The main topics of this chapter can be summarized as follows:
16.1 What Makes the Climate Change?
The two components of climate change are forcings and feedbacks. Natural climate forcings, which have operated throughout geological time, include solar evolution and cycles, continental drift, continental collisions and mountain building, volcanism, orbital variations, and ocean current cycles. Feedbacks include melting of ice, snow, and permafrost (changing albedo and releasing GHGs); temperature-related changes to solubility of CO2; and vegetation growth.
16.2 Anthropogenic Climate Change
The key contributors to anthropogenic climate change are our use of fossil fuels and our increasing numbers, although other important factors include what we eat and how we produce it.
16.3 Implications of Climate Change
The most reliable indicators of climate change are those that we can detect by looking at records going back for decades. These include temperature and other climate parameters, of course, but also sea-level rise and the incidence of major storms. Some of the implications of climate change include changes to the distribution of disease vectors and pests, and an increase in the incidence and severity of heat waves.
Questions for Review
- What property of greenhouse gases allows them to absorb infrared radiation and thus trap heat within the atmosphere?
- Explain why the emission of CO2 from fossil fuel use is a climate forcing, while the solubility of CO2 in seawater is a climate feedback.
- Explain how the positioning of Gondwana at the South Pole contributed to glaciation during the Paleozoic.
- Most volcanic eruptions lead to short-term cooling, but long-term sustained volcanism can lead to warming. Describe the mechanisms for these two different consequences.
- Using the orbital information on eccentricity, tilt, and precession, we could calculate variations in insolation for any latitude on Earth and for any month of the year. Why is it useful to choose the latitude of 65° as opposed to something like 30°? Why north instead of south? Why July instead of January?
- If the major currents in the oceans were to slow down or stop, how would that affect the distribution of heat on Earth, and what effect might that have on glaciation?
- Explain the climate implications of the melting and breakdown of permafrost.
- Much of the warming of the Paleocene-Eocene thermal maximum is thought to have been caused by the release of CH4 from sea-floor methane hydrates. Describe what would have to have happened before this could take place.
- Burning fossil fuels emits CO2 to the atmosphere via reactions like this one: CH4 + O2 —-> CO2 + 2H2O. Describe some of the other ways that our extraction, transportation, and use of fossil fuels impact the climate.
- Explain why, even if we could stop our impact on the climate tomorrow, we would still be facing between 1 m and 2 m of additional sea-level rise.
- Use the Internet to research West Nile virus, and explain why its spread into Canada from the United States is related to climate change.