Why is the atmosphere becoming drier? The roles of atmospheric processes and vegetation feedbacks, and their implications for future climate change

Climate change is a long-term shift in the properties of our atmosphere. One of these properties is relative humidity. Relative humidity describes the amount of water vapour in the air, relative to the temperature of the air. Dry air has a low relative humidity, while fog has a high relative humidity. Observation data shows that relative humidity is decreasing globally over land since the year 2000, especially in regions of mid-latitudes.

My project will be exploring three possible causes, or drivers, for declining near surface relative humidity over land:

Dynamical drivers, so called modes of variability (e.g. wind and pressure pattern)

Thermodynamical drivers (temperature and, consequently, greenhouse gases)

Land-based drivers (transpiration of plants and large-scale land cover changes, such as deforestation)

I am working with global monitoring products and earth observation data for land use, evapotranspiration and soil moisture. I will also be using computer simulations based on this data, and ecosystem studies. I hope to find out more about water, the fundamental element for life, and the representation of atmosphere-land exchange processes in climate models that predict the future.

This interdisciplinary research is carried out in collaboration with the Climate Monitoring and Attribution Group of the Met Office.

Outreach and Engagement

Climate change expert, COP26 Universities Network. The COP26 Universities Network is a growing group of more than 40 UK-based universities working together to raise ambition for tangible outcomes from the UN COP26 Climate Change Conference.

Co-chair Environmental Sustainability Rotary Action Group (ESRAG) Great Britain & Ireland. ESRAG assists Rotary clubs, districts and multi-districts in planning, implementing and evaluating service projects, building awareness, and inspiring action.

In December 2019 Florentine gave a gave a 90 second speech on sustainability alongside globalism and growth to House of Lords. Find out more here.

Along with another Grantham Scholar Florentine wrote a blog about her experiences at COP24. Read: A day at COP: what’s it like to be at the biggest climate conference in the world?


Simionesei et al., 2018 – Modeling Soil Water Dynamics and Pasture Growth in the Montado Ecosystem Using MOHID Land

Florentine gave a talk at the American Geophysical Union Fall Meeting 2019 in San Francisco – and also wrote a paper about her talk. 

Why is the atmosphere becoming drier? – An investigation of the role of dynamical drivers on recent trends in relative humidity

Social media


Florentine Weber



Professor Colin Osborne

Department of Animal and Plant Sciences

Dr Rob Ryant

Department of Geography

Dr Kate Willett

UK Met Office Hadley Centre