Climate change refers to changes to long term atmospheric conditions. The change to the climate occurring now is the increasing global average temperature due to anthropogenic positive radiative forcing. What anthropogenic positive radiative forcing means is that humans are causing the climate to get warmer. Radiative forcing can be explained as a gases’ ability to affect the earth’s energy balance. The earth receives energy from the sun which is an energy input and then loses energy as infrared radiation. Earth’s energy balance is the relationship between the energy inputs and outputs. Greenhouse gases affect the earth's energy output by trapping more heat close to earth causing an average temperature increase.
Climate change is happening because humans are altering the composition of the atmosphere by adding large amounts of carbon dioxide and other greenhouse gases. Anthropogenic or human caused sources of carbon dioxide include the burning of fossil fuels and deforestation. While carbon dioxide (CO2) is the most prevalent, it is not the only greenhouse gas. Other greenhouse gases include nitrous oxide (N2O), methane (CH4) and water vapor (H2O). [1] Concentrations of carbon dioxide, methane and nitrous oxide have all increased in the atmosphere because of human activity since 1750. One statistic shows that, “In 2011 the concentration of these greenhouse gases were 391 ppm, 1803 ppb, and 324 ppb and exceeded the preindustrial levels by about 40%, 150% and 20% respectively.” [3] This information is concerning because these levels of carbon dioxide, methane and nitrous oxide are higher than they have been in the last 800,000 years according to ice core data. [3] Ice cores provide this data through ancient air bubbles trapped in the ice which tell us past atmospheric conditions.
Carbon dioxide and other greenhouse gases keep the planet at a livable temperature through the greenhouse effect. This effect is where shortwave radiation from the sun reaches the earth’s surface, warms it and is reradiated as long wave radiation. This long wave radiation is trapped by greenhouse gases in the lower atmosphere or lost to space. Human contributions of carbon dioxide and other greenhouse gasses to the atmosphere however, absorb outgoing radiation are causing an increase in the global average temperature.
There is no question the climate of the earth is getting warmer.[2] The increasing temperature as well as its effects are setting records for the most recent decade to millennia. Effects we are already seeing include warming of the ocean, receding glaciers and decreased extent of the polar ice cap, rising sea level, and warmer surface temperatures. [3]. Each of the last three decades has been successively warmer at the earth’s surface than any preceding decade since 1850. [3]. Globally averaged combined land and ocean temperature data as calculated by a linear trend show a warming of 0.85 degree C over the period 1880 to 2012 According to the observed globally averaged combined land and ocean surface temperature anomaly data from 1850 - 2012 there is a clear upward trend toward higher temperatures [3].
There are many projected effects of climate change that are very likely occur by the late 21st century. These changes to the earth include: warmer and/or fewer cold days and nights over most land areas; warmer and/or more frequent hot days and nights over most land areas; warm spells/heat waves frequency and duration increases over most land areas; heavy precipitation events increase in frequency, intensity and or amount of heavy precipitation; and increased incidence and/or magnitude of extreme high sea level.[3] Other effects include the ocean temperature rising. The ocean is warming the fastest near the surface and the first 75 m of depth at a rate of about 0.11 degrees C per decade since 1971 to 2010 according the the IPCC [3]. Effects to the cryosphere include the Greenland and Antarctic ice sheets have been getting smaller, glaciers all over the world are disappearing. [3]. Due to both ice melting and warmer temperatures which cause thermal expansion sea level has gone up almost 20 cm from 1901 to 2010. [3] A less obvious effect of the increasing concentration of CO
2
in the atmosphere is ocean acidification. “The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide (a weak acid in water), causing ocean acidification and a drop in pH according to the 2013 IPCC.
Climate change is a problem for many reasons. There are many potential effects of this warming including sea level rise, melting ice caps, changing spatial distribution of disease vectors, ocean acidification and changing weather patterns. These are only a few of the many different known impacts of climate change. Each of these different effects of climate change will put stress on different areas of infrastructure from flooding coastal roads to diseases increasing their range.