25 Things You Didn't Know About... Climate Change

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1. Earth is running a fever. Scientists report a planet-wide average temperature around 57.9°F, up from an average of 56.5°F as of 100 years ago.

2. As early as 1908, Swedish chemist Svante Arrhenius took what ended up being an incredibly accurate stab at estimating how much the globe would warm if industrial emissions doubled CO2 in the atmosphere: 5°C. The catch is: Arrhenius didn’t expect such a doubling until at least year 4000.

3. A recent publication in Science (Schmittner, 2011), claims that climate sensitivity, the temperature change that occurs upon a doubling of atmospheric carbon dioxide (CO2) concentration, is lower than once thought: 2.3°C. This might give us time to lower the probability of “imminent extreme climatic change”, but it doesn’t change that we are heading for a bad place if we don’t mind our carbon footprint.

4. 30,000,000,000 metric tons: the amount of carbon dioxide (CO2) that human activities release into the atmosphere each year.

5. Oceans are becoming more acidic due to uptake of carbon dioxide – at a rate 100 times faster than any such change in the last few million years (Henson 2011. p. 136). This acidification translates into negative impacts for marine ecosystems.

6. Advanced computer models that incorporate factors such as volcanic activity, solar activity, greenhouse gas emissions, ozone depletion, and aerosol pollution cannot reproduce the most recent warming trend unless they include the impact of human-activity-generated greenhouse gases. (Henson 2011, p. 10)
Image of Climate Attribution based on published data.

7. Scientists use satellites to measure sea surface temperatures, based on infrared and microwave radiation emitted by water molecules. Radiation wavelengths vary with temperature, and thus, using advanced satellite-based instruments such as the Moderate Resolution Imaging Spectroradiometers on board NASA satellites, scientists can infer sea surface temperatures globally. Spectroradiometers measure electromagnetic radiation (i.e. light) at various wavelengths.

Sea Surface Temperature Anomaly in September 2011: Temperatures of the top 1 millimeter of the ocean that deviate from average conditions set during 1985-1997. Blue shows temperatures that were cooler than average, white shows near-average temperatures, and red shows where temperatures were warmer than average. NASA

8. Weather data compilers such as NOAA use techniques to filter out the heating effects of big cities, known as the ‘heating-island effect’, from global temperature checks. In other words, scientists take care to separate any localized heating observed in heavy urban areas due to paved roads and dense building structures from reports of rising global temperatures. NASA even removed some of their satellites from global temperature data collection when regions covered by these satellites were shown to light up like a Christmas tree in the night sky as viewed from space. However, other scientists’ studies have shown that urban effects might not affect city-dwelling satellite data as much as once feared. In short, city lights are not significantly contributing to observed climatic changes.

Image by Craig Mayhew and Robert Simmon, NASA GSFC. Based on data from the Defense Meteorological Satellite Program.

9. The height of the troposphere – the ‘weather’ or lowest layer of Earth’s atmosphere – increased by 200 meters, from its normal range of 8-16km, between 1979 and 1999, according to a 2003 study at the U.S. Lawrence Livermore National Laboratory (Henson, 2011, p. 201). This increase in height can be related to warming in the troposphere.

10. Other than temperatures, climate scientists study changes in rain and snow coverage, water vapor, cloud cover, atmospheric carbon dioxide levels, and amount of sunlight that reaches the Earth’s surface. These various factors can give us a ‘bigger’ picture of climate change.

11. It is true that the sun has produced more sunspots in recent decades (Henson 2011. P. 275), but the resultant increases in UV light contribute little to 20th century warming, according to the IPCC and other experts.

12. Some scientists argue that increased solar activity in sunspots is preventing cosmic-ray-induced formation of clouds in Earth’s atmosphere, thus letting more sunlight reach Earth’s surface. They argue that this effect is the cause for recent observed global warming. This reasoning has not been vetted by substantial research as yet, as have CO2-induced warming models, and a majority of scientists discredit this reasoning.

13. The release of pollutant airborne particles, such as aerosols, may actually be causing ‘global dimming’ in some cases, preventing sunlight from reaching the earth’s surface due to the reflective and light-scattering properties of these particles. Aerosols also extend the lifespans of clouds, which also prevent sunlight from reaching the Earth’s surface to some degree, thereby potentially mitigating the current global warming crisis. Does this take away from the fact that aerosols are often toxic and hazardous to human health, especially when distributed in the air we breathe? Ironically, initiatives to ‘clean up’ the atmosphere may actually speed up already fast-paced global warming by letting more sunlight in, if no alternative mitigating actions are taken.
Image showing Aerosol-contamination in northeastern India and Bangladesh

14. Some ‘geoengineering’ scientists and proponents are even pushing for intentional release of sulphate aerosols into the stratosphere in order to ‘cool’ the earth and mitigate current climate change.

15. Then again, some absorbing aerosols may enhance global warming by absorbing more energy from sunlight and keeping heat in. This warming effect has been shown to depend on the amount of cloud cover. (Chand et al, 2009)

Recent NASA Video showing soot, also known as black carbon, throughout the planet. “The Indo-Gangetic plain, one of the most fertile and densely populated areas on Earth, has become a hotspot for emissions of black carbon (shown in purple and white).” – NASA

16. A major volcano (for example Krakatoa 1883) can release enough light-reflecting materials into the atmosphere to cool the globe by >1°C for over 1 year (Henson, 2011, p. 7).

17. Carbon dioxide and other greenhouse gases do the job of keeping the heat trapped in once energy from the sun enters our atmosphere.

18. Fly by day, not by night: contrails left behind planes as they fly may help reflect sunlight during the day, but they keep heat in at night. Fly during the day to help mitigate climate warming.

19. Many airlines are now encouraging ‘green’ aircraft landings: by descending in a smooth, continuous fashion instead of the traditional stair-step technique, planes can reduce vibrational noise and save on fuel. Are you flying green?

20. Winter gets Further Away: As temperatures rise more drastically in the Northern hemisphere than they currently do in other parts of the globe, locals in Alaska and the Canadian Artic report the strange arrival of animal species not known to those parts, including robins and swallows.

21. The idea that local temperatures should reflect warming is a myth – some regions may cool slightly while the Earth warms on average. Measuring climatic changes is in fact a complex science, and the symptoms of global warming are not evident to the individual eye.

22. Many non-scientists confuse ozone depletion, caused by harmful gases such as CFCs, and global warming. Ozone itself is a greenhouse gas, as are CFCs, and can be harmful to human health when in the lower atmosphere. Think of the difference between ‘good’ and ‘bad’ cholesterol – the ozone in the stratosphere is ‘good’ ozone – it keeps an excess of cancer-causing UV light from reaching the Earth’s surface. ‘Holes’ in this layer can have a cooling effect in the stratosphere, because ozone absorbs energy from sunlight. However, this cooling does not offset the current drastic warming in the troposphere caused by greenhouse gases such as carbon dioxide, CFCs, methane, and ‘bad’ ozone.

23. If current global warming trends ARE caused by natural changes, then we should be able to identify these changes. But a significant body of research has progressively ruled out, at least as of today, such natural warming causes as volcanic activity, solar activity, and variations in earth’s orbit.

24. Global ‘cooling’ factors include ozone changes and sulfate aerosol pollution. These factors can complicate measurement of overall global warming.

25. “Human-induced warming of the climate system is [now] widespread.” – published by the IPCC in 2007

References: Henson 2011, Rough Guide to Climate Change, 3rd Edition