Recently a call went forth for super-brief "elevator pitches" about global warming. I am no expert, but have followed the science, events and drama for more than 20 years. Here goes my stab at slimming the topic to the core:
The Earth has an invisible secret: we are covered with a very effective, very warming blanket. This blanket is our atmosphere, and it contains a crucial ingredient; thin heat-trapping gases. These so-called “greenhouse” gases are dilute; just 1 part per thousand. Without this insulation warming us the Earth would average a chilly -18 °C. The blanket warms our planet up by an amazing 33 °C.
Here’s the problem: we are steadily making the blanket much thicker. Compared to a century or so ago, our air now contains over twice (~110% more *) the insulating gases. With steadily increasing insulation over us, the Earth is inevitably heating up, and at an increasing pace.
Luckily, the added blanket or two won't double-up the heating by another 33 °C: we'd all be pretty sunk if the Earth were heading for average temperatures above +40 °C. With blankets one naturally gets diminishing returns; the first one gives the most warming, the second one, not so much. Climate scientists have carefully measured, calculated and checked, but blankets, even earth-sized ones, are basically simple. With the gasses added to date they can’t see how Earth can avoid warming by at least 2 - 3 °C. Worse, when we hit blanket number 3 (or 4) Earth's average warming will inevitably pass 6 °C.
So warming is happening (see the chart below). The only real questions are: how long will it take, and what will the peak be? See my following posts.
Temperature data from four international science institutions. All show rapid warming in the past few decades. The 10 warmest years in the 134-year record all have occurred since 1998, with 2010, 2005 and 2015 ranking as the warmest years on record. The coldest was 1912.
Credit: NASA. http://climate.nasa.gov/faq/
And that is my "elevator pitch". I hope you find it useful -
* Source: Carbon Dioxide Information Analysis Center (CDIAC), posting updated Feb 2014. Totaling the "Increased radiative forcing" column gave an eyebrow-lifting 3.28 W/m2 . Of this, 1.88 is due to CO2, 1.40W/m2 is due to gases other than CO2: other gases boost the CO2 blanket by 74%.
Is the "Greenhouse Effect" a dated term?
Here's a question for you:
The term "greenhouse effect" is slightly, in some ways, more accurate.
But is it confusing? A greenhouse is abstract, while everyone understands blankets.
Let me know what you think.
Updated April 27, 2015