Contributions to Climate Summit

Politicians will meet at the Climate Summit in Paris to discuss the IPCC (Intergovernmental Panel on Climate Change) report. It provides an overview of the current state of climate knowledge, based on the work of thousands of scientists all over the world.  Delft researchers have also contributed in various ways.

What’s it all about again? The UN Climate Summit, which will be held from 30 November to 11 December in Paris, is the 21st annual session of the Conference of Parties, or COP21, held within the framework of the 1992 UN Framework Convention on Climate Change (UNFCCC). Politicians discuss the latest version of the IPCC report (Assessment Report), which is updated every six years to include the latest data and scientific insights relating to the greenhouse effect and climate change. The current report is the fifth and is therefore called AR5. The report is divided into three parts, drawn up by Working Groups. The first part addresses the physical aspects of climate change (based on monitoring, models and projections). Part II assesses the impact of climate change on ecosystems, industry, cities, health and well-being. The last part, drawn up by Working Group III, focuses mainly on strategies for mitigating climate change through changes in energy use, transport, buildings, agriculture and industry.

Most of the Delft contributions were in Working Group I, in particular Chapter 3 (Observations: Ocean), Chapter 4 (Observations: Cryosphere), Chapter 7 (Clouds and Aerosols) and Chapter 13 (Sea Level Change).
Prof. Pier Siebesma, from the Department of Geo-science & Remote Sensing at the Faculty of Civil Engineering and Geosciences (CEG) and the KNMI in De Bilt, coordinated the European Euclipse research programme between 2010 and 2014, in which TU Delft, KNMI and ten other European universities and research institutes took part. The objective was to improve understanding of the role of clouds in climate change. Chapter 7 (clouds and aerosols) refers to 11 publications on the Euclipse project. Prof. Harm  Jonker, Dr Stephan de Roode, Dr Johan van der Dussen and Dr Sara dal Gesso also took part in Euclipse on behalf of TU Delft.

Dr Ernst Schrama of the Astrodynamics & Space Missions research group in the Faculty of Aerospace Engineering contributed as a reviewer to Chapter 4 on the cryosphere and Chapter 13 on sea level change. These chapters also include several references to articles written by him. According to Schrama, the most important research outcome is the monitoring of the mass balance of grounded ice sheets on Greenland and Antarctica, carried out using the GRACE gravity satellite together with his then PhD student Dr Bert Wouters (currently working at IMAU, Utrecht). They concluded that Greenland is losing 270 gigatons of ice a year, and Antarctica 130 gigatons. Is that a lot? ‘The speed at which this is happening is disturbing,’ says Schrama. ‘Since Roman times, the sea level has risen by about 60 centimetres in total, while it is currently rising by about 30 centimetres a century.’

Chapter 4, on the mass balance of grounded ice sheets, also refers to research carried out by Dr Cornelis Slobbe, Dr Pavel Ditmar and Dr Roderik Lindenberg (Geoscience & Remote Sensing at CEG). In their 2009 article in Geophysics Journal International, they combined ICESat measurements (of ice sheet elevations) with measurements from GRACE (of changes in ice-sheet mass). They were therefore the first to make a distinction between volume changes in snow and ice, based on the different densities. It is because of this that we now know that, although a lot of snow falls on the glaciers in Greenland, the net loss in ice mass is higher.

Dr Riccardo Riva and Prof. Bert Vermeersen (Geo-science & Remote Sensing at CEG) looked at the resulting sea level change caused by the melting of ice sheets, as the water mass does not spread evenly across the globe. Their articles are cited in Chapter 13 of Working Group I (Sea Level Change) and Chapter 23 of Working Group II on regional projections for Europe. They calculated a sea level rise of 80 cm in Hamburg and London by the end of the 21st century (but a drop of 10 cm in Finland). They also noted that the sea level rise could be significantly higher (an extra 90 cm) due to ice melting in the South Pole region.

Finally, Dr. Miren Vizcaino co-authored Chapter 13 on Sea Level Change and contributed articles cited in the text. Vizcaino also works at the Department of Geoscience & Remote Sensing at CEG, where she uses climate models to predict the melting of ice sheets on Greenland and Antarctica for the coming centuries. Over a timeframe of thousands of years, she in fact sees Greenland turning green. The advanced model (Atmosphere-Ocean General Circulation Model) not only calculates the impact of the environment on the ice, but also the impact of the melting ice on the environment. An example is the weakening of the warm Gulf Stream as warm salty water from the tropics sinks less slowly in the arctic seas as a result of local warming and the influx of fresh melt water. In a world with CO2 levels twice as high compared to pre-industrial levels (560 ppm vs. 280 ppm; we are now at 400 ppm), Vizcaino’s model predicts a weakening of the Gulf Stream over the next 200 years followed by a slight recovery after 2200.

Although the editors have attempted to include all
contributions by TU Delft scientists to the IPCC report, they do not claim to be exhaustive.

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