Institutes | Max Planck Institutes | MPI for Meteorology

Climate Engineering employs technical methods to mitigate climate change without lowering anthropogenic CO₂ emissions. One of these methods, the artificial increase of ocean alkalinity, has been proposed to enhance the oceanic uptake of atmospheric CO₂ and counteract the ongoing ocean acidification. We used a global biogeochemical model to show that artificial ocean alkalinity input must be 200 times higher than the input by natural weathering flux to hold the global seawater pH close to today’s value. The effects on ocean biogeochemistry would be substantial.

2012

Impact of irrigation on the South Asian summer monsoon

2012, Max Planck Institute for Meteorology

Hagemann, Stefan; Saeed, Fahad

The Indian subcontinent is one of the most intensely irrigated regions of the world. Using the regional climate model REMO distinct feedbacks of the monsoon circulation with irrigation processes could be shown. With irrigation, a significant model bias in temperature and mean sea level pressure over NW India/Pakistan was removed. Moreover conditions were created favourable for currents from Bay of Bengal to intrude deep into western India and Pakistan that have been unrealistically suppressed before. Thus, the representation of irrigated water is unavoidable for a realistic monsoon simulation.

2011

Limited climate response of very large volcanic eruptions

2011, Max Planck Institute for Meteorology

Timmreck, Claudia

Extremely large volcanic eruptions have been linked to global climate change, biotic turnover, and, for the Younger Toba Tuff eruption 74,000 years ago, near‐extinction of modern humans. One of the largest uncertainties of the estimated climate effects in previous model studies involves the aerosol size distribution. A huge sulfate load causes higher collision rates, larger particle sizes, and rapid fall out, which in turn greatly affects radiative feedbacks. Incorporating aerosol microphysical processes into global model simulations results in a smaller climate effect than estimated before.

2010

The big melt: sea ice in a changing climate

2010, Max Planck Institute for Meteorology

Notz, Dirk

Scientists are currently puzzled by the behavior of Arctic sea ice: Following a sharp and unexpected decline in summer 2007, the ice-covered area has increased both in 2008 and in 2009. At MPI for Meteorology, scientists carry out research to understand these ups and downs. They also examine what their results mean for the future evolution of the polar bear's habitat. For their studies, the researchers use sophisticated computer models, but they also carry out field measurements in the Arctic to better understand the physical properties of sea ice.

2009

Preindustrial agriculture: climate change without oil and coal

2009, Max Planck Institute for Meteorology

Pongratz, Julia; Reick, Christian H.

The vegetation covering the continents has a decisive influence on the climate. Through the uptake of CO₂ from the atmosphere, plants play a central role in the global carbon cycle. Furthermore, they influence the exchange of energy, water, and momentum between the atmosphere and the land surface. Via land use, humans are altering these processes. The study presented here investigates the expansion of agriculture over the last millennium. It shows that humans had a strong influence on climate, especially on the regional scale, already before industrialization began.

2008

Influence of pollution on climate change – new insights from satellite data and climate models

2008, Max Planck Institute for Meteorology

Kinne, Stefan; Quaas, Johannes

Particles suspended in the atmosphere, so-called aerosols, reflect sunlight and alter cloud properties. In the global mean anthropogenic pollution aerosol by these direct and indirect effects cools the climate. The studies presented here in which new comprehensive remote sensing data are used show that for the direct as well as for the indirect effect former estimates for the climate effect of anthropogenic aerosol have been exaggerated.

2007

Stability of the Atlantic Meridional Overturning Circulation

2007, Max Planck Institute for Meteorology

Jungclaus, Johann; Baehr, Johanna; Haak, Helmuth; Jacob, Daniela; Koenigk, Torben; Marotzke, Jochem

The evolution and stability of the meridional overturning circulation in the Atlantic under global warming conditions, its observational characteristics, and the detectability of such anthropogenic changes have been investigated with the MPI-M climate model. For realistic projections of the climate evolution in the 21st century, the model indicates a reduction of 30-42%, but no total breakdown of the overturning circulation. Natural variability on time scales of days to decades requires long-term observations in the Atlantic to detect a potential decrease.

2006

Earth System Research Partnership

2006, Max Planck Institute for Meteorology

Marotzke, Jochem; Andreae, Meinrat; Heimann, Martin

Earth system research is the science of global change, whether caused naturally or by humans. Earth system research requires the amalgamation of previously unrelated scientific disciplines and the appreciation of the Earth as a system of interacting compartments. In-situ measurements, satellite remote sensing, and numerical modelling are the pillars of Earth system research and have advanced dramatically in recent years. The Earth System Research Partnership is the association of the Max Planck Institutes dedicated to Earth system research, with further contributions by several Max Planck and other institutes.

Long-range transport of persistent chemicals and distribution among various environment media – model investigations

2006, Max Planck Institute for Meteorology

Lammel, Gerhard; Semeena, V.S.; Feichter, Johann; Guglielmo, Francesca; Leip, Adrian

Many environmental pollutants are slowly degrading (persistent) and very mobile. Results of simulations using a global multicompartment model which is based on an atmosphere general circulation model are presented. The integration of soils, vegetation, air, ocean and ice is mandatory in order to describe the environmental fate, i.e. transports and transformations, of slowly degrading and semivolatile substances. This class of substances includes the so-called persistent organic pollutants (POPs) and other pesticides and industrial chemicals. The investigations elucidate the combined effects of climate and substance properties on transport and distribution of pollutants and allow to quantify persistence and long-range transport potential.

2005

Impact of carbonaceous aerosoles

2005, Max Planck Institute for Meteorology

Feichter, Johann

Since begin of the industrial revolution levels of the greenhouse gases carbon dioxide, methane and nitrous oxide have risen dramatically. Fossil fuel combustion, increasingly intensive agriculture and an expanding global human population have been the primary causes for this rapid increase. The same increases in fossil fuel burning and biofuel use have also led to an increase in the emissions of sulphur dioxide, soot and particulate organic matter which form aerosol (=suspended particulate matter) in the atmosphere. Most aerosols cool the atmosphere by increasing Earth's reflectivity, but aerosols containing soot warm it by absorbing sunlight. Cleaner fuel technologies are today leading to a reduction in sulphate emissions. Unlike carbon dioxide and sulphur dioxide emissions, soot emissions are largest in developing countries and are still increasing. According to future emission scenarios, the most polluted regions in the first part of the 21th century will be found at lower latitudes whilst aerosol emissions have decreased in North America and Europe. The most notable climate response as calculated by the MPI Earth-System Model to this latitudinal shift in atmospheric aerosol load is a mitigated surface warming and a wetter soil in highly polluted regions and a pronounced warming and drying in regions where the aerosol load is decreasing.

2004

The simulation of glacial cycles with a complex Earth system model

2004, Max Planck Institute for Meteorology

Mikolajewicz, Uwe; Gröger, Matthias; Marotzke, Jochem; Schurgers, Guillaume; Vizcaíno, Miren

What causes the sequence of ice ages and interglacials is one of the big unsolved questions of Earth system science. Interactions between atmosphere, ocean, ice, and oceanic and terrestrial biosphere are likely to be crucial. Here, we describe the fundamentals and first results of the most complex extant Earth system model for the simulation of long timescales. Interactive land vegetation enhances the climate change caused by variations in the Earth’s orbital parameters, and thus constitutes a positive feedback even in a complex Earth system model.