Ice cores reveal frequent natural climate changes
Slices of ice cores drilled from the Earth's depths in Antarctica and Greenland reveal details of our planet's climate history.
Ice cores are cylinders of ice drilled out of an ice sheet or glacier, sometimes to depths of more than two miles, especially in Antarctica.
The oldest continuous ice core records date back some 800,000 years in Antarctica and more than 125,000 years in Greenland. These core samples contain vital information about past temperatures, precipitation patterns and various aspects of the environment throughout the ages, including carbon dioxide levels.
Each ice core sample encloses small bubbles of air that contain precise details of the atmosphere at a given period in history. From these air bubbles, it is possible to directly measure the precise concentrations of gases like carbon dioxide and methane in past millennias.
The ice core samples in both Greenland and Antarctica show us the concentrations of both carbon dioxide and methane have varied greatly at times in the past 400,000 years, based on the chart above (from www.daviesand.com).
From the air bubbles in our oldest Antarctic ice core samples, we easily can see that changes in carbon dioxide (CO2) levels mirrored the prevailing climate of the time. There were low concentrations of the carbon dioxide during the cold periods and much higher levels during the warmer times as in recent years. In fact, the chart does show that we're experiencing the highest concentration of carbon dioxide today than during the last 400,000 years.
The natural climate changes of the past 800,000 years were relatively gradual in most cases, but many abrupt changes were likely seen, particularly during the sudden onset of major ice ages. According to an article in Scientific American published in May 2013, plankton in oceans may absorb more of the carbon dioxide than once previously thought. And, it's also been discovered that types of igneous rock, or volcanic rock, will also absorb carbon dioxide, but over a longer period of time.
Over time, major and minor ice ages have often followed periods of abnormal warming. There is speculation that the plankton and other carbon dioxide absorbing lifeforms or substances go into 'overdrive' to decrease those levels, resulting in the cooler periods. Perhaps our friend, Robert Felix, may be right after all in his prediction of an overdue, imminent major ice age arriving in the near future. Again, only time will tell.
North Idaho weather outlook
It was raining again Thursday morning after 10 days of mostly dry and sunny weather across the region. On Monday, we got a taste of summer with an afternoon high of 87 degrees, June's warmest reading, on Player Drive.
Following the late week showers, better weather with lots of sunshine was expected to return for the annual Ironman event on Sunday. The outlook for July 4th, this upcoming Friday, was calling for afternoon highs locally in the upper 70s or lower 80s with partly cloudy skies. The winds should calm to less than 5 miles per hour after a breezy day by late evening.
Longer-term, both Meteorologist Randy Mann and I still anticipate a warm and dry July through September across the Inland Northwest thanks to a large stationary high pressure ridge that will 'camp out' over our part of the country. We may see local readings soar to near the century mark sometime during the July 12-19 'full moon' cycle and again in early to mid August.
The weather outlook for the North Idaho Fair and Rodeo in late August still looks good, partly cloudy and warm, but not too hot.
Cliff Harris is a climatologist who writes a weekly column for The Press. His opinions are his own. Email sfharris@roadrunner.com
CliffHarris
Weather Gems
Weekly Weather Almanac
• Week's warmest temperature: 87 degrees on June 23
• Week's coldest temperature: 51 degrees on June 25
• Weekly precipitation: 1.23 inches
• Precipitation month to date: 4.57 inches
• Normal precipitation month to date: 1.87 inches
• Precipitation month to date last year: 3.44 inches
• Precipitation year to date: 21.02 inches
• Normal precipitation year to date: 13.89 inches
• Precipitation last year to date: 14.69 inches
• Normal annual precipitation: 26.77 inches
• Total precipitation last year: 25.93 inches
• Precipitation predicted this year: 33.70 inches
• Wettest month on record (since 1895): 9.91 inches in December 1933
• Wettest year on record (since 1895): 43.27 inches, 2012
• Driest month on record (since 1895): 0.00 inches (14 times)
• Driest year on record (since 1895): 15.18 inches, 1929
Readings taken week ending 3 p.m. Sunday, June 29