May 3, 2004Advanced Instiute on Vulnerability Global Change and the Earth System Jill Jäger Co-Director, Advanced Institute on Vulnerability to Global Environmental Change

May 3, 2004Advanced Instiute on Vulnerability Global Change and the Earth System An integrated Earth System Planetary machinery The Anthropocene Era The responses of the Earth System to human activities Consequences for human well-being Towards Earth System Science and Global Sustainability

May 3, 2004Advanced Instiute on Vulnerability An Integrated Earth System The extent to which, over the geologically recent past, the Earth behaves as a single, interlinked, self-regulating system was illustrated in 1999 with the publication of the 420,000 year record from the Vostok ice core This systematic behaviour is due to a combination of external forcing (e.g. Solar radiation) and a large and complex array of feedbacks and forcings within the Earth‘s environment

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability The Nature of Global Change Global change is more than climate change The world‘s population has doubled since 1960 Since 1950 the global economy has increased by more than a factor of 15 Economy inequality is increasing

May 3, 2004Advanced Instiute on Vulnerability The Nature of Global Change World petroleum consumption increased by a factor of 35 since 1960 Transport accounts for 25% of world energy use Urbanisation increased 10-fold in the 20th Century Interconnectedness is increasing rapidly (communication, travel, globalisation of economies)

May 3, 2004Advanced Instiute on Vulnerability The Nature of Global Change Nearly 50% of the land surface has been transormed by direct human action More nitrogen is now fixed through fertilization and fossil fuel combustion than is fixed naturally More than half of all accessible freshwater is appropriated for human purposes Concentrations of greenhouse gases have increased substantially

May 3, 2004Advanced Instiute on Vulnerability The Nature of Global Change Coastal wetlands are significantly affected (e.g., loss of 50% of the world‘s mangrove ecosystems) 47 – 50% of marine fish stocks are fully exploited; 15 – 18% overexploited; 9 – 10% depleted Extinction rates are increasing sharply in marine and terrestrial systems

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability Planetary Machinery Without humans the Earth System functioned within domains characterised by well-defined limits and periodic patterns Interconnections among physical, chemical and biological processes; between land, ocean, and atmosphere Rapid, abrupt changes can occur

May 3, 2004Advanced Instiute on Vulnerability Connectivity via the oceans and their currents Exchange of water between surface and deep ocean Driven by cooling of surface water in polar regions Thermohaline circulation (i.e. Salinity plays a role too) Metaphor – a conveyor belt moving water, heat, and other properties and substances around the world‘s ocean basins

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability More connectivity Q: Why do we find carbon sink areas in the Indian Ocean? A: An aerosol plum from South Africa provides iron and nutrients, supporting enhanced biological activity and as a result the carbon sink in the South Indian Ocean Link between continental, terrestrial ecosystems and their remote (up to 5000 km) marine equivalents

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability The Anthropocene Era The planet is now dominated by human activities Human changes are complex, interacting, often exponential in rate, and globally significant in magnitude Human driving forces are also complex and interactive No evidence that the Earth System has previously experienced these types, scales, and rates of change („no-analogue“ situation)

May 3, 2004Advanced Instiute on Vulnerability Drivers of Change Industry Energy and transport Provision of food* Forestry Recreation and tourism

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability Evidence of Change Land cover Greenhouse gas concentrations, photo- oxidants, aerosols Hydrological cycle Coastal and marine environments Biological diversity*

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability Socio-economic drivers Urbanisation Globalisation*

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability The Response of the Earth System to Human Activities Human impacts do not have separate, simple cause-effect responses The responses cascade through the Earth System The responses seldom follow linear chains; they interact with each other (damping or amplifying)

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability A Cascade of Effects Triggered by Fossil Fuel Combustion Q: How can use of an air conditioner in a midwestern American home or a drive down a German Autobahn influence the ability of an African farmer in the Sahel to grow food for his family? Fossil fuel combustion -> production of sulphate aerosols -> changed radiative balance near Earth‘s surface -> near- surface cooling regionally

May 3, 2004Advanced Instiute on Vulnerability The Cascade Continues Cooling in Europe in North America in 1960s – 1980s -> changed latitudinal temperature gradient between North Atlantic Region and tropics and subtropics -> changed atmospheric circulation -> shift position of African Monsoon over Northern Africa ->changed rainfall patterns, including drying climate in the Sahel

May 3, 2004Advanced Instiute on Vulnerability Multiple and Interacting Changes Over the last 4 or 5 decades an increasing number of stresses of human origin have begun to interact with the natural disturbance daynamics of coral reefs Increasing nutrient and sediment loadings (agricultural and industrial activities), intensive fishing, tourism, increasing atmospheric CO2 (changes carbonate chemistry), warming of the upper ocean layers (thermal stress -> bleaching Reduced resilience of reefs to external perturbations 58% of world‘s coral reefs at medium to high risk

May 3, 2004Advanced Instiute on Vulnerability Living with Global Change Implications for human well-being Basic goods and services provided by the Earth System (e.g. Food, water, air quality) Impacts are not the same around the world The concept of VULNERABILITY provides a useful framework within which to study the consequences of global change Abrupt changes and surprises are also possible

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability

May 3, 2004Advanced Instiute on Vulnerability Towards Earth System Science and Global Sustainability What will be the nature of changes in the Earth System over the coming decades? What are the implications for humankind? What type and scale of management responses are consistent with the scientific knowledge base? How must science itself change to tackle the challenges ahead?

May 3, 2004Advanced Instiute on Vulnerability Global Change and the Earth System The Earth is a system that life itself helps to modulate Global change is much more than climate change. It is real, it is happening now, and it is accelerating The human enterprise drives multiple, interacting effects that cascade through the Earth System in complex ways The Earth‘s dynamics are characterised by critical thresholds and abrupt changes The Earth is currently in a „no-analogue“ state