Thin ice and the importance of Quaternary geology

From NASA Earth Observatory:

2011 Sea Ice Minimum

From the description (emphasis added):

In September 2011, sea ice covering the Arctic Ocean declined to the second-lowest extent on record. Satellite data from NASA and the National Snow and Ice Data Center (NSIDC) showed that the summertime ice cover narrowly avoided a new record low.

[…]

Melt season in 2011 brought higher-than-average summer temperatures, but not the unusual weather conditions that contributed to the extreme melt of 2007, the record low. “Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels,” said Walt Meier of NSIDC. “This probably reflects loss of multi-year ice in the Beaufort and Chukchi seas, as well as other factors that are making the ice more vulnerable.”

The low sea ice level in 2011 fits the pattern of decline over the past three decades, said Joey Comiso of NASA’s Goddard Space Flight Center. Since 1979, September Arctic sea ice extent has declined by 12 percent per decade.

“The sea ice is not only declining; the pace of the decline is becoming more drastic,” he noted. “The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover.”

While the sea ice extent did not dip below the record, the area did drop slightly lower than 2007 levels for about ten days in early September 2011. Sea ice “area” differs from “extent” in that it equals the actual surface area covered by ice, while extent includes any area where ice covers at least 15 percent of the ocean.

Arctic sea ice extent on September 9, 2011, was 4.33 million square kilometers (1.67 million square miles). Averaged over the month of September, ice extent was 4.61 million square kilometers (1.78 million square miles). This places 2011 as the second lowest ice extent for both the daily minimum and the monthly average. Ice extent was 2.43 million square kilometers (938,000 square miles) below the 1979 to 2000 average.

Climate models have suggested that the Arctic could lose almost all of its summer ice cover by 2100, but in recent years, ice extent has declined faster than the models predicted.

A few years back, I blogged about a report that the Arctic Ocean may have been ice-free around 6000-7000 years ago, so this may be a natural cycle. Or it may be caused by human-induced global warming. I don’t know. I ended that post with the following:

I’m not a global warming denier, which bothers some of my friends. I do believe that human activities are affecting Earth’s climate. This does point out, however, the importance of geological studies of Quaternary (ice age to present) climate systems. Whatever is happening today, even if caused by humans, can only be fully understood in its geological context.

Grace and Peace

Mapping the harvest

From NASA’s Earth Observatory this week: Poor harvest in Kenya

NASA
Credit: NASA

From NASA’s description:

Ten million people could face hunger in Kenya after a poor harvest, Kenya’s government warned on January 9, 2009. According to the Associated Press, the government declared a state of emergency to free up funds for food aid.

This image, which shows vegetation conditions between January 1 and January 10, 2009, shows part of the reason for the failed crops. Developing drought settled over eastern Kenya, slowing plant growth. Areas in which plants were growing less vigorously than average are brown, while areas in which plants were growing well are green.

Satellite data like this, if properly used, could help relieve the suffering of millions.

Grace and Peace

Climate change survey

From CNN: Surveyed scientists agree global warming is real.

The results of a University of Illinois survey of scientists include the following:

  • 90% of the scientists surveyed agreed that global temperatures have risen compared to levels from before 1800.
  • 82% agreed that human activity been a significant factor in this increase of mean global temperatures.
  • 97% of climatologists surveyed agreed with anthropogenic global warming (AGW).
  • At the other end of the spectrum, only 47% of petroleum geologists agreed with this.

The researchers chose scientists listed in the the American Geological Institute’s Directory of Geoscience Departments, 2007 edition.

Geologists in general have been more skeptical about AGW than have other scientists, though I’ve noticed a considerable shift on this in publications of the Geological Society of America and the American Geological Institute. Two reasons for this skepticism that have been proposed are:

  1. A deep historical perspective. Geologists know that Earth’s climate has fluctuated throughout its history by purely natural means, and that a number of factors have caused this, including changing brightness of the sun, changing oceanic circulation patterns, plate tectonics, and cyclical variations of Earth’s orbit. The Quaternary Period, i.e. the past 1.8 million years, has had an especially variable climate, with long glacial maximum periods, punctuated by interglacial periods, such as the one we live in now.
  2. The close association of geology to the fossil fuel industries. Perhaps there is something psychological here, with a denial that the oil, gas, and coal that we are so closely tied to are the cause of something bad.

I think it is significant that 97% of climatologists surveyed believe global warming is real and that humans have been a significant factor in this. But climatologists will continue to need the input of geologists to gain a fuller understanding of how Earth’s climate works, in both the short term and long term.

Grace and Peace

Global warming and solar cycles

If you are a regular reader of The GeoChristian, you know that I lean towards the validity of anthropogenic global warming (AGW), which is the idea that human activities are causing the Earth to become warmer. Much of the debate–on both sides–is driven by ideology more than science, but I have found the scientific arguments on the AGW side to be stronger.

The AGW proponents say that variations in greenhouse gases, such as carbon dioxide, are the primary drivers of climate change at the present time. They acknowledge that the Earth’s climate naturally varies, and that greenhouse gases are not the only factors in climate change, but warn that the present changes in climate are outside of the natural range.

