Global Warming
Throughout its long history, Earth has warmed and cooled time and again. Climate has changed when the planet received more or less sunlight due to subtle shifts in its orbit, as the atmosphere or surface changed, or when the Sun’s energy varied. But in the past century, another force has started to influence Earth’s climate: humanity

How does this warming compare to previous changes in Earth’s climate? How can we be certain that human-released greenhouse gases are causing the warming? How much more will the Earth warm? How will Earth respond? Answering these questions is perhaps the most significant scientific challenge of our time.

What is Global Warming?
Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels. The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly doubled in the last 50 years. Temperatures are certain to go up further.

Graph of global mean temperature from 1880 to 2009.
Despite ups and downs from year to year, global average surface temperature is rising. By the beginning of the 21st century, Earth’s temperature was roughly 0.5 degrees Celsius above the long-term (1951–1980) average. (NASA figure adapted from Goddard Institute for Space Studies Surface Temperature Analysis.)

Earth’s natural greenhouse effect
Earth’s temperature begins with the Sun. Roughly 30 percent of incoming sunlight is reflected back into space by bright surfaces like clouds and ice. Of the remaining 70 percent, most is absorbed by the land and ocean, and the rest is absorbed by the atmosphere. The absorbed solar energy heats our planet.

As the rocks, the air, and the seas warm, they radiate “heat” energy (thermal infrared radiation). From the surface, this energy travels into the atmosphere where much of it is absorbed by water vapor and long-lived greenhouse gases such as carbon dioxide and methane.

When they absorb the energy radiating from Earth’s surface, microscopic water or greenhouse gas molecules turn into tiny heaters— like the bricks in a fireplace, they radiate heat even after the fire goes out. They radiate in all directions. The energy that radiates back toward Earth heats both the lower atmosphere and the surface, enhancing the heating they get from direct sunlight.

This absorption and radiation of heat by the atmosphere—the natural greenhouse effect—is beneficial for life on Earth. If there were no greenhouse effect, the Earth’s average surface temperature would be a very chilly -18°C (0°F) instead of the comfortable 15°C (59°F) that it is today.

See Climate and Earth’s Energy Budget to read more about how sunlight fuels Earth’s climate.

The enhanced greenhouse effect
What has scientists concerned now is that over the past 250 years, humans have been artificially raising the concentration of greenhouse gases in the atmosphere at an ever-increasing rate, mostly by burning fossil fuels, but also from cutting down carbon-absorbing forests. Since the Industrial Revolution began in about 1750, carbon dioxide levels have increased nearly 38 percent as of 2009 and methane levels have increased 148 percent.

Graphs of atmospheric carbon dioxide and methane from 1750 to 2009.
Increases in concentrations of carbon dioxide (top) and methane (bottom) coincided with the start of the Industrial Revolution in about 1750. Measurements from Antarctic ice cores (green lines) combined with direct atmospheric measurements (blue lines) show the increase of both gases over time. (NASA graphs by Robert Simmon, based on data from the NOAA Paleoclimatology and Earth System Research Laboratory.)

The atmosphere today contains more greenhouse gas molecules, so more of the infrared energy emitted by the surface ends up being absorbed by the atmosphere. Since some of the extra energy from a warmer atmosphere radiates back down to the surface, Earth’s surface temperature rises. By increasing the concentration of greenhouse gases, we are making Earth’s atmosphere a more efficient greenhouse.

Published Jun 3, 2010

Global Temperature Record Shattered: 2015 Hottest Year

YorkDailyRecord Published 12:19 p.m. ET Jan. 20, 2016

It’s official. NASA announced today that 2015 was the hottest year on record since record keeping began in 1880. NASA stated, “Globally-averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius).”

The warming trend continues unabated. There was no “pause” or “hiatus” as previously claimed but the diminishing cohort of self-proclaimed climate change deniers.

Our planetary fever has risen by a full 1.0oC (1.8oF) since the latter part of the 19th Century. This temperature increase is primarily driven by human activities which dump ever larger quantities of carbon dioxide CO2 into our atmosphere. Our pre-industrial CO2 was approximately 280 ppm. By the time Sputnik was launched in 1957, atmospheric CO2 was accurately recorded as 313 ppm. We passed the 400 ppm threshold in 2014.

Our planet has a fever that must be addressed. The Paris Agreement--universally signed by all UNFCCC member Parties--sets our global society on a new economic and energy path into the future. Climate change is a civilization challenging issue, but one that can be addressed if we take action now. There are great opportunities in addressing the material and energy solutions to climate change mitigation and the multidisciplinary mechanisms for adapting to climate change.

Sub-nationals and businesses around the globe are taking action. There remains a singular political block that refuses to accept the scientific documentation that global climate change is a reality. This powerful block includes ideologically entrenched climate-denying US legislators. Contact Rep. Scott Perry and ask him to be a leader on climate change. Put a price on carbon.