Our Changing World
Polluted air, brighter clouds, cooler climate?
Clouds in the sky exhibit a variety of forms and patterns. Their complexity not only puzzles the casual observer but also poses a significant challenge for climate science: clouds cool the planet by reflecting sunlight back to space, but it is uncertain how strong this cooling turns out under climate change. Cooling could increase as particulate air pollution makes clouds more reflective. This is strikingly illustrated by the bright tracks that ship exhaust can create in overlying clouds. We will discuss why such ship tracks do not tell the whole story of particulate-cloud-climate cooling.
Assistant Professor of Atmospheric Science
"Unknown" Antarctic firn captures hidden ice records
Observing the polar ice sheets provides an opportunity to understand the potential drivers of planetary-scale climate system and global sea level rise on the Earth. The Antarctic Ice Sheet (AIS) alone stores ~90% of the world’s ice, equivalent to an approximately 65 m rise in global sea level after melting. The surge in atmospheric temperatures causes more production of surface meltwater, which transports through the transitional product of snow and ice called firn. Near the surface, the low-density firn layer also provides a porous medium for meltwater however it could be influenced by the roughness of the top surface. This urges the need to study the Antarctic firn for understanding the current state of ice sheet mass balance.
Fixing a use-by date for aircraft
Aircraft are susceptible to fatigue: due to repeated cycles of loading damage will appear and slowly grow in the aircraft’s structure. Small damages are no issue, but if they grow too large, parts of the plane could break off. So, to keep flying safe, aircraft need a use-by date, after which they should be overhauled or even replaced.
In this talk, John-Alan will explain how we determine this use-by date for traditional aluminium alloys, why this is more complicated for new composite materials, and why a crucial part of his work is breaking stuff.
John Alan Pascoe (@ja_pascoe)
Evidence of accelerating sea level rise at the Dutch coast
Global mean sea-level rise (SLR) has been accelerating since the 1960s, reaching rates of more than 3 mm/year during the last three decades. Along individual coastlines, however, detection of an acceleration in SLR is challenging, because the long-term signal is obscured by a large natural variability. Our analysis of 100-year-long tide gauge observations along the Dutch coast shows that, since the early 1990s, sea level rise has accelerated from 1.7±0.3 mm/year to 2.7±0.4 mm/year. Similar changes have occurred in the past, but only the most recent ones can be detected with high confidence.
Riccardo Riva (@remriva)
Delft University of Technology