Earth System Science talks will return in September 2021
Contact Address:
The Earth System Science Program
Earth & Planetary Sciences
[Unit Detail]
Frank Dawson Adams Building[Map],
3450 University Street,
Montreal, QC, Canada, H3A 0E8.
Tel: (514)-398-6767 | Fax: 514.398.4680
Earth’s climate, hydrology, biogeochemistry, and biological systems are intimately linked. Water, because of its thermal and chemical properties plays an essential role in the partitioning and transport of energy in the Earth’s climate, and in the store and transport of chemical mass in both the biotic and abiotic functioning of the Earth System. Until recently, humans have paid little attention to the global hydrological cycle, but it is now accepted that human activity appropriates between twenty and forty percent of all renewable freshwater. This, in turn, slows river transport and increases the residence time of water on continents by several months or more. This, in turn, alters the timing of freshwater input to the oceans and retains enough water on the continents to reduce sea level by several millimetres. Unfortunately, the distribution of freshwater resources does not follow the pattern of population density or growth. Currently more than a third of the world’s population faces critical water shortages. A major deficiency in global climate models is poor representation and prediction of the spatial and temporal dynamics of the global hydrological cycle.
Biogeochemistry examines the cycling of elements and compounds under the control of biological, geochemical, and hydrological processes. Unlike water, biogeochemistry is not directly related to the transport of heat at the global scale, but it is the study of the metabolism and what drives the metabolism of the planet earth. However, the biological function of some ecosystems, such as tropical forests, can have a global affect on water movement. Globally, the study of biogeochemistry focuses on the cycling of carbon, nitrogen, phosphorus, and sulphur. Humanity has altered the carbon cycle by transferring carbon from the slow geologic cycle operating over periods of hundreds of millions of years, to the rapid contemporary carbon cycle operating over hundreds of years, and by transforming forests into agro-ecosystems.
The potential implications of altering the concentration of CO2 have been well documented, but even more dramatic is humanity’s alteration of the global nitrogen cycle. Through fertilizer production and the inadvertent nitrogen chemistry associated with the internal combustion engine, humans now fix – i.e. transform the inert form of nitrogen into biologically available forms – more nitrogen annually than the entire biosphere of the Earth System!
At the continental to regional scale sulphur emissions have altered the acidity of terrestrial and aquatic ecosystems, at the same time as increasing the aerosol content of the atmosphere and consequentially the Earth’s albedo.
The key questions in the study of global cycles are:
Climate change has been occurring ever since the Earth was formed 4.6 billion years ago. A first-order problem of climate change research is to distinguish between human influences, and influences caused by natural processes (Earth’s orbit, tectonics, etc.). A second major challenge in climate research is to reduce uncertainty in climate predictions, especially for the next 100 years. Finally, a truly grand challenge in climate research is predicting the next ice age.
To meet the grand challenge of understanding climate variability, we require the following approaches:
The prediction of the next ice age will be accomplished with the application of a new class of Earth system models known as EMICs: Earth system Models of Intermediate Complexity. These models combine both the geophysical and biospherical aspects of the Earth system. The modeling can be accomplished with a deeper understanding of the global biogeochemical cycles that modulate our climate under orbital forcing.
Human alterations of the Earth’s land surface are proceeding at unprecedented rates and are affecting key processes in the Earth System. Land use and land cover changes contribute to local and regional climate change as well as global climate warming, alter global biogeochemical cycles, are the primary source of soil degradation and loss of biodiversity, and influence, by altering ecosystem services, the ability of biological systems to support human needs. An improved understanding of land use/cover change thus is central in Earth Systems Science and for the study of global environmental change. Two major international scientific research initiatives sponsored by the International Geosphere-Biosphere Programme (IGBP) and the International Human Dimensions Programme on Global Environmental Change (IHDP) address the critical role of land use/cover change in Earth system functions – the Land Use and Land Cover Change Project (LUCC) and the new Global Land Project (GLP).
The key questions of land use/cover change research are:
We need to comprehend how energy is transferred among the various components of the Earth system. Examples include ocean-atmosphere energy transfer, venting of hot hydrothermal fluids on the ocean floor, river flows, fossil fuel burning, and extreme events such as hurricanes and volcanic eruptions. There is also a pressing human component in our increasing demand for energy, both immediate and long-term. Therefore we need to evaluate traditional energy sources against new ones and ask the questions:
Earth's resources also include water, soils, minerals, metals, and biota. They are a fundamental element of the Earth system, and are all exploited intensively by humans. Water is so important and so basic to humans that it is the topic of a separate "grand challenge". Soils play a fundamental role in biodiversity and agricultural production. Minerals and metals are the basis of our modern-day economy and lifestyle. Biota define life as we know it, regulate weather and climate, and are significantly impacted by human activity.
For these various resources, we must address four other basic questions:
Humans are becoming increasingly vulnerable to extreme events such as hurricanes, floods, wildfires, and volcanic eruptions. This is the result of several factors. First, the Earth system may be changing, and so increasing the likelihood of extreme events. Second, people choose to live in areas that are aesthetically or economically attractive, yet especially vulnerable, such as along coasts, near forests and volcanoes, and on floodplains. Increasing urbanization of the world's population is exacerbating the problem. Some urban centres are vulnerable to extreme events, yet are growing rapidly, placing more and more people at risk. Some examples are instructive. Naples is located on the flanks of Mount Vesuvius, a volcano certain to erupt in the next tens to hundreds of years. Los Angeles is a megacity vulnerable to earthquakes and wildfire (a medium-sized earthquake in 1994 caused ~$40 billion in losses). Miami, and other east coastal cities of North America, are vulnerable to hurricanes (Hurricane Andrew in 1992 inflicted ~ $30 billion in losses). Vancouver is vulnerable to very large earthquakes, landslides, and possible tsunami waves. Bangladesh is hit repeatedly by devastating hurricanes and associated flooding, causing enormous loss of life.
Because these events typically involve several components of the Earth system (e.g., volcanoes involve Earth's mantle, crust, surface, and atmosphere), they should be studied using an Earth system approach. To deal with these issues requires six fundamental approaches:
One of today’s great challenges in Earth System Science is to determine the entire Earth’s current state over a vast range of spatial scales. Determining this state requires not only a large array of instrumentation, but also the capability to assimilate the resulting large amounts of data into a coherent representation of the Earth-Ocean-Atmosphere system. The design of instrumentation to routinely document phenomena, which have previously only been seen in high-resolution computer models, is a challenge that requires the collaboration of the engineering and scientific communities. The need to define the state of the Earth System at the highest possible resolution in space and time has never been greater.
We address this grand challenge with the following approaches: