Courtesy of Jorge Strelin
WASHINGTON — Nations from around the globe gathered in Copenhagen Monday at the start of two weeks of climate change discussions hosted by the United Nations. Although a troubled U.S. economy has many Americans focused on more immediate concerns, international support for global warming changes is widespread. Here’s a basic vocabulary to aid in understanding the complexities of climate change:
Bipolar Seesaw
The world’s oceans flow in and out of one another (known as thermohaline circulation), but the circuit operates in a delicate balance. As the globe heats up and glaciers begin to melt at accelerated rates, thermohaline circulation can become thrown off, and this effect is known as the bipolar seesaw.
Cosmic Ray Dating
Believe it or not, scientists can use rays sent down from outer space to date icebergs and accurately identify the history of climate change on earth. Cosmic rays that constantly fly through the atmosphere split atoms and create Beryllium-10 and other isotopes that then fall to the earth’s surface. Evidence of these atoms imbedded in ice can help identify when certain warming events have taken place through the years.
Heinrich Events
Named after its founder, scientist Hartmut Heinrich, this describes six specific events that took place during the last ice age. When huge groups of icebergs broke off from glaciers, they began to travel through the North Atlantic and erode. As they melted, they left chunks of rock and debris behind; each large group is referred to as a Heinrich Event, denoted as H1 through H6.
Ice Cores
Using special drills, scientists are able to cut into glaciers and dig down, pulling out three-foot-long, four- to five-inch-wide cylinders, or ice cores. These can be used to identify climate records going back hundreds of thousands of years.
Courtesy of Richard Alley
Ice Sheets
When it comes to ice, is anything bigger than a glacier? If it measures larger than 20,000 square miles, then yes, and it’s called an ice sheet. One-tenth of the earth’s surface is buried by ice; the Antarctic and Greenland ice sheets (the only current ice sheets on earth) are the major contributors.
Ice Rafting
Debris can be carried hundreds or thousands of miles via ice, whether it’s by a glacier advancing or simply by a piece of ice that’s broken off into the ocean; this is called ice rafting. Dirt and rock was carried via ice rafting and later dumped into the ocean during the Heinrich Events.
Little Ice Age/Last Ice Age
This refers to a cold period that lasted from the fourteenth to the mid-nineteenth century. In order to get a more accurate picture of the earth’s warming, climate scientists have labeled climate periods dating back tens of thousands of years through studying ice cores drilled out of glaciers.
Meltwater
As the globe warms, glaciers slowly begin to melt, which can cause them to retreat. Scientists can measure a glacier’s meltwater over the course of a year to track the results of climate change on the world’s glaciers. Years of more meltwater versus years of less meltwater can mean different things for the big picture of climate change.
Courtesy of Adi Torfstein
Moraine
As glaciers advance and retreat, they leave rock and dirt behind. Over time, this debris can accumulate and form a moraine, or a long, ridged hill; scientists can point to moraines to help identify the effects of climate change.
Mystery Interval
Orbital changes in sunlight, atmospheric carbon dioxide and a shutdown in the oceanic conveyor belt all came together 17,500 years ago and may have caused the end of the last ice age. Changes during this termination, however, have been so perplexing, that climate scientists George Denton and Wally Broecker have taken to calling it the mystery interval.
Ocean Conveyor Belt
Warm waters and the salt content of the oceans determine the water’s overall density. As surface waters are driven by winds, the oceans ultimately mix together in deep-sea basins. Also known as thermohaline circulation, this refers to the overall circulation of the oceans across the globe.
Sea Ice
Because ocean waters contain salt, freezing and climate change occurs differently than it would in fresh water. Sea ice refers to frozen ocean water, as opposed to icebergs, which are frozen fresh water.
The Big Dry/The Big Wet
Climate scientists often focus their studies on specific areas of the world, and then come together to share findings with one another in order to get a full view of today’s warming effects. The Big Dry and the Big Wet refers to climate changes that are taking place in Australia, where floods ravage Queensland, while at the same time Tasmania is plagued by extreme drought and heat. Experts need to understand the Big Dry and the Big Wet in order to contextualize the overall effects of climate change.
Westerlies
Winds play a large role in climate change, as they direct cyclones, move the surface ocean waters and ultimately aid in the flow of the ocean conveyer belt. The Westerlies are the winds between 35 and 65 degrees latitude that blow from west to east; they primarily come from the northwest in the southern hemisphere and the southwest in the northern hemisphere.
Younger Dryas
This is an event that ended 11,500 years ago that scientists refer to as part of “abrupt” climate change. Although at that time the cold appeared to be halted on earth, the Younger Dryas returned conditions to nearly ice-age proportionality. Slow warming following the event is what led to 10,000 years of relative climate stability.