COP 21 Must Succeed or Else

IETVIN 1995, the ice-shelf named Larsen-A on the Antarctic Peninsula collapsed, followed by the Prince Gustav ice shelf, 60 kilometers to the north. In 2002, the adjoining Larsen B ice shelf followed suit. The Wordie Ice Shelf broke away from the Antarctic Peninsula and vanished in 2009. The Wilkins Ice Shelf has been splintering for several years and is now hanging precariously to the coast.

\In other words, much of Antarctica is warming, but the Antarctic Peninsula, the region that reaches northward toward the tip of South America, is actually the most rapidly warming part of the Southern Hemisphere, as temperatures have increased by about 2.8 degrees Celsius over the last 50 years.

Even if ice shelves don’t collapse, their surfaces partially melt during summer, and this, according to new research, they are now doing at a rate more than ten times greater than 600 years ago. The level of melting observed today is unique in the context of the past 1000 years.

Corals are seen at the Great Barrier Reef. Rising carbon dioxide levels in the world’s oceans due to climate change, combined with rising sea temperatures, could accelerate coral bleaching, destroying some reefs before 2050.

Inevitably, much of the climate attention focuses on the planet’s surface – because that’s the part where we live. But 90 percent of global warming goes into heating, not the land or atmosphere, but the ocean. Because it takes far more energy to heat up the entire ocean than the lower atmosphere or a surface layer of ice, the amount that the ocean has warmed is much less than on land: on average, about 0.025 degrees Celsius a decade – or slightly more than one-tenth of a degree Celsius over the past 50 years.

This warming does not just affect the surface of the sea; 30 percent of ocean warming takes place in waters deeper than 700 meters, and some has even occurred in the deepest abysses of the oceans. Deep-water warming is most pronounced in the Southern Ocean around Antarctica.

Multiple measurements, using both satellites and tide gauges, show a rise in global sea levels. On average, since 1993, the sea has been rising by 3.18 mm per year primarily as a consequence of thermal expansion due to warming, and to the melting of ice sheets.

Naturally, as is to be expected, this rise contains marked spatial and temporal variations. Regionally and locally, changes may be greater or lower, affected not only by thermal expansion but factors ranging from local wind patterns to the mining of groundwater aquifers. In late 2010 and early 2011, sea levels underwent a sharp fall, not a rise, caused as NASA researchers pointed out by a transition from a strong El Niño to one of the strongest La Niñas in recent memory.

The sudden fall in sea levels is easily explained. The sudden El Niño to La Niña shift in the Pacific changed rainfall patterns all across the globe, bringing massive floods to places like Australia and the Amazon basin. The water to power that rainfall came from the ocean, the level of which consequently fell. Since then, sea levels have resumed rising at an accelerated clip of approximately 10 mm a year.

The fact that the ocean is warming – and particularly the discovery of warming in the deep ocean – underlines an important point: the planet is accumulating more heat. Satellite measurements of incoming and outgoing radiation, as well as studies that have combined measurements for land, ice, atmosphere and the ocean have all shown that the planet is accumulating heat, and doing so at a growing rate.

Making a direct connection between climate change and extreme weather events is not straightforward. Weather, after all, is short-term and highly variable. There have always been and always will be storms and heat waves. Climate scientists are careful not to scribe any specific weather event to global warming. However, climate creates the conditions in which weather takes place and scientists have long suspected that a changing climate will make certain weather events more likely and others more extreme.

Cop 21 must succeed where others have failed. We must cap the rise in temperature at 1.5 degrees Celsius or we will perish, which is why we have adopted the motto “1point5tostayalive”: 1.5 to stay alive!

Leave a Reply

Your email address will not be published. Required fields are marked *