Monday, July 17, 2017

Largest Iceberg Ever

Last week it was widely reported that a one trillion tonne (metric ton) iceberg – one of the biggest ever recorded - has broken away or “calved” from the Larsen C Ice Shelf in Antarctica. The calving occurred sometime between Monday, July 10th and Wednesday July 12th 2017, when a 2,250 square mile section of Larsen C finally broke away. The iceberg’s volume is twice the volume of Lake Erie.

The development of the rift in the ice shelf was monitored over the past year using data from the European Space Agency Sentinel-1 satellites, reported by researchers at the MIDAS project team at Swansea University in Whales who study Antarctica. Though the iceberg weighs more than a trillion tonnes (1,000,000,000,000 metric tons), it has had no immediate impact on sea level because it was already floating before it calved away. The calving of this iceberg leaves the Larsen C Ice Shelf 12% smaller in area. Although the remaining ice shelf will continue naturally to regrow, the landscape of the Antarctic Peninsula changed forever, and the Swansea researchers say that the new configuration is potentially less stable. There is a risk that Larsen C may eventually disintegrate as did its neighbor, Larsen B, which disintegrated in 2002 following a calving event in 1995.

The first though we all have is global warming, but Scientists say global warming has caused the ice shelves to thin, but they differ on whether the latest event can be blamed on climate change. Dr Martin O'Leary, a Swansea University glaciologist and member of the MIDAS project team, said of the recent calving:

"Although this is a natural event, and we're not aware of any link to human-induced climate change, this puts the ice shelf in a very vulnerable position. This is the furthest back that the ice front has been in recorded history. We're going to be watching very carefully for signs that the rest of the shelf is becoming unstable."

Other scientists point to global warming. So far the global temperature rise has been about 1 degree Celsius (1.78 degrees Fahrenheit) from pre-industrial times and last year was was the third year in a row reported to be the warmest year on record. According to the International Energy Agency, IEA, policies that are now being pursued by developed nations, are predicted (by the accepted group of climate models) to produce a long-term average temperature increase between 3.6 °C and 5.3 °C (6.5-10 degrees Fahrenheit above pre-industrial conditions), with most of the increase occurring during this century.

Even the Paris Climate Accord signed by 196 nations at the United Nations last year on Earth Day only put the nations on a course to reduce carbon dioxide emissions from the combustion of fossil fuel. The agreement lacks any clear path on how the nations will maintain the 2 °C rise limit let alone the 1.5 °C above pre-industrial temperature limit. The carbon reductions committed to under the agreement are inadequate to meet that goal, and neither China nor India representing about a third of world greenhouse gas emissions have committed to any reductions. Instead those nation merely project when their greenhouse gas emissions will peak.

President Obama entered into the Paris Climate Accord without Senate ratification. The White House claimed that the president has the legal authority to ratify the accord without the two-thirds Senate vote required for treaties. Saying at the time that the pact negotiated by 196 countries was merely an “executive agreement.” President Trump withdrew from the accord in 2017.

The international efforts to take action to stop or limit climate change began at the Earth Summit in Rio de Janeiro in 1992 and continued with the Kyoto Treaty negotiated at the U.N. Framework Convention on Climate Change (UNFCCC) in 1997 which required that by 2013 the industrialized countries cut their greenhouse gas emissions by an average of 5% below 1990 levels. Developing nations (like China and India) were not required to reduce greenhouse gas emissions and the United States, which at the time was the largest emitter of greenhouse gasses, did not sign the Kyoto Treaty. Canada withdrew from the Kyoto Treaty in 2011. In all only 36 nations were party to the Kyoto Treaty.

Nonetheless, world CO2 emissions have continued to increase, blowing through each “tipping point” identified by the scientists. The first “tipping point” where global temperatures could be held within 2°C above pre-industrial levels was reached when world CO2 emissions from burning fossil fuel reached 32.6 billion metric tons of CO2 annually around 2012. The “Tipping Point” was called the 450 Scenario (for the CO2 concentration) which limits global warming to 2 degrees by limiting  the maximum concentration of greenhouse gases in the atmosphere to 450 parts per million of CO2 equivalents. Current concentration is a bit over 400 ppm depending on season but is expected to continue to rise without significant reductions in CO2 emissions.

Now the hoped for scenario is the 4°C Scenario. This senario takes into account all the pledges to limit emissions and improve energy efficiency made for the Paris Climate Accord and requires significant additional cuts in emissions in the period after 2050. The current worst case scenario, is the 6°C Scenario. This scenarios largely an extension of current trends. Primary energy demand and CO2 emissions would grow by about 60% from 2013 to 2050. In the absence of any further efforts to stabilize the atmospheric concentration of CO2, the average global temperature rise above pre-industrial levels is projected to reach almost 5.5°C in the long term and almost 4°C by the end of this century. This month Science ran a map showing the estimated economic costs to the United States if the temperature increases 6°C.  You can look at it here. Meanwhile, U.S. carbon emissions peaked in 2007 and World CO2 emissions appear to have stabilized.

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