Tag: sea ice

Global Science Report: Sea Ice Expansion in the Southern Hemisphere Is Real and Driven by Falling Temperatures

While there’s been thousands of legacy media stories about the very real decline in summer sea-ice extent in the Arctic Ocean, we can’t find one about the statistically significant increase in Antarctic sea ice that has been observed at the same time.

Also, comparisons between forecast temperature trends down there and what’s been observed are also very few and far between. Here’s one published in 2015:

Observed (blue) and model-forecast (red) Antarctic sea-ice extent published by Shu et al. (2015) shows a large and growing discrepancy, but for unknown reasons, their illustration ends in 2005.

Observed (blue) and model-forecast (red) Antarctic sea-ice extent published by Shu et al. (2015) shows a large and growing discrepancy, but for unknown reasons, their illustration ends in 2005.

For those who utilize and trust in the scientific method, forming policy (especially multi-trillion dollar policies!) on the basis of what could or might happen in the future seems imprudent. Sound policy, in contrast, is best formulated when it is based upon repeated and verifiable observations that are consistent with the projections of climate models. As shown above, this does not appear to be the case with the vast ice field that surrounds Antarctica.

According to the most recent report by the Intergovernmental Panel on Climate Change (IPCC), CO2-induced global warming will result in a considerable reduction in sea ice extent in the Southern Hemisphere. Specifically, the report predicts a multi-model average decrease of between 16 and 67 percent in the summer and 8 to 30 percent in the winter by the end of the century (IPCC, 2013). Given the fact that atmospheric CO2 concentrations have increased by 20 percent over the past four decades, evidence of sea ice decline should be evident in the observational data if such model predictions are correct. But are they?

Thanks to a recent paper in the Journal of Climate by Josefino Comiso and colleagues, we now know what’s driving the increase in sea-ice down there. It’s—wait for it—cooling temperatures over the ocean surrounding Antarctica.

Global Science Report: Antarctic Updates

The northern end of the Antarctic Peninsula is Warming Fast
BBC, August 23, 2012

No, it’s not. When BBC reported this, the Northern Peninsula hadn’t on average warmed a lick in thirty years.

In the 1990s and early part of this century, news reports about the dramatic warming of the northernmost Antarctic Peninsula—the tip of the 800-mile dagger pointed at the heart of Tierra del Fuego—were a common staple. And, while scientists wouldn’t write this in the literature, they were happy to blame it on dreaded carbon dioxide on television, as paleoclimatologist Robert Mulvaney did in the 2012 BBC feature.

The story has become increasingly curious. Marc Oliva of the University of Lisbon recently examined the high quality weather stations over the northern peninsula and the nearby South Shetland Islands. There is a decent warming trend, averaging around 1.5⁰C, from the beginning of the data in 1957 (the year when Antarctica was instrumented as a part of the International Geophysical Year) to the early 1980s, or about a quarter-century. That’s a warming, if it continued (and surely it would!), of 6⁰C per century. The warming that gets huge attention is actually only from a single station, Faraday (now renamed Vernadsky), which warmed roughly 2.5⁰C during the same period. If that continued (and surely it would!), that’s 10⁰C/century!

Oliva et al. wrote that the “Faraday/Vernadsky warming trend is an extreme case, circa twice those of the long-term records from other parts of the AP.” The variability in the Faraday/Vernadsky record is also huge—around three times as much as other stations in the area, probably because it is often at the edge of the sea-ice.

Spinning Global Sea Ice

NASA takes the (frozen) cake with this one.

It just released a report on global sea ice coverage that opens with the following sentence:

Sea ice increases in Antarctica do not make up for the accelerated Arctic sea ice loss of the last decades, a new NASA study finds.

NASA continued:

Furthermore, the global ice decrease has accelerated: in the first half of the record (1979-96), the sea ice loss was about 8,300 square miles (21,500 square kilometers) per year. This rate more than doubled for the second half of the period (1996 to 2013), when there was an average loss of 19,500 square miles (50,500 square kilometers) per year – an average yearly loss larger than the states of Vermont and New Hampshire combined.

Could have fooled us!

Figure 1 shows the sea ice coverage (anomalies) measured by satellite, as reported today by the University of Illinois at Urbana-Champaign’s website Cryosphere Today for the period since 1979 for the Arctic (left panel) and Antarctic (right panel). There has been an overall decline in Northern Hemisphere sea ice and a contemporaneous increase in Southern Hemisphere sea ice. It is also worth noting that the decline in Northern Hemisphere ice stopped about eight years ago, even as the within-year variability has gotten larger (perhaps because of thinning at the margins).

 

Figure 1. (left) Northern Hemisphere sea ice area anomalies (million square kilometers) from 1979 to present. (right) same for Southern (image source: Cryosphere Today).

Put them together and what do you get?  See Figure 2—the global sea ice history from 1979 through early 2015. The blow-up shows the last 10 years.

 

Figure 2. Global sea ice area anomalies (red line, million square kilometers) from 1979 to present. The insert shows the data since 2006 (image source: Cryosphere Today).

With the data available to us (and what NASA used, too), let’s check the veracity of NASA’s claims.

Is it true that increases around Antarctica don’t compensate for Arctic decreases? Nope.

The global ice anomaly (Figure 2) for the past two years has remained very close to the 30-yr (1979-2008) average.  This has happened because the increases around Antarctica have completely made up for the losses in the Arctic.

Is the loss of global sea-ice accelerating? Again, nope.

Look at the inset in Figure 2. It represents the second half of the period that NASA has offered to support its acceleration conclusion. Since 2006 (the past 9 years), global sea ice has increased.

How on earth can an extended period of increase be used as support for an accelerating decrease?!