The Basics of Climate Change

What is the difference between climate and weather?

Weather defines the daily conditions of a location through measures such as temperature, precipitation, cloud cover, humidity, and wind speed. The climate in a particular region is defined by the prevailing weather conditions and patterns in the area over a long period of time, usually several decades. The climate of an area is affected by its location in terms of latitude, proximity to water bodies, and altitude. The terrain of the area will also affect its climate. Climates are classified into categories such as desert, rainforest, or tundra based on the average weather variables -typically precipitation and temperature.

What is climate change?

Climate change is a shift in the statistical distribution of the long-term average weather conditions. This is not a short-term phenomenon like El Niño. These can include changes in mean (increasing average temperature or decreasing average precipitation in a year) and/or in the deviation or spread of weather variables (i.e. more frequent or intense storms).

How does it work?

The Earth’s climate fluctuates naturally over time. This is the result of several factors, such as the Earth’s orbit around the sun changing shape, a shift in the tilt of the axis of Earth’s rotation, variation in the solar cycles, and natural changes in ocean or atmosphere circulation. These fluctuations normally occur gradually, most of them being predictable. Additionally, the Earth’s atmosphere contains naturally occurring greenhouse gasses, such as carbon dioxide and methane. These keep the Earth warm and livable by trapping heat. This is called the greenhouse effect, and without it, temperatures would average about 0°F instead of the current average of 57°F. The atmosphere works like a glass room, in that the sun can shine through and warm up the inside, but not all of the heat can escape. Greenhouse gases in the Earth’s atmosphere like methane and carbon dioxide, which come from sources such as the burning of fossil fuels (oil, coal, or natural gas) and agriculture, enhance the greenhouse effect.

While the greenhouse effect is natural, the accelerated emissions of greenhouse gases by humans have made the phenomenon heat the Earth at an unnaturally high rate, which causes global warming. There are many aspects of the Earth’s system that can exacerbate or dampen this heating once it has started in a feedback mechanism. One example of a positive feedback is the sea ice, which covers a large part of the Polar Regions. The white surface of the ice reflects the sun’s radiation, sending much of the heat back out to space. Global warming has caused some of the sea ice to melt, which creates open water. The open water is a much darker color that absorbs most of the radiation reaching it from the sun, causing even more heating and ice melting, which leads to more open water, and the cycle continues. Given complications such as feedback loops, it takes complex climate models to provide a clear understanding of how the climate might change in the future.

Do civil engineers have to worry about it?

The consistent answer from transportation agencies is that climate change is a serious threat. We are already seeing record numbers of billion-dollar disasters caused by more severe storms, record heat waves, and some sea level rise due to climate change. Many of these events have impacted transportation infrastructure. In the future, we will likely see changes in annual average temperature or precipitation, as well as shifts in the frequency and severity of extreme weather events.

How do we know that this is happening?

The scientific community has known about climate change for a long time. We are able to observe changing trends in temperature, precipitation, storms, and other indicators, as well as make projections about what could happen in the future based on human decisions and action. National and regional infrastructure engineering reports have found the National Climate Assessment as well as climate.gov and climate.nasa.gov to be reliable resources for climate change information.

Moving forward

If we understand and start to prepare for the impacts of climate change that will likely occur, we can develop best practices and new technologies needed to foster a sustainable future. Increased research into the intersection of climate change and infrastructure is a large part of this, as infrastructure will be heavily impacted by global warming. The ICNet focuses on enabling the advancement of this research. Read more about why infrastructure and climate change research is important and about the intersection of fields.

Resources on anthropogenic climate change
http://weather.climate25.com/
How do we know that humans are causing global warming?

Need more explanations?
Bill Nye the Science Guy
Teaching Climate Literacy

Comprehensive national and international studies
http://nca2014.globalchange.gov/
https://www.ipcc.ch/report/ar5/

Make a difference
http://www.nature.org/greenliving/carboncalculator/
http://www.epa.gov/climatechange/wycd/