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WAVELENGTH DEBATE Q


Sea ice changes


Sea ice did decrease in parts of the Arctic during the temporary warming of the 1930s. But the cover of Arctic sea ice is now signifi- cantly less than it was then. Moreover, the shrinkage of areas like the Baffin Island ice cap has now exposed land plants that last saw the light of day 4,000 years ago. Something very unusual is going on, caused by growing warmth. And it is not just that the areal coverage of sea ice is shrinking – so too is its thickness. By contrast, in the Antarctic we see a slight


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growth of sea ice. It seems counterintuitive, until we realise that a wall of wind around Antarctica keeps warm air from the north away. Most of the melting going on down there is caused by warm deep water welling up beneath thick Antarctic coastal ice shelves, melting them from below. The fresh melt- water thus released moves out over the adjacent salt water and readily freezes, increasing the area of seasonal sea ice at the ocean’s surface. Warming in one place (under ice shelves) is causing freezing in another (the Southern Ocean surface).


Sea level changes


Satellites and tide gauges measure changes in sea level. Tide gauge data has to be adjusted with reference to GPS, which shows whether the gauges are moving up or down. In some places, where former ice caps were removed (e.g. Scotland) the land is rising. These changes can be accounted for mathematically. The overall result is that from a global


network of observations we can see that sea level is now rising faster than it was early in the 20th century. Independent confirmation comes from sea level data preserved in coastal sediments. Satellite data agrees with tide gauge data, which in turn agrees with sediment archives (all of them independent). Those data give us a clear global picture


that about one-third of the rise comes from the warming and expansion of the ocean, one-third from melting glaciers (e.g. Andes), and one-third from melting ice sheets (Greenland and Antarctica). A great deal is now known about what sea


level is and how it is changing, not least from the studies carried out and the data archived at the UK’s Permanent Service for Mean Sea Level, at Liverpool University. For those who wish to know more, a great many books and research papers document what is understood, and what these data mean.


IMarEST’s role in studying climate change:


The IMarEST recognises the significant threat posed to humanity by climate change. It has gained observer status at the Intergovernmental Panel on Climate Change, where it supports and endorses the Panel’s work. In addition, as a non-governmental


organisation in consultative status with the IMO, the


IMarEST works to support the initiatives undertaken by the IMO to reduce emissions from shipping.


In this context, a number of IMarEST Special Interest Groups (SIGs), including on Operational Oceanography, Emissions from Shipping, Alternative Fuels and Ocean Acidification, are working on


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The astronomical data show we should still be in the Little Ice Age for at least another 1,000 years


Ocean understanding


A consensus statement recently released by the Ocean Climate Nexus (an initiative of the European Marine Board and the Consortium for Ocean Leadership) highlights the role of the ocean in the climate system. The Earth’s climate and the ocean are fundamentally linked in ways we still do not fully understand. The ocean plays a key role as a climate regulator and in buffering the damaging effects of climate change. But the human activities that cause climate


change, predominantly greenhouse gas emissions, are also affecting the health of the ocean, making it warmer and causing acidification. It is imperative that we work together to solve the unanswered questions. Global ocean observation is key to understand- ing oceanic processes. There is an urgent need to improve our capability of projections of future states of marine systems and, in turn, to link these to climate.


projects to inform our membership and the wider community in accordance with the IMarEST vision of safe and sustainable seas.


The IMarEST will consult on, and re-issue its position statement on climate change in 2016. Members wishing to become involved should email technical@imarest.org


Shipping and climate change


As Koji Sekimizu, IMO Secretary-General, made clear in the organisation’s statement on climate change, no industry or sector can be excluded from efforts to reduce global greenhouse gas emissions. Although shipping remains the most efficient form of transporting goods, and lubricates 90% of world trade, it is incumbent on the industry to make its own contribution.


Final word by Malcolm Latarche:


The response to my original article contains too many statements to react to within the limited space allowed, but taking the section title ‘Where we are now’, IMarEST’s response makes the point that astronomical data shows we should still be in the Little Ice Age for at least another 1,000 years and it is likely that it is human industrial activity that has prevented this. I would argue that even if this is the case, it highlights the very beneficial aspects of so called climate change in that world poverty has been massively reduced, hunger – although still present – has been reduced through increased food production and the human condition has never been higher. On the subject of food production we


should look at the increasing yield of crops since CO2


has been increasing, with record


global harvests being achieved on a regular basis despite claims that climate change will result in reduced yields. My use of the word hysteria in the title is


justified as evidenced by recent events since it was written. Taking just two of those, it has been seriously suggested by ‘scientific’ organisations in the US that those with opposing views should be charged under the Racketeer Influenced and Corrupt Organi- zations Act and in France the dismissal of a TV meteorologist for writing a book questioning the motives of catastrophic anthropogenic global warming (CAGW) proponents.


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