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‘State of the Climate’ report with findings from TU Wien researchers published

The ‘State of the Climate’ report has just been published. In this assessment of the global climate system, researchers from the CLIMERS group at TU Wien have published articles on soil moisture and Vegetation Optical Depth (VOD), thus contributing to a differentiated picture of the consequences of climate change.

Johanna Lems and Ruxandra-Maria Zotta from the CLIMERS group in front of a screen displaying a climate image they created. Both are smiling.

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Johanna Lems and Ruxandra-Maria Zotta from the CLIMERS group in front of an image showing global climate change

World map showing soil moisture anomalies. Colours: white, green, brown.

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Soil moisture anomalies in 2024

The latest ‘State of the Climate’ report* has just been published, a globally recognised assessment of the global climate system. Researchers from the CLIMERS group at the Department of Geodesy and Geoinformation at TU Wien also contributed. Johanna Lem's analysis of the global development of soil moisture and Ruxandra-Maria Zotta's contribution on Vegetation Optical Depth (VOD), opens an external URL in a new window illustrate the different regional consequences of climate change and the resulting risks for humans and the environment. Both fields of research are closely linked to questions of water availability, vegetation resilience and agricultural productivity. These publications emphasise the important contribution of geodetic remote sensing to international climate research.

Extreme deviations in humidity worldwide

Johanna Lems' analysis shows: The year 2024 was wetter worldwide than the average for the years 1991 to 2020, although there were clear regional differences. While North America, South Africa, Northern Europe and large parts of Asia suffered from severe drought, unusually high soil moisture levels were recorded in East Asia, Northern Australia, East Africa and the Sahel.

Such deviations are occurring more and more frequently and are increasingly manifesting themselves in the form of extreme droughts and floods. For example, Ukraine experienced extreme drought in 2024, while large-scale flooding occurred in the Sahel. Soil moisture is a key environmental parameter: It influences heatwaves, forest fire risks, crop yields and the risk of flooding and is therefore essential for the development of early warning systems and adaptation strategies.

Vegetation changes between stability and decline

Ruxandra-Maria Zotta's contribution deals with Vegetation Optical Depth (VOD), a satellite-based parameter that records the attenuation of microwave radiation by plants. VOD serves as an indicator of the water content and density of vegetation and, in 2024, shows a clear north-south gradient: While VOD values remained largely stable in the northern hemisphere, decreases were observed in the global south. South Africa stands out in particular, presumably as a result of the El Niño phenomenon. In contrast, heavy rainfall had a positive effect on vegetation in Australia, the Sahel and parts of the USA.

Long-term developments are also visible: for example, reforestation programmes in China, increasing agricultural intensification in India and progressive deforestation in South America, Mongolia and southern Africa. The basis for these analyses is the VODCA v2 dataset (Zotta et al., 2024), which combines more than 35 years of global vegetation monitoring.

Long-term data for global climate understanding

The contributions from Vienna show that long-term satellite data, open science and international cooperation are indispensable for reliably recording climatic changes. Remote sensing makes environmental processes visible on a continental scale and creates a solid basis for well-founded decisions in research, politics and society. 

 

*The annually published State of the Climate Report is regarded as one of the central scientific sources on global climate development. Based on satellite data, climate models and ground-based measurements, it documents global changes with high spatial and temporal resolution. It is published by the US climate agency NOAA, which has come under political and financial pressure under the Trump administration, but is nevertheless continuing its scientific work. 

Original publication

Complete report:
Blunden, J. and J. Reagan, Eds., 2025: “State of the Climate in 2024”. Bull. Amer. Meteor. Soc., 106
(8), Si–S513 https://doi.org/10.1175/2025BAMSStateoftheClimate.1, opens an external URL in a new window  

Chapter with the soil moisture and VOD sections:
Dunn, R. J. H., J. Blannin, K. M. Willett, N. Gobron, and G. A. Morris, Eds., 2025:
Global Climate [in “State of the Climate in 2024“]. Bull. Amer. Meteor. Soc., 106 (8), S11–S172,
https://doi.org/10.1175/BAMS-D-25-0102.1, opens an external URL in a new window 
 

Contact information

Johanna Lems
Research Group Climate and Environmental Remote Sensing
Department of Geodesy and Geoinformation
TU Wien
johanna.lems@geo.tuwien.ac.at

Ruxandra-Maria Zotta
Research Group Climate and Environmental Remote Sensing
Department of Geodesy and Geoinformation
TU Wien
ruxandra-maria.zotta@geo.tuwien.ac.at