Beate Gertrud Liepert is a professor at Bard College in the Hudson Valley of New York. Her research focuses on climate variability: inter-annual changes, centennial time scales, the water and energy cycles.
Beate Gertrud Liepert is a professor at Bard College in the Hudson Valley of New York. Her research focuses on climate variability: inter-annual changes, centennial time scales, the water and energy cycles.
Beate got her diploma in Meteorology at the Institute of Meteorology and Institute of Bioclimatology and Air Pollution Research, Ludwig Maximilians University of Munich, Germany. In 1995 she obtained a PhD in Natural Science at the Institute of Meteorology, Department of Physics, Ludwig-Maximilians University Munich, Germany. [1]
Beate pioneered research on global dimming, which is the reduction of atmospheric transparency due to air pollution and inter-decadal cloud changes. She worked on implications of global dimming for climate: how and to what extend air pollution masks global warming, and how air pollution can spin down the hydrological cycle in a warmer and moister world. Some of her theoretical studies deal with climate forcing and feedbacks as studied in models and observations. She developed a climate model evaluation and ranking system that relies on first physical principles and self-consistency. Aerosol and solar radiation measurements in urban, as well as rural environments are also part of her research agenda, as is studying the effects of light quality on plant growths and ecosystems. More recently she started applying her knowledge to solar energy resource assessments and optimizing photovoltaic systems as alternative to fossil fuel and nuclear technologies. [1]
Beate contributed a section on global dimming to the Intergovernmental Panel on Climate Change 4th Assessment Report “Scientific Basis” (chapter 3.4.4.2) that won the 2007 Nobel Peace Prize. [2] [3]
The scientific community has been investigating the causes of climate change for decades. After thousands of studies, it came to a consensus, where it is "unequivocal that human influence has warmed the atmosphere, ocean and land since pre-industrial times." This consensus is supported by around 200 scientific organizations worldwide, The dominant role in this climate change has been played by the direct emissions of carbon dioxide from the burning of fossil fuels. Indirect CO2 emissions from land use change, and the emissions of methane, nitrous oxide and other greenhouse gases play major supporting roles.
Cloud albedo is a measure of the albedo or reflectivity of a cloud. Clouds regulate the amount of solar radiation absorbed by a planet and its solar surface irradiance. Generally, increased cloud cover correlates to a higher albedo and a lower absorption of solar energy. Cloud albedo strongly influences the Earth's energy budget, accounting for approximately half of Earth's albedo. Cloud albedo is influenced by the conditions of cloud formation and variations in cloud albedo depend on the total mass of water, the size and shape of the droplets or particles and their distribution in space. Thick clouds reflect a large amount of incoming solar radiation, translating to a high albedo. Thin clouds tend to transmit more solar radiation and, therefore, have a low albedo. Changes in cloud albedo caused by variations in cloud properties have a significant effect on global climate, having the ability to spiral into feedback loops.
Cloud feedback is a type of climate change feedback, where the overall cloud frequency, height, and the relative fraction of the different types of clouds are altered due to climate change, and these changes then affect the Earth's energy balance. On their own, clouds are already an important part of the climate system, as they consist of water vapor, which acts as a greenhouse gas and so contributes to warming; at the same time, they are bright and reflective of the Sun, which causes cooling. Clouds at low altitudes have a stronger cooling effect, and those at high altitudes have a stronger warming effect. Altogether, clouds make the Earth cooler than it would have been without them.
The sulfate or sulphate ion is a polyatomic anion with the empirical formula SO2−4. Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid.
Global dimming is a decline in the amount of sunlight reaching the Earth's surface. It is caused by atmospheric particulate matter, predominantly sulfate aerosols, which are components of air pollution. Global dimming was observed soon after the first systematic measurements of solar irradiance began in the 1950s. This weakening of visible sunlight proceeded at the rate of 4–5% per decade until the 1980s. During these years, air pollution increased due to post-war industrialization. Solar activity did not vary more than the usual during this period.
Radiative forcing is a concept used to quantify a change to the balance of energy flowing through a planetary atmosphere. Various factors contribute to this change in energy balance, such as concentrations of greenhouse gases and aerosols, and changes in surface albedo and solar irradiance. In more technical terms, it is defined as "the change in the net, downward minus upward, radiative flux due to a change in an external driver of climate change." These external drivers are distinguished from feedbacks and variability that are internal to the climate system, and that further influence the direction and magnitude of imbalance. Radiative forcing on Earth is meaningfully evaluated at the tropopause and at the top of the stratosphere. It is quantified in units of watts per square meter, and often summarized as an average over the total surface area of the globe.
MOPITT is an ongoing astronomical instrument aboard NASA's Terra satellite that measures global tropospheric carbon monoxide levels. It is part of NASA's Earth Observing System (EOS), and combined with the other payload remote sensors on the Terra satellite, the spacecraft monitors the Earth's environment and climate changes. Following its construction in Canada, MOPITT was launched into Earth's orbit in 1999 and utilizes gas correlation spectroscopy to measure the presence of different gases in the troposphere. The fundamental operations occur in its optical system composed of two optical tables holding the bulk of the apparatus. Results from the MOPITT enable scientists to better understand carbon monoxide's effects on a global scale, and various studies have been conducted based on MOPITT's measurements.
Earth's energy budget is the balance between the energy that Earth receives from the Sun and the energy the Earth loses back into outer space. Smaller energy sources, such as Earth's internal heat, are taken into consideration, but make a tiny contribution compared to solar energy. The energy budget also takes into account how energy moves through the climate system. The Sun heats the equatorial tropics more than the polar regions. Therefore, the amount of solar irradiance received by a certain region is unevenly distributed. As the energy seeks equilibrium across the planet, it drives interactions in Earth's climate system, i.e., Earth's water, ice, atmosphere, rocky crust, and all living things. The result is Earth's climate.
