Natural Hazards and Disasters

Class 13: Climate Change Impacts, Land Use, Biological Hazards, and Extinction

Class slides

Sea Level Rise

On long time scales, 1^oC corresponds to about 25 m in sea level. Based on that, a large sea level rise over several centuries (several meters to >20 m) can be expected due to global warming. This will lead to horizontal migration of coasts. It will also cause significant pollution of inundated coastal areas and waters. A main challenge is to prepare for loss of coastal cities. There are large uncertainties in terms of how fast the sea level rise will happen. Knowledge about the current and near-term sea level rise is changing rapidly.

Heat Waves

Heat waves are rapidly increasing in number and severity. Recent heat waves have caused large numbers of fatalities (on the order of 10,000 and 100,000). The economic impact of heat waves is growing. Heat waves are expected to be one of the major impacts of climate change.

Droughts

In the past, droughts in combination with large-scale famine have been the most severe hazards, which killed up to 40 million people. Famines have been constraint in recent decades due to the transition to industrialized agriculture. However, the expected increase in frequency and severity of droughts due to modern climate change has the potential to inflict major disasters.

Cold Spells

Modern climate change is having an impact on atmospheric and ocean circulation, and this leads to changes in the temperature range in many locations. Besides heat waves, this can also cause cold spells. Here cold spells are temperatures that are lower than previously experienced in a given location. Having new low-temperature extremes can have a major impact on ecosystems. For example, cold spells in Florida in 2010 with temperatures as low as 10^oC turned out to kill a large amount of fish and other animals.

Wildfires

Wild fires are strongly impacted by modern climate change. Droughts cause stress in forests. Tree-killing insects find better conditions due to global warming. Particularly dry and winding periods combined with a growing amount of fuel in the forests leads to more and more intense fires.

Land use

In 1700, a global population of about 650 million people was using less than 1% of the earth's icefree land surface. Today, more than 7 billion people are using almost 50%, and it is expected that this increases by 2045 to close to 60%. It can be expected that the rapid reduction of land available to other animals and ecosystems as well as the rapidly increasing segmentation of the land will lead to a state shift in the global biosphere with unpredictable outcomes.

Biological Hazards

Human beings have always been exposed to biological hazards in form of bacteria, viruses, insects, plants, birds and other animals. These sources can cause a variety of health effects ranging from skin irritation and allergies to infections (e.g., tuberculosis, AIDS), cancer and so on. Snake bites account for more than 500,000 death a year and more than 1.2 million people are severely impacted by snake bites. Malaria is an important cause of death.

While many of these hazards have been reduced through human actions, others are increasing. Modern climate change is impacting viruses, insects, and invasive species. The overload of the ocean with nutirents has increased harmful algal blooms, and these are crrating toxic products.

An invasive species is a plant, fungus, or animal species that is not native to a specific location, which has a tendency to spread to a degree that can cause damage to the non-human and human environment, including human economy and human health. While native insects and diseases contribute to the death of old and stressed trees and lead the way to the regeneration of trees and forests, non-native insects and pathogens can dramatically alter this cycle.

Extinction

Human direct impacts and anthropogenic changes in land use combined with pollution have increased the extinction rates far above the pre-human background rates. In absolute, albeit rough, terms the “normal background rate” of extinction has been estimated to be 0.1 extinctions per million species per year. By contrast, the current extinction rate is more on the order of 100 extinctions per million species per year

Main Terms and Concepts

Hazard

Definition: A hazard is a change of the system state that can lead to system degradation and/or a reduction of the system's capability to function.

Vulnerability

Definition: Vulnerability is the inability of a system to withstand the effects of a hostile environment.

Disaster

Definition: A disaster is the loss of lives and property; often as the result of a hazardous event.

Risk

Mitigation

Mitigation can refer to the reduction of the hazard or the impacts of the hazard. In modern times, general mitigation has to focus on reducing the flows in the Earth's life-support systme and limit the growth of the human sphere.

Adaptation

Adaptation refers to system changes that enable a system to better cope with changing conditions. In modern times, the changing conditions will often come as surprises and adaptation has to focus on being better prepared for surprises.

Role of Humanity

Humanity has evolved into a major force in the earth system and in order to not cause a global catastrophe or extinction-class event, it is mandatory that humanity learns to operate a planetary system.

Class Reading List:

BARRIOPEDRO, D., FISCHER, E. M., LUTERBACHER, J., TRIGO, R. M., GARCÍA-HERRERA, R., 2011. The Hot Summer of 2010: Redrawing the Temperature Record Map of Europe. Science, DOI: 10.1126/science.1201224. http://science.sciencemag.org/content/early/2011/03/16/science.1201224.

Klinenberg, E., 2002. A Social Autopsy of Disaster in Chicago. University of Chicago Press.

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