system are “likely” to be crossed, including the: i) collapse of the Greenland ice sheet; ii) collapse of West Antarctic ice sheet; iii) abrupt thaw of permafrost; and iv) die-off of 70-90% of tropical and subtropical coral reefs. Further, at ~1.6°C of warming, abrupt loss of sea ice over the Barents Sea north of Scandinavia is expected. The most clear-cut impacts on humanity will stem from the many centuries to millennia of ongoing sea-level rise that will occur as these ice sheets collapse resulting in stronger storm surges and increased coastal flooding. As the reefs die, fisheries will collapse depriving fisher people of income and threatening food security. And, as lands thaw, entire communities—particularly Indigenous communities—will be forced to migrate. 1.5°C is not a solution. It only worsens already occurring human rights violations.
An additional limitation of the Paris temperature targets is the absence of any clear framework to limit the amount of time States can allow the Earth to stay at a dangerous temperature. This too should be considered by courts because the magnitude and duration with which we overshoot a safe level of heating matters for human life and health. In an even more recent study on climate tipping points published in January 2023, scientists examined how much the risk of crossing critical tipping thresholds is amplified if we overshoot 1.5°C and 2.0°C. The analysis reveals that even temporary overshoots of low magnitudes can increase tipping risks by up to 72% compared with non-overshoot scenarios. Together, the September 2022 and January 2023 studies found that the only safe level of global warming is 1.0°C or less.
To be clear, the Paris Agreement is undoubtedly a significant and important achievement of international negotiation and cooperation, as well as a milestone framework treaty. However, seven years have passed and the additional scientific evidence indicating the immense dangers of allowing global heating to continue up to—and then linger at—the Paris temperature targets has grown substantially. The inclusion, use, and reliance on inadequate outdated targets cuts against the very underpinnings of the Paris Agreement. In the Preamble, States recognized that the “need for an effective and progressive response to the urgent threat of climate change” must be based on “the best available scientific knowledge”. Yet, States—including Council of Europe Member States—have not updated their commitments in consideration of the updated science. Given the gravity of the rights at stake, courts should not make this same mistake and recognize that an abundance of trustworthy scientific evidence holds that the Paris temperature targets would be a flawed reference point for determining State compliance with their human rights obligations under the Convention. Ultimately, temperature targets do not address the heart of the issue: CO2 pollution.
Protecting Human Rights: The 350 ppm Standard
To uphold human rights, instead of focusing on outdated, negotiated temperature targets, all courts should instead consider scientists’ findings as to what is necessary to stabilise the Earth’s current energy imbalance (EEI). The EEI concept, although rarely used in policy discussions, is what climate scientists describe as the “most critical” metric for determining “the prospects for continued global warming and climate change.”
EEI is driven by elevated atmospheric concentrations of greenhouse gases—mainly carbon dioxide (CO2) as measured in parts per million (ppm)—that are produced by human activities, particularly fossil fuel combustion. Average atmospheric CO2 levels were approximately 419 ppmin 2022, 139 ppm higher than the pre-industrial level of 280 ppm. This too matters.
Scientific consensus indicates that to restore the stability of Earth’s climate so as to protect human life and health, States must reduce atmospheric concentrations of CO2 to an ecologically sustainable level of 350 ppm (“350 ppm standard”). To achieve this, emissions must be brought to zero, not net-zero, as quickly as possible through steep reductions within the next decades with richer countries moving fastest, and emissions phased out by 2050 at the latest. Removal of legacy CO2, emissions will additionally need to be implemented in a manner that respects human rights to prevent worsening many of the climate disasters the world has experienced in the last few decades. The laws of physics make clear that restoring Earth’s energy balance is the only way to safeguard the Convention rights of people who will otherwise endure catastrophic climate harms.
Importantly, EEI also reflects the gravity and urgency of the current climate crisis much more accurately than the Paris temperature targets. Global average surface temperature has already reached 1.1°C–1.3°C above pre-industrial levels, which can give the erroneous impression that an unused ‘budget’ remains for States to continue safely emitting CO2 before reaching the Paris temperature target of 1.5°C. By contrast, measurements of atmospheric CO2 have already reached 419 ppm, overshooting the scientifically endorsed 350 ppm limit. In other words, States are literally and figurately in the red on their carbon emissions budget.
The consequence of this CO2 overshoot is that today, humanity is immersed in a climate emergency that has implications for State obligations with regards to impacts that have already been sustained. An ever-increasing body of scientific evidence verifies the devastating outcomes: floods, fires, droughts, mega-storms, and heatwaves are all made more frequent and severe by climate change, resulting in death, injury, disease, loss of homes and livelihoods, forced migration, food and water shortages, poverty, and violence. Furthermore, ongoing melting of glaciers and ice sheets continues to raise sea level, inundating coastlines and exacerbating storm impacts, with glaciers and the Greenland ice sheet melting to continue for decades and centuries, respectively, even at the current level of global warming.
We sit at a precipice where it is no longer enough to do our best. We must instead do what is required. And we know the solution. Scientists across the globe have fastidiously documented that the temperature targets set forth in the Paris Agreement not only fail to protect rights, but put the very rights Applicants seek to exercise at dire risk. They have also mapped out a science-based path to minimize the extreme dangers posed to human life, health, and well-being from the climate emergency: the 350 ppm standard. This year, the Grand Chamber will deliberate on the Court’s precise role in applying the laws of science to the rights protected by the Convention. Alone the Grand Chamber judgements will not solve the climate crisis. But together, in solidarity with other judgements, humanity just might have a chance.
 “Best available science” is the most up-to-date science that: i) maximizes the quality, objectivity, and integrity of information, including statistical information; ii) uses multiple peer-reviewed and publicly available data; and iii) clearly documents and communicates risks and uncertainties in the scientific basis for its conclusions.
 One of several key challenges with temperature targets is that they cannot be precisely equated to a corresponding level of atmospheric concentration of CO2 discussed in the following section setting out the “350 ppm standard”. However, 350 ppm of atmospheric CO2 on a multi-decadal to century timescale equates to an ~1.0°C increase above pre-industrial levels, meaning <1.0°C of additional heating is consistent with the 350 ppm standard.