Climate sensitivity is a key measure in climate science and describes how much Earth's surface will warm for a doubling in the atmospheric carbon dioxide (CO2) concentration. Its formal definition is: "The change in the surface temperature in response to a change in the atmospheric carbon dioxide (CO2) concentration or other radiative forcing." This concept helps scientists understand the extent and magnitude of the effects of climate change.
Earth's climate system is a complex system with five interacting components: the atmosphere (air), the hydrosphere (water), the cryosphere, the lithosphere and the biosphere. Climate is the statistical characterization of the climate system. It represents the average weather, typically over a period of 30 years, and is determined by a combination of processes, such as ocean currents and wind patterns. Circulation in the atmosphere and oceans transports heat from the tropical regions to regions that receive less energy from the Sun. Solar radiation is the main driving force for this circulation. The water cycle also moves energy throughout the climate system. In addition, certain chemical elements are constantly moving between the components of the climate system. Two examples for these biochemical cycles are the carbon and nitrogen cycles.
Polar amplification is the phenomenon that any change in the net radiation balance tends to produce a larger change in temperature near the poles than in the planetary average. This is commonly referred to as the ratio of polar warming to tropical warming. On a planet with an atmosphere that can restrict emission of longwave radiation to space, surface temperatures will be warmer than a simple planetary equilibrium temperature calculation would predict. Where the atmosphere or an extensive ocean is able to transport heat polewards, the poles will be warmer and equatorial regions cooler than their local net radiation balances would predict. The poles will experience the most cooling when the global-mean temperature is lower relative to a reference climate; alternatively, the poles will experience the greatest warming when the global-mean temperature is higher.
Solar radiation modification (SRM), also known as solar radiation management, or solar geoengineering, refers to a range of approaches to limit global warming by increasing the amount of sunlight that the atmosphere reflects back to space or by reducing the trapping of outgoing thermal radiation. Among the multiple potential approaches, stratospheric aerosol injection is the most-studied, followed by marine cloud brightening. SRM could be a temporary measure to limit climate-change impacts while greenhouse gas emissions are reduced and carbon dioxide is removed, but would not be a substitute for reducing emissions. SRM is a form of climate engineering.
Marine cloud brightening also known as marine cloud seeding and marine cloud engineering is a proposed solar radiation management climate engineering technique that would make clouds brighter, reflecting a small fraction of incoming sunlight back into space in order to offset anthropogenic global warming. Along with stratospheric aerosol injection, it is one of the two solar radiation management methods that may most feasibly have a substantial climate impact. The intention is that increasing the Earth's albedo, in combination with greenhouse gas emissions reduction, carbon dioxide removal, and adaptation, would reduce climate change and its risks to people and the environment. If implemented, the cooling effect is expected to be felt rapidly and to be reversible on fairly short time scales. However, technical barriers remain to large-scale marine cloud brightening. There are also risks with such modification of complex climate systems.
Mark Zachary Jacobson is a professor of civil and environmental engineering at Stanford University and director of its Atmosphere/Energy Program. He is also a co-founder of the non-profit, Solutions Project.
Stratospheric aerosol injection (SAI) is a proposed method of solar geoengineering to reduce global warming. This would introduce aerosols into the stratosphere to create a cooling effect via global dimming and increased albedo, which occurs naturally from volcanic winter. It appears that stratospheric aerosol injection, at a moderate intensity, could counter most changes to temperature and precipitation, take effect rapidly, have low direct implementation costs, and be reversible in its direct climatic effects. The Intergovernmental Panel on Climate Change concludes that it "is the most-researched [solar geoengineering] method that it could limit warming to below 1.5 °C (2.7 °F)." However, like other solar geoengineering approaches, stratospheric aerosol injection would do so imperfectly and other effects are possible, particularly if used in a suboptimal manner.
Patterns of solar irradiance and solar variation have been a main driver of climate change over the millions to billions of years of the geologic time scale.
Cirrus cloud thinning (CCT) is a recent form of climate engineering. Cirrus clouds are high cold ice that, like other clouds, both reflect sunlight and absorb warming infrared radiation. However, they differ from other types of clouds in that, on average, infrared absorption outweighs sunlight reflection, resulting in a net warming effect on the climate. Therefore, thinning or removing these clouds would reduce their heat trapping capacity, resulting in a cooling effect on Earth's climate. This could be a potential tool to reduce anthropogenic global warming. Cirrus cloud thinning is an alternative category of climate engineering, in addition to solar radiation management and greenhouse gas removal.
Ulrike Lohmann is a climate researcher and professor for atmospheric physics at the ETH Zurich. She is known for her research on aerosol particles in clouds.
Glenn Edmond Shaw is an American scientist specializing in atmospheric physics, especially relating to global climate change and long-range transport of aerosol material. He is Emeritus Professor of Physics and Atmospheric Science at the University of Alaska Fairbanks and a member of the scientific staff of the Geophysical Institute. He conducted research on global atmospheric transport of aerosols and feedback of biogenic aerosols on global climate. He and Kenneth Rahn did research on the sources and climatic effect of Arctic haze. He did pioneering work on the scientific concept of climate homeostasis through the sulfur cycle and atmospheric aerosol.
Georgiy L. Stenchikov is an applied mathematician and climate scientist focusing on studies of physical processes that govern the Earth's climate. He is a professor in the Department of Earth Science and Engineering at the King Abdullah University of Science and Technology in Saudi Arabia.
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