Wissenschaft fordert mehr Ehrgeiz bei Klimaverhandlungen

Offener Brief

"Scientists urge parties at COP26 to fully acknowledge the latest and most comprehensive assessment of climate change science, included in the last IPCC reports, especially the Sixth Assessment Report Climate Change 2021: The Physical Science Basis (Climate Report) released in August 2021. We, climate scientists, stress that immediate, strong, rapid, sustained and large-​scale actions are necessary to hold global warming to well below 2°C and pursue efforts to limit it to 1.5°C, and thereby limit future risk and needs for adaptation over the next decades to centuries.

COP26 is a historic moment for the fate of climate, societies and ecosystems, because human activities have already warmed the planet by around 1.1°C and future greenhouse gas emissions will determine future additional warming. The Climate Report unequivocally shows the extent of human-​induced climate change. Almost half of the carbon dioxide accumulated so far in the atmosphere has been emitted in the last 30 years. Greenhouse gas concentrations are at the highest levels in human history, leading to rates of warming unprecedented in more than 2000 years and unprecedented climate extremes in recent years. Cumulative greenhouse gas emissions to date already commit our planet to key changes of the climate system affecting human society and marine and terrestrial ecosystems, some of which are irreversible for generations to come.  

Progress in climate science since the IPCC Fifth Assessment Report (2013, 2014), as assessed in the Special Reports on 1.5°C (2018), on Climate Change and Land (2019), and on Ocean and Cryosphere in a Changing Climate (2019), and the 2021 Climate Report, has shown the implications of global warming in excess of 1.5°C. The remaining CO2 budgets compatible with a stabilisation of global warming at 1.5°C are rapidly shrinking (500, 400, and 300 GtCO2 since early 2020, for probabilities of 50%, 67% and 83%, respectively, of limiting global warming to 1.5°C), and highlight the urgent need for a rapid and sustained decline of global emissions, under consideration of climate justice and equity. Given the current yearly emissions of ca. 40GtCO2/yr, these remaining budgets would be exhausted by ca. 2027 to 2033 in the absence of marked decreases in emissions. This highlights the need for immediate reductions of CO2 emissions to achieve both the temperature goal of the Paris agreement and to also contribute to increased climate resilience.

Thousands of scientists from around the world have worked over several years to deliver the evidence base that underpins the Climate Report, which has undergone worldwide expert and government reviews. We now have the most comprehensive and robust assessment to date of how the climate has changed in the past and how it can change in the future, depending on decisions and actions taken today."