The study challenges the idea that the climate of northern Africa dried out around 3 million years ago, a time when the earliest known hominids appear in the fossil record.

"Climate adaptation finance should shift from the quantity of finance to its quality and risk-reducing impacts. The current adaptation finance system will unlikely have the desired impact of reducing climate risks to vulnerable people," says researcher Jasper Verschuur of Delft University of Technology in an article in Science, written with fellow researchers from the University of Oxford and the London School of Economics.

In a Policy Forum, Jessica Espey and colleagues argue that waning support for accurate collection and curation of population data worldwide threatens to compromise crucial evidence-based government planning. “We live in an era of seemingly unlimited data, where our digital activities may generate nearly constant information streams, yet some of our most essential infrastructure – demographic information – is deteriorating, introducing known and unknown bias into decision-making,” write the authors. Accurate population data are fundamental to effective governance. Most countries rely on national censuses, which are traditionally conducted every 10 years, to supply this information. But according to Espey et al., fewer nations are completing censuses, and many are undercounting marginalized populations. For example, at the close of the 2020 census cycle, 204 countries or territories – encompassing 85% of the world’s population – had conducted at least one census between 2015 and 2024. Yet by July 2024, 24 of these, representing roughly one-quarter of the global population, had not published their findings. This reflects a significant decline from the 2010 round, when 214 countries conducted and released census data, encompassing 93% of the global population. Moreover, even when censuses are carried out, they increasingly suffer from declining response rates and growing coverage errors – particularly in the undercounting of vulnerable populations such as ethnic minorities and young children. In the United States, for instance, the 2020 census likely missed nearly 3 million Latino individuals and close to 1 million children under the age of five.

In this Policy Forum, the authors outline several reasons for this general decline: eroding trust in institutions, COVID-19 disruptions, budget cuts to statistical offices, and collapsing international support for data collection programs. In order to address this “quiet crisis,” Espey et al. suggest adopting register-based systems, harnessing geospatial technologies and AI, and producing small-area population estimates. However, technical innovations alone are not enough, note the authors; governments must also restore public trust by showing how data informs daily life, ensuring strong privacy protections, and promoting collaboration across sectors. “In an era of growing challenges, from climate change to economic inequality, accurate population data are not a luxury – they are essential infrastructure for healthy, resilient, functioning societies,” write the authors.

The central estimate of the remaining carbon budget for 1.5°C is 130 billion tonnes of carbon dioxide (CO2) (from the beginning of 2025). This would be exhausted in a little more than three years at current levels of CO2 emissions, according to the latest Indicators of Global Climate Change study published today in the journal Earth System Science Data, and the budget for 1.6°C or 1.7°C could be exceeded within nine years.