Lelo Nxumalo

The satellite time-lapse you see here isn't a simulation. It's a terrifying, real-world look at the 2024 Rio Grande do Sul floods, a climate catastrophe unfolding in just a few frames. The GIF begins in early 2024, showing the city of Porto Alegre and the Guaíba Lake under normal conditions. The land is green, and the rivers are calm. But as the dates advance to late April / early May, the final frame shows a horrifying transformation. A deluge of dark, sediment-filled water explodes from the riverbanks, swallowing entire landscapes and swamping the northern parts of the metropolitan area. This is what it looks like when a region receives months' worth of rain in just a few days—an event scientists have directly linked to the intensifying power of climate change. Methodology: This time-lapse was generated using Sentinel-2 satellite ima...

This analysis reveals significant land use changes across South America over two decades. The most striking trend is agricultural expansion at the expense of natural ecosystems. Croplands surged by 225,461 km² (+39.2%) , while Evergreen Broadleaf Forests—primarily the Amazon—declined by 287,426 km² (-4.4%) . This forest loss, equivalent to roughly the size of Italy, underscores ongoing deforestation pressures. Critical Findings: Grasslands expanded dramatically by 349,686 km² (+10.0%) , potentially reflecting forest conversion to pasture Permanent Wetlands experienced a catastrophic 49.9% decline , losing nearly 150,000 km², raising concerns about ecosystem services and biodiversity Savannas contracted by 128,693 km² (-3.5%) The spatial pattern shows concentrated deforestation along the "arc of deforestation" i...

What should we do with carbon tax revenue? New modeling suggests that for the US economy, cash dividends beat tax cuts. The US Context: A "Narrow Base" for Carbon Pricing To understand the economic impact of a carbon tax, we must first understand the structure of the US economy. Our calibration to 2022 data reveals a striking asymmetry: the "Brown Sector" (fossil fuels, heavy industry, utilities) accounts for just 3.7% of US GDP and employs only 1.8% of the workforce, yet it generates 55.7% of national greenhouse gas emissions . This concentration presents a unique policy opportunity. A $100/ton carbon tax targets a tiny sliver of economic activity to achieve massive reductions. In our simulation, this tax drives a 41% reduction in emissio...

How well do quarterly changes in PMI predict economic growth? An analysis of 10+ years of data (Q1 2015 - Q3 2025) When it comes to tracking economic momentum, quarterly changes in Purchasing Managers' Index (PMI) data provide valuable signals about GDP growth. My analysis of over 10 years of data reveals which PMI indicators are the most reliable for economic forecasting. Manufacturing PMI: Moderate but Significant Both ISM and S&P Global manufacturing PMI show statistically significant correlations with manufacturing GDP growth, with S&P Global slightly outperforming. Manufacturing PMI Growth Correlations ISM Manufacturing PMI: r = 0.451 (p = 0.0027) S&P Global Manufacturing PMI: r = 0.520 (p = 0.0004) ...

The Institute for Supply Management's (ISM) Manufacturing Purchasing Managers' Index remains one of the most closely watched economic indicators in the United States. As we reflect on recent trends spanning both the past two years and the broader decade-long trajectory, a nuanced picture of American manufacturing emerges—one marked by resilience, structural challenges, and the enduring impact of global disruptions. The Recent Struggle: Two Years of Persistent Contraction The past two years have been particularly challenging for U.S. manufacturing. From November 2023 through October 2025, the PMI has remained in contraction territory for an overwhelming majority of the period—hovering around an average of 48.4, well below the critical threshold of 50 that separates expansion from contraction. ...