The Earth is an incredibly complex planet, and it is difficult to integrate all of the factors that go into something as complex as weather and climate. The issues involved include greenhouse gases, variations in the intensity of solar radiation; cosmic rays, ground cover, ocean circulation patterns, orbital variations, and others. Despite decades of intense research, it is still not possible to say with certain how much of the Earth’s natural greenhouse warming comes from the various greenhouse gases present, such as carbon dioxide, water vapor, and methane. (Don’t forget that the greenhouse effect itself is an extremely good thing; Earth would be about 30°C (50°F) colder without it).

The London Times has an article on the influence of solar activity and cosmic rays on climate: An experiment that hints we are wrong on climate change. The article examines recent experimental evidence that indicates that observed fluctuations in climate, both now and in the past, have been the result more of changes in solar output than greenhouse gases.

AGW advocates would say that we cannot wait for a couple more decades of research in order to take action. Overall, I agree, because many of the actions they say we must take are good whether AGW is true or not. Examples include increasing energy efficiency, simplifying our consumptive lifestyles, and developing sustainable, renewable energy alternatives.

Grace and Peace

New York tsunami, 300 BC

From National Geographic: Meteorite Triggered Ancient New York Tsunami?tsunami_hokusai

A meteorite impact off Long Island 2,300 years ago may have set off a huge tsunami that flooded the New York City region, a new study says.It’s not known whether any ancient settlements were in the path of the proposed killer waves, but “any significant tsunami today would be devastating and likely to flood places like lower Manhattan,” Vanderbilt University geologist Steven Goodbred said.

Geology provides many ways to keep us humble.

Painting: The Great Wave off Kanagawa by Hokusai, 1832

Grace and Peace

Catastrophic space storms

Livescience.com: Perfect Space Storm Could be Catastrophic on Earth, Study Concludes

Solar activity has just passed the low point in its 11-year  cycle, and is expected to peak again around 2012. It is believed that about every 100 years or so, there is a particularly intense solar storm, which could disrupt power supplies on Earth on a catastrophic scale, as well as damage satellites.

A new study from the National Academy of Sciences outlines grim possibilities on Earth for a worst-case scenario solar storm.

Damage to power grids and other communications systems could be catastrophic, the scientists conclude, with effects leading to a potential loss of governmental control of the situation.

The prediction is based in part on major solar storm in 1859 caused telegraph wires to short out in the United States and Europe, igniting widespread fires. It was perhaps the worst in the past 200 years, according to the new study, and with the advent of modern power grids and satellites, much more is at risk.

“A contemporary repetition of the [1859] event would cause significantly more extensive (and possibly catastrophic) social and economic disruptions,” the researchers conclude.

Grace and Peace

The Pliocene as a model for the 21st century?

The US Geological Survey has a news release regarding climate during the mid-Pliocene Epoch, between 3.0 and 3.3 million years ago: Getting Warmer? Prehistoric Climate Can Help Forecast Future Changes. Scientists used paleontological data (i.e. fossils) to reconstruct surface water and deep-ocean temperatures, as well as ocean circulation patterns. Here are some of the findings:

  • Global average temperatures in the mid-Pliocene were 2.5°C (4.5°F) greater than today. This is in the range of temperatures predicted by the Intergovernmental Panel on Climate Change (IPCC) for later in the 21st century.
  • CO2 levels were only slightly higher than what is found today. This implies that the atmosphere currently has enough CO2 to cause a couple of degrees of warming. It could be the other way around: the higher CO2 levels could have been caused by the higher temperatures; either way, there is a correlation between high CO2 levels and higher temperatures.
  • Warming was much greater in the North Atlantic and Arctic than in other oceanic areas. While worldwide temperatures in the Pliocene were on the order of 2.5°C warmer than today, temperatures in the North Atlantic were up to 18°C warmer, bringing the average annual temperature in some areas from -2°C to 16°C, which is temperate rather than polar. This is radical–and in this case, natural–climate change. It is also consistent with computer models that predict greater warming in polar regions than in the rest of the world during the 21st century.
  • One of the conclusions was that “the likely cause of mid-Pliocene warmth was a combination of several factors, including increased heat transport from equatorial regions to the poles and increased greenhouse gases.”

Here’s a map showing the sea surface temperature (SST) anomaly for August, which is a comparison of the Pliocene SST with today’s SST. The dark blotch over the North Atlantic is the area that experienced the most extreme warming in the Pliocene compared to today. The yellow areas were about 2°C warmer than today. Note also  the warmer area off the Pacific coast of South America. This indicates an el Niño-like warming of the east Pacific surface waters in the Pliocene.

pliocenesurfacetemperatures

This study shows again the importance of a geological perspective when talking about climate change:

  • Not only is the present a key to the past, the past is a key to the present. By better understanding climate change in the Pliocene, we can get a better idea of the effects of warming in the 21st century. Being that the geometry of ocean basins has not changed appreciably since the Pliocene, the temperature and circulation patterns present in the Pliocene could be a good model for changes that could occur if global temperatures do increase by 2°C in the 21st century.
  • Geology gives us a context for climate change in the present. We cannot hope to distinguish between natural climate fluctuations and human-caused climate change if we don’t have a good grasp of natural climate change that has occurred over the past few millions of years.

Grace and peace