March 2015 was the warmest March in a 136 years of records, and CO2 levels are now higher than they have been in 800,000 years. If you are an environmental activist, or someone who cares and wants to help, you may find yourself confronting a denialist campaign that sows doubt and confusion. Here is some useful information about the current state of global warming.
Doubt: Petroleum interests and paid denialist employ scientific doubt to rationalize non-action, but this is a trick. Scientific knowledge is built on doubt. Every process in nature involves multiple influences, no observer knows all the factors, and everything science knows is framed by a margin of doubt. Nevertheless, science has observed enough to know that global warming is real, and that the primary cause is human activity.
The fundamental hypothesis: In 1896, using known observations of energy radiance and conduction, Swedish chemist Svente Arrhenius introduced the fundamental postulate: “If the quantity of carbonic acid [CO2] increases … the temperature will increase.” CO2 in the atmosphere absorbs reflected light, adding heat to the Earth system.
Greenhouse effect: Greenhouses store heat because light changes when reflected. Solar energy enters and passes through a greenhouse glass, or our atmosphere, at “short” wavelengths (0.1 – 4 microns or millionths of a meter). Once reflected, light is polarized and has a longer wavelength (4-50 microns). Carbon dioxide absorbs light at around 15-microns, other gases, such as methane, absorb at other wavelengths, and this absorbed light energy adds heat to the Earth system.
“Global warming” defined: Temperature is always fluctuating, but Climatologists have defined “Global warming” as a relatively large change in a short time, specifically: 0.4°C in one century. Earth’s temperature has increased by 0.8°C in one century, a state of global warming. (Goddard)
Weather vs. Climate: Weather is local and short term; climate is regional or global, and long term. A cold winter is weather, and does not indicate the direction of climate change.
Do humans contribute to global heating? Yes. We contribute to heating because we produce CO2 and other greenhouse gases in the atmosphere and because we reduce carbon-sequestering plant life. The tars sands in Canada does both, producing vast amounts of carbon while destroying forests.
Human carbon emissions. World carbon emissions through Fossil fuels, cement, land-use change, and other sources were about 1 billion tons / year a century ago. Those emissions are now about 10 billions tons / year (9.9 billion tons in 2013, CO2Now). You may hear of “carbon dioxide emissions” around 35 billions tons, and this is because a ton of carbon produces about three-and-a-half tons of CO2.
Rate of change: These emissions are now about 61% higher than they were in 1990 (the Kyoto Protocol reference year), and still increasing at about 2.5% per year, on track to double in 28 years.
Sources of CO2: Carbon emissions are dominated by China, the US, Europe, and now India. The primary sources are coal, oil, gas, and cement manufacturing. Meanwhile, carbon uptake by plant life is reduced through deforestation and ocean acidification.
CO2 in atmosphere: Before the industrial revolution, some two hundred years ago, atmospheric carbon-dioxide fluctuated around 280 parts per million (ppm). Today, by March 2015, CO2 has reached 401.5 ppm (Scripps), a 43% increase in two centuries.
Rate of CO2 increase has, itself, been accelerating. In the 1950s, atmospheric CO2 was increasing at about 0.5 ppm per year; by 1970, by 1 ppm per year, and is now increasing by 2.1 ppm / year.
Feedback and runaway: The danger civilization faces is that we can easily lose control of global warming. The heating itself causes feedbacks within the ecological system, which in turn increase heating. These include:
1. Methane from melting permafrost, a more potent greenhouse gas than CO2.
2. Albedo: Ice melt reduces reflection, and increases heat absorption.
3. Water Vapour: Warming adds moisture, a greenhouse gas, to the atmosphere.
4. Forest loss: Each year, we lose about 15 million hectares of forests.
5. Acidic seas: reduces aquatic life and carbon capture.
6. Fires: A hotter climate increases fires that release CO2 and reduce forest cover.
The effects: NASA, the UN, and scientific agencies around the world have observed and reported on the effects of global warming. The picture above (Justin Sullivan, Getty Images) shows the effects of drought on California’s Lake Oroville. Here are some of the observed effects of global warming:
Heat: Earth’s average temperature has increased by 0.8°C in one century.
Arctic: average temperature increase is about twice the global average.
Ocean temperature has increased to depths of 3,000 meters.
Rate of warming has nearly doubled in the last 100 years.
Warmest years: Of the last 12 years, 11 rank among the warmest since 1850.
Ice melt: Glaciers and polar ice melting in Northern and Southern hemispheres.
Sea level has risen about 20 cm in a century, and the rate of rise is increasing.
Extreme weather: more intense tropical storms, heat waves, drought.
Precipitation has increased in eastern Americas, northern Europe, and Asia.
Drying and drought in Southwest US, Mexico, Mediterranean, southern Africa.
Species: Diversity loss due to climate changes and habitat destruction.
Agriculture disruptions, such as reduced yields from warmer and wetter climates.
Ocean Acidification: The oceans are about 30% more acidic compared to the pre-industrial era, killing off sea life and reducing vital coral reef ecosystems.
Press link for more: Rex Weyler | greenpeace.org
jpratt27 
“A cold winter is weather, and does not indicate the direction of climate change.”
But a hot summer is climate?
And why are we constantly told about record temperature? Weather or climate?
And what other scientific field has the weather/climate dichotomy?
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