Deniers keep citing evidence of increasing sea ice around Antarctica as evidence that global warming is not real. So, let’s review the facts.
Antarctica sea ice is increasing. Take look at this plot:
This shows the annual extent of sea ice in May every year up to this year (the last complete month). Keeping in mind the seasons are opposite in the south, this represent the ice extent as the region is approaching the heart of winter. You can see that there is a trend of increasing ice and this last May, (the last plus mark on the right) was the highest ice extent ever recorded.
At this point deniers are going, “See, we told you so!” and this would be just one more example of how deniers ignore anything they don’t want to see.There are major differences between the Arctic and the Antarctic. See a discussion about this from NSIDC here. Among those differences are the circumpolar currents in the atmosphere and the oceans that isolate Antarctica and make it a unique environment. Another difference is even bigger – land ice. Deniers conveniently ignore the fact that Antarctica is the largest reservoir of land ice in the world. What is going on with the land ice?
The reality is that Antarctica is losing ice in large amounts. One of the reasons sea ice is increasing is because it is coming from the land ice that is sliding into the ocean. Evidence indicates is losing land ice at a rate of over 100 billion tons a year. That is enough to raise the sea level in excess of a millimeter per year. That may not sound like much, but in ten years that amounts to a one-centimeter rise in world sea levels and that does not include other sources of sea level rise.
A NASA/ESA study incorporating more satellite data than past studies confirmed that both Greenland and Antarctica are losing ice mass.
The loss of land ice is increasing and it was recently determined that the massive West Antarctica Ice Sheet has reached the point of no return. Even if we stopped emitting greenhouse gases today, the ice sheet will still melt.
The evidence is conclusive, the total amount of ice in the Antarctic region is decreasing, not increasing.
So, if deniers want to talk about ice in the Antarctic region, make sure they include the land ice. Its a very different story when you do.
Researchers with NASA and the University of California – Irvine have released the results of their study of the West Antarctic Ice Sheet (WAIS) have found the ice sheet can no longer be prevented from melting into the sea. They studied how the speed of the ice has increased over recent decades, the slope of the land that it is traveling over and how much of the ice sheet is floating on sea water.
A key part of their research is the finding that the grounding line is retreating for all of the glaciers studied. The grounding line is the last location where the glacier is supported by land. Seaward of that line the ice is floating in sea water. This sea water is warmer than the ice and melts it. Over recent decades, the grounding line has been retreating as the glaciers get lighter and float higher. At the same time, the water has been getting warmer, melting the ice at a faster rate.
This information, combined with the finding that there is no landform under most of the glaciers to slow them down and they they reach the conclusion the melting will continue. But, much of the land the ice is located on is actually below sea level, so as the glaciers retreat, the sea water will follow and continue to melt the ice. All of these findings lead to the conclusion that it is now inevitable the ice sheet will completely melt.
How long will it take to melt all of the ice sheet? Probably centuries before it is all gone. But, there will be substantial effects to the world’s sea level starting even today and getting worse over time. By itself, the WAIS will increase the world sea level by about four feet.
So what? If it isn’t going to happen for centuries then we really don’t have to worry about it now. Let the people centuries from now worry about it. They will probably have better technology to deal with the problem that anything we have today. That is the position of the climate change deniers and, just like everything else they say, it is wrong.
It may take some centuries for the sea level to rise by the total four feet, but we will be seeing increases of inches within the coming decades and that is enough to lead to substantial coastal flooding and loss of land. What this means is that we are going to incur the cost of this sea level rise today. Not centuries from now. Today.
So, once again, take out your checkbook and made out a check to the climate change deniers. They keep telling us there is nothing to worry about and we keep believing them.