What is Global Warming?

There is virtually no doubt in the scientific community today that the planet is currently undergoing a global climate change, commonly known as global warming.

Earth has gone through several episodes of global climate change in the past caused by the Milankovitch cycles which led to ice ages and intermittent warmer periods, the latest of which we are living in now. However, this newest global climate change was not sparked by natural causes. The Fifth Assessment Report from the Intergovernmental Panel on Climate Change (IPCC), published in 2014, concluded that there is a probability of over 95% that this global warming is being caused primarily by human activities, especially by producing carbon dioxide. 

Global warming is the aggravation of the Earth’s natural heating system, caused by “the Greenhouse Effect”.  The Earth is heated by sun rays, which are partially absorbed by the Earth’s surface, and partially reflected, as shown by the image below.  The energy that the Earth initially absorbed from the sun is then radiated back to space in the form of longer wavelengths, from the infrared part of the spectrum.  But part of the waves are trapped in the Earth’s atmosphere by certain gases (called greenhouse gases), which then re-transmit the heat back to Earth. That way, the Earth’s heat is better contained, similar to placing a lid on a pot when cooking.

Earth's_greenhouse_effect_(US_EPA,_2012)

Source: US Environmental Protection Agency (EPA).

This is very beneficial to the life on Earth because without the greenhouse effect, the surface temperature of our planet would be around -18°C (-0°F), instead of the much warmer temperature it is today (about 14.6°C, or 59°F). However, the problem is that now there is too much heat being retained by the gases in the atmosphere, making life conditions harder. Our ice caps are melting and the sea level is rising because of global warming, affecting millions of people that live near shores and species that depend on colder environments.

Global warming is essentially due to the increase of the concentration of greenhouse gases in our atmosphere. These gases include carbon dioxide (CO2), water vapor, methane (CH4), nitrous oxide (NO2), and ozone (O3).  Since humans started producing large quantities of CO2 by burning fossil fuels such as coal and oil, the global surface temperature has raised by 0.8°C  (as demonstrated on the graph below by IPCC).

IPCC_temp_2014

Source: IPCC 5th Assessment Report, 2014.

The atmospheric concentrations of CO2 have never been higher over the last 800 thousand years, which is further proof that our emissions of CO2 are the main culprit of global warming. Even during the last intervals between ice ages, the concentration of CO2 in the atmosphere did not exceed 280 ppm (parts per million) – while the 2014 average annual concentration of CO2 in the atmosphere is 398.55 ppm. Scientists estimate that for the Earth to avoid permanent damage, we need to bring the concentration of CO2 back to 350 ppm, which is called “the safety level”.

co2-800k-620x353

Using ice-core data and data from Keeling Curve, scientists have reconstructed the atmospheric concentrations of carbon dioxide over 800,000 years. Time is represented in kyr (thousand years). Source: Scripps Institute of Oceanography.

Climate change, while no stranger to our planet, has never had the same characteristics of the current global warming, essentially human influenced. We’re pushing our planet to limits it hasn’t known in the last million years, and dooming species to the 6th mass extinction the planet has ever known. The question is not so much how we can stop this, but of whether or not we will. We can live without producing so much carbon dioxide – we’ve done so for the last 200,000 years. The tricky part is finding out how to do so without losing any of our scientific progresses, and finding comfortable lives for everyone – humans and ecosystems alike.

The goal of this website is to aid you in your quest to become a global citizen, using your own resources fairly, and helping others come to the same conclusion. Reducing our CO2 emissions is a necessity, but it doesn’t have to be hard. It all depends on the will to act.


Read more:

What causes Global Warming?

Bibliography

CO2 Now. Annual Data Atmospheric CO2. http://www.esrl.noaa.gov/gmd/ccgg/trends/ff.html

Chivian,E., Bernstein, A., 2008. Sustaining Life. Oxford University Press, pg. 63-65.

IPCC: What is Global Warming? https://www.ipcc.unibe.ch/publications/wg1-ar4/faq/wg1_faq-1.3.html

IPCC 5th Assessment Report, 2014, Summary for Policymakers: http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_SPMcorr1.pdf

NOAA Earth System Research Laboratory: Carbon Trends. http://www.esrl.noaa.gov/gmd/ccgg/trends/ff.html

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One response to “What is Global Warming?

  1. Pingback: What causes Global Warming? | The Earth Tribune